Test 2 😮💨 Flashcards
(636 cards)
1
Q
What responds almost instantaneously to changes in the body?
A
SNS reflexes (short term)
2
Q
Where are aortic baroreceptors located?
A
on aortic arch
3
Q
What are the aortic baroreceptors a product of?
A
Vagus nerve→longer nervous pathway
4
Q
Where are carotid baroreceptors located?
A
At the bifurcation of the carotid artery on each side (carotid sinus)
5
Q
What is the carotid sinus?
A
Bifurcation of the carotid artery where carotid baroreceptors are located on each side
6
Q
How does the carotid sinus attach to the brainstem?
A
Glossopharyngeal nerve
7
Q
What is responsible for making sure BP and CO remain stable when the body is undergoing change?
A
Aortic and Carotid baroreceptors work hand in hand to stabilize BP and CO
8
Q
What is the main pressor in the CV system?
A
Norepinephrine
9
Q
Where is Norepi released in the CV system?
A
Released around all of the blood vessels and helps regulate SVR
10
Q
What are the 2 ways norepi and epi can be released?
A
Can be released locally by nerves or can be dumped into circulation by adrenal glands
11
Q
How do circulating catecholamines improve CO?
A
↑contractility, improve CO
12
Q
How do circulating catecholamines improve BP?
A
Increase BP by increasing SVR
13
Q
Why is adequate BP crucial?
A
Need to have a good BP to perfuse organs
14
Q
What are the 2 protected vascular/circulatory beds where flow is maintained at all costs?
A
Coronary circulation
Central nervous system (brain& SC)
15
Q
How does the body maintain perfusion to the protected vascular beds when there is a perfusion issue or problems in the system?
A
The body will try to divert blood from areas of un-needed perfusion to areas where perfusion is crucial for survival
16
Q
Which areas of the body can function without perfusion for a while?
A
GI system→has the ability to shunt blood away from system when body is undergoing stress
**still limit to how under perfused it can be
17
Q
What is released by the body in response to changes in osmolarity?
A
Vasopressin→usually not involved in large amounts `
18
Q
Under what circumstance does the body (CNS) release vasopressin?
A
Emergency circumstances when BP is really low→CNS dumps vasopressin into the system to try to increase SVR further than what EPI and NE are doing on their own
19
Q
What controls aldosterone?
A
Renin Angiotensin Aldosterone Axis (RAAS): can be important part of reflex to help increase BP
20
Q
Where are the stretch receptors located in the lower pressure parts of circulation?
A
Right atrium
Large veins leading up to the right atrium
21
Q
Explain the direct neural connection between the low pressure side of the heart and the kidneys:
A
When there is an increase in stretch or pressure, the low pressure areas have reflexes by the ANS
→Increase stretch= increase output by the kidney
22
Q
How does the ANS promote increase UOP when the atria are stretched out more than normal?
A
Reduction in sympathetic tone to the kidneys causes an increase in urine output→over long enough time should reduce blood volume
23
Q
Why can increase blood volume be a bad thing?
A
Could cause too much extra stretch in the heart
The more blood the lower the circulation rate→promotes clotting
24
Q
How does increase blood volume promote lower circulation rate?
A
If CO is 5L/min and blood volume is 8L then blood will probably move slower through the system
Slower blood tends to cause coagulation problems (increase risk for clots with a lot of blood in the veins and its not being turned over quickly)
25
What hormones are used to for the low pressure parts of the heart to communicate with the kidney?
Atrial Natriuretic Peptide (ANP)/ Atrial Natriuretic Factor (ANF)
26
What is the body's built in system to prevent volume retention once it gets to a point where the stretch is not benefitting the heart?
BNP/ANP hormones
27
Where is ANP/ANF produced?
peptides/proteins formed in the atria (predominately right atria)
28
Describe the MOA of ANP:
Atria is stretched out→ ANP is released → gets rid of sodium and water → increases UOP
29
What does "natriuri" mean?
Referring to sodium
30
Is there ANP in the left atrium?
More in the RA than LA but in both to some extent
31
Where is brain natriuretic peptide formed?
Heart ventricles when the ventricles are stretched out
32
How does BNP cause diuresis?
Same way as ANP→ causes sodium and water excretion so increase UOP by the kidney
33
What lab is used to figure out how heart failure treatment is progressing?
BNP
BNP ↓ if doing things helping the system
BNP ↑ means ventricles are getting more stretched
34
How long are the effects of BNP/ANP?
Do not have long term effects
Only last a week or so then they stop being effective natriuretic agents
35
Does the body stop producing ANP/BNP after a certain amount of time?
Even if levels are elevated in the blood, ANP/BNP arent really working after a few weeks
Reason why we give diuretics to achieve same thing ANP/BNP were doing before they stopped having effect
36
What is the most active response/reflex from the SNS?
CNS ischemic response
37
When does the CNS ischemic response occur?
Happens when someone has had low brain/brainstem perfusion for a few minutes
38
What is involved in the CNS ischemic response?
EX: BP is 20 post MI
Will have every CV system reflex change being made to try to increase/stabilize BP→SNS maxes out everything useful to try to increase BP/volume
39
What happens if one of the CNS reflexes to body changes is taken away?
The overall ability of the system to compensate will not be normal if one of the reflexes is taken away
40
What would happen if the body's ability to produce vasopressin is taken away? What if patient is on beta blocker?
Wont be able to help increase HR/BP
Wont be able to get HR up as much
41
___________ takes all CV system reflexes offline to some extent
Anesthesia (the deeper the anesthetic, the less compensatory mechanisms we have to work with)
42
What is normal ECF volume in healthy person?
14L
43
What portion of ECF is plasma?
1/4-1/5 (in CV system)
44
What portion of ECF is interstitium?
3/4- 4/5 (in between cells)
45
If starting blood volume is 5L what portion is plasma?
3L plasma
46
What is normal plasma oncotic pressure?
28mmHg
47
What are the plasma proteins that make up plasma oncotic pressure?
Fibrinogen, Albumin, Globulins
48
What happen to plasma fluid volume if 1L of blood is rapidly removed from the body?
600cc plasma lost
400cc RBC lost
There would be a shift of fluid from the ISF into the CV system→ fluid moves around and makes up for fluid lost with hemorrhage
49
What happens as a result of losing plasma proteins with hemorrhage?
Plasma oncotic pressure decreases→ might make it more difficult to keep volume in CV system
50
What is one of the major things that keeps fluid in the CV system?
Plasma oncotic pressure
51
What factor from hemorrhage works against the body's ability to redistribute fluid?
Loss of colloids from blood loss would work against fluid redistribution
52
What is the best way to treat hemorrhage?
Replace what is missing:
Plasma
NS (w caution)
Dextran/ Hetastarch
53
Why does NS sometimes cause issues when using for volume resuscitation?
No colloids so only 1/4-1/5 will stay in CV and the other 3/4-4/5 will go to ISF
Most ISF places in the body have space to accommodate extra fluid→ but not the lungs
There is ISF in the lungs but its a very thin to allow for gas exchange→ lots of NS boluses could cause pulmonary edema
54
What is dextran/hetastarch?
Synthetic colloid made of large sugar molecules (breaks down over time)
Big enough to stay in CV system and provide some degree of oncotic pressure
55
What is the explanation for why a bolus of crystalloid initially improves CO/BP then BP drops again?
Over time NS/LR bolus if moving from vascular to ISF (20-25% stays in CV)
Stretch relaxation of the veins
56
What is stretch relaxation?
Property of large veins→ response to smooth muscle that lines the walls of large veins
When large veins become tight the smooth muscle relaxes in response causing reduced venous pressure over a period of minutes
57
What happens when the SNS kicks in when someone is hemorrhaging?
Reverse stretch relaxation
58
What is reverse stretch relaxation?
Autonomic ANS overriding what the smooth muscle in the veins wants to do on their own (relax)
Mass SNS activity gets rid of stretch relaxation and does reverse stretch to tighten the veins
59
What happens tissues in the body that arent adequately perfused?
Cell necrosis/death (unplanned cell death)
60
What is shock?
Tissue dysfunction to all parts of the body that need nutrients that arent being adequately delivered
61
What happens when under-perfused tissues die?
Everything inside the cell is released into the environment and can cause conditions to worsen
62
What is something inside dead cells that is harmful when released?
Potassium--causes hyperkalemia
SVR probably low in someone with shock, probably acidotic now hyperkalemic→will be difficult to fix situation
63
What is one tissue that is super sensitive to shock?
Liver→if the liver has been under-perfused for some time usually starts to go bad the earliest when its lacking perfusion
64
How can cardiac output be measured?q
PA cath with thermodilution
Flowtrac
Estimate CO by looking at blood gas numbers
65
Where do samples for blood gas calculations for CO estimate come from?
Usually PA catheter but can come from clean vein
66
How much O2 is in the arteries normally?
200mL/L or 20mL/dL
67
How much O2 is in the tissues? Why is this number lower than the artieries?
150mL/L or 15mL/dL
In tissues some of the O2 is unloaded for the tissue to consume→ tissue then produces CO2 →CO2 unloads into vein to be returned to the lungs and blown off CO2 and re-oxygenate the blood
68
What is Ficks equation?
69
What do we have to know to solve for CO using Ficks equation?
Patients O2 demand
How much O2 they are consuming
How much O2 is in the blood
70
What is an oxygen content number?
Taking into account all O2 that is dissolved as well as bound to Hgb
71
How much O2 is dropped off by each dL of blood moving through systemic circulation if Arterial O2= 20mLO2/ dL of blood and venous O2= 15mLO2/ dL?
5mLO2/dL of blood
72
What is a health persons O2 consumption per minute?
250 mLO2/ min
73
How much blood do have to have going around in a circle each minute to deliver a total of 250mL over the course of that minute when each dL of blood is unloading 5mL of O2?
(250mL/min)/ 5mL= 50dL of blood/ min= 5L/min = CO
74
What is the hearts ability to increase its output beyond its resting level?
Cardiac reserve
75
What is cardiac reserve if able to increase CO to 25L/min?
400%
76
What would be cardiac reserve if CO can increase up to 30L/min?
500%
77
Healthy adults should have an upper limit of CO of 25mL/min. What is their cardiac reserve?
400%
78
What is an expected cardiac reserve for extreme athletes?
600%--baseline CO may be elevated
79
Cardiac reserve _________ with age.
Decreases
80
How does severe valve disease effect cardiac reserve?
Reduces amount of blood the heart can pump→ may not have any cardiac reserve
81
What is an expected cardiac reserve for moderate coronary artery disease?
Heart cant perfuse itself easily that decreases cardiac reserve to around 200%
82
Why does cardiac reserve decrease with age?
Older people are usually more sedentary and cardiac reserve is usually reduced as a function of age and further reduced from bad health
83
What percent of the population has a congenital bicuspid aortic valve?
1-2%→ causes opening to not be as large
84
What does negative pressure in the thorax apply to?
Everything in the thorax (heart tissue, lung tissue, etc)
Thorax is a continuous sealed unit
85
How many sections does the diaphragm have?
2 leaflets (right and left)
86
What happens with inspiration if right half of diaphragm is paralyzed and left half is functioning normally?
Left lung will sink
Right lung will raise up
87
Which lung is biggest?
Right lung is bigger than left lung
* Left lung has carve out for heart
88
Where in the thorax is the top of the lungs in a healthy person?
Can go up past 1st rib or clavicle
89
Where is the apex of the lung?
Top of lung
90
What are the coverings on the inside and outside of the lungs called?
Pleura
91
What are the names of the different pleura and where are they located?
Visceral pleura→ lining that coats the outside of the lungs
Parietal Pleura→ piece of connective tissues that is stuck to inside of the thorax
92
What does visceral mean?
Organ
93
Is there space between the 2 pleura layers?
Potential space
The 2 tissues sit right next to each other with a coating of mucus to allow sliding around in the chest
94
Where is the pain coming from if you have an infection in the outer tissues of the lungs?
Pain from friction and inflammation in the lung tissue
95
What happens to the lungs and the diaphragm on inspiration?
Diaphragm contracts down further into the abdomen allowing the lungs to expand (diaphragm also pulls lungs down with it)
96
What happens when the lungs are stretched out from diaphragm contraction during inspiration?
It creates negative pressure in the lungs to suck air in from environment
97
Where is the diaphragm anchored?
Lumbar spine
98
Opening in the diaphragm for the vena cava to return blood to the heart:
Caval Aperture
99
Opening in diaphragm for esophagus to get food from mouth to stomach:
Esophageal Aperture
100
Opening in diaphragm for aorta to bring arterial blood into abdomen:
Aortic Aperture
101
What is the primary muscle tissue in the diaphragm?
Skeletal muscle tissue
102
What is the large white section of the diaphragm?
Central tendon→ big section of connective tissue
103
What is the purpose of a tendon in the body?
Fasten skeletal muscle to bone
104
What is an exception in the body to the usual definition of tendon?
Central tendon
105
What is the purpose of the central tendon?
Provides a platform in the middle of the diaphragm where the heart sits
106
What is the definition of ligament?
Bone to bone connection
107
Which nerve innervated the diaphragm?
Phrenic nerve→ runs on either side of the neck past the heart and innervates each side of the diaphragm
One phrenic nerve for each leaflet
108
Why is the phrenic nerve in a difficult spot?
Issues with regional anesthesia and phrenic nerve in area of big nerve plexus (cervical/brachial) that are the target of blocks
If regional anesthetic leaks out into where phrenic nerve is, it can cause the phrenic nerve to not work normally
109
What happens if one phrenic nerve isnt working?
In a healthy person this is ok→ only need one phrenic nerve to stay alive
If someones lungs are messed up and one phrenic nerve is blocked then it might be a bad outcome
110
What is the primary muscle of ventilation?
Diaphragm
111
Which muscles can help with breathing if we need to increase rate of ventilation?
- Scalene muscle
- Intercostal muscles (between ribs)
- Abdominal muscles
112
Where do accessory muscles at the top of the thorax anchor?
Anchor into base of skull or top of neck→ provides a platform to pull rib cage up or prevent thorax from being pulled down as the diaphragm contracts
113
What are the other muscles aside from the diaphragm called when they are involved with ventilation?
Accessory muscles
114
What is the top of the upper airway?
Larynx
115
What part of the airway is after the larynx?
From the larynx air can be drawn into the lungs from the trachea
116
What part of the airway comes after the trachea?
Splits to divide trachea into 2 main stem bronchi
117
How many generations of airways are in the respiratory system?
24 generations
118
Where does the airway start?
Trachea (generation 0)
119
What are the first generation airways?
2 mainstem bronchi
120
Which parts of the airway are for air conduction? What generation?
Trachea (0)
Bronchi (1,2,3)
Bronchioles (4,5)
Terminal bronchioles (6,7,8,9,10,11,12,13,14,15,16)
121
What is the split point after each mainstem bronchi?
Bronchioles→ smaller, usually have a number of bronchioles
122
What are the bronchioles made up of?
Tougher cartilage supporting the bronchioles to keep the larger airways open and patent
123
What is the function of conducting zones in the lungs?
Conduit to get fresh air in and allow old air out
124
What is the purpose of the transitional zone?
Between conducting and respiratory zones
Small amount of gas exchange happening (a few alveoli)
125
What part of the airway is in the transitional zone?
Respiratory bronchioles
126
What generation are the respiratory bronchioles?
17,18,19
127
What part of the airway is in the respiratory zone? Which generation?
Alveolar ducts (20,21,22)
Alveolar sacs (23)
128
What happens in the respiratory zone?
Gas exchange occurs
129
What part of the airway divides conducting zone and respiratory zone?
Respiratory bronchioles
130
What are the alveoli made up of?
Soft tissue (No cartilage)
131
What is the typical diameter of the trachea in an adult?
2cm (1.8cm)
132
What is the normal length of an adult trachea?
12cm
133
What happens to diameter and cross sectional area as we move down the airway?
Branching of the airway causes diameters to get smaller→ very narrow diameter in the alveolar sacs
Total cross sectional area increases with more paths as its branching
134
Normal breathing:
Eupnea
135
Respiratory distress:
Dyspnea
136
No breathing:
Apneic
137
Funny sounds coming from the lungs:
Stridor
138
What disease processes is stridor associated with?
Asthma or lung tumor
wheezing, sounds like a recorder if its a lung tumor
139
Slow breathing:
Bradypnea
140
Rapid breathing:
Tachypneic
141
Change in breathing with change in body position:
Orthopnea
Breathing normally when sitting up but struggling to breath when laying down
142
Fast, over breathing (breathing more deeply)
Hyperpnea
143
Ventilation that occurs in excess of metabolic demands:
Hyperventilation
144
Insufficient ventilation for metabolic demands:
Hypoventilation
145
Big lungs that are larger than they should be
Hyperinflation
146
What is an example of a disease process with hyperinflation?
COPD→ lose of connective tissue in the lungs makes it easier for lungs to expand causing large lungs in the chest
147
What is the criteria for cyanosis?
When there is lots of deoxyhemoglobin
5g or greater of deoxyhemoglobin in each dL of blood
148
What is the threshold for cyanosis?
Whatever normal venous O2 content looks like
149
Lack of O2 at the tissue level:
Hypoxia (localized)
150
Lower than normal O2 in entire system:
Hypoxemia (arterial blood-global O2 deficit)
151
Excess CO2 in the blood:
Hypercapnia
152
What can cause hypercapnia?
Hypoventilation (COPD)
153
Deficiency of CO2 in the blood:
Hypocapnia/ Hypocarbia
154
O2 levels above normal:
Hyperoxia (tissues/organs)
155
Collapse of functional lung units (portion or region of lung):
Atelectasis
156
1mmHg = ______ cmH2O
1.36
157
What are cmH20 used instead of mmHg for thoracic pressures?
Thoracic pressures are really low→cmH2O gives a greater resolution at low pressures
water is less dense than Hg→ allows us to see differences better by stretching out the scale
158
What does "P" variable mean?
Pressure
159
What is total gas "content" referring to?
Combination of O2 attached to Hgb as well as O2 dissolved in solution (total gas in a sample)
160
What is the variable for arterial?
"a"
161
What does PaO2 mean?
pressure of dissolved O2 in arterial sample
162
What is a normal PaO2?
around 100
163
What is the variable for alveolar?
"A"
164
What is PAO2 measuring?
Pressure of dissolves O2 in alveolar gas
165
What is the variable for venous?
"v"
166
What is the variable for ventilation?
"V"
167
Is it easier to measure inspired or expired air?
Expired
168
What is VE measuring and how is it measured?
Expired ventilation: measured by looking at expired CO2
169
What is VI measuring?
Inspired gas analysis: looking at gas going into patient (much harder to measure)
170
What is VO2?
Volume of O2 absorbed each minute
250mL/min normally
171
What does a variable with a dot over the top of it mean?
dot= per minute
172
What is a volume is reference to the lungs?
Amount of air in the lungs
173
What is a capacity?
Individual volumes are combined into capacities
174
What is lung compliance?
Stretchiness
Low lung compliance is harder to ventilate
175
What would ventilation be like if lungs were high compliance?
easier to ventilate
176
What is the inverse of compliance?
Elastance: measure of resistance
High compliance= low elastance
Low compliance= high elastance
177
What is a normal tidal volume (VT)?
0.5 L in and 0.5L out on each breath
178
What is total capacity of the lung (TLC)?
Max amount of air we can get into both lungs
Normal healthy lungs= 6L (3L for each lung)
179
What volumes are added to give total lung capacity?
Tidal volume + Inspired reserve volume + Expiratory reserve volume + Residual volume= Total capacity
180
What is functional residual capacity measuring (FRC)? What is normal?
Amount of air in the lungs after a normal breath is expired
* Normal is to have 3L in the lungs in between each breath
181
What is the reason for the ability to hold our breath?
FRC→ Provides a reservoir of air in the lungs that O2 can be absorbed from (not as efficiently as taking in fresh air)
182
What is the reason for FRC?
* Helps stabilize blood gases→ if there wasnt already in the lung there would be short spike in O2 in blood for a short period of time then would come back down
* Helps prop the airways open→ Makes it easier to get fresh air in
183
Why do respiratory zones rely on FRC to get fresh air in?
Respiratory zones (alveoli level) dont have cartilage supporting them: may be helpful to holf airways open to allow fresh air in
184
Lower lung volumes can cause ___________.
Atelectasis: The lower the lung volume the less air holding airway open
185
What is ERV measuring and what is normal level?
Expiratory reserve volume: Volume of air the we could push out of the lungs after normal expiration (effort to push out)
1.5L in upright healthy person
186
What is RV?
Residual volume: air that CANT be pushed out of the lungs no matter how hard we try
normal amount is 1.5L
187
What is normal IRV?
Inspiratory reserve volume: amount of air we can inspire in addition to normal VT (starts at the end of normal inspiration)
2.5L
188
What is the vital capacity of the lungs?
Working volume of the lungs → Air we can move in and out of the lung in one maximal effort
* total amount of air we could expire if we inspire to total lung capacity (6L) then expire as much air as we can
189
What volumes are added to get vital capacity (VC)?
IRV (2.5L) + VT (0.5L) + ERV (1.5L) = VC (4.5L)
190
What is inspiratory capacity?
The amount of air we can take in starting from FRC and going up to TLC
IRV (2.5L) + VT (0.5L) = IC (3.0L)
191
What lung volume is effected by position change?
Unhealthy lungs→ Lay back/body position change → causes part of ERV to be squeezed out from gravity
192
What is a normal respiratory rate?
12 bpm
193
What is a normal respiratory cycle length?
1 breath every 5 seconds → normal respiratory cycle occurs over 4 seconds
* 2 seconds for inhalation
* 2 seconds for exhalation
* 1 second in between
194
What is the pleural pressure in the lungs between breaths?
-5 cmH2O
195
What is the thoracic pressure at the end of inspiration?
-7.5 cmH2O
196
What causes thoracic pressure to drop with inspiration?
Diaphragm pulling down on closed system to create a vacuum in the chest→ pulls in 500cc VT
197
How long does it take to inspire full 500cc tidal volume?
2 seconds
198
When does inspiration flow rate peak? What rate is the air moving at?
Fastest air moving in at 1second into inspiration
*Air moving at 0.5L/sec
199
How is inspired vs expired air depicted in a graph?
Inspired air is negative
Expired air is positive
200
How is air flow measured?
Volume (L) / Time (sec)
201
What happens to thoracic pressure during inspiration?
Thoracic pressure is decreasing linearly over the course of 2 second during inspiration
* pressure decrease causes air to be pulled into the chest*
202
When is gas pressure in the alveoli the lowest? What is the pressure?
Lowest gas pressure in the alveoli 1 second into inspiration → -1 cmH2O
203
What is alveolar pressure when there is no air moving in or out of the lungs (between breaths)?
0 cmH2O→ should be the same as the pressure in the environment
204
Peak inspiration occurs when alveolar pressure is ____.
Lowest (-1cmH2O in normal lung)
205
What happens to alveolar pressure when the diaphragm contracts (inspiration)?
The pressure around the alveoli is more negative→ negative pressure pulls on walls of alveoli and the airways → walls are being opened→ pressure inside alveolus decreases
206
What happens if the pressure in the alveolus is less than the pressure in the environment?
Air gets sucked into the lugs
When pressure is SUPER negative air comes in very quickly and stretches out alveoli tissue
207
What is normal environmental pressure?
0cmH2O
208
How is air in the alveoli from inspiration expired?
Diaphragm relaxes, use elastic recoil in the alveoli tissue to push the air out
Rely on passive tissue recoil to push air out of the lungs
209
What happens to alveolar pressure when the inspiration is over?
The alveolar pressure is 0cmH2O when inspiration ends
Pressures have equilibrated from outside and inside environment
210
What is the maximum change in pressure (delta P) during normal breathing?
-1cmH2O
211
Rate at which air is moving is dependent on ______ _______.
Delta P (change in pressure)
212
Which direction is air flowing if inside alveoli is negative?
Sucks air in
213
Which direction is air flowing if inside alveoli is positive?
Pushes air out→ Relax diaphragm with expiration
214
When does expired airflow peak?
Halfway through expiration when alveolar pressure is +1cmH2O
215
What are the fluctuations of pleural pressure with normal breathing?
-5cmH2O → -7.5cmH2O → -5cmH2O
216
Why is it a concern if there are abnormal amounts of recoil in the lungs? Examples?
* Could cause problems getting air in or problems getting air out
*COPD- cant get air out
* Fibrosis- cant get air in
217
___________ takes longer in people that have messed up lungs.
Expiration
218
What is expiration dependent on?
Amount of recoil
219
What are variables for intrapleural pressure?
P(IP) or P(Pl)
220
What is the variable for alveolar pressure?
P(A)
221
What is transpulmonary pressure/ transmural pressure ?
P(TP)
Comparing pressures between 2 lungs compartments→ looking at pleural pressure and alveolar pressure
222
What is the transpulmonary pressure when the lung is in between breaths?
5 (difference between 0 and -5)
223
What is transpulmonary pressure responsible for?
Pressure used to fill the lungs up with air (always putting air into the lungs)
224
Which direction would air be flowing if transpulmonary pressure increases in a healthy system?
Should have air going into the lungs
225
Which direction would air flow if transpulmonary pressure decreases in a healthy system?
Air going out of the lungs
226
Transpulmonary pressure is highly dependent on __________ _________.
Pleural pressure
227
What is the functional gas exchange unit in the lung?
Alveoli
228
How does the alveoli function for efficient gas exchange?
Each alveolus is surrounded by lots of capillaries for gas exchange
229
What happens in regard to blood flow the further down in the lung?
Increased blood flow and less pulmonary vascular resistance
230
Blood flow through the lungs is dependent on _________?
Gravity
231
How does gravity affect lung perfusion?
Gravity determines which part of the lungs gets the best perfusion
232
What is the best position if one lung is bad?
Put the better lung down because it has better gas exchange and blood flow
Wouldn't want more blood running through the bad lung (would mess with gas exchange)
233
How many perfusion zones are there in the lungs?
4
234
What is zone 2 in the lungs?
Intermittent flow depending on BP (sometimes on, sometimes off)
*BP high= more blood flow
*BP low= less blood flow
235
What is the formula for zone 2 blood flow?
Pa > PA > Pv
236
What type of blood flow is happening in zone 3 and where is this in the lungs?
Lower in the lungs (bottom of the lung in upright person)
Continuous blood flow (always on)
Blood is heavy so intravascular pressures are higher in areas that are lower
237
What are the vessels like in zone 3?
Higher pressure d/t gravity = wider vessels
Wider vessels → Less resistance to perfusion → More blood flow
238
What is the formula for zone 3 perfusion?
Pa > Pv > PA all the time
239
When is zone 1 perfusion present?
In unhealthy lungs (not in healthy lungs)
240
What type of perfusion is zone 1?
Always off blood flow
No parts of the lung are completely turned off to blood flow in a healthy person
241
Which place has the highest risk for zone 1 to occur? Why?
In upright position: highest risk for zone 1 would be the apical/superior parts of the lung (at the top)
Vascular pressures are lower so its hard to perfuse the apical/superior parts of the lung
242
What is the formula for zone 1?
PA > Pa > Pv = no blood flow because the capillaries and large blood vessel will be compressed by the high alveolar pressure
243
What is the main thing that can cause zone 1 lack of blood flow?
Positive pressure ventilation
244
How would PPV changes affect blood flow compared to normal?
During normal breathing alveolar pressure only fluctuates between 1 and -1
PPV= lowest PEEP 5 which is 5x higher than what system is use to→ pressure used to push air into the lungs can compress BVs that are highly compliant (messes with blood flow distribution pattern)
245
What is the average blood flow through the lungs? Where is most of the blood flow in the lungs happening?
5L/min
Most blood flow is happening at the bottom parts of the lung and much less blood flow is happening at the top of the lung
246
What is zone 4 blood flow?
Section when blood flow tapers off in the upright person→ lungs are suspended in the chest but the base of the lung is supported by the diaphragm
Some of the blood vessels get compressed at the base of the lung by resting on diaphragm causing decrease blood flow
247
Is zone 4 still continuous blood flow?
Yes, Still continuous blood flow just less bloos flow at the base of the lungs d/t gravity compressing the blood vessels
248
Areas in the lung with the highest perfusion we would expect to see ___________ blood flow
Highest
249
Hoe does gravity affect perfusion?
*Gravity makes the blood weight more --more weight= more distended blood vessels and faster flow
250
What does the term "dependent" lung refer to?
The part of the lung that is closest to the ground and gets the most blood flow
251
Which perfusion zones does a healthy person have?
Only Zone 2 and 3
252
What type of blood flow is in a healthy person?
Pulsatile blood flow (zone 2) at the top of the lungs and continuous blood flow (zone 3) at the bottom of the lung
253
What is alveolar pressure, pleural pressure, and elastic recoil pressure (transpulmonary pressure) at the start of a respiratory cycle?
No air coming in yet
Alveolar pressure: 0
Pleural pressure: -5 cmH2O
Elastic recoil pressure: +5 cmH2O
254
What is alveolar pressure comparable to?
The pressure outside the body
255
What is the pressure in the atmosphere at sea level?
0 or 760mmHg/torr
256
What is the purpose of pleural pressure of -5 cmH2O between breaths?
Holding alveolus open→ Inward recoil of the alveoli is prevented by -5 cmH2O
257
Why do alveolar walls want to recoil?
Alveoli are made of elastic tissue→ elastic tissue wants to recoil into a smaller size container
258
By preventing recoil of the alveolus, pleural pressure is keeping _____ in the lungs
Functional Residual Capacity (FRC)
259
What happens to alveoli and recoil pressure in the lungs during initial inspiration?
Pleural pressure decreases when diaphragm contracts--before air comes in recoil pressure is the same
Inward recoil pressure is outweighed by the pleural pressure force tying to expand the lung→ Alveolar pressure drops to -1 from the higher pleural force stretching the alveoli open
260
What happens when the alveoli pressure is -1 compared to the atmospheric pressure of 0?
Creates a delta P to suck air into the lungs
261
What physically happens to the alveolus as air comes into the lungs with inspiration?
Increases the size of the alveolus by stretching the walls
262
How does the body prevent the overstretching of alveoli?
At some point the alveoli pressure has to get back to 0
When pleural pressure is -6 at the end of inspiration the only way to get alveolar pressure back to 0 is to have recoil pressure of +6
263
What are the mechanics of expiration and recoil pressure?
Passive recoil force empties the lung (passively)
264
What happens during expiration with pleural pressure, recoil pressure, and alveolar pressure?
Diaphragm relaxes and pleural pressure increases (from -6 to -5)
Recoil pressure is still +6 but there is less pull on the alveolus→recoil force is greater than pleural pressure= alveolar pressure of +1
+1 is alveolus compared to atmosphere pressure gives delta p to empty the lung
265
What happens to alveoli and recoil pressure as the alveoli empty with expiration?
Recoil pressure decreases
Alveoli decrease in size
266
What are the pressures at the end of expiration?
Alveoli pressure: 0
Pleural pressure: -5 cmH2O
Transpulmonary pressure (recoil): +5 cmH2O
267
What is another name for recoil pressure?
Transpulmonary pressure
268
What is the equation if find alveolar pressure?
Alveolar pressure= Pleural pressure + Transpulmonary pressure (recoil)
P(A) = P(IP) + P (ER) OR
P(A) = P(IP) + P(TP)
269
What does the variable P(ER) stand for?
Elastic recoil pressure
270
What increases recoil pressure int he alveoli?
Alveoli dont want air in them→ More volume in the alveoli stretches the walls and provides more recoil
The more the lung is stretched= the more recoil
271
What is the difference between P(ER) and P(TP)?
They are the same thing
Transpulmomary pressure= elastic recoil pressure
272
What is transpulmonary pressure?
The force that gets air into the lungs regardless of how the lung is being ventilated
273
What happens to lung volume when transpulmonary pressure goes up?
Lung volumes go up--more air get pushed into the lung
274
What happens to lung volumes when transpulmonary pressure goes down?
Lung volumes go down
275
Changes in lung volumes is usually a function of changes in ____________ ____________.
Transpulmonary pressure
276
What can increase transpulmonary pressure?
PPV and normal breathing
277
Is pulmonary vascular resistance a set number?
No, PVR is not static→ it changes based on conditions
278
What is the biggest passive influence on PVR?
Gravity: decreases PVR
Dependent regions of the lung have lower vascular resistance than less dependent regions of the lung
279
What are other influences that PASSIVELY increase PVR?
* Increase/decrease lung volumes
* High interstitial pressure
* Increased blood viscosity
* Positive pressure ventilation
280
What happens if lung volumes are decreased below FRC?
PVR increases
281
How does increase right heart cardiac output decrease PVR?
Increases pulmonary artery pressure → more distended vessel from higher pressure→ PVR decreases
282
What would you expect to happen to PVR with increase PAP, increase LA pressure, Increase pulmonary blood flow, and increased CO?
PVR decreases through recruitment and distension
The more blood our heart pumps the lower the PVR
283
How does increase blood viscosity increase PVR?
Thicker blood= more difficult to get through circuit= increase PVR
284
How does positive pressure ventilation increase PVR?
Compresses everything in the chest and increases PVR
285
What are some active influences that increase PVR?
* Norepi/Epi
* Alpha adrenergic agonists
* Sympathetic simulation of the lungs
* PGF(2a) & PGE2
* Thromboxane
* Endothelin
* ANG II
* Histamine
* Changes in alveolar gas (hypoxia/hypercapnia)
* Low pH of mixed venous blood
286
How do alpha agonists increase PVR?
Constriction of arterioles
287
How does SNS stimulation of the lungs increase PVR?
Constricts BVs and increase PVR
Pushes blood out of the lungs→ lungs are a small reservoir for blood (catecholamines squeeze on the vessles and push the blood out of the lungs)
288
How do prostaglandins (PGFa2 and PGE2) increase PVR?
These PGs constrict BV and increase PVR
289
Why does histamine cause increase in PVR?
Venoconstrictor in the lungs (different than systemic)
290
What are active influences that decrease PVR?
* Increase in Parasympathetic tone (more blood in lungs)
* Decreased SNS tone
* Acetylcholine
* Beta agonists
* PGE1
* PGI2 (prostacyclin)
* NO
* Bradykinin
291
What is the name for PGI2?
Prostacyclin
292
How does increases parasympathetic tone decrease PVR?
More blood in the lungs
293
What inhalable antihypertensive agent was used for pulmonary HTN?
PGI2 (prostacyclin)
294
What is the lowest possible lung volume?
residual volume (RV): 1.5L
295
What is the highest possible lung volume?
total lung capacity (TLC): 6L
296
What lung volume is in between TLC and RV on the PRV/lung volume graph? Is it directly between the 2?
function residual capacity (FRC)→ skewed to the left because there is a large IRV
IRV > ERV so FRC isnt right in the middle of the graph
297
Where is the lowest point of pulmonary vascular resistance?
Normal FRC
Makes sense because this is where we spend most of our lives in FRC → fitting that it would be easier for the heart to pump
298
What happens to PVR if lung volumes increase or decrease from FRC?
PVR increases
299
What is pulmonary vascular resistance made up of?
Extraalveolar blood vessels
Alveolar blood vessels
300
What are characteristics of the extraaleveolar blood vessels?
Big/fat pulmonary blood vessels
301
What are the extraalveolar blood vessels primarily affected by?
Pleural pressure
302
What happens to extraalveolar blood vessels when the pleural pressure is more negative?
The large BVs get pulled further apart by negative pleural pressure in the lungs
The more negative the pleural pressure= the wider the BV
303
What happens to PVR as a result of wider extraalveolar BVs?
Lowers PVR when pleural pressure is low by increasing the diameter of the vessels
304
What happens to PVR when pleural pressure is high (more positive)?
walls of the blood vessels are more narrow= increase PVR
305
When is extraalveolar vascular resistance high?
At low lung volumes → function of how much the blood vessel is being pulled apart when pleural pressure is very high
306
When is extraalveolar vascular resistance low?
At high lung volumes → Function of how much the blood vessels are being pulled apart when pleural pressure is really low
307
At what point are lung volumes balances out?
FRC
308
How do you get to lower lung volumes than FRC and what does this do to pleural pressure?
* Would have to give effort to push air out of lungs to get below FRC
* This force makes the pleural pressure much more positive to get lower lung volumes
309
What happens to extraalveolar pressure as a result of low lung volumes?
* Increased pleural pressure to get lung volumes below FRC
* Positive pleural pressure pushes on the walls of extraalveolar vessels→ increases PVR →increases extraalveolar vascular resistance
310
How do alveolar BVs compared to Extraalveolar BVs?
Alveolar Bvs are smaller→ microscopic level
BVs that are attaches to alveoli
311
What is another name for alveolar blood vessels?
Pulmonary capillaries→ embedded in the wall of the alveoli
312
If you were to look at alveoli in cross section, how would pulmonary capillaries look??
Multiple pulmonary capillaries that line the wall of each alveolus
313
What happens in the alveolar blood vessels when more air is put into the alveoli?
Stretches out the pulmonary capillary around the alveolus
Makes capillary more narrow and longer → increases PVR
314
Where else in the body do blood vessels get longer?
Nowhere else, this is unique to the alveolar blood vessels in the lungs
315
How do high lung volumes affect alveolar vascular resistance?
Stretches out alveolar BV creating a more narrow and longer capillary= increased alveolar vascular resistance
316
What happens to alveolar capillary at low lung volumes?
Not as much air in alveoli→ capillary gets winder and shorter → alveolar vascular resistance decreases
317
How is total pulmonary vascular resistance calculated?
TPR= alveolar vascular resistance + extraalveolar vascular resistance
318
What are alveolar and extraalevolar vascular resistance at FRC?
Alveolar and extraalveolar resistance are both low at FRC
*reason why PVR is lowest at this lung volumes*
319
What happens to vascular resistance (alveoli, extraalveolar, and total) with PPV?
AIr isnt normally pushed into the lungs
lung volumes are increasing, but pleural pressure isnt decreasing
alveolar vascular resistance would increase, extraalveolar vascular resistance would increase → total PVR would increase
320
What affects the diameter of the pulmonary capillary?
Alveolar volume
low lung volume: shorter/wider capillary
high lung volume: longer/narrow capillary
321
What happens to extraalveolar blood vessels at low lung volumes?
Pressure inside the chest is more positive than normal →compresses larger BVs and increases extralaveolar vascular resistance
322
What happens to extraalveolar blood vessels at high lung volumes?
Pressure inside the chest is more negative→ stretches out the large BVs and decreases extraalveolar vascular resistance
323
What are A and C showing?
A= inside healthy alveolus
C= Pulmonary capillaries→ in the walls of the alveoli next to where the air is (as close to the air as possible)
Healthy lung should be dry
324
Is water a barrier for gas exchange?
Shouldnt be because the lungs should be dry→ if there is too much water in the lungs (extra fluid) gets in the way fo gas exchange
325
Why does increase CO lower PVR but it doesnt happen with systemic circulation?
Systemic system doesnt have as much give compared to pulmonary circuit
Pulmonary circuit is very compliant→ diameter can stretch when more blood is pumped through
326
What does distension of cardio vascular system do to PVR?
More blood being pumped through pulmonary blood vessels= compliant vessels get wider and decreases PVR
327
Distension can occur in response to ______ and _______.
Air (in the lungs)
Blood ( in CV system)
328
What happens as a result of distension of blood vessels?
*Vessels get wider
* Recruitment: More pathways for blood to go through when more blood is added to the system
329
What happens with recruitment?
Additional pathways give a more parallel system and lowers PVR
More places for the blood to go= easier for the blood to get through the circuit
330
What allows for distension and recruitment of pulmonary vessels?
Increased cardiac output
331
Do healthy lungs use every alveoli?
No, Healthy lungs have alveolar units here and there that arent always being used for ventilation and perfusion
332
Is it a good thing to not use all the alveoli available?
Yes, helps to protect those alveoli from harsh exposure
333
What is this showing in regards to increase pulmonary vessel diameter?
Distension from increase CO leading to increase bloo flow
334
What is this indicating by showing more paths that blood is taking in the pulmonary circulation?
Recruitment: Results from increase CO causing increase blood flow
335
What happens to PVR if right heart output is reduced?
PVR increases
vicious cycle with R heart failure: low CO leads to higher PVR, higher PVR leads to even lower R CO
336
Pressure driving gas movement is related to ___________ pressure
Atmospheric
337
What is the atmospheric pressure at sea level?
1 atm= 760 torr= 760 mmHg
338
What is atmospheric pressure the product of?
Gravity and everything above us in the atmosphere
339
_______ helps to retain the gas in the atmosphere
gravity
340
Dry atmospheric gas discounts _______.
Humidity
341
_________ altitude= lower atmospheric pressure
High
342
Low altitude= ________ atmospheric pressure
Higher
343
Does O2 concentration change at higher altitude?
Same amount of O2 concentration just less amount of atmosphere
EX: Airplane still 21% O2 but atmospheric pressure is alot lower
344
What is needed to get gas into the body?
* Gas
* Pressure
345
What is atmospheric gas composition?
79% N2
21% O2
0.04% CO2 (negligible)
346
What is CO2 used by?
Plants--release O2 into atmosphere in exchange for CO2
347
What does the variable [ ] indicate?
Concentration
348
What does variable "F" indicate?
Fractional
349
How is partial pressure of one gas calculated?
Total pressure of all gas x gas concentration of interested gas (as decimal)
350
What is the total pressure of all gas in the atmosphere?
760 mmHG
351
What is the partial pressure of N2, O2, and CO2 in dry atmospheric gas?
N2: 600.3 mmHg
O2: 159.0 mmHg
CO2: 0.3 mmHg
352
What happens to gas pressure with inspired humidified gas?
When water vapor is inserted--it displaces and dilutes the other gasses
Can only have a total pressure of 760 at sea level so if water vapor pressure is added--it decreases the other gasses
353
What is the partial pressure of water vapor (PIH2O)?
47mmHg
354
What variable indicated inspired gas?
"I"
355
How is the partial pressure of a gas calculated when water vapor is added? EX: PIO2
PIO2= FIO2 (21%) x Pb (barometric pressure) - PIh2o (partial pressure of water vapor)
0.21 (760-47)= 149mmHg PIO2
356
How can water vapor be eliminated from inspired gas?
It cant be→ We have to take into account the presence of water vapor because it happens very quickly
lungs are a humid environment
357
If water vapor displaces O2, it could also displace ________ __________.
Volatile Anesthetics
358
What is the PIN2?
0.79 (760 - 47) = 564 mmHg
359
What is the partial pressure of inspired O2 and CO2?
PIO2= 149mmHg
PICO2= negligible so can say 0
360
What happens to the tidal volume of fresh air when its inhaled?
* 350cc of VT makes it to the lungs and mixes with preexisting gas
*150cc of VT is dead space gas
361
What happens to PAO2 and PACO2 when the 350cc inspired gas gets to the lungs?
* PAO2 goes up
* PACO2 in preexisting gas goes down
362
What happens after the inspired air gets into the alveoli over the course of the respiratory cycle?
A portion of the O2 is absorbed by the blood in the lungs and the CO2 is unloaded into the alveolar air
363
What are the alveolar gas pressures after O2 is absorbed in the blood and CO2 is unloaded in the alveoli?
PAO2: 100mmHg (some absorbed by blood)
PACO2: 40 mmHg (unloaded from the blood)
Gasses that exist after the incoming air is mixed with whatever is in the lungs and after equilibration with pulmonary blood gases
364
Pulmonary arterial blood should look the same as _________ _________ _________ blood.
Deoxygenation systemic venous blood
365
What foes PO2 stand for and what is the value?
PO2= deoxygenation systemic venous blood= 40mmHg
366
What is PCO2? What is a normal value?
systemic venous CO2= 45mmHg
367
What happens to gas pressures when the systemic blood is fed into the lung (pulmonary capillaries) and then is brought back to systemic through pulmonary vein?
O2 is absorbed by the blood and some CO2 is unloaded from the blood into the alveoli
PaO2= 100mmHg
PaCO2= 40mmHg
368
What is the difference in pulmonary vein gas pressures and pulmonary artery gas pressures?
Pulmonary artery:
* PO2= 40mmHg
* PCO2= 45mmHg
Pulmonary vein:
* PaO2= 100mmHg
* PaCO2= 40mmHg
O2 partial pressure increases by 60mmHg
CO2 partial pressure decreases by 5mmHg
369
Why does PaO2 have such a big increase compared to PaCO2 if equal amount of O2 absorbed and CO2 expired?
The changes we see (bigger increase in PaO2) is d/t solubility
* CO2 is very soluble in blood→ reason why PaCO2 only drops by 5mmHg as blood moves through pulm capillaries
* O2 is a lot less soluble and is also stored on hgb→ PaO2 change is much larger
370
Which gas is more soluble in blood: O2 or CO2?
Co2 is much more soluble in blood
O2 is less soluble and is stored on Hgb (reason why PaO2 change is greater is magnitude)
371
What is the function of breathing in fresh air at the level of the lung?
*Delivers nutrients to the tissues
* Helps absorb O2 and unload CO2
372
What should be the PaO2 and PAO2 after alveolar gas equilibration in a healthy 20 year old? (more specific number)
104mmHg
373
How is pulmonary venous blood diluted?
Pulmonary venous blood (arterial circulation) gets diluted with bronchial add mixtures
374
Tissues of the lungs have their own __________ _________.
Circulatory system
375
What percent of CO is made up of circulatory system in the lungs?
1% CO from systemic arterial circulation
376
What is the function of the lung tissue having its own circulatory system?
Helps deliver nutrients to tissues in the lungs that arent able to get nutrients from the pulmonary blood moving through the lung
377
Where does the venous part of pulmonary circulation (pulmonary artery) empty into?
Left atrium
378
Why is pulmonary systemic PaO2 slightly lower than PaO2 in pulmonary vein?
Pulmonary venous O2 (104mmHg) is higher d/t 1% cardiac output that gets mixed in with oxygenated pulmonary venous blood
379
How does age affect PaO2?
PaO2 goes down with increased age
380
What would PaO2 be in a healthy 90 year old?
Lower than 100→ probably around 80mmHg
381
At what age do the lungs start declining?
Age 20
382
What changes would occur with increase ventilation with unchanged pulmonary blood flow?
Higher PAO2, Lower PACO2
would also have changes in patient blood gas
383
How does alveolar N2 level compare to partial pressure of inspired N2?
Should be about the same
384
What portion of VT is used for gas exchange? What happens to the rest?
350cc makes it to the lungs for gas exchange
150cc dead space
385
What is 150cc "dead space" gas used for?
Used as a filler gas to push other gas into the lungs
dead space= last portion of inspired breath at isnt used for gas exchange
386
What happens to fresh air once it gets pushed into the lung (concentration wise)?
Fresh air is diluted with the preexisiting gas
387
What are the 2 types of dead space gas?
* Anatomical dead space
* Alveolar dead space
388
Where does anatomical dead space usually occur?
In the conducting zones of upper respiration system
*the dead space gas that is used to push each VT into the lungs*
389
When does alveolar dead space occur?
Usually occurs in unhealthy lungs
When something is wrong and the lungs are ventilating an alveolus that isnt perfused
390
Where is the location of alveolar dead space? compared to anatomical dead space?
Alveolar: Dead space within the lung
Anatomical: conducting zones
391
How does the body try to eliminate alveolar dead space?
Directing blood flow to areas that are well perfused (hypoxic pulmonary vasoconstriction)
392
What is an example used in class of alveolar dead space?
PE→ clot in the large artery in the lung→ ventilating that part of the lung but the lung isnt being perfused = ALVEOLAR dead space
393
What is physiologic dead space? When does this happen?
Both alveolar and anatomical dead space put together
* even if healthy→ increased alveolar dead space with age (80-100) is unavoidable
394
In general, the healthier you are the less _____________ dead space you have
alveolar
395
What dead space would be common to see in healthy 20 year old?
Anatomical dead space
396
How do ventilation requirements change with increases in alveolar dead space?
Increase ventilation to make up for some of the air going to places where gas exchange isnt occurring
397
What is a common cause of alveolar dead space (aside from aging)?
Positive pressure ventilation can produce alveolar dead space in a system being stressed
398
What is the variable for alveolar dead space? How can VT be calculated with it?
VD= dead space/filler gas
VT = VD + VA (gas exchange)
399
What does VA variable represent?
Alveolar ventilation (good alveoli being ventilated)
400
How is minute ventilation calculated? What is the variable?
Minute dead space ventilation + Alveolar dead space ventilation= Total minute ventilation
Minute ventilation= VE
401
How is minute alveolar ventilation calculated?
Amount of alveolar ventilation we have in one breath x number of breaths in one minute
(350) (12) = 4.2L/min
402
How is minute dead space ventilation calculated?
(150) (12) = 1.8L
403
How are VE and VT related?
Total minute ventilation= tidal volume over 1 minute
404
What is a normal total minute ventilation (VE)?
4.2 + 1.8= 6 L/min
405
What amount of air is measured with total minute ventilation?
All of the expired air
406
Total minute ventilation is the same as measuring ___________
Tidal volume over 1 minute
(.5 x 12) same as (4.2 + 1.8)
407
What is the expired gas a combination of?
Dead space gas inhaled (stays concentrated) and alveolar gas
Gas expired is more diluted because its a combination of dead space gas and alveolar gas
408
What is the area called between dead space gas and alveolar gas with inspiration?
Transitional area
409
What happens to PAO2 with increased ventilation?
PAO2 should rise higher than 104
410
What happens to PAO2 with reduced ventilation?
PAO2 is lower→bringing in less fresh gas and the gas already in the lung has a lower O2 pressure
411
What happens with PACO2 when alveolar ventilation is higher than normal?
PACO2 in the lungs would be lower than normal→CO2 in the lungs would be diluted out more than normal
412
What happens to PACO2 with lower than normal alveolar ventilation?
Higher alveolar CO2
413
What is the pulmonary capillary hydrostatic pressure?
7mmHg
414
What is the blood oncotic pressure in the pulmonary capillary?
28mmHg
415
What is the one force in the pulmonary capillaries that favors reabsorption?
Pulmonary capillary oncotic pressure
416
Which forces favor filtration (outward movement) from the pulmonary capillary?
* Pulmonary capillary pressure
* Pulmonary Interstitium
* Interstitial protein osmotic pressure
417
What is the pressure in pulmonary interstitium?
-8mmHg
418
What factors allow for pulmonary interstitial pressure to be more negative than the interstitium in systemic circulation?
* Lungs are surrounded by -4mmHg pleural pressure
* Lymphatics are active in the lungs→ drops hydrostatic interstitial hydrostatic pressure
419
What is the interstitial protein osmotic pressure in the pulmonary system?
14mmHg (double systemic system)
420
What is the net filtration pressure in the pulmonary capillaries?
8 + 7 + 14= 29 -28 = +1mmHg
421
Which system has a higher NFP: pulmonary or systemic?
Pulmonary has more NFP (+1mmHg)
Systemic NFP (0.3mmHg)
422
When would the lymphatic system in the lungs have a hard time working?
Ventilating someone with high pressure→ blood vessels are easily compressed→ lymphatics are easily compressed as well (may not be working as well)
Obstruction of lymphatics can happen with tumor or high PPV
423
________ is a major obstacle to gas exchange
Fluid
424
Why is it important to keep the lungs dry in order to have good gas exchange?
O2 is not very soluble in water
425
What is a normal Left atrial pressure? What can left atrial pressure get up to before resulting in pulmonary edema?
Normal: 2mmHg
Can get up to: 23mmHg
426
How dose the body safe guard against starling forces that would potentially cause pulmonary edema?
Body allows for some pressure back up in the lungs before it results in pulmonary edema
If enough of the forces are out of whack it could lead to pulm edema
427
What puts people at risk for pulmonary edema?
* Large amount of blood loss (loss of colloids)
* Left heart failure→ eventually pressures get high enough to cause pulmonary edema
428
How is NFP calculated into flow?
Kf (filtration coefficient) multiplied by the NFP to get a fluid flow rate
429
What does the variable Q stand for?
Flow/ perfusion of blood through the tissue
430
What units would a fluid flow rate be in?
Volume/unit time
431
What factors can cause pulmonary edema?
* Increased capillary permeability
* Increase capillary hydrostatic pressure
* Decrease in interstitial hydrostatic pressure
* Decrease in colloid osmotic pressure
432
What can cause increased pulmonary capillary permeability?
* infection
* ARDS
* Too much O2
These things make the capillaries porous and proteins can leak out into interstitium
too many proteins in interstitium causes fluid to leak out
433
What happens to pulmonary capillaries with inhaled toxins/ pollutants?
Turns capillaries into swiss cheese→ creates colloid problem in the interstitial fluid
434
What causes increase capillary hydrostatic pressure?
Increased left atrial pressure→ Left ventricular infarction or Mitral Stenosis
435
What causes decrease in interstitial hydrostatic pressure?
* Chest tube striping
* Rapid evacuation of pneumo/hemo thorax
Makes the pressure in the chest lower than it should be
436
What is an a concern from anesthesia standpoint with a healthy/young patient during emergence?
If the patient is waking up and trying to inhale against a closed airway→ Can generate really negative thoracic pressures (-50 to -60) → causing flash pulmonary edema
437
How low can thoracic pressure get? Why is this bad?
-50 or -60cmH2O
Decreases interstitial hydrostatic pressure and can cause flash pulm edema
438
What can cause decreases in colloid osmotic pressure?
* Too much IV fluid
* Protein starvation→ harder for the body to produce plasma proteins
* Renal problems→ spilling plasma proteins into urine (proteinuria)
439
What are some other general etiologies of pulmonary edema?
* Insufficient lymphatic drainage
* Interstitial Fibrosis
* Head injury
* High altitude pulmonary edema
440
What could cause insufficient lymphatic drainage?
Tumors or high vent pressures
441
How does interstitial fibrosis lead to pulmonary edema?
Scar tissue on lymphatics makes then hard to function--build up of fluid if lymphatics arent working
442
What would cause pulmonary edema to develop after a head injury?
Head injury causes loss of chunk of SNS→ Can lead to too much fluid or blood in the lungs
443
What is the reason for pulmonary edema from high altitude?
Unknown the exact mechanisms of it
444
Why is perfusion lower at the apex of the lung compared to the base?
Blood vessels at the apex are smaller diameter and lower internal pressures
445
What is the goal for air flow with ventilation?
VQ matching ✅
Want to direct fresh air to areas with high blood flow (base of lung)
446
What is VQ matching dependent on?
Pleural pressure gradient→ pleural pressure is more negative at the top of the lung and more positive at the base of the lung
447
How does transpulmonary pressure at the top of the lung differ from the base?
Higher transpulmonary pressure at the top of the lung than at the base of the lung
448
What is the purpose of higher transpulmonary pressure at the top of the lung?
Higher transpulmonary pressure will keep the alveoli more distended→ As the air comes in and fills the alveoli they start to resist further filling
When the alveoli at the top of the lungs are full, the air goes somewhere else where its easier to flow
449
We spend most of the time in the upright position: How does this affect the blood vessels at the base of the lung?
Blood vessels at the base of the lung are larger in size compared to the blood vessels at the top of the lung
450
How do the alveoli compare at the top of the lung to the base of the lung?
Alveoli at the top of the lung are physically larger than alveoli at the base of the lung
Alveoli at the top of the lung are more full all the time
Alveoli at the base of the lung are more empty most of the time (smaller)
451
What does it meant about the compliance of the alveoli at the top of the lung if they are bigger?
Alveoli are larger and less compliant (arent able to accept a bunch more air)
452
Which part of the lung get more ventilation and why?
The base of the lung:
* Transpulmonary pressure is more positive (-1.5cmH2O)
* Alveoli are smaller and more compliant
453
What happens as as result of the higher vascular pressure at the base of the lung in regards to blood flow?
More recruitment and distention
↓
Lower resistance
↓
Greater blood flow
454
What creates the pleural pressure gradient in the lungs?
The pleural pressure gradient is a result of the lungs being suspended in the chest→ follows the topography of the chest and is related to gravity
455
Why is the pleural pressure more positive at the base of the lung?
The lung is resting on the diaphragm
456
What is a normal pleural pressure at FRC at the top of the lungs?
-8.5 cmH2O
457
__________ pressure is what hold alveoli open.
Pleural
458
What does the pleural pressure gradient do to the alveoli?
Allows for various degrees of fullness of the alveoli in that area
459
What are characteristics of alveoli at the top and base of the lung at FRC?
Top: -8.5cmH2O pressure gradient makes teh alveoli pretty full (lots of force to keep the alveoli open
Bottom: Less pleural pressure to keep the alveoli open (usually more empty alveoli at the base)
460
Where does fresh air want to flow in an upright lung at FRC?
* Air goes where its easiest to go
* would be easier for the air to go to the alveoli at the base of the lung where volume is better accepted than the top of the lung
(top of lung is already pretty full)
461
What does alveolar compliance measure?
How easy it is for air to get into the alveoli
462
At FRC alveoli at the top of the lungs are ____% full.
60%
463
At FRC alveoli at the bottom of the lungs are ___% full
25%
464
Why is it important that pleural pressure gradient caused by gravity follow a similar pattern as perfusion gradients?
Allows for good blood flow and good ventilation to the base of the lung
GOOD VQ MATCHING ✅
465
Can the alveoli be emptied to 0%?
No
466
What is the lower limit of alveoli capacity? Why?
20% → Lower limit of what alveolar capacity can be in a healthy lung
Pushing on the alveoli also puts pushing on small airways → when small airway collapses then you cant push more air out of the alveoli (small airway collapses when there is around 20% alveolar capacity left)
467
What is variable can we look at if we want to know alveolar distending pressure?
Transpulmonary pressure: pressure available to put air into the lungs
468
If alveolar pressure is 0, what would transpulmonary pressure be at FRC in the base of the lungs?
Pleural pressure= -1.5
so
Transpulmonary pressure= +1.5 cmH2O
469
At transpulmonary pressure of +1.5 we are able to fill alveoli at the base of the lung to ____% of their capacity
25%
470
If pleural pressure at the top of the lung is -8.5cmH2O what would transpulmonary pressure be? What does this mean?
TPP: +8.5cmH2O→ this is enough distending pressure to fill the top of the lungs up to 60% of capacity
471
When air is put into the lungs it follows a curve: what is indicated by the curve flattening out at the top?
Getting more difficult to put air in at the top of the lung once its near capacity
small amounts of air put into the lung use a lot of transpulmonary pressure→ NOT COMPLIANT SYSTEM at the top of the lung
472
What does the steep slope at the bottom of the curve indicate?
Indicates it is easy to put air into the lung with just a little increase in transpulmonary pressure
Very compliant at the base of the lung
473
Air always flows to places with the highest ___________.
Compliance
474
What is the term for the difference in behavior of the lung tissue on inspiration and expiration?
Hysteresis
475
When is the lung more compliant: Inspiration or expiration?
Lung is more compliant on expiration than inspiration
*Steeper curve with expiration= more compliant
476
What are the pressures for each variable?
P(is)= -8mmHg
P(c)= 7mmHg
p(pl)= 28mmHg
p(is)= 14mmHg
477
The lung is suspended in the chest with connection to the _______.
Hilum
478
What happens to pleural pressure when trying to get to RV?
Takes effort to push the air out of the lungs to get to RV→ makes pleural pressure more positive at RV than FRC
479
What is the pleural pressure at the apex of the lung at RV?
-2.2 cmH2O
480
What would transpulmonary pressure be at the apex of the lung at RV is alveolar pressure is 0?
TPP= +2.2 cmH2O
481
What does a +2.2cmH2O TPP at the apex of the lung at RV allow for alveolar filling?
Fills alveoli at the apex to 30% capacity
Airways are still open at the top of the lung (high compliance)
482
What is pleural pressure and transpulmonary pressure at the base of the lung at RV?
Pleural pressure: +4.8cmH2O
TPP: -4.8cmH2O
483
What does a transpulmonary pressure of -4.8cmH2O do to the alveoli?
Alveoli will be as empty as they can be (20% capacity)
484
What happens when the small airways collapse?
No more air is pushed out of the alveoli→ when small airway collapses there is usually 20% of alveoli capacity left with air
485
What is the compliance like at the base of the lung at RV?
Not compliant at all
486
What happens at the base of the lung at RV if TPP is increased to 0?
No change in air coming in (no compliance bc alveoli are collapsed)
Eventually the base of the lung will start to accept volume but needs increased TPP (+5 ish?)
487
What happens to air flow in a lung at RV?
Alveolus at 30% capacity at the apex of the lung is able to accept air better than the base of the lung with the collapsed alveoli
First portion of inspired breath would go to the top of the lung (open and empty)
488
How do we get air into the collapsed alveoli at the base of the lung at RV?
would have to do some work to get them open
489
How are alveoli connected to one another?
They share walls and airways→ connected by connective tissue
490
What happens to the lungs at RV when the inspired air starts to fill the apex of the lung?
The top of the lung starts to fill up which stretches the walls of the airway in the lower parts of the lung
pulls the collapsed alveoli at the base to stretch them out so they can fill with air
491
What happens if lungs are missing connective tissue?
The alveoli will not be physically connected and the top alveoli wouldnt be able to help pull open collapsed alveoli at the base
492
Why is it not the best for our body to hang out at RV all the time?
Base of the lung is getting good continuous blood flow but the alveolar arent open so no fresh air getting to the base
Leads to VQ mismatch and messes up blood gases
493
What happens to lungs during general anesthesia?
Person is usually anesthetized, paralyzed, and on back→ leads to very low lung volumes
494
What is one of the factors that keeps FRC (3L) in the lungs? What can reduce FRC?
*Body positioning→ Supine position reduces amount of air in the lungs
* Muscle relaxation of all the skeletal muscle around the lungs reduces lung volumes further
495
Patients under GA are typically at low lung volumes. How do we get higher lung volumes?
Pressure
496
What is the built in system of the body to direct blood flow to better ventilated areas when there is VQ mismatch?
Hypoxic pulmonary vasoconstriction
497
What are the 2 sets of smooth muscle in the lungs?
* Pulmonary blood vessels smooth muscle
* Airway smooth muscle
498
Where is pulmonary blood vessel smooth muscles located and what is its function?
Located just upstream of the pulmonary capillaries
Determines how much blood goes through the capillaries by constricting or relaxing
499
What is the function of airway smooth muscle?
Can function to direct ventilation or perfusion where it is needed
500
How does vascular smooth muscle function to detect changes in alveolar gas tension?
* Poorly ventilated region of the lung→ Alveolar gas in this are (PAO2) would be low → causes upstream vascoconstriction
"hypoxic pulmonary vasoconstriction"
501
What is the most important controller to direct blood flow to areas with better ventilation for better gas exchange?
Hypoxic pulmonary vasoconstriction: BVs upstream constrict in response to alveolar hypoxia
Prevents blood gas changes
502
How does the rest of the body respond when there is lack of O2 to the tissue? How does this differ in the lung?
* Rest of the body would vasodilate BVs in response to hypoxia to improve perfusion
* the lungs constrict to divert blood to better areas→ we dont want improved perfusion of a poorly ventilated lung (would mess up ABG)
503
What is a secondary trigger to upstream vasconstriction?
Increase PACO2 in poor ventilation
**Primary response is from decrease PAO2
504
What mediates all vascular smooth muscle constriction?
Membrane potentials
505
What happens with ion conductance in response to general anesthesia?
GA all open K+ channels (hyperpolarize)
*Causes vascular smooth muscle to relax and interferes with hypoxic pulmonary vasconstriction
506
How does GA cause issues in the lungs? How is this managed?
GA interferes with bodies ability to compensate for lung problems by taking away hypoxic pulmonary vasoconstriction
*can cause pulmonary blood vessels to relax and allow blood flow to areas that it normally wouldnt
Part of the reason why we use supplemental O2 during GA
507
What is airway smooth muscle sensitive to?
Environmental conditions
508
What happens in the airway smooth muscle if there is a clot in the lung causing poor perfusion?
Alveolar gas will look close to inspired gas when ventilation is normal but blood flow isnt (PAO2= 150, PACO2= 0)
Airway smooth muscle can react by tightening up small airways (tries to direct fresh air to better perfused area)
509
What is the stimulus for airway smooth muscle to constrict and direct ventilation to other areas?
Hyperoxia
510
What does constriction of airway smooth muscle safe guard against?
Alveolar dead space
511
What would happen is you ventilate someone with 100% O2 for 1 day?
* Increases PAO2
* Turn capillaries into swiss cheese (oxidative stress)
* Tighten up airways
causes airway reactivity (part of ARDS→hard to ventilate patient when small airways are overly reactive)
512
Volatile anesthetics relax ___________ and ________ smooth muscle?
Vascular smooth muscle and airway smooth muscle
513
What happens to volume if the lungs with a change in position from standing to supine?
Everything in abdominal cavity slides up against inferior part of diaphragm and pushes air out of the lung
514
What is FRC when in supine position compared to standing?
FRC is decreased to 2L when supine
*1L of air was pushed out of the lungs from abd contents pushing up on lung
515
What other instances, aside from laying down might decrease FRC?
In obese patients→ More weight pushing on diaphragm
516
What happens to VC, IRV, ERV, VT, RV, IC, and FRC when the body changes from a standing to supine position?
IRV increases
VT would be constant
ERV decreases
RV stays the same
VC stays the same
inspiratory capacity increases when supine
FRC decreases when supine
517
What is a basic spirometer used to measure?
* Lung volumes
* Lung capacities
Measures how the lung volume is changing when someone is breathing (tracking amount of air coming in and leaving the patient)
518
Distance between max expiration and max inhalation readout on spirometry would be the _____ _______.
Vital capacity
519
How does the basic spirometry record an inspiration?
Pushes water heater up--causes maker to trace pattern on paper
520
What is something basic spirometry is incapable of measuring?
* Incapable of measuring anything that has RV as a component to it
* Not able to get that amount of air out of the lungs so there is no way to measure it with basic spirometry
521
What volumes would we not be able to measure with basic spirometry?
*TLC (VC + RV)
* FRC (RV+ ERV)
522
What lung volumes are added up to calculate VC when using a basic spirometry?
IRV + ERV + VT
523
What device can measure RV?
Advanced spirometry→can measure RV with indicator gas (measurement gas)
524
What gases are used for indicator gas in the advanced spirometry? (inert gases)
Noble gases (last column on periodic table)
* He (cheap and inert)
* Ne/Ar (rare and expensive)
* Xe/Rn
525
What is the element Rn?
Radon
526
Is Rn an inert gas?
Radon as a noble gas is inert→ but the version we have in the ground is extremely reactive
527
What is the second leading cause of lung cancer (after smoking)?
Radon found in the ground→ common to test for it in basements
528
How does advanced spirometry function to measure RV and FRC?
By using indicator gas (usually He)
529
What happens with advanced spirometry over a few minutes as the patient breathes in the He?
He makes its way into the volume of the air already in the lungs → He concentration is reduced because its diluted out with the air in the lungs
530
What can we calculate from advanced spirometry if we know the starting volume of the indicator gas and the starting concentration and the amount He is diluted?
Can figure out how much volume was in the patients lungs when they were hooked up to the machine (FRC)
531
What is the end quantity of He in the circuit when using advances spirometry?
The starting quantity of He will be the same as the end quantity of He
532
What is an essential part of the advanced spirometry since it uses indicator gas?
* Need a source of O2 in the system
* Need CO2 absorbent system
533
T/F: In advanced spirometry CO2 is scavenged and O2 is fed into the system at the same rate?
True: Makes sure there is enough O2 to keep patient alive and well
534
How can RV be estimated with the advances spirometry?
ERV- FRC
535
What are the necessary components for the advanced spirometry to perform measures with it?
* He meter
* CO2 absorbent
* O2 source
536
What happens to lung volumes with increased transpulmonary pressure?
Lung volume increases
537
What does the slope of a line indicate about the compliance of the system?
Increased slope= more compliant
Decreased slope= less compliant
538
What is the patho of emphysema?
Loss of elastic tissue in the lungs
*Makes alveoli more stretchy and more compliant than normal
539
_______ _______ is what holds everything together in the lung and allows for elastic recoil.
Elastic tissue
540
What would happen to vital capacity in a patient with obstructive lung disease?
Vital capacity would be higher than normal→ around 6L in the graph
(norma is 4.5L)
541
What happens to transpulmonary in a patient that has emphysema?
Transpulmonary pressure is lower and the lung is being filled more→ increasing TPP would put A LOT of air into the lung
BUT more difficult to get the air out
542
Why is it difficult to get air out of the lung in a patient with emphysema?
The loss of elastic recoil prevents passively pushing air out of the lung
543
Obstructive lung diseases generally cause abnormally ______ lung volumes.
high
544
What happens to the ability to fill the lungs in a patient with fibrosis?
Restrictive lung disease= system is less compliant and harder to fill
545
What is an example of a disease process that decreases the slope the line and what does this indicate?
Fibrosis
*Decreases slope of the line= less compliant lung
546
What is the patho of fibrosis?
Scare tissue laid down on the inside of the alveoli and small airways→Makes it harder for lung to expand
547
What happens to vital capacity in a patient with restrictive lung disease?
Reduced vital capacity → less than 4.5L
Usually requires more transpulmonary pressure to get VC up
548
What is the difference between TLC and RV?
Vital capacity
549
Restrictive lung diseases ________ all volumes and capacities in the lungs.
Reduce
550
What is the difference between the inspiratory loop and the expiratory loop?
Hysteresis
551
Is the lung more compliant on inspiration or expiration?
Large expiratory maneuver
552
What causes the decreased compliance on inspiration compared to compliance on expiration?
Takes time for the lung to expand with inspiration from low lung volumes
Takes time for the lung to start accepting air
553
What is needed to get the lung to start inflating if part or all of the lung is collapsed?
Increase pressure to help get the air into the lungs
(Increase PTP)
554
What component in an air filled lung contributes to hysteresis and the decreased compliance of the system?
Surface tension
555
Is there fluid inside the alveoli?
Yes, there should be a thin layer of fluid for the air water interface where water meets gas
556
If given the choice water molecules would prefer to be around _________ molecules
Water
557
What does water molecules sticking together in the lung provide?
Surface tension
558
__________ __________ is a large contributor to the overall compliance of the lungs
Surface tension
559
What happens to compliance with increased surface tension?
Decreased compliance= difficult to put air into the lungs
560
What happens to compliance in the lungs with decreased surface tension?
Increased compliance= easier to fill the lungs with air
561
What is the cause of periods where the system has very low compliance?
Increased surface tension
562
How does the lung behavior change if filed up with saline instead of air?
Saline lung→ the hysteresis narrows alot (basically the same curves) and the system is more compliant
Takes away the air water interface= no surface tension
563
How does inspiration differ from saline filled lung and air filled lung?
* Saline filled lung doesnt have a period where volume isnt going up but pressure is (no surface tension in the saline filled lung)
*In air filled lung we have to apply 8cmH2O before the lung starts to inflate
564
Why do we (CRNAs) care about surface tension?
All patients are at low lung volumes when they are anesthetized, paralyzed, and laying on their back → Makes it more difficult to put air into lungs that arent full at low lung volumes (d/t surface tension)
565
How does the body control surface tension in the lung?
Surfactant
566
How does surfactant work?
Gets in between the water molecules and breaks them up
breaks the surface tension to make it easier to get air into the lungs
567
What produces surfactant in the lungs?
Cells: Type 2 alveolar cells, Clara (Club) cells
568
What is surfactant made up of?
* Phospholipids
* 4 surfactant proteins (SP)
569
What are the surfactant proteins and their properties?
* SP-A: Hydrophilic
* SP-D: Hydrophilic
*SP-B: Hydrophobic
* SP-C: Hydrophobic
Its good to have a mix of water soluble and lipid soluble factors to break the tension at the air water interface
570
What percent of surfactant do the surfactant proteins make up? What SP is the largest contributor?
10%
SP-D→ SP-A→SP-B→SP-C
571
What are the 2 most abundant phosphatidyl compounds for surfactant? What percent of surfactant do they make up?
Dipalmitoylphosphatidylcholine (31%)
Unsaturated Phosphatidylcholine (31%)
572
What other phosphatidyl compounds makes up 9% of surfactant?
Phosphatidylglycerol
Phosphatidylinositol
573
What lipids make up 6% of surfactant?
Phosphatidylserine
Phosphatidylethanolamine
Sphingomyelin
574
What is the remaining amount of surfactant made up of?
Neutral proteins (9%)
Other lipids (4%)
575
What does amphipathic mean?
Compound that has an area that is water soluble and an area that is fat soluble
Charged head (water soluble)
Lipid tail (water insoluble)
576
Where are surfactant precursor compounds (phospholipids and surfactant proteins) produced?
By cells in the lungs
* Type 2 alveolar cells
* Clara (Club) cells
577
Secretory cells that line the upper airway and secrete mucus and a little surfactant:
Goblet cells → more for producing mucus in the upper airways than surfactant
578
Secretory cells that line the lower airways/deeper airways and are important for surfactant production?
Clara/Club cells
579
Secretory cells inside the alveoli not used for gas exchange:
Type 2 alveolar cells
580
How do the shapes of type 2 and type 1 alveolar cells differ?
Type 2→ cube shaped to give more space for things that are specialized for protein and lipid production/excretion
Type 1→ very thin and long
581
What do type 2 alveolar cells need in them to be able to perform their function?
Things specialized for protein and lipid production and excretion
*Nucleus
*ER
* Golgi aparatus
* Lamellar body (store and pack surfactant)
582
What would happen if secretory cells were flat?
Wouldnt work out because they would have a long distance to travel
583
What is the process that releases surfactant to surfactant storage areas?
Exocytosis
584
Type 2 alveolar cells cover ____- ____% of overall surface area inside the lungs
5-10%
585
How do type 2 cells compare to type 1 cells in terms of quantity?
2X as many type 2 cells as type 1 cells
*More type 2 cells but they dont take up as much real estate as the type 1 cells
586
What cells are good for gas exchange, not secretion?
Type 1 alveolar cells
587
Type 1 alveolar cells make up ___- ___% of overall surface area in the lungs.
90-95%
take up more real estate because they are long
588
Where do surfactant precursors go once it goes out of the type 2/club cell via exocytosis?
Tubular myelin: netting
589
What is the structure and function of tubular myelin?
Cross hatches structure with pieces of myelin sitting on top of eachother
*surfactant proteins and lipids hang out on the mesh
590
What happens to the surfactant precursor molecules on the tubular myelin when the lungs fill up with air under normal conditions?
Alveolar pressure is reduced to a negative with inspiration→ pulling air in and stretching the alveoli out
When the alveoli inflates→ some of the surfactant molecules get knocked off the netting and float up to the air water interface where they become active surfactant molecules
591
Where does surfactant become active surfactant molecules?
When it floats up the the air/water interface and works to reduce surface tension
592
What functions as a storage place for the inactive surfactant precursor molecules?
Tubular myelin
593
What happens to surfactant over time?
Lipids and proteins fall apart
Type 2 cells makes more surfactant to replace the surfactant that has worn out→ produce surfactant at the same rate it is falling apart
594
What would happen if the type 2 cells arent producing as much surfactant compared to how much is falling apart?
Imbalance in this system causes problems
Lack of surfactant causes increased surface tension in the lungs
595
What happens to the surfactant when it falls apart over time?
Alveolar macrophages scavenge the leftover pieces and break them down into component parts that are taken back up into surfactant producing cells to recycle
596
Why is increased surface tension in the lungs bad?
Makes it much more difficult to put air into the lungs
597
What happens to surfactant when someone is on positive pressure ventilation?
Inspiratory pressures are positive (when normally negative) → wont have the same effect on releasing surfactant from tubular myelin
expanding lung volume would get some surfactant to release but not the same as normal healthy breathing (with negative pressure)
598
What happens with surfactant release if an upstream airway collapsed?
Not filling up alveolus→ no stretching of alveoli wall to release surfactant → eventually surfactant in collapsed area will run out because it is not being replaced by filling the lung up with air in a normal fashion
Surfactant is falling apart at normal rate and scavenged by the macrophages but its not being released from the netting and not decreasing surface tension
599
Why is it difficult to re-recruit a section of collapsed lung with a surfactant deficiency?
The surface tension will be higher in the collapsed are compared to the area that is open
would have to get healthy part of lung SUPER open to recruit the collapsed section→ requires increased pressure
600
How does timing of atelectasis affect re-expansion of the lung?
* If the lung just collapsed→ it would be easier to re-recruit
* If it has been collapsed for awhile→it will take longer to re-recruit since the surfactant is gone
601
How would you go about trying to re-expand a portion of a lung that has been collapsed for a day?
* Increase inspiratory pressures
(challenge with PPV → want to try to keep the lung open because if it collapses it very hard to fill up with air)
602
What is a type of cell found in the lung that is a secretory cell as well as an inflammatory mediator in the lungs?
Mast cell
603
What is the most common compound released from mast cells? What is the effect on the airway?
Histamine→Irritates the airways and causes airway smooth muscle vasoconstriction
604
How many alveoli do we have as young adults?
500 million (we lose some as we age)
605
Can the lung reproduce alveoli?
Lungs have the capability to produce new alveoli but at a slow pace
606
What happens to alveoli if someone has a lobectomy?
There will probably be an increase in alveoli in the other lung over time (if the person is healthy)
607
Why arent alveoli reproduced to help people with chronic lung disease?
The rate of alveolar loss with chronic lung disease far outweighs the ability of the lungs to produce new alveoli
608
How many pulmonary capillaries per alveoli?
1000 pulmonary capillaries
609
How many square meters of surface area are available for gas exchange in the lungs?
70 square meters (size of a tennis court)
610
We can think of alveolar walls as a _______
Spring
611
What 2 things make up elastic recoil pressure in the alveoli?
* Surface tension (2/3)
* Tissue Factors (1/3)
612
When are there changes with the elastic tissue in the alveoli?
Chronic lung disease
613
How many layers of elastic tissue is in a normal alveoli?
2 layers→allows for normal FRC (3L) with normal pleural pressure (-5cmH2O)
614
What happens to elastic tissue in the alveoli with restrictive lung disease? What does this do to lung volumes?
Adding more elastic tissue to the alveoli→ harder to fill with air because there is more tissue recoil
normal pleural pressure + extra elastic tissue= lower lung volumes (harder to fill)
615
What happens to elastic tissue in the alveoli in obstructive lung diseases? What does this do to lung volumes?
Removes elastic tissue from the alveoli → easier to fill with air
normal pleural pressure + less elastic tissue= higher lung volumes (less tissue resisting filling with air)
616
How does lung size compare between restrictive and obstructive lungs?
Restrictive lungs= small
Obstructive lungs= large
617
How does surface tension contribute to alveolar elastic recoil pressure?
Thin layer of water inside alveoli and small airways→ water wants to be by other water molecules
Creates elastic recoil when the water wants to be by other water→ creates a force to push air out of the lungs
618
What is associated with every lung disease?
Surfactant deficiency
619
What is the force that causes water to aggregate together?
Surface tension
620
What happens with surfactant is applied at the air/water interface?
Cuts surface tension by spreading out the water→makes the alveoli easier to fill with air
621
What is in tap water that leaves water spots?
Calcium, sodium, minerals
622
What is crucial in order to fill the lungs with air?
Adequate surfactant
623
What else does surfactant do to help improve gas exchange?
Gives ability to keep the lungs dry
Easier to have gas exchange through thin layer of water compared to a think drop
624
What is the variable for airway resistance?
R (AW)
625
High lung volumes= _______ airway resistance
Low
626
Low lung volumes= _______ airway resistance
High
627
What happens to airway diameter at RV?
Alveoli is smaller and the airway is more narrow
628
What happens if you try to forcefully expire from low lung volume?
Expiration would be difficult because airway resistance is high and narrow airway makes the air come out slow
629
What happens to airway diameter at TLC?
Alveolus gets bigger and the airway gets wider
630
What happens if you forcefully expire from TLC?
expire from high lung volume= easy expiration because airway resistance is low
AND
Airway diameter is wider so air would come out of the lungs quickly
631
What is the term that describes large airways being held open by negative pleural pressure?
Traction: Low pleural pressure physically pulls large BV and airways open with traction
632
In a normal lung, how much transpulmonary pressure (PER-recoil pressure) has to be applied to fill the lung up to TLC?
Transpulmonary pressure of +30cmH2O
633
Is the normal lung, what would pleural pressure have to be to keep the airways open at TLC?
-30cmH2O
634
How do large and small airways differ in the way they maintain patency?
Large airways: dependent on pressure (pleural pressure)
Small airways: dependent on volume
635
How are pressure and volume linked in the lungs?
Need low pleural pressure to have high volume
Low pleural pressure= traction on large airways
High volume= open up small airways
636
How do you calculate anatomic dead space?
1cc/ lb of ideal body weight
