pulmonary physiology Flashcards
(84 cards)
1
Q
___ is the gold standard for gas exchange
A
ABG (O2 tension in blood)
2
Q
Q is proportional to
A
P/R
3
Q
R is proportional to
A
length x viscosity / radius ^4
4
Q
Q =
A
VA (velocity x area)
so velocity is Q/A
5
Q
mVe =
A
Vt x RR
minute ventilation = tidal volume x respiratory rate (depth x frequency)
6
Q
VT=
A
VD + VA
dead space + alveoli
7
Q
compliance =
A
volume/pressure
8
Q
Fick’s law of diffusion is proportional to
A
diffusion constant x (A x P)/T
9
Q
PaCO2 is proportional to
A
VCO2/VA
CO2 in blood is dependent on/proportional to CO2 produced/alveolar ventilation
10
Q
Henderson-Hasselbach
A
pH = pK + log(HCO3-/C02)
simplified: pH ~ HCO3- (pH directly related to bicard - base)
pH ~ 1/PaCO2 (pH inversely related to CO2 in blood)
CO2 + H2O H2CO3 H+ + HCO3-
11
Q
respiratory system can be divided
A
- conduction portion
- condition the inspired air: warm to body temp, filter (remove particles), saturate with H20 vapor
- bulk transport of air
- respiratory portions
- gas exchange function (in alveolar sacs)
12
Q
ventilation
A
- process by which air moves into lungs (inspiration) and out of lungs (expiration)
- how: muskulotskeletal pump
- why: need tiniest pressure gradient for exchange
- pressure fluctuations
- accomplished by coordination of respiratory muscles, rib cage, and lungs
13
Q
dead space and alveolar volume
A
- efficacy of breath tells you nothing about depth of breath
- VT = VD + VA (tidal volume = dead space volume + alveolar volume)
- still some dead space in respiratory zone
- respiratory bronchioles only have a few alveoli
14
Q
hypoventilation
A
retaining CO2: if you only ventilate dead space and alveoli
15
Q
hyperventilation
A
blowing off CO2: raises pH (alkaline)
why you use brain paper bag in panic attack
16
Q
hypoxemia
A
low O2 in blopd
17
Q
hypoxia
A
low O2 in tissues
18
Q
ischemia
A
lack of blood flow
19
Q
dead space and alveolar volume
A
- VD - dead speace volume
- physiologic: non-perfused alveolus, changeable
- anatomic: areas without alveoli, not changeable
20
Q
mVe =
A
- mVe = VT x RR = (VD + VA) x RR
- mVe is volume of air inhaled in one minute, and ventilation is dead space and alveolar ventilation
- dead space increases in COPD
21
Q
distribution of blood flow
A
- majority of breath to the bottom of the lung
22
Q
lung compliance
A
- change in volume/change in pressue
- 1/elasticity
- ability of tissue to expand
- decreased compliance = stiffer
23
Q
surface tension and compliance
A
- surface tension wants to collapse alveoli
- surfactant lessens surface tension – produced by T2 pneumocytes
24
Q
surfactant
A
- breaks bonds on liquid molecules to lessen surface tension and increase compliance for easier breathing
- reduces surface tension to decrease muscular effort to ventilate lungs
- composed of lipids and proteins
- lipoprotein: secreted by alveolar epithelium (T2 cells) into alveoli
- both hydrophilic (on inside of air-liquid interface) and hydrophobic/lipophilic (outside)
- break H+ bonds of interface to increase compliance
- separate with breathing in – keep small alveoli from collapsing
- anti-bacterial, prevents infection: immune effect to protect against invaders (proteins A and D)
25
alveoli
* alveolar walls are T1 pneumocyte, surfactant is T2
* alignment of surfactant molecules
* resident macrophage
* air:liquid surface
26
static pressure-volume (PV) curve
* lungs get stiffer with greater volume
* compliance = volume/pressure
* higher change in volume for change in pressure is compliance
* lower change in volume for change in pressure is stiff
27
the top of the lung has ____ compliance than the bottom of the lung
lower
28
with decreased compliance, patients breathe ____ to compensate
faster (increase RR)
29
factors that impact air flow and resistance
* Q = P/R
* laminar (easy to move)
* turbulent: need greater pressure
* resistance
* radius, airway length, gas viscosity, lung volume
* larger airways generally have higher velocity and thus more turbulent flow
* Q = VA: as cross section area of branching airways increase -\> slower velocity -\> laminar flow (less resistance, so less pressure needed)
30
cross sectional area and bronchial tree
31
sympathetic stimulation stimulates ____ for \_\_\_\_, and parasympathetic stimulation stimulates ____ for \_\_\_\_
* sympathetic stimulation (NE) stimulates beta2 receptors for bronchodilation
* parasympathetic stimulation (ACh) stimulates muscarinic receptors for bronchodilation
32
non-uniform lung ventilation
* regional obstruction
* asthma, foreign body, mucus plug
* regional changes in elasticity
* pneumonia, pulmonary fibrosis, atelectasis
* regional dynamic compression - hole/bullous in lung
* COPD, pneumothorax
* regional limitation to expansion
* scoliosis, burn injury, rib fracture/muscle guarding
33
work of breathing
* work of respiratory muscles to over come the elastic and resistance factors from airways, lungs, and chest wall to expand the chest and lungs
* elastic factors: compliance (stiffness) of lungs, chest wall, and abdominal contents
* airway resistance: bronchospasm, airway inflammation, and swelling and secretions
* work to get air in
34
conducting zone
trachea to terminal bronchioles
35
upper respiratory tract
* nose, pharynx, and larynx
* provides 1st line of defense against infection
* filters, warms, humidifies air
36
lower respiratory tract
* trachea begins at C6
* directly superior to beginning of trachea is larynx (vocal chords)
* trachea bifurcates (carina) into 2 mainstem bronchi (right and left) at sternal angle (2nd rib space)
* T4/T5 when supine, T7 when standing
* trachea is 16-20 cartilaginous rings (hyaline cartilage)
* flexible but rigid to keep trachea open
* each ring is open posteriorly (for flexibility) covered by trachealis muscle
37
tracheal/bronchial epithelium
psudostratified columnar epithelium
* ciliated: into sol layer (more liquid), push gel layer up into airway to catch gunk - airway defense
* spit out or to stomach
* mucus secreting goblet cells and glands
* lymphoid tissue
* airway secretions (mucus) line RT and form 2 layers - sol and gel layers
* bronchial wall epithelium lined by cilia in sol layer
* sol layer is less viscous than gel layer, allowing cilia to beat freely
* during forward stroke, cilia tips hit gel layer to propel it centrally to larger airways and mouth
38
\_\_\_ bronchioles have ____ and continue as ____ bronchioles, which then open into ____ and individual \_\_\_
terminal bronchoiles have no alveoli and continue as respiratory bronchioles (have alveoli), which then open into alveolar ducts and individual alveoli
39
gas exchanging zone
* acinus describes functional gas exchange unit, consiting of
* respiratory bronchioles
* alveolar ducts, alveolar sacs, alveoli
* acinus is distal to terminal bronchiole
40
alveoli
* walls composed of squamous epithelium (T1 and T2)
* T1 are very thin
* 95% of alveolar surface area
* function for gas exchange
* T2 synthesize and secrete
* reduce surface tension and allow alveoli to remain open
* also may be resident alveolar macrophages (dust cells)
41
respiratory cycle
* inspiration
* external pressure \> intrathoracic pressure
* expiration
42
musculoskeletal pump
* external intercostal muscles: aid in quiet and forced inhalation
* elevation of ribs, expand thoracic cavity
* internal intercostal muscles: aid in forced expiration (quiest is passive)
* depress ribs, decrease dimensions
* both external and internal innervated by intercostal nerves
43
Boyle's law
P related to 1/v
* PV = k (pressure x volume = constant)
44
zone of apposition
angle formed by rib cage and diaphragm
more acute is normal
45-90 is "flattened diaphragm"
45
rib cage moves in ___ movement, and sternum moves in \_\_\_
bucket handle
pump handle
46
abdominal paradox
* sign of diaphragmatic dysfunction
* paradoxical inward motion of abdomen as rib cage expands in inspiration
* seen in high SCI (C5 or above)
47
sniff test
* assesses motion of diaphragm during a short, sharp inspiratory effort through nostils
* descent of diagphragm will be seen in people without disorder
* with unilateral/bilateral diaphragm paralysis, there is a paradoxical (cephalad) movement of paralyzed diaphragm
48
flail chest
* multiple fractures in a single rib -- multiple floating segments
49
pulmonary function testing (PFT
* MIP, MEP, MVV
50
maximal inspiratory pressure (MIP)
* lowest pressure developed during a forceful inspiration against an occluded airway
* primarily measures inspiratory muscle strength
* recorded as negative number in cm H20 or mmHg
* AKA negative inspiratory force (NIF)
51
maximal expiratory pressure (MEP)
52
maximal voluntary ventilation (MVV)
* total volume of air exhaled during 12 seconds of rapid, deep breathing
* primarily measures breathing reserve (respiratory muscle endurance)
* liters/minute
* rapid, deep breathing for 12-15 seconds: measured volume is indication of respiratory muscle endurance
53
respiratory muscle fatigue
* supply: energy availability
* muscle blood flow, O2 content
* demand: energy requirements
* work of breathing, strength, mechanical efficiency
* psychologic and neurologic factors
54
factors that influence breathing
* hypothalamus -- emotions, pain
* cortex -- voluntary control
* chemoreceptors
55
chemoreceptors and breathing
* central: in medulla oblongata
* responds to increase CO2 that passed through BBB
* H+ stimulates receptors for increased breathing depth and increased rate
* peripheral: in aortic/carotid bodies
* responds when PaO2 \< 60 mmHg --\> increase ventilation
* synergistic with higher PaCO2
* also responds to pH decreases --\> increase ventilation
* hypoxic drive
56
changes in peripheral chemoreceptors
normal CO2 is 40
normal O2 is 90
57
hypoxic drive with chronic elevated PCO2 levels
seen in emphysema
58
FIO2
* fraction inspired air O2
* 0.21 = 21% (dry) room air
* inhaled air: 0.21 x 760 mmHg = 160 mmHg of O2
* PAO2 = alveolar O2
* PaO2 = O2 dissolved in arteries
59
henry's law
* explains how gases dissolve across alveoli-capillary membrane
* amount of gas absorbed by a liquid is directly proportional to the partial pressure and solubility of the gas in the liquid
* air-liquid interface = alveolar-capillary membrane
* CO2 is 20xs more soluable than O2
* CO2 diffuses across alveolar-capillary membrane faster than O2
60
fick's law of diffusion
* passive exchange of gas between lung and blood/blood and tissues and organs is dependent on
* concentration gradient (changes in partial pressures) of gases
* supplemental O2 changes pressure gradient of alveolus and venous blood
* solubility of the gases (CO2 \> O2) - diffusion constant
* surface area (A) available for diffusion
* membrane thickness
61
gas diffusion and lung
* alveoli provide high SA for gas exchange with pulmonary blood
* average 480 million
62
at rest, there is ____ time for full equilibration of oxygen
* sufficient
* resting conditions: pulmonary capillary blood is in contact with alveolus for about 0.75 seconds total and fully equilibriuated with alveolar oxygen after about 0.25 seconds
63
lung disease ____ diffusion
* impairs
* in exercise: pulmonary blood flow is quicker (less time for gas exchange)
* those with lung disease are unable to oxygenate pulmonary blood fully and thuss have a limited ability to exchange gases
* limits performance and ADLs
64
CO2 diffuses across alveolar-capillary membrane ____ times fast than oxygen
* 20
* so factors are less likely to compromise CO2 transfer from blood to alveoli
65
O2 content of blood (delivered to tissues) is dependent on
* PaO2 (dissolved O2 in blood)
* hemoglobin concentration (Hgb)
also blood flow (CV function)
66
O2 transportation
* 2 forms
* dissolved in plasma (2%)
* reversibly bound to hemoglobin (98%)
67
Bohr effect
* increased CO2 (decreased pH) --\> decreased Hb affinity for O2
* promotes "unloading" (think muscle)
68
oxyhemoglobin dissociation curve
69
CO2 transport (VCO2)
* 3 ways CO2 is transported
* bicarbonate (HCO3-) in RBC and plasma (60%)
* carbaminohemoglobin (30%)
* dissolved gas (10%)
70
haldane effect
* deoxyhemoglobin (after "unloading") can carry more CO2
71
pulmonary circulation pressures
* P system artery \> P pulmonary artery
72
pulmonary circulation
* Q = P/R
* rate of blood flow through pulmonary circulation = flow rate through systemic
* but RV driving pressure is very low (10-15 mmHg)
73
pulmonary vascular resistance (afterload) is
* low
* low capillary hydrostatic pressures produce less net filtration than produced in system capillaries
* lungs are "dry"
74
pulmonary circulation autoregulation
* hypoxic vasoconstriction -- pulmonary arterioles constric when alveolar PO2 decreases (decrease PAO2)
* matches ventilation/perfusion ratio
75
recruitment and distention in responses to increased \_\_\_\_
* cardiac output
* PVR (afterload) remains low even with increase CO
76
distribution of pulmonary blood flow and ventilation
* blood flow and ventilation is greater at the base than at the apex
77
are ventilation and perfusion evenly matched across the lung
* no, under normal circumstances, they are not evenly matched
* Ventilation = V
* Perfusion = Q
78
low V/Q
shunt
V \< Q
79
high V/Q
dead space
Q \< V
80
V = Q
81
perfusion is \_\_\_\_
* regional -- heterogenous
* gravity effect
* cardiac output
* pulmonary vascular resistance (PVR)
* zone I: alveoli \> arterial \> venous
* airflow \> blood flow (dead space)
* zone II: arterial \<\> alveoli \> venous
* airflow \<\> blood flow (mixed)
* zone III: arterial \> venous \> alveoli
* blood fow \> airflow (shunt)
82
ventilation and perfusion
83
blood gas changes with exercise
* SpO2 and PaO2 constant
* pH and PaCO2 down
* mVe = RR x Vt
84
ventilation/perfusion relationships
