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1
Q

What is the moist inspired Pio2 of a normal healthy dog in Denver, Colorado where the barometric pressure is 640 mmHg? Assume a body temperature of 37 oC.

A

PIO2= (PB-PH2O)*FIO2 PIO2= (640-47)*0.21 = 124.53

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2
Q

Define: Ventilation

A

movement of gas from the environment to gas exchange space; i.e. the lung

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3
Q

What is the driving force behind gas movement?

A

pressure gradient

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4
Q

What are the goals of ventilation?

A

provide oxygen (for metabolism) and remove carbon dioxide

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5
Q

What is the oxygens source/sink?

A

source- environment sink- mitochondria

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6
Q

What is carbon dioxides source/sink?

A

source- mitochondria sink- environment

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7
Q

How is ventilation measured?

A

breathing frequency times tidal volume

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8
Q

You are asked to assist in monitoring the respiratory function of an anesthetized horse. Part of the protocol involves monitoring the CO2 concentration of the expired gas using a CO2 analyzer. What is the estimated PCO2 of the alveolar gas if the analyzer reads 5% CO2 end-tidal sample? Assume you are in the VMTH and the barometric pressure is 765 mmHg, the body temp. of the horse is 38oC and you are measuring dry gas as it enters the analyzer.

A

PCO2= FCO2*(PB) PCO2= (0.05)*(765)= 38.25 mmHg

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9
Q

You are going scuba diving in the Bahamas for spring break. You will be using a Heli-Ox gas mixture containing 20% oxygen and 80% helium. You will be diving at depths equivalent to 3 atmospheric pressures. What will be the moist inspired PO2 at that depth?

A

PIO2= (3PB-PH2O)*0.20 PIO2= ((3*760)-47)*0.20 PIO2= 446.6

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10
Q

Why is intrapleural pressure generally less than atmospheric. What happens to intrapleural pressure during deep inspiration and during a Valsalva maneuver?

A

Two pleural membranes are stuck together with an unexpandable layer of water between them (pleural fluid). The pulling force of the chest wall wanting to expand outward acts against the collapsing force of the lung to create a negative pressure inside the pleural space (-5 cmH2O @ rest = PPL). At rest, pressure in the alveolus is the same as atmospheric, which is zero. However, during inspiration, PA becomes negative allowing atmospheric air to flow into the lungs down the pressure gradient. During deep inspiration pleural pressure becomes more negative as the chest wall expands Valsalva maneuver involves forced expiratory effort with a closed glottis.

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11
Q

What happens to the volume of the lungs and thorax during pneumothorax?

A

lungs collapse (decrease volume), chest volume increases (barrel chested)

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12
Q

What determines the elastic recoil of the lung?

A

lung is a meshwork of connective tissue that is composed of elastic fibers; stretching these elastic fibers from their resting position will create a retracting force; surfactant also contributes

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13
Q

What determines the resting position of the lung-thoracic cavity system?

A

resting position of the lung-thoracic cavity is determined by the balance of the expanding forces of the chest wall and the collapsing forces of the lung (FRC=40)

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14
Q

What happens to this position when there is a decrease in lung elastic recoil such as with emphysema?

A

lungs are less able to contract back to their normal resting position due to an increase in compliance, so resting position of the lungs would be more extended than normal (higher FRC at rest)

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15
Q

Differentiate between anatomical dead space and physiological dead space.

A

Anatomical: volume of all space of the respiratory system besides the alveoli and their closely related gas exchange areas Physiological: when alveoli themselves are non or partially functional because of absent or poor blood flow through adjacent pulmonary capillaries

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16
Q

Use: VT= 450 mL RR= 20 bpm Dead space = 45 mL to determine a) Minute ventilation b) Alveolar ventilation c) Dead space/Tidal volume ratio

A

a) VE= VT*f = (450)(20) = 9000 mL/min = 9 L/min b) VA= (VT-VD)*f = (450-45)*20 = 8100 mL/min = 8.1 L/min c) VD/VT = 45/450 = 1:10

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17
Q

You have performed pulmonary function tests on a dog and have obtained the following data: VT= 350 mL Ppl (end of inspiration) = -2 cmH2O Peak air flow = 0.50 L/sec Airway pressure at peak airflow = 5 cmH2O Determine a) compliance of the lung, CL b) airway resistance, RAW

A

a) must be @ 0 flow for compliance CL = change V/ change PPL CL = 350 mL/2 cmH2O = 175 mL/cmH2O = 0.175 L/cmH2O (normal lung compliance = 0.20 L/cmH2O) b) RAW= change PA/change V = change P airway/change airflow RAW= 5 cmH2O /0.50 L/sec = 10 cmH2O/L/sec

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18
Q

You are asked to examine a Florida panther in your clinic that has been injured. The animal, though restrained, is frightened in your examining room and is in pain. This causes the animal to hyperventilate. What will happen to PAO2 and PACO2 if the minute ventilation doubles

A

PAO2 will increase due to the increase of net inflow of air and O2 PACO2 will decrease because CO2 is removed quicker than can be added to the blood

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19
Q

Define: TLC

A

Total lung capacity TLC = VC + RV TLC = FRC + IC TLC = RV + ERV + IC

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20
Q

Define: FRC

A

Functional residual capacity, resting lung volume FRC = TLC - IC FRC = ERV + RV FRC = (TLC-VC) + ERV

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21
Q

Define: VC

A

Vital capacity, inspiration to maximum capacity VC = TLC - RV VC = IC + ERV

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22
Q

Define: VT

A

Tidal volume, normal breath above FRC Volume of air inspired per breath Units usually in mL

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23
Q

Define: RV

A

Residual volume, volume of air remaining in the lung after full expiration (forced); amount of air left in lungs if lungs are removed from the chest cavity RV = TLC - VC RV = FRC - ERV RV = TLC - (IC+ERV)

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24
Q

Define: ERV

A

expiratory reserve volume, maximal volume of air that can be expired by forceful expiration after the normal tidal expiration ERV = FRC - RV ERV = TLC - (IC+RV)

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25
Diagram of ERV, Vt, VC, RV, FRC, TLC
26
What are the major functions of the respiratory system?
To bring O2 from the atmosphere to the lungs/tissues/mitochondria and to remove CO2 (and other metabolic wastes) from the tissues/mitochondria back to the atmosphere
27
Diagram the structural organization of the tubular system of the mammalian respiratory system.
nasal cavity (mouth) -\> trachea -\> large bronchi -\> small bronchi -\> bronchioles -\> respiratory bronchioles -\> alveolar system
28
How large are alveoli in mammals?
0.20 mm in diameter
29
What is the structure of the alveolar epithelium?
Membranous (Type I) Pneumocytes- squamous, 97% Granular (Type II) Pneumocytes- thicker, produce surfactant Pulmonary Macrophages- within connective tissue septa, lining and lumen
30
What is the relationship between the alveolar epithelium and the pulmonary capillaries?
Site of gas exchange, fused basal lamina and endothelium, diameter is about 5 micrometers so the RBCs touch the wall of the vessel allowing for easy diffusion
31
What is meant by the term "partial pressure of a gas" or "tension of gas"?
Partial pressure of a gas is the fraction of the total pressure of a mixture of gasses that is due to one component of the mixture
32
How is the partial pressure of a gas calculated?
Dalton's Law PCO2 = PB \* FiCO2
33
With which gases are we most concerned with in dealing with respiration and what are their normal partial pressures: a) air b) alveoli c) venous blood d) arterial blood
O2 and CO2 a) PO2- 149 mmHg, PCO2- 0 mmHg b) PO2- 100 mmHg, PCO2- 40 mmHg c) PO2- 40 mmHg, PCO2- 45 mmHg d) PO2- 100 mmHg, PCO2- 40 mmHg
34
What is meant by the "partial pressure of a gas in a liquid"?
Henry's Law At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid
35
Which gas (CO2, O2 or N2) is most soluble in water? How does this aid in it passing membranous barriers?
CO2 is most soluble in water; water readily diffuses through most membranes
36
What is the partial pressure of water in the alveoli?
47 mmHg
37
The inspired air is approximately 21% O2 in a dog that you have in your clinic. If the barometric pressure is 730 mmHg and the water vapor pressure of H2O at 38oC is 50 mmHg, what is the moist inspired PO2?
PO2 = (PB-PH20@38oC)\*FIO2 PO2 = (730-50)\*0.21 PO2 = 142.8
38
What forces are responsible for air movement into and out of the alveoli? What produces these forces?
Forces: Into and out of Alveoli from ATM- pressure gradient Into and out of Blood to Alveoli- concentration gradient Forces into alveoli are caused by the expansion of the thoracic wall which creates the negative pressure within the alveoli to establish a pressure gradient with the ATM Forces out of the alveoli are created by the abdominal muscles and the lung elastic recoil which creates a more positive PA than ATM, driving air out
39
Contrast normal breathing in air with artificial respiration from a pump.
Ventilator creates a positive pressure inside the tubes of the machine Air is forced in down the pressure gradient contraction of the abdominal muscles + collapsing force of the lung create the positive pressure and the air leaves during expiration (active)
40
What muscles provide the work required to change the pressure in the alveoli? Which muscle is most important in mammals?
Inspiration: external intercostals, diaphragm Expiration: internal intercostals, abdominal muscles Most important: diaphragm
41
What characteristics of the lung and chest wall allow passive expiration during quiet breathing?
recoil/elasticity of lung tissue surface tension dome shape of diaphragm
42
What is responsible for the subatmospheric pressure which exists between the parietal and visceral pleura? Why do these membranes adhere to each other?
Thorax is lined with serous membrane (parietal pleura) and outer surface of lung is lined with another serous membrane (visceral pleura) Have conflicting forces acting upon them which creates a negative pleural pressure Thin layer of pleural fluid holds the two layers together (Hydraulic condition)
43
What are the major resistances to breathing?
Elastic resistance- compliance of the lung, tendency of lung to collapse when the volume is above FRC Properties of the tubes- decreasing diameter increases resistance, greater the length the greater the resistance, opposes air moving through them
44
What produces the elastic recoil of the lungs? What is the measure of elastic recoil called?
created by connective tissue network composed of elastic fibers that form a meshwork throughout the lung, stretching these will create a retracting force elastic recoil = compliance C = change V/ change P or slope ratio of lung volume to pressure curve
45
What is surface tension?
force that acts at a gas-liquid interface which tends to reduce the surface area of the interface; net attractive force of a water molecule is toward other molecules of water, with a air-liquid interace, the net attractive force is inward, whic pulls the molecule into the liquid
46
Where does surface tension occur in the lung?
air-alveolar interface
47
How is surface tension in the lung produced?
water molecules along the alveolar surface at the alveolar-air interface are attracted toward each other and away from the air, pulling them closer together and causing a collapsing force around the "bubble" of air
48
How does surface tension influence the alveolus?
surface tension creates a collapsing force that must be overcome by a certain pressure to avoid total collapse of the alveoli
49
What is Laplace's law and how does it relate to the alveolus?
P = 2t/r P= pressure t= wall tension r= radius of alveolus formula for the minimum pressure needed to keep the alveolis from collapsing; small radii=greater tendency to collapse
50
What is a surfactant and how does it work?
substance that works to reduce the air-liquid interface surface tension works by having a hydrophilic end that associates with water and a lipid end that is hydrophobic and associates with the air surface the orientation prevents the interaction of water molecules with air and reduces surface tension
51
What is the surfactant in the alveolus and how does it operate to alter surface tension during inspiration? expiration?
produced by Type II alveolar cells Inspiration: as lung expands, surfactant layer thins and surface tension increases, producing a greater collapsing force with increasing lung expansion Expiration: as lung volume decreases, surfactant layer thickens and surface tension decreases (less collapsing force), which prevents the collapse of the alveoli at low lung volumes
52
What advantages does the variable surface tension of the alveoli have with respect to prevention of alveolar collapse during expiration and with respect to aiding passive expiration?
surfactant layer increases in thickness during expiration, decreasing the collapsing force of surface tension, preventing collapse of alveoli upon inspiration, surfactant layer is spread out more with increasing volume making it less able to combat surface tension; the greater surface tension creates a collapsing force that partakes in passive breathing
53
Distinguish between total minute ventilation and alveolar minute ventilation.
total minute ventilation: total amount of air breathed during respiration in one minute (volume of system breathed in one minute) (L/min) alveolar minute ventilation: amount of air that goes into and out of the alveoli in one minute
54
Define: Respiratory frequency
(f) number of breaths each minute
55
Define: minute ventilation
VE volume of air that enters and leaves the lungs per minute
56
When a large collie was at rest, its minute ventilation was 7.5 L/min and RR of 30 bpm, what was its tidal volume?
VE = VT\*f 7500 mL/min = VT\*30bpm VT=VE/f VT = 7500/30 = 250 mL/breath
57
The tidal volume in a normal human is about 500 mL when at rest. Approximately 350 mL of the tidal volume reaches the alveoli. What is the volume of the dead space in this person?
VD=VT-Vt= 500-350 = 150
58
During exercise, a dog with a respiratory dead space of 25 mL had a tidal volume of 51 mL and a RR of 40 bpm. What is the alveolar ventilation?
Vt=VT-Vd=51-25=26 mL Va=26\*40=1040 mL/min= 1.04 L/min
59
Through what structures does a molecule of O2 pass on its way from the alveolus to the inside of the RBC?
surfactant and fluid -\> alveolar lining cell -\> fused basal lamina of membranous pneumocyte and endothelium -\> endothelial cell -\> blood plasma -\> erythrocyte plasma membrane
60
How long does it take for alveolar PO2 to come to equilibrium with the pulmonary capillary blood?
PO2 equilibrium 0.25 seconds
61
How long does it take a RBC to pass through a pulmonary capillary?
RBC passage 0.75 seconds (transit time)
62
What effect on PO2 of the arterial blood would you expect during exercise if the rate of blood flow through the pulmonary capillaries doubled?
diffusion limited, "safety factor" in transit time which allows for equilibrium to be reached even with increased flow, 2x flow rate would still reach equilibrium
63
What are the factors that determine the diffusion of O2 between the alveoli and blood?
concentration gradient, membrane thickness (x), surface area (A), permeability, solubility (alpha)
64
What are various ways O2 and CO2 are carried by the blood?
O2: dissolved, protein bound CO2: dissolved, protein bound, Bicarbonate (major storage form)
65
What is the relation between the hemoglobin saturation and the partial pressure of O2 in the blood?
hemoglobin saturation increases with increases in PO2 but the relationship is not linear (sigmoid) with the first binding site and the last binding site requiring the greatest change in PO2 for binding to be achieved (PO2 of 60 mmHg has highest affinity of O2 binding hemoglobin)
66
How much O2 is carried by 100 mL of blood in normal man when the PO2 is: a) 600 mmHg? b) 100 mmHg? c) 50 mmHg?
CaO2 = (1.39\*[Hb]\*%Sat)+(0.003\*PO2) a) = (1.39\*15\*1)+(0.003\*600) = 22.65 mLO2/dl b) = (1.39\*15\*0.97)+(0.003\*100) = 20.5245 mLO2/dl c) = (1.39\*15\*0.87)+(0.003\*50) = 18.2895 mLO2/dl
67
What is the relationship between PCO2 and CO2 content in the blood?
directly proportional (CO2 dissociation curve)
68
In hydration of CO2 in the blood, CO2+H2O \<-\>H2CO3, what enzyme is required to accelerate the reaction and where is it located?
carbonic anhydrase, located in the RBC
69
What are buffers in the blood?
Phosphate Bicarbonate Protein (Hemoglobin)
70
How is CO2 transported in the blood? How much of the total CO2 is transported in each form?
Hemoglobin (4%/2.1 mLCO2/dl) Dissolved (6%/2.9 mLCO2/dl) Bicarbonate (90%/42 mLCO2/dl)
71
Which organ system in the body excretes the most acid per day? In what way does it do this?
Respiratory system eliminates CO2 from the body, with every CO2 molecule eliminated by expiration, an H+ is bound to H2O removing it from solution, thus eliminating the acid from the solution
72
Name four conditions which would result in a left shift of the O2-Hb dissociation curve?
Increased pH Decreased CO2 Decreased Temperature Decreased 2,3-DPG
73
List the principle causes of hypoxemia and examples of a clinical situation leading to each?
1) Hypoxic hypoxemia (high altitude) 2) Alveolar hypoventilation (asthma)(marble) 3) Diffusion limitation (pulmonary edema) 4) Shunt (atrial septal defect, horse anesthesia) 5) Partial obstruction (asthma,VA/Q mismatch)
74
Describe the effect that both increased PCO2 and decreased PO2 would have on the output level (minute ventilation) from the respiratory center.
increased PCO2 and decreased PO2 will both cause an increase in minute ventilation and a hypoxic response an increased minute ventilation would allow more CO2 to be blown off (washout) and more O2 to be absorbed through the alveoli by increasing PAO2
75
What are the chemoreceptors that sense blood gas composition? To which variable(s), [H+], PCO2 or PO2 are the chemoreceptors sensitive?
Oxygen: peripheral; carotid bodies- connect to brainstem via CNIX, aortic bodies- connect to brainstem via CNX, sensitive to PO2 Carbon Dioxide: peripheral (same as O2), central- in CNS, inside blood-brain barrier, sensitive to H+ ion by dissociation of CO2 and H2O into H+ and HCO3-
76
What are the sensors provide the CNS with information of the adequacy of lung inflation? How do these receptors affect respiratory drive neurons?
Slowly adapting pulmonary stretch receptors Rapidly adapting receptors Vagal lung C fibers
77
What are the sensors of muscle pump function? What information doe these receptors provide the respiratory control centers?
pg 85/86
78
Where are the groups of respiratory neurons in each side of the brainstem? What are the two pontine centers that help produce normal respiratory rhythm? What do these pontine centers do to the medullary oscillator?
a
79
What is the Hering-Breuer inflation reflex? What are some other reflexes that affect respiration?
a
80
Is this respiratory or olfactory epithelium? List 2 ways to differentiate the two?
Respiratory Contains goblet cells, thinner (respiratory), more regular border
81
Histo2
a
82
Histo3
83
Histo 4
84
Histo 5
a
85
Histo 6
86
Histo 7
87
Histo 8
a
88
Histo 9
89
Histo 10
90
Histo 11
91
Histo 12
92
Histo 14
93
Histo 15
94
Histo16
95
Histo 17
96
Histo 18
97
Histo 19
98
Histo 20
a
99
Lung develop
a
100
Lung development
a
101
What produces the resistance to air flow by the tubular system of the lungs?
102
During what part of the respiratory cycle is resistance the greatest? Least?
Greatest- expiration Least- inspiration
103
What clinical conditions cause an increase in resistance to airflow?
Asthma (blockage; bronchoconstriction)

Respiration (1 decks)

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