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NPLEX - Physiology > Respiratory physiology > Flashcards

Respiratory physiology Flashcards

1
Q

Where is the medullary respiratory center located?

A

in the reticular formation

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2
Q

Minute ventilation=

A

tidal volume(liters/breath) x frequency (breaths/minute)

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3
Q

What happens to physiologic dead space during exercise?

A

it decreases

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4
Q

What is the Bohr effect?

A

in the peripheral tissue, increased H+ shifts the dissociation curve to the right unloading O2

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5
Q

Where are the central chemoreceptors for breathing and what stimuli increase breathing rate?

A

medulla; decreased pH (or increased CO2 which combines with water to make H+) of CSF

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6
Q

Under what conditions does 2,3-BPG accumulate? What is the effect of 2,3-BPG on hemoglobin A?

A

low oxygen conditions. this will cause a right shift in HbA. 2,3 BPG binds to the beta subunit of Hb and thus lowering the affinity of oxygen for Hemoglobin (to release this oxygen to other tissues)

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7
Q

What is the pressure of alveolar O2 and CO2

A

PO2=100mmHg; PCO2=40mmHg

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8
Q

What is V/Q at the base of the lung?

A

V/Q = 0.6 (wasted perfusion)

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9
Q

Where is the major site of airway resistance?

A

medium-sized bronchi

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10
Q

What is the composition of fetal Hb and how are its properties different from adult Hb?

A

composition: 2 alpha and 2 gamma chains; this causes a left-shift in the saturation curve resulting in increased affinity for O2 due to decreased affinity to 2,3-DPG

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11
Q

Ventilation of alveoli without perfusion is called ____.

A

dead space

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12
Q

In the pleural cavity, oncotic pressure favors the movement of fluid (into/out of) the pleural space.

A

out of

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13
Q

A failure of gas exchange manifests as (hypoxemia/hypercapnea) while a feailure of the respiratory pump manifests as (hypoxemia/hypercapnea).

A

hypoxemia; hypercapnea

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14
Q

Does hyperventilation result in respiratory alkalosis or acidosis?

A

respiratory alkalosis

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15
Q

Factors that shift oxygen dissociation curve to the left(8)`

A

CO2, low 2,3-BPG, hypothermia, alkalosis, HbF, methemoglobin, carbon monoxide, stored blood

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16
Q

What is the inspiratory reserve volume (IRV)?

A

air in excess of tidal volume that moves into lung on max inspiration

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17
Q

V/Q»1 is known as ___

A

dead space

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18
Q

Compare the amount of physiological and anatomical dead space in the healthy individual.

A

they are nearly equal. Lung diseases tend to increase the physiological dead space.

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19
Q

At the base of the lung, there is greater ventilation, perfusion, or both?

A

both are greater

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20
Q

CO2 transport: CO2 is transported form tissue to lungs in these 3 forms: ____

A
  1. bicarbonate
  2. bound to hemoglobin
  3. dissolved CO2
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21
Q

Vital capacity is everything except?

A

residual volume

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22
Q

What increases physiologic dead space? (4)

A

tumors, pneumonia, infection, fluid in lungs, anything that reduces surface area for gas exchange

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23
Q

What is the formula for inspiratory capacity(IC)?

A

IRV+TV

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24
Q

What is the ideal V/Q ratio?

A

V/Q= 1 (permits adequate oxgenation)

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25
Q

What is the formula for total lung capacity (TLC)?

A

IRV+TV+ERV+RV

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26
Q

At what point in the breathing cycle is alveolar pressure equal to zero?

A

at FRC, just before inspiration

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27
Q

In normal health, is O2 perfusion or diffusion limited?

A

perfusion - gas equilibrates along the length of the capillary

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28
Q

In the pleural cavity, hydrostatic pressure favors the movement of fluid (into/out of) the pleural space.

A

into

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29
Q

Does surfactant increase or decrease recoil? surface tension? compliance?

A

lowers lung recoil
lowers surface tension
increases compliance

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30
Q

In the oxygen-hemoglobin dissociation curve, what is a right shift?

A

this is a decreased affinity of hemoglobin for O2 and facilitates unloading of O2 to the tissue

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31
Q

V/Q= is known as a ____.

A

shunt

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32
Q

What is the formula for total lung capacity (TLC)

A

TLC=IRV+TV+ERV+RV

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33
Q

What is the normal V/Q ratio?

A

0.8

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34
Q

Central chemoreceptors (in brain) respond to ___ and ___ but do not directly respond to ____.

A

pH; pCO2; pO2

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35
Q

Lungs are elastic. The elastins and collagens in the interstitium causes lungs to ____ when expanded.

A

recoil

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36
Q

What is V/Q at the apex of the lung?

A

V/Q=3(wasted ventilation)

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37
Q

Factors that shift oxygen dissociation curve to the right. (4)

A

CO2, high 2,3-BPG, fever, acidosis

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38
Q

List the inspiratory muscles used during forced inspiration.

A

pectoris minor, SCM, scalenes

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39
Q

What is the functional reserve capacity (FRC)?

A

RV+ERV (volume in lungs after normal espiration)

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40
Q

CO2 transport: What is the Haidane effect?

A

oxygenation of hemoglobin promotes the dissociation of CO2 from hemoglobin

41
Q

T/F: Pulmonary circulation is normally a low-resistance, low-compliance system

A

false- low-resistance, high-compliance

42
Q

Normal pleural fluid is becarbonate (rich/poor) and protein (rich/poor)

A

bicarbonate-rich

protein-poor

43
Q

What molecule causes off-loading of O2 from Hb in tissues?

A

2,3 -diphosphoglycerate

44
Q

Distinguish tachypnea from hyperpnea from hyperventilation.

A

tachypnea=fast rate of breathing (>20/min) for whatever reason.
hyperpnea= increased ventilation that meets a metabolic need (fever, post-exercise etc)
hyperventilation= increased ventilation that exceeds metbolic need, often producing symptoms diziness, paesthesia, etc.)

45
Q

Obstructive lung disease involved increased lung _____, restrictive lung disease involves decreased lung _____.

A

resistance; compliance

46
Q

Where is surfactant produced?

A

type II alveolar cells

47
Q

Define the ‘residual volume’ (RV)

A

air in lung at max expiration

48
Q

What is a normal respiratory rate at rest?

A

12-14 breaths/min

49
Q

What is the tidal volume(TV)?

A

air that moves into lung with each quiet inspiration (nl=500ml)

50
Q

What is the formula for inspiratory capacity (IC)?

A

IC= IRV+TV

51
Q

Thorax is elastic which cause chest to expand and oppose the recoil of lungs. What structure(s) contribute to this elasticity?

A

costal cartilages

52
Q

What are physiologic adaptations in high altitude? (7)

A

alveolar P(O2) is decreased, arterial P(O2) is decreased (hypoxemia), hyperventilation, respiratory alkalosis, increased EPO, increased 2,3-DPG hypoxic pulmonary vasoconstriction

53
Q

Respiratory acidosis-2 causes

A

HYPERventilation, aspirin ingestion (early)

54
Q

What are the four mechanisms of hypoxemia?

A

hypoventilation, V/Q mismatch, shunt, low inspired pO2

55
Q

Is hypo or hyperventilation the copensatory response to alkalosis?

A

hypoventialtion

56
Q

Which of the following is diffusion limited CO2, N2O, or CO?

A

CO-gas does not equilibrate by the time the blood reaches the end of the capillary

57
Q

How does resistance change with radius?

A

resistance=1/r4. As radius decreases, resistance increases.

58
Q

When does a human embryo start to produce surfactant?

A

at seven months.

59
Q

Oxygen-hemoglobin dissociation curve: A right shift is caused by an increase or decrease in each of the following factors; P50, metabolic needs, PCO2, temperature, H+, pH, altitude, and 2,3 -DPG

A

increase in all but pH

60
Q

What is the relationship between compliance and elasticity?

A

inversely related

61
Q

What limits gas exchange in pulmonary capillaries normally? HOw does this change during exercise?

A

perfusion normally. becomes diffusion limited during strenuous exercise.

62
Q

What happens to the mean values of arterial P(O2) and P(CO2) during exercise?

A

they do not change

63
Q

What is the formula for vital capacity (VC)?

A

TV+IRV+ERV

64
Q

V/Q= 0 implies what serious problem?

A

airway obstruction (shunt)

65
Q

The apices of the lungs receive better _____ while the bases of the lungs receive better _____.

A

ventilation; circulation

66
Q

ACh _____ airway resistance, catecholamines ______ resistance.

A

increases (bronchoconstricution); decreases (bronchodialtion)

67
Q

What does surfactant do? What is surfactant? What makes surfactant?

A

it decreases alveolar surface tension which increases compliance. It is made of dipalmitoyl phosphatidylcholine (lecithin) and it is produced by type II pneumocytes

68
Q

CO2 transport: What percentage of CO2 is transported in the form of bicarbonate?

A

0.9

69
Q

Oxygen-hemoglobin dissociation curve: Decreased affinity of hemoglobin for O2=shift_____.

A

right

70
Q

Which binding site of Hb has the highest affinity for O2? Why is this important?

A

the fourth binding site–> it allows maximal loading of O2 in the lungs and unloading in the tissues

71
Q

In asthma, FEV1 is _____ and FEVf1/FVC is _____.

A

reduced; reduced

72
Q

In emphysema, FEV1 is ___ and FEV1/FVC is ____.

A

reduced; reduced

73
Q

T/F: It is possible for a patient to hypoventilate and at the same time to be suffering from tachypnea

A

true

74
Q

What is the intracellular enzyme that converts CO2 into H2CO3?

A

carbonic anhydrase

75
Q

List the expiratory muscles used during forced expiration.

A

internal intercostals, obliques, rectus abdominus

76
Q

H2CO3 is broken down into H+ and HCO3. What happens to the HCO3?

A

HCO3 is pumped out of the red blood cell in exchange for Cl-

77
Q

Organisms such as TB that thrive in high O2 flourish in the apex or base of the lung?

A

apex

78
Q

What is the main drive for ventilation?

A

H+ ions from dissociated H2CO3 which stimulate central chemoreceptors.

79
Q

Cor pulmonale and subsequent RV failure are a consequence of pulmonary ____.

A

hypertension

80
Q

What happens in restrictive lung disease to TLC, RV FRC, FEV1, FVC and FEV1/FVC?

A

reduction in TLC, FRC, and RV. A reduction in FEV1 and FVC with a normal or increased FEV1/FVC ratio suggests a restrictive pattern

81
Q

What is the formula for vital capacity (VC)?

A

VC=TV+IRV+ERV

82
Q

What is lung compliance? How is compliance altered in emphysema? In fibrosis?

A

it’s the change in volume with a change in pressure. Increased compliance means more air flows in with a given change in pressure. Decreased compliance means the opposite. Emphysema=very compliant; fibrosis=not compliant

83
Q

What is the normal value of FEV1/FVC?

A

70%-80%

84
Q

Where are the peripheral chemoreceptors for breathing and what stimuli increase breathing rate? (3)

A

carotid and aortic bodies; decreased P(O2) (if less than 60mmHg), decreased pH, increased P(CO2)

85
Q

When is O2 diffusion limited? (3)

A

exercise, emphysema, fibrosis

86
Q

What is the expiratory reserve volume (ERV)?

A

air that can still be breathed out after normal expiration

87
Q

List the inspiratory muscles responsible for normal breathing.

A

diaphragm and external intercostals

88
Q

Oxygen-hemoglobin dissociation curve; Fetal Hb curve is shifted toward the ____.

A

left (increased affinity for O2)

89
Q

What is the action of 2,3 -DPG on hemoglobin?

A

binds to hemaglobin so that hemoglobin releases more 02

90
Q

During exercise (increased cardiac output), the vessels in the apex of the lung___ so that V/Q approaches ___.

A

vasodilate such that V/Q approaches 1 (versus normal apex V/Q of 3)

91
Q

What pathologic process has a deficiency of surfactant?

A

neonatal RDS (Respiratory distress syndrome)

92
Q

How is CO2 carried in the blood? (3)

A

5% dissolved; 5% attached to Hb; 90% as bicarbonate

93
Q

Name the five factors that cause a right shift?

A

high CO2, high acid/altitude, high DPG (2,3-DPG), exercise and increased temperature

94
Q

What determines oxygen content? What determines PO2?

A

hemoglobin concentration determines content (1.34ml O2 combines with each gram of hemoglobin). Amount of oxygen dissolved in plasma determines PO2 (0.3ml O2 per 100ml plasma).

95
Q

What are the peripheral chemoreceptors for breathing and what stimuli increase breathing rate?

A

carotid and aortic bodies; decreased P(O2) (if less than 60mmHg), decreased pH, increased P(CO2)

96
Q

T/F: Pleural pressure is always lower than alveolar pressure under normal conditions.

A

true

97
Q

What is an easy way to clinically differentiate between a shunt and a V/Q mismatch?

A

administer 100% O2. If patient has a shunt, pO2 won’t respond. If patient has V/Q mismatch, pO2 will increase.

98
Q

In pulmonary fibrosis, FVC is _____.

A

reduced

99
Q

Increased anion Gap-4 causes

A

renal failure, lactic acidosis, ketoacidosis, aspirin ingestions

NPLEX - Physiology (10 decks)

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