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Transition Block > Physiology > Flashcards

Physiology Flashcards

1
Q

What is shortness of breath?

A

subjective awareness of breathing discomfort

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2
Q

Where is the respiratory rhythm generated?

A

medulla

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3
Q

What area modifies the respiration rhythm of the medulla?

A

pons

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4
Q

What is the purpose of the Hering-Breur reflex?

A

guard against hyperinflation- stretch receptors in the bronchi and bronchioles

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5
Q

What stimulates the juxtapulmonary receptors?

A

pulmonary capillary congestion and pulmonary oedema; PE

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6
Q

What is the result of stimulation of the juxtapulmonary receptors?

A

rapid shallow breathing

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7
Q

What factors stimulate the respiratory centres?

A

hypoxia; hypercapnia; acidosis; central arousal eg anxiety; increased body temp; pain; joint movements during exercise

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8
Q

What is the function of the peripheral chemoreceptors?

A

sense tension of oxygen and carbon dioxide and hydrogen in the blood

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9
Q

Where are central chemoreceptors located?

A

near the surface of the medulla

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10
Q

what is the function of the central chemoreceptors?

A

respond to hydrogen in the CSF

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11
Q

What substance readily diffuses across the BBB?

A

carbon dioxide

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12
Q

Why is CSF less buffered than blood?

A

contains less protein

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13
Q

Where does the hypoxic drive of respiration come from?

A

peripheral chemoreceptors

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14
Q

When is hypoxic drive of respiration stimulated?

A

when arterial PaO2 drops below 8kPa

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15
Q

When is hypoxic drive of respiration important?

A

COPD; high altitudes

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16
Q

Which chemorecetpors are invovled in the hydrogen drive of respiration?

A

peripheral chemoreceptors

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17
Q

What is the effect on the central chemoreceptors in hypoxia?

A

directly depresses the central chemorecetpors and repsiratory centre when <8kPa

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18
Q

What is the dominant control of ventilation?

A

increased CO2 in arterial blood

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19
Q

What is the function of the pleura in the ventilatory pump?

A

provides transmural pressure gradient to allow lungs to expand

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20
Q

What are the muscles of active expiration?

A

internal intercostal muscles; abdominal muscles

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21
Q

What are the accessory muscles of inspiration?

A

SCM; scalenus

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22
Q

What are the major muscles of inspiration?

A

external intercostal muscles; diaphragm

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23
Q

What are the 3 pressures important in ventilation?

A

atmospheric pressure; intra-alveolar pressure; intrapleural pressure

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24
Q

What are the forces that keep the alveoli open?

A

transmural pressure gradient; pulmonary surfactant; alveolar interdependence

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25
Q

What are the forces promoting alveolar collapse?

A

elasticity of stretched pulmonary connective tissue fibres; alveolar surface tension

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26
Q

What is the priamry determinant of airway resistance?

A

radius of the conducting airway

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27
Q

What is dynamic airway compression?

A

rising pleural pressure during active expiration compresses the alveoli and airway

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28
Q

Why does dynamic airway compression cause no problems in normal lungs?

A

increased airway resistance causes an increase in airway pressure upstream which opens the airways by increased the dirivng pressure

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29
Q

What is compliance?

A

measure of the effort that has to go into stretching or distending the lungs

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30
Q

What is the result of less compliant lungs?

A

more work is needed to produce a given degree of inflation

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31
Q

What does the gas exchanger consist of?

A

alveoli; pulmonary capillaries; interstitial space

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32
Q

what are the walls of the alveoli made up of?

A

type 1 alveolar cells

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33
Q

What is the major determinant of the rate of transfer?

A

partial pressure gradients of oxygen and carbon dioxide

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34
Q

Why is approximately equal amounts of CO2 and O2 transferred across the membrane if the partial pressure gradient is smaller for CO2?

A

diffusion coefficient for CO2 is much higher than O2

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35
Q

What is stroke volume?

A

volume of blood ejected by each ventricle per heart beat

36
Q

What determines the diastolic length of myocardial fibers?

A

end diastolic volume

37
Q

What determines the end diastolic volume?

A

venous return

38
Q

What is Frank-Starling curve?

A

increasing end diastolic volume increases the stroke volume

39
Q

What effect does heart failure on the frank-starling curve?

A

shifts to the right

40
Q

What is normal PaO2 at pulmonaru arteries?

A

13.3kPa

41
Q

What is average PO2 at systemic capillaries?

A

5.3

42
Q

What is the significance of flat upper portions of the haemoglobin curve?

A

moderate fall in alveolar PO2 will not much affect oxygen loading

43
Q

What is the significance of the steep lower part of the haemoglobin curve?

A

peripheral tissues get a lot of oxygen for a small drop in capillary PO2

44
Q

What is inspiratory capacity equal to?

A

inspiratory reserve volume + tidal volume

45
Q

What is functional residual capacity equal to?

A

residual volume + expiratory reserve volume

46
Q

What is vital capacity equal to?

A

expiratory reserve volume + inspiratory capacity

47
Q

What is tidal volume?

A

volume of air entering or leaving lungs during a single breath

48
Q

what is the inspiratory reserve volume?

A

extra volume of air that can be maximally inspired over and above the typical resting tidal volume

49
Q

What is residual volume?

A

minimum volume of air remaining in the lungs even after a maximal expiration

50
Q

What is vital capacity?

A

maximum volume of air that can be moved out during a single breath following maxmial inspiration

51
Q

What is FEV1?

A

volume of air that can be expired during the first second of expiration

52
Q

What is FEV1 %?

A

FEV1/FVC

53
Q

What is Henry’s Law?

A

amount of a gas dissolve is proprotional to the partial pressure of the gas

54
Q

What is oxygen delivery index equal to?

A

oxygen content of arterial blood x cardiac index

55
Q

What is the cardiac index?

A

relates cardiac output to the body surface are

56
Q

What is the oxygen content of arterial determiend by?

A

the haemoglobin concentration and the saturation of Hb with O2

57
Q

What does the partial pressure of inspired oxygen depend on?

A

total pressure (atmospheric ) and proportion of oxygen in gas mixutre

58
Q

What does presure of inspired air equal?

A

atmospheric pressure-water vapour pressure

59
Q

What is co-operativity?

A

binding of one O2 to Hb increases the affinity of Hb for O2

60
Q

What is the Bohr effect?

A

a shift of the curve to the right

61
Q

what effect does increased 2,3-biphsophoglycerate have on the Hb curve?

A

shifts to the right

62
Q

How many haem groups are there per molecule of myoglobin?

A

one

63
Q

What is the difference between the Hb and myoglobin curves?

A

hb curve is sigmoid whereas myoglobin curve is hyperbolic

64
Q

When does myoglobin release O2?

A

very low PO2

65
Q

What is the function of myoglobin?

A

provides a short-term storage of O2 for anaerobic conditions

66
Q

What does the presence of myoglobin in the blood indicate?

A

muscle damage

67
Q

How are cardiac myocytes electrically coupled?

A

gap junctions

68
Q

What is the function of the desmosomes within the intercalated discs?

A

provide mechanical adhesion between adjacent cardiac cells- ensure tension is trasmitted

69
Q

How are actin and myocin arranged within myofibrils ?

A

into sarcomeres

70
Q

What is the thin filament?

A

actin

71
Q

What is the thick filament?

A

myosin

72
Q

What ion is required to switch on cross bridge formation?

A

calcium

73
Q

What is the release of calcium from the sarcoplasmic reticulum dependent on in cardiac muscle?

A

extra-cellular calcium

74
Q

What is a restrictive pattern of FEV1/FVC%?

A

> 75%

75
Q

What is an obstructive pattern of FEV1/FVC%?

A

<75%

76
Q

What happens to the compliance of the lungs in emphysema?

A

increases

77
Q

What happens to the total lung volume in emphysema?

A

increases

78
Q

why is CO2 less affected than O2 in pulmonary fibrosis?

A

CO2 diffusion coefficient is much higher so isn’t as affected as O2

79
Q

Can functional residual capacity be measured on spirometry?

A

no- can’t measure residual volume

80
Q

What is normal functional residual capacity of a young adult man?

A

2.2L

81
Q

Why is the partial pressure of oxygen not reduced in anaemia?

A

partial pressure is a measure of dissolved oxygen

82
Q

Why are patients sat up in heart failure?

A

fluid goes to the bottom- to help them breathe

83
Q

What is the effect of nitrates?

A

venodilation to reduce preload to the heart

84
Q

What is the effect of CCBs in heart failure?

A

depresses the myocardium

85
Q

What medications are patients with heart failure put on?

A

ACEi; beta blocker; statin; furosemide

86
Q

What is the Cushing’s reflex?

A

hypertension and bradycardia

Transition Block (35 decks)

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