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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
What are the forces promoting alveolar collapse?
elasticity of stretched pulmonary connective tissue fibres; alveolar surface tension
26
What is the priamry determinant of airway resistance?
radius of the conducting airway
27
What is dynamic airway compression?
rising pleural pressure during active expiration compresses the alveoli and airway
28
Why does dynamic airway compression cause no problems in normal lungs?
increased airway resistance causes an increase in airway pressure upstream which opens the airways by increased the dirivng pressure
29
What is compliance?
measure of the effort that has to go into stretching or distending the lungs
30
What is the result of less compliant lungs?
more work is needed to produce a given degree of inflation
31
What does the gas exchanger consist of?
alveoli; pulmonary capillaries; interstitial space
32
what are the walls of the alveoli made up of?
type 1 alveolar cells
33
What is the major determinant of the rate of transfer?
partial pressure gradients of oxygen and carbon dioxide
34
Why is approximately equal amounts of CO2 and O2 transferred across the membrane if the partial pressure gradient is smaller for CO2?
diffusion coefficient for CO2 is much higher than O2
35
What is stroke volume?
volume of blood ejected by each ventricle per heart beat
36
What determines the diastolic length of myocardial fibers?
end diastolic volume
37
What determines the end diastolic volume?
venous return
38
What is Frank-Starling curve?
increasing end diastolic volume increases the stroke volume
39
What effect does heart failure on the frank-starling curve?
shifts to the right
40
What is normal PaO2 at pulmonaru arteries?
13.3kPa
41
What is average PO2 at systemic capillaries?
5.3
42
What is the significance of flat upper portions of the haemoglobin curve?
moderate fall in alveolar PO2 will not much affect oxygen loading
43
What is the significance of the steep lower part of the haemoglobin curve?
peripheral tissues get a lot of oxygen for a small drop in capillary PO2
44
What is inspiratory capacity equal to?
inspiratory reserve volume + tidal volume
45
What is functional residual capacity equal to?
residual volume + expiratory reserve volume
46
What is vital capacity equal to?
expiratory reserve volume + inspiratory capacity
47
What is tidal volume?
volume of air entering or leaving lungs during a single breath
48
what is the inspiratory reserve volume?
extra volume of air that can be maximally inspired over and above the typical resting tidal volume
49
What is residual volume?
minimum volume of air remaining in the lungs even after a maximal expiration
50
What is vital capacity?
maximum volume of air that can be moved out during a single breath following maxmial inspiration
51
What is FEV1?
volume of air that can be expired during the first second of expiration
52
What is FEV1 %?
FEV1/FVC
53
What is Henry's Law?
amount of a gas dissolve is proprotional to the partial pressure of the gas
54
What is oxygen delivery index equal to?
oxygen content of arterial blood x cardiac index
55
What is the cardiac index?
relates cardiac output to the body surface are
56
What is the oxygen content of arterial determiend by?
the haemoglobin concentration and the saturation of Hb with O2
57
What does the partial pressure of inspired oxygen depend on?
total pressure (atmospheric ) and proportion of oxygen in gas mixutre
58
What does presure of inspired air equal?
atmospheric pressure-water vapour pressure
59
What is co-operativity?
binding of one O2 to Hb increases the affinity of Hb for O2
60
What is the Bohr effect?
a shift of the curve to the right
61
what effect does increased 2,3-biphsophoglycerate have on the Hb curve?
shifts to the right
62
How many haem groups are there per molecule of myoglobin?
one
63
What is the difference between the Hb and myoglobin curves?
hb curve is sigmoid whereas myoglobin curve is hyperbolic
64
When does myoglobin release O2?
very low PO2
65
What is the function of myoglobin?
provides a short-term storage of O2 for anaerobic conditions
66
What does the presence of myoglobin in the blood indicate?
muscle damage
67
How are cardiac myocytes electrically coupled?
gap junctions
68
What is the function of the desmosomes within the intercalated discs?
provide mechanical adhesion between adjacent cardiac cells- ensure tension is trasmitted
69
How are actin and myocin arranged within myofibrils ?
into sarcomeres
70
What is the thin filament?
actin
71
What is the thick filament?
myosin
72
What ion is required to switch on cross bridge formation?
calcium
73
What is the release of calcium from the sarcoplasmic reticulum dependent on in cardiac muscle?
extra-cellular calcium
74
What is a restrictive pattern of FEV1/FVC%?
>75%
75
What is an obstructive pattern of FEV1/FVC%?
<75%
76
What happens to the compliance of the lungs in emphysema?
increases
77
What happens to the total lung volume in emphysema?
increases
78
why is CO2 less affected than O2 in pulmonary fibrosis?
CO2 diffusion coefficient is much higher so isn't as affected as O2
79
Can functional residual capacity be measured on spirometry?
no- can't measure residual volume
80
What is normal functional residual capacity of a young adult man?
2.2L
81
Why is the partial pressure of oxygen not reduced in anaemia?
partial pressure is a measure of dissolved oxygen
82
Why are patients sat up in heart failure?
fluid goes to the bottom- to help them breathe
83
What is the effect of nitrates?
venodilation to reduce preload to the heart
84
What is the effect of CCBs in heart failure?
depresses the myocardium
85
What medications are patients with heart failure put on?
ACEi; beta blocker; statin; furosemide
86
What is the Cushing's reflex?
hypertension and bradycardia

Transition Block (35 decks)

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