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1MB Respiratory > Physiology > Flashcards

Physiology Flashcards

1
Q

Air flows from a region of ___ pressure to ___ pressure

A

High, low

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2
Q

Intra-alveolar pressure must be greater than atmospheric pressure for air to flow into the lungs. True/False?

A

Intra-alveolar pressure must be less than atmospheric pressure, since air flows from high to low pressure

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3
Q

At constant temp, as the volume of a gas increases, the pressure exerted _____ (Boyle’s Law)

A

Decreases

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4
Q

Before inspiration, intra-alveolar pressure = atmospheric pressure. True/False?

A

True

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5
Q

Which 2 forces hold the lung and thoracic wall in close opposition?

A

Intrapleural fluid cohesiveness
Negative intrapleural pressure

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6
Q

Describe intrapleural fluid cohesiveness

A

Water molecules present in intrapleural fluid are attracted to each other/resist being pulled apart
This causes pleural membranes to stick together

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7
Q

Describe the effect of sub-atmospheric intrapleural pressure

A

Creates a transmural pressure gradient across the lung and chest wall, causing lungs to expand outwards while the chest squeezes inwards (inspiration)

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8
Q

Intra-alveolar pressure = 760
Intrapleural pressure = 756
What happens across the lung wall?

A

Lungs expand outwards

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9
Q

Intrapleural pressure = 756
Atmospheric pressure = 760
What happens across the thoracic wall?

A

Chest squeezes inwards

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10
Q

Contraction of the diaphragm causes the volume of thorax to increase in which direction?

A

Vertically

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11
Q

What is the function of external intercostal muscle in inspiration?

A

Lifts ribs up, pushes out sternum

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12
Q

What is a pneumothorax?

A

Air in the pleural space

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13
Q

What is the function of surfactant?

A

Reduces alveolar surface tension

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14
Q

Smaller alveoli have a greater tendency to collapse. True/False?

A

False
More likely to collapse

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15
Q

What secretes surfactant?

A

Type II alveoli

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16
Q

What cause respiratory distress syndrome in new borns?

A

Not enough surfactant, leading to high alveolar surface tension

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17
Q

Describe alveolar interdependence

A

When one alveoli starts to collapse, surrounding alveoli recoil in resistance, pulling the collapsing alveoli open

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18
Q

What are the 2 main accessory muscles of respiration?

A

Scalenus
Sternocleidomastoid

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19
Q

What is meant by tidal volume?

A

Volume of air entering/leaving the lungs in a single breath

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20
Q

What is meant by inspiratory reserve volume?

A

Volume of air that can be maximally inspired beyond the tidal volume

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21
Q

What is meant by inspiratory capacity?

A

TV + IRV

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22
Q

What is meant by expiratory reserve volume?

A

Volume of air that can be maximally expired beyond the tidal volume

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23
Q

What is meant by residual volume?

A

Volume of air remaining in lungs after maximal expiration

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24
Q

What is meant by functional residual capacity?

A

Volume of air remaining in lungs following normal expiration
ERV + RV

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25
What is meant by vital capacity?
Volume of air that can be maximally expired following maximal inspiration TV + IRV + ERV
26
What is meant by total lung capacity?
Maximum volume of air the lungs can hold VC + RV
27
Residual volume can be measured with a spirometer. True/False?
False
28
What is meant by forced vital capacity?
Volume of air that can be forcefully maximally expired following maximum inspiration
29
In obstructive airways disease, FVC is low and FEV1 is low, but the FEV1/FVC ratio stays the same. True/False?
False FVC is normal/low, FEV1 is low, FEV1/FVC ratio is reduced
30
In restrictive airways disease, FVC is ___ and FEV1 is ___, and the FEV1/FVC ratio is ____
Low, low, normal
31
What is the primary determinant of resistance to airflow?
Radius of the conducting airway
32
Intrapleural pressure falls during expiration. True/False?
False Rises during expiration; falls during inspiration
33
What is meant by dynamic airway compression?
The rising intrapleural pressure during expiration compresses the alveoli and airway
34
What is pulmonary compliance?
How easy/difficult it is to stretch the lungs
35
Low pulmonary compliance means that the lung does not have to work as hard to inflate. True/False?
False Decreased compliance means more effort isrequired to inflate the lungs
36
What is anatomical dead space with regards to airways?
Part of the airways where gas exchange does not occur
37
Pulmonary Ventilation = volume of air breathed in and out per minute = ?
RR x TV
38
Alveolar ventilation is greater than pulmonary ventilation. True/False?
False It is less than pulmonary ventilation due to dead space
39
Blood flow is faster at the top of the lungs. True/False?
False Faster at the bottom
40
V/Q ratio is better at the top of the lungs. True/False?
True
41
Accumulation of CO2 as a result of _____ perfusion leads to _____ airflow (by _____ airflow resistance)
Increased, increased, decreasing
42
Accumulation of O2 as a result of ____ ventilation leads to pulmonary vaso____
Increased, vasodilation
43
The partial pressure of O2 is less than the partial pressure of CO2. True/False?
False
44
What is the diffusion coefficient of a gas?
The solubility of the gas in membranes
45
The diffusion coefficient of CO2 is __ times that of O2
20
46
The amount of gas that will dissolve in a given volume is proportional to the ________ of the gas at equilibrium within the liquid (Henry's Law)
Partial pressure
47
If the partial pressure is increased, less gas will dissolve. True/False?
False More gas will dissolve
48
PO2 is normally ___ mm Hg (___ kPa)
100 mm Hg, 13.3 kPa
49
Most O2 is transported in the blood in the dissolved form. True/False?
False Most is bound to haemoglobin
50
What is the primary determination of haemoglobin O2 saturation?
PO2
51
When the concn of haemoglobin is decreased, what happens to oxygen saturation? Why?
Stays the same Remaining haemoglobin is still fully saturated as PO2 remains the same, but less haemoglobin means there is less oxygen being carried in total - but saturations are normal!
52
Binding of one O2 to haemoglobin increases affinity of Hb for O2. True/False?
True
53
What is the Bohr Effect?
Increased release of O2 from Hb at tissues (sigmoid shifts to right)
54
Where is myoglobin mainly present?
Skeletal and cardiac muscle
55
Presence of myoglobin in the blood indicates what?
Muscle damage
56
What are the 3 methods of CO2 transport in the blood?
Solution As bicarbonate As carbamino compounds
57
Most CO2 is transported in the blood as what?
Bicarbonate
58
Which enzyme catalyses formation of bicarbonate?
Carbonic anhydrase in RBCs
59
What is the Haldane Effect?
Removing O2 from Hb increases Hb's affinity for CO2 and CO2-generated H+ i.e. O2 will be released at tissues; this will increase affinity of Hb for CO2; thus CO2 will be taken up from tissues!
60
Which part of the brain is the main rhythm generator of breathing?
Medulla
61
The breathing rhythm is generated by a group of neurones called the ________
Pre-Botzinger Complex
62
Where is the Pre-Botzinger Complex located?
Upper end of medulla
63
Inspiration is caused by firing of which neurones?
Dorsal respiratory group neurones
64
When are ventral respiratory group neurones fired? What do they excite?
In active expiration (hyperventilation) after increased firing of dorsal respiratory group neurones Excite secondary muscles of respiration
65
The rhythm generated in the medulla can be modified by neurones in what other part of the brain?
Pons
66
What is the function of the Pneumotaxic Centre in the pons?
Inhibits inspiration; stimulated when dorsal respiratory group neurones fire
67
What is the function of the Apneustic Centre in the pons?
Prolong inspiration; impulses from here excite the inspiratory area of the medulla
68
Stretch receptors can influence the respiratory centres in the brain. What do they do and guard against?
Inhibit inspiration Guard against overinflation of lungs
69
Joint receptors influence respiratory centres in the brain, how?
Moving limbs leads to increased breathing
70
What is the function of chemoreceptors?
Sense values of gas/chemical tensions
71
Chemoreceptors which sense tension of O2, CO2 and [H+] in the blood
Peripheral chemoreceptors
72
Where are peripheral chemoreceptors located?
Carotid + aortic bodies
73
Where are central chemoreceptors located?
Near the medulla
74
What separates CSF from blood?
Blood-brain barrier
75
CO2 and [H+] diffuse readily across the blood-brain barrier. True/False?
False Only CO2 diffuses readily
76
Stimulation of peripheral chemoreceptors (by [H+]) causes hypoventilation and CO2 retention. True/False?
False Hyperventilation and CO2 elimination

1MB Respiratory (13 decks)

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