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Respiratory system > Physiology > Flashcards

Physiology Flashcards

1
Q

What is tidal volume?

A

Volume of air breathed in an out of the lungs at each breath
500mL

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2
Q

What is expiratory reserve volume?

A

Max. volume of air which can be expelled from the lungs at the end of a normal expiration
1100mL

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3
Q

What is inspiratory reserve volume?

A

Max. volume of air which can be drawn into the lungs at the end of a normal inspiration
3000mL

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4
Q

What is residual volume?

A

Volume of gas in lungs at end of max. expiration
1200mL

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5
Q

What is vital capacity?

A

Max amount of air that we can voluntarily expire after a maximum inspiration
TV+IRV+ERV=VC
4600

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6
Q

What is total lung capacity?

A

Maximum volume of air the lungs can hold
VC+RV= TLC

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7
Q

What is inspiratory capacity?

A

The volume of air that can be inspired after a normal expiration
TV+IRV=IC

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8
Q

What is functional residual capacity?

A

Volume of air left in the lungs after a normal, passive exhalation
ERV+RSV

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9
Q

What is Boyle’s Law?

A

The pressure exerted by a gas is inversely proportional to its volume

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10
Q

What muscles are used in inspiration?

A

External intercostals
Diaphragm

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11
Q

What muscles are used in expiration?

A

Rest- passive
Severe load- internal intercostals and abdominal muscles

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12
Q

What is Alveolar pressure (Pa)?

A

Pressure inside thoracic cavity
-ve or +ve compared to atmosphere

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13
Q

What is intrapleural pressure (Pip)?

A

Pressure inside pleural cavity
-ve compared to atmosphere

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14
Q

What is transpulmonary pressure (Pt)?

A

Difference between Pa and Pip
Always +ve because Pip is -ve

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15
Q

What are the mechanics of inspiration?

A

Pa< atmospheric pressure so air moves into lungs
Volume of thoracic cage increases making Pip more -ve

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16
Q

What are the mechanics of expiration?

A

Pa> atmospheric pressure so air moves out of the lungs
Volume of thoracic cage decreases making Pip less -ve

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17
Q

What is surface tension?

A

Attraction between water molecules on alveolar surface membrane leading to a natural tendency to recoil

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18
Q

What is surfactant?

A

Detergent like fluid produced by type 2 alveolar cells

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19
Q

What is the function of surfactant?

A

Reduces surface tension thus increasing lung compliance

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20
Q

When is surfactant most effective?

A

Small alveoli because surfactant molecules are closer together

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21
Q

What is compliance?

A

Lung’s ability to stretch and expand, allowing air in

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22
Q

What 3 factors determine lung compliance?

A

Elastic forces
Airway resistance
Surface tension

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23
Q

What is high compliance?

A

Large increase in lung volume for small decrease in Pip
E.g. emphysema

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24
Q

What is low compliance?

A

Small increase in lung volume for large decrease in Pip
E.g. fibrosis

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25
What is pulmonary ventilation?
Total air movement in and out of the lungs TV x RR= 6000ml/min
26
What is alveolar ventilation?
Fresh air getting to alveoli for gas exchange Air to alveoli: TV- dead space= 350 Alveolar ventilation: 350 x RR= 4200ml/min
27
What is anatomical dead space?
Volume of gas occupied by conducting airways 150mL
28
What is the normal alveolar PO2 and PCO2?
pO2= 13.3kPa/ 100mmHg pCO2= 5.3kPa/ 40mmHg
29
What is hyperventilation?
pO2= 120mmHg pCO2= 20mmHg
30
What is hypoventilation?
pO2= 30mmHg pCO2= 100mmHg
31
What happens to alveolar ventilation across the height of the lung?
Declines from base to apex Base- high compliance Apex= less compliance
32
What are the 2 blood supplies to the lungs?
Pulmonary- gas exchange Bronchial- nutrition
33
What is PaO2 and PaCO2?
Arterial partial pressure Reflects lung values PaO2= 100mmHg PaCO2= 40mmHg
34
What is PvO2 and PvCO2?
Mixed venous blood partial pressure Reflects tissue values PvO2= 40mmHg PvCO2= 46mmHg
35
What factors determine rate of diffusion of gases?
Partial pressure gradient Gas solubility Available surface area Membrane thickness Short distance
36
Why does CO2 diffuse quickly despite a poor partial pressure gradient?
CO2 is very soluble in water
37
What are obstructive lung pathologies?
Obstruct airflow - Asthma - COPD: chronic bronchitis, emphysema
38
What are restrictive lung pathologies?
Restriction of expansion - Fibrosis - Oedema - Pneumothorax - Infant respiratory distress syndrome
39
What does spirometry measure?
Lung volumes where RV is not a component
40
What is FEV1/FVC?
FEV1= 4L FVC= 5L FEV1:FVC= 80%
41
What happens to FEV1/FVC in obstructive lung disease?
FEV1= 1.3L FVC= 3.1L FEV1:FVC= 42%
42
What happens to FEV1/FVC in restrictive lung disease?
FEV1= 2.8 FVC= 3.1 FEV1: FVC= 90%
43
What is the distribution of blood flow in the lungs?
Base= high blood flow because Pa>PA. Alveoli compressed Apex= low blood flow because PA> Pa. Arterioles compressed
44
What is V/Q mismatch 1?
Q>V Base of lung
45
What is V/Q mismatch 2?
V>Q Apex of lung
46
What is shunt?
Alveoli are perfused but not ventilated Pulmonary vasoconstriction and bronchial dilation
47
What is alveolar dead space?
Alveoli are ventilated but not perfused Pulmonary vasodilation and bronchial constriction
48
What is physiological dead space?
Alveolar DS+ Anatomical DS
49
How does oxygen travel in the blood?
200ml O2/L whole blood - 3mL O2 dissolved in plasma - 197mL O2 bound to Hb
50
What is haemoglobin's affinity for oxygen?
100mmHg O2= 100% saturation 60mmHg O2= 90% saturation <60mmHg O2= haem groups have lower affinity
51
Why is PO2 normal in anaemia?
Anaemia reduces number of O2 binding sites on Hb but not the saturation so PO2 remains normal
52
What 4 factors affect the oxygen- haemoglobin dissociation curve?
pH PCO2 Temp DPG
53
What causes increased affinity for oxygen?
Shift to left - Rise in pH - Decrease in PCO2 - Decrease in temp - Rise in DPG
54
What causes decreased affinity for oxygen?
Shift to right (Bohr effect) - Fall in pH - Increase in PCO2 - Increase in temp
55
How does CO2 travel in the blood?
7% dissolved in plasma 23% combines with deoxyhaemoglobin to form carbamino compounds 70% combines with water to form carbonic acid which dissociates into HCO3 and H+. HCO3 is exchange for Cl-
56
What are the types of Hb?
HbA- 2 alpha chains, 2 Beta chains HbA2- 4 beta chains HbF- 2 alpha chains, 2 gamma chains Glycosylated Hb
57
Why do HbF and myoglobin have higher affinity for oxygen>
Foetal Hb- extract O2 from maternal blood Myoglobin- extract O2 from arterial blood for skeletal and cardiac muscle
58
What are the 5 types of hypoxia?
Hypoxaemic Anaemic Stagnant Histotoxic Metabolic
59
What nerves control ventilation?
Phrenic nerve- diaphragm Intercostal nerve- external intercostals
60
What are the 2 groups of chemoreceptors?
Central Peripheral
61
What are central chemoreceptors?
In medulla Respond directly to H+ which reflects PCO2 Primary ventilatory drive
62
What are peripheral chemoreceptors?
In carotid and aortic bodies Respond to PO2 and plasma H+ Secondary ventilatory drive
63
What happens to chemoreceptors in chronic lung disease?
PaCO2 becomes chronically elevated, so individuals become desensitised and instead rely on PO2 to stimulate ventilation through peripheral chemoreceptors This is hypoxic drive
64
What happens to H+ in increased ventilation?
H+ decreases Alkalosis
65
What happens to H+ in decreased ventilation?
H+ increases Acidosis

Respiratory system (11 decks)

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