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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
Q

What is pulmonary ventilation?

A

Total air movement in and out of the lungs
TV x RR= 6000ml/min

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26
Q

What is alveolar ventilation?

A

Fresh air getting to alveoli for gas exchange
Air to alveoli: TV- dead space= 350
Alveolar ventilation: 350 x RR= 4200ml/min

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27
Q

What is anatomical dead space?

A

Volume of gas occupied by conducting airways
150mL

28
Q

What is the normal alveolar PO2 and PCO2?

A

pO2= 13.3kPa/ 100mmHg
pCO2= 5.3kPa/ 40mmHg

29
Q

What is hyperventilation?

A

pO2= 120mmHg
pCO2= 20mmHg

30
Q

What is hypoventilation?

A

pO2= 30mmHg
pCO2= 100mmHg

31
Q

What happens to alveolar ventilation across the height of the lung?

A

Declines from base to apex
Base- high compliance
Apex= less compliance

32
Q

What are the 2 blood supplies to the lungs?

A

Pulmonary- gas exchange
Bronchial- nutrition

33
Q

What is PaO2 and PaCO2?

A

Arterial partial pressure
Reflects lung values
PaO2= 100mmHg
PaCO2= 40mmHg

34
Q

What is PvO2 and PvCO2?

A

Mixed venous blood partial pressure
Reflects tissue values
PvO2= 40mmHg
PvCO2= 46mmHg

35
Q

What factors determine rate of diffusion of gases?

A

Partial pressure gradient
Gas solubility
Available surface area
Membrane thickness
Short distance

36
Q

Why does CO2 diffuse quickly despite a poor partial pressure gradient?

A

CO2 is very soluble in water

37
Q

What are obstructive lung pathologies?

A

Obstruct airflow
- Asthma
- COPD: chronic bronchitis, emphysema

38
Q

What are restrictive lung pathologies?

A

Restriction of expansion
- Fibrosis
- Oedema
- Pneumothorax
- Infant respiratory distress syndrome

39
Q

What does spirometry measure?

A

Lung volumes where RV is not a component

40
Q

What is FEV1/FVC?

A

FEV1= 4L
FVC= 5L
FEV1:FVC= 80%

41
Q

What happens to FEV1/FVC in obstructive lung disease?

A

FEV1= 1.3L
FVC= 3.1L
FEV1:FVC= 42%

42
Q

What happens to FEV1/FVC in restrictive lung disease?

A

FEV1= 2.8
FVC= 3.1
FEV1: FVC= 90%

43
Q

What is the distribution of blood flow in the lungs?

A

Base= high blood flow because Pa>PA. Alveoli compressed

Apex= low blood flow because PA> Pa. Arterioles compressed

44
Q

What is V/Q mismatch 1?

A

Q>V
Base of lung

45
Q

What is V/Q mismatch 2?

A

V>Q
Apex of lung

46
Q

What is shunt?

A

Alveoli are perfused but not ventilated
Pulmonary vasoconstriction and bronchial dilation

47
Q

What is alveolar dead space?

A

Alveoli are ventilated but not perfused
Pulmonary vasodilation and bronchial constriction

48
Q

What is physiological dead space?

A

Alveolar DS+ Anatomical DS

49
Q

How does oxygen travel in the blood?

A

200ml O2/L whole blood
- 3mL O2 dissolved in plasma
- 197mL O2 bound to Hb

50
Q

What is haemoglobin’s affinity for oxygen?

A

100mmHg O2= 100% saturation
60mmHg O2= 90% saturation
<60mmHg O2= haem groups have lower affinity

51
Q

Why is PO2 normal in anaemia?

A

Anaemia reduces number of O2 binding sites on Hb but not the saturation so PO2 remains normal

52
Q

What 4 factors affect the oxygen- haemoglobin dissociation curve?

A

pH
PCO2
Temp
DPG

53
Q

What causes increased affinity for oxygen?

A

Shift to left
- Rise in pH
- Decrease in PCO2
- Decrease in temp
- Rise in DPG

54
Q

What causes decreased affinity for oxygen?

A

Shift to right (Bohr effect)
- Fall in pH
- Increase in PCO2
- Increase in temp

55
Q

How does CO2 travel in the blood?

A

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
Q

What are the types of Hb?

A

HbA- 2 alpha chains, 2 Beta chains
HbA2- 4 beta chains
HbF- 2 alpha chains, 2 gamma chains
Glycosylated Hb

57
Q

Why do HbF and myoglobin have higher affinity for oxygen>

A

Foetal Hb- extract O2 from maternal blood
Myoglobin- extract O2 from arterial blood for skeletal and cardiac muscle

58
Q

What are the 5 types of hypoxia?

A

Hypoxaemic
Anaemic
Stagnant
Histotoxic
Metabolic

59
Q

What nerves control ventilation?

A

Phrenic nerve- diaphragm
Intercostal nerve- external intercostals

60
Q

What are the 2 groups of chemoreceptors?

A

Central
Peripheral

61
Q

What are central chemoreceptors?

A

In medulla
Respond directly to H+ which reflects PCO2
Primary ventilatory drive

62
Q

What are peripheral chemoreceptors?

A

In carotid and aortic bodies
Respond to PO2 and plasma H+
Secondary ventilatory drive

63
Q

What happens to chemoreceptors in chronic lung disease?

A

PaCO2 becomes chronically elevated, so individuals become desensitised and instead rely on PO2 to stimulate ventilation through peripheral chemoreceptors
This is hypoxic drive

64
Q

What happens to H+ in increased ventilation?

A

H+ decreases
Alkalosis

65
Q

What happens to H+ in decreased ventilation?

A

H+ increases
Acidosis

Respiratory system (11 decks)

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