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Year 1 MBChB Respiratory > Physiology > Flashcards

Physiology Flashcards

1
Q

What is internal respiration?

A

Gas production by cells

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2
Q

What is external respiration?

A

O2 and CO2 exchange between environment and body cells

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3
Q

What is LaPlace’s Law + how to alter it?

A

Tension on a vessel wall depends on the thickness of the wall + tension is decreased by increasing thickness and vice versa

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4
Q

What is Henry’s Law?

A

PP of a gas is proportional to the amount dissolved in a liquid

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5
Q

What is Boyle’s Law + increased …. means decreased …?

A

PP of a gas is inversely related to its volume + volume and pressure

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6
Q

Normal atmospheric pressure?

A

760 mm Hg

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7
Q

Normal intrapleural pressure?

A

756 mm Hg

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8
Q

Normal intrapulmonary pressures at different breathing stages?

A

760 mm Hg, 759 mmHg then 761 mmHg

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9
Q

What are the main muscles of inspiration and what is their nerve supply?

A

Diaphragm (C3,4,5) and external intercostals (T1-11)

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10
Q

2 ways in which the thorax expands with the lungs?

A
  • Water molecules in pleura resist being pulled apart

- Transmural pressure gradient keeps lungs and thorax separate

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11
Q

Explain the transmural pressure gradient?

A

Intrapulmonary pressure (760) pushes out against the intrapleural pressure (756) + the pressure across the thorax (760) pushes in against the intrapleural pressure (756)

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12
Q

Role of surfactant?

A

Lowers the surface tension of smaller alveoli

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13
Q

What produces surfactant?

A

Type II alveoli (mainly) + component from Club/Clara cells

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14
Q

Explain alveolar interdependence?

A
  • Membranes of outer alveoli are stretched in towards a collapsed alveoli
  • They then recoil and pull the membrane of collapsed alveoli with them
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15
Q

2 key factors that control lung contraction?

A

Elasticity of connective tissue + alveolar surface tension

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16
Q

Is airway resistance low or high in healthy people?

A

Low

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17
Q

What key thing determines airway resistance?

A

Airway radius

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18
Q

Explain how upper airways are kept open during expiration?

A
  • Intraplural presure rises and puts pressure on lower airways
  • Increased pressure upstream keeps airways open
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19
Q

Explain why people with OLDs are prone to a collapsed airway?

A
  • During expiration the increased intrapleural pressure keeps upper airways open
  • In OLDs the pressure gradient is lost over obstruction and airways collapse
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20
Q

What is pulmonary ventilation and how do you calculate it + normal value?

A
  • Volume breathed in/out per min
  • TV X RR
  • 6
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21
Q

What is alveolar ventilation and how do you calculate it + value?

A
  • Volume exchanged between alveoli and atmosphere
  • TV - dead space X RR
  • 4.2
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22
Q

What is the main determinant of pulmonary ventilation?

A

The tidal volume

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23
Q

Is pulmonary or alveolar ventilation the smallest and why?

A

Alveolar due to dead space

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24
Q

What is anatomical dead space?

A

Part of the airway that are non-conducting

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25
Q

What is alveolar dead space?

A

Alveoli that are well ventilated but not perfused

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26
Q

2 variable factors that affect gas exchange at different areas of the lung?

A

Ventilation (V) and perfusion (Q)

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27
Q

Is V/Q mismatch normal?

A

Yes- V/Q normally varies between regions of the lung

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28
Q

Effect of increased O2 on pulmonary vs systemic arterioles?

A

Vasodilation vs vasoconstriction

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29
Q

Effect of decreased O2 on pulmonary vs systemic arterioles?

A

Vasoconstriction vs vasodilation

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30
Q

Forced expiration muscles and their nerve supply?

A

Internal intercostals (T1-11) + abdominal muscles (intercostal nerves)

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31
Q

Forced inspiratory muscles and nerve supply?

A

Sternocleidomastoid + scalenus (both spinal accessory CNXI)

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32
Q

3 main factors affecting alveolar gas exchange?

A
  • PP of a gas
  • Fick’s Law (membrane thickness/area)
  • Diffusion coefficient
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33
Q

Does O2 or CO2 have a greater PP or diffusion coefficient?

A

O2 has greater PP and CO2 has greater diffusion coefficient

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34
Q

Normal tidal volume?

A

500 ml

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35
Q

Normal total lung capacity?

A

57000 ml/5.7 litres

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36
Q

Term for normal volume of air breathed in and out?

A

Tidal volume (VC)

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37
Q

Term for extra forced air breathed in?

A

Inspiratory reserve volume (IRV)

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38
Q

Term for IRV + TV?

A

Inspiratory capacity (IC)

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39
Q

Term for extra forced air breathed out?

A

Expiratory reserve volume (ERV)

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40
Q

Term for volume of air that cannot be expelled from lungs?

A

Residual volume (RV)

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41
Q

Term for ERV + RV?

A

Functional residual capacity (FRC)

42
Q

Term for volume inhaled + exhaled at force?

A

Vital capacity (VC)

43
Q

What 2 things form the total lung capacity?

A

VC + RV

44
Q

Name for pores between alveoli?

A

Pores of Kohn

45
Q

The main determinant of Hb% saturation is?

A

The pO2

46
Q

Oxygen dissociation curve shift to the left means a … in O2 delivered to tissue?

A

Decreased

47
Q

Oxygen dissociation curve shift to the right means a … in O2 delivered to tissue?

A

Increase

48
Q

6 factors that shift the oxygen dissociation curve left?

A

HbF, low CO2, low H, low temperature, low 2,3-DPG and carboxyhaemoglobin (CO)

49
Q

Why does CO shift the oxygen dissociation curve to the left?

A

When CO binds Hb to form carboxyhaemoglobin it increases Hb affinity for O2

50
Q

4 factors that shift the oxygen dissociation curve to the right?

A

High CO2, high H, high temperature and high 2,3-DPG

51
Q

pO2 is determined by O2 dissolved + O2 bound to Hb? True or False?

A

False - pO2 is only determined by O2 dissolved in the blood

52
Q

Explain the Bohr effect and a region of the body it takes place?

A
  • Increased CO2/H decreases Hb affinity for O2 + decreased CO2/H increased Hb affinity for O2
  • Takes place at metabolically active cells when CO2/H displaces O2 from Hb
53
Q

Explain the Haldane effect and a region of the body it takes place?

A

Increased O2 decreases Hb affinity for CO2/H + decreased O2 increases Hb affinity for CO2/H
- Takes place in the lungs when incoming O2 displaces CO2 from Hb so it can be expelled

54
Q

Hb structure + graph shape?

A

2 alpha, 2 beta subunits + sigmoidal curve

55
Q

HbF structure + function?

A

2 alpha, 2 gamma subunits + higher O2 affinity allows foetus to receive O2 even if mother’s pO2 is low

56
Q

Mb structure + function + graph shape?

A

One subunit, short term skeletal/cardiac muscle O2 storage + hyperbolic curve

57
Q

Main 2 factors affecting pO2?

A

Pressure of inspired air (750 mm Hg) + proportion of O2 in inspired air

58
Q

Main way CO2 is transported?

A

As HCO3/bicarbonate

59
Q

10% of CO2 is transported as this?

A

Dissolved CO2

60
Q

30% of CO2 is transported as this + example?

A

Carbamino compunds + carbaminohaemoglobin

61
Q

Give the chemical reaction of CO2 in red blood cells + what happens to the products?

A
  • CO2 + H2O H2CO3 (carbonic acid) HCO3 (bicarbonate) + H

- H is absorbed by Hb and HCO3 leaves the cell via chlorine exchange to buffer the blood

62
Q

How does Hb act as a buffer?

A

Absorbs hydrogen ions

63
Q

Main site of breathing rhythm generation?

A

Pre-Botzinger complex in the medulla

64
Q

Controls normal respiration?

A

Dorsal respiratory group

65
Q

Controls forceful expiration?

A

Ventral respiratory group

66
Q

Controls inhibition of of inspiration + where it is located + what happens if it is damaged?

A

Pneumotaxic centre + in the pons + breathing is in long gasps called apneusis

67
Q

Controls prolonged inspiration?

A

Apneustic centre

68
Q

Important respiratory reflex + function + sensors/control centre?

A

Hering-Breuer + prevents overinflation of the lungs + pulmonary baroreceptors signal to the medulla

69
Q

The PP of which gas controls breathing under normal conditions?

A

PCO2

70
Q

Normal MAP of pulmonary arteries + pulmonary hypertension value?

A

12-20 mm Hg + > 25 mmHg

71
Q

Where are central chemoreceptors found and what do they mainly detect?

A

In the medulla + CO2/H/pH of CSF

72
Q

Where are peripheral chemoreceptors found and what do they mainly detect?

A

In the aortic/carotid bodies + pO2 of arteries

73
Q

Peripheral chemoreceptors drive increased respiration when pO2 falls below?

A

60 mm Hg

74
Q

Can CO2 + H cross the BBB + what this means for arterial changes?

A

Yes + no + central chemoreceptors mainly respond to CSF but if responding to arterial components it can only respond to CO2

75
Q

Enzyme involved in the Hb CO2 reaction?

A

Carbonic anhydrase

76
Q

Target SaO2% in healthy people?

A

94-98%

77
Q

Target SaO2% in people with underlying disease?

A

88-92%

78
Q

SaO2% that requires ABGs to be taken?

A

< 92%

79
Q

Which 2 places is blood taken for an ABG?

A

Radial or femoral artery

80
Q

3 step summary of interpreting an ABG?

A
  • Look at H+ to see if it is alkalosis or acidosis
  • Look at HCO3 and PCO2 and whichever has the biggest change will be the type (metabolic or respiratory)
  • Look to see if there is a change in the value of the other measurements for compensation
81
Q

3 causes of respiratory acidosis?

A

OLDs, RLDs and hypoventilation (many causes)

82
Q

What is FEV1?

A

Volume of forced air expelled in 1 second

83
Q

What is FVC?

A

Total volume of forced air expelled

84
Q

FEV1 of a healthy vs unhealthy person?

A

> 80% vs < 80%

85
Q

FEV1/FVC of a healthy vs unhealthy person?

A

> 0.7 vs < 0.7

86
Q

What is pulmonary compliance + a decreased value means?

A

Effort needed for lungs to stretch and recoil + more effort to inflate

87
Q

OLDs have a …. pulmonary compliance and …. elastic recoil?

A

Increased and decreased

88
Q

RLDs have a …. pulmonary compliance and …. elastic recoil?

A

Decreased and increased

89
Q

Anemic hypoxia is caused by?

A

Less Hb to carry oxygen

90
Q

Circulatory hypoxia is caused by?

A

Reduced blood flow to tissue

91
Q

Hypoxic hypoxia is caused by + example?

A

Low pO2 causing low SaO2% + high altitudes

92
Q

Toxic hypoxia is caused by + 2 examples?

A

Poisoning + CO and cyanide

93
Q

Low value of pO2 and high value of pCO2 that stimulates chemoreceptors ( + which ones) to affect the respiratory centre in the medulla?

A

pO2 < 60 mm Hg (peripheral) and pCO2 > 70-80 (central)

94
Q

VIP and NO released by parasympathetic fibres cause?

A

Smooth muscle relaxation

95
Q

OLDs move the flow volume loop to the left or right + why + shape of top half?

A

Left + air trapping causes increased volume + slope

96
Q

RLDs move the flow volume loop to the left or right + why + shape of loop?

A

Right + reduced lung volume due to fibrosis + smaller version of normal

97
Q

Physiological dead space = …. + …?

A

Anatomical dead space + alveolar dead space

98
Q

Dalton’s law of partial pressures?

A

Total pressure of a gas mixture is the sum of the PPs of the individual gases

99
Q

Sympathetic innervation only affects what 2 things in the airways?

A

Blood vessels and goblet cells

100
Q

Where are M1, M2 and M3 in airways + role?

A

M1 (ganglia) allow rapid Ach action on nicotinic receptors, M2 (postganglionic neurone) inhibit Ach, M3 (SM cell) allow contraction

Year 1 MBChB Respiratory (3 decks)

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