respiration Flashcards

1
Q

4 variables for respiratory physiology

A

volume, pressure, temperature, motion

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2
Q

what is boyle’s law

A

P is inversely proportional to 1/V

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3
Q

what is the partial pressure of saturated water vapour at 37ºc

A

47mmHg

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4
Q

what does it mean when you say inspired air is saturated with water vapor

A

water vapor is diluting the gases

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5
Q

Pressure and % of O2 in inspired gas

A

21kPa, 21%

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6
Q

partial pressure of O2 when it reaches the alveoli

A

19.9kPa

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7
Q

what is Daltons law of partial pressure

A

pressure exerted by each gas in a mixture of gases is independent of the other gases present

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8
Q

what is the PO2 in arterial blood

A

13.3kPa

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9
Q

what is the PCO2 in arterial blood

A

5.3kPa

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10
Q

what is the PO2 in the alveoli

A

13.3 kPa

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11
Q

what is the PCO2 in the alveoli

A

5.3kPa

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12
Q

what is the PO2 in venous blood

A

5.3kPa

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13
Q

what is the PCO2 in venous blood

A

6.0kPa

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14
Q

what happens during inspiration

A
  1. ribcage expands
  2. lungs stretch
  3. diaphragm moves downwards
  4. alveolar pressure reduced
  5. air drawn in
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15
Q

what happens during in expiration

A
  1. rib cage contracts
  2. lungs contract
  3. diaphragm moves up
  4. alveolar pressure increased
  5. air pushed out
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16
Q

what is PVR

A

pulmonary ventilation rate

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17
Q

PVR equation

A

respiration rate x tidal vol

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18
Q

what is the average PVR during rest

A

6l/min

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19
Q

what is the average PVR during exercise

A

120l/min

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20
Q

what does AVR mean

A

alveolar ventilation rate

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21
Q

what is AVR

A

the actual amount of air reaching the alveoli, to calculate it you need to allow for the ‘wasted’ ventilation of dead spaces

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22
Q

what is perfusion (Q)

A

deoxygenated blood passes through the lungs and becomes re-oxygenated

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23
Q

what is the ventilation perfusion ratio (VA/Q)

A

a ratio of alveolar ventilation to blood flow

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24
Q

ventilation-perfusion ratio in dead space

A

1.normal ventilation but no perfusion
2. no capacity to carry O2 away or bring CO2 to alveoli
3. No gas exchange between the alveoli and the blood so alveoli equilibrates with atmosphere

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25
Q

ventilation-perfusion ratio in shunt

A
  1. no ventilation, normal perfusion
  2. No new O2 in system
  3. alveoli equilibrates with venous blood
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26
Q

what is lung compliance like at high pressure

A

low as lung is stiffer

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27
Q

what part of lung is more compliant, base or apex

A

base

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28
Q

what ensues compliance

A

elastic recoil

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29
Q

how much lung compliance is healthy

A

high

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30
Q

what is tidal volume (TV)

A

vol of air entering and leaving w each normal breath

31
Q

what is inspiratory reserve volume (IRV)

A

extra volume inspired w force over TV

32
Q

what is expiratory reserve volume (ERV)

A

extra volume expired with force over TV

33
Q

what is the vital capacity (VC)

A

TV + IRV + ERV

34
Q

what volumes are measured using spirometry

A

TV, IRV, ERV

35
Q

what is residual volume (RV)

A

volume of air in lungs after the most forceful expiration

36
Q

what is functional residual capacity (FRC)

A

air remaining in lungs after normal expiration

37
Q

what is total lung capacity (TLC)

A

maximum volume of air the lungs can hold

38
Q

FRC equation (V2)

A

V1 x (C1-C2)/C2

39
Q

what is altered if lung expansion is compromised

A

alterations in lung parenchyma

40
Q

what is the effect of pulmonary fibrosis/ scoliosis on FVC and FEV

A

FVC reduced, FEV1.0 is relatively normal

41
Q

effect of obstructive deficit on lungs

A
  1. airway obstruction
  2. narrowed airways
  3. resistance increased in expiration
42
Q

examples of 2 disorders causing obstructive deficit

A

Asthma, Chronic obstructive pulmonary disease

43
Q

how is carbon dioxide transported

A
  1. carbaminohaemoglobin
  2. bicarbonate
44
Q

carbon dioxide transport via carbaminohaemoglobin

A
  1. CO2 binds to globin
  2. reduced Hb has greater affinity for CO2 than oxygenated Hb
  3. O2 unloading allows for CO2 pick up
  4. Hb-CO2 bond is very weak so CO2 easily released to alveoli
45
Q

carbon dioxide transport via bicarbonate

A
  1. CO2 more soluble in H2O than O2 is
  2. reaction leads to acid base balance
46
Q

CO2 reaction in RBCs

A
  1. reacts w H2O to form HCO3- and H+
  2. H+ removed by binding to Hb (HHb)
47
Q

what happens with plasma bicarbonate (CHLORIDE SHIFT)

A

bicarbonate ions diffuse into plasma. Cl- ions diffuse into cell to maintain electrical neutrality (CHLORIDE SHIFT)

48
Q

what causes respiratory acidosis

A

hypoventilation (decrease in respiratory stimuli)

49
Q

what happens in lungs when there is respiratory acidosis

A
  1. decrease in pH
  2. increase in [H+]
  3. increase in CO2
50
Q

how are the effects of respiratory acidosis countered in the kidney

A
  1. increase [H+]
  2. increase HCO3- reabsorption
51
Q

what causes respiratory alkalosis

A

hyperventilation

52
Q

what happens in lungs when there is respiratory alkalosis

A
  1. increase in pH
  2. decrease in [H+]
  3. decrease in CO2
53
Q

how are the effects of respiratory alkalosis countered in the kidney

A
  1. increase [H+]
  2. increase HCO3- excretion
54
Q

what forms in metabolic acidosis

A

ketone bodies -> in uncontrolled diabetes

55
Q

what happens as a result of metabolic acidosis

A
  1. decreased ability of kidneys to excrete H+ and reabsorb HCO3-
  2. decreased pH
  3. decreased HCO3-
56
Q

what compensation happens as a result of metabolic acidosis

A
  1. increased ventilation
  2. increased H+ excretion
  3. increased HCO3- reabsorption
57
Q

what causes metabolic alkalosis

A

nausea, vomiting, diarrhoea, ingestion of a base

58
Q

what happens as a result of metabolic alkalosis

A
  1. decreased acid
  2. increased base
  3. increased pH
  4. increased HCO3-
59
Q

what compensation happens as a result of metabolic alkalosis

A
  1. decreased ventilation
  2. increased H+ reabsorption
  3. increased HCO3- excretion
60
Q

how is ventilation controlled chemically

A

via central chemoreceptors (CCRs) and peripheral chemoreceptors (PCRs)

61
Q

CCRs

A

found in medulla and sensitive to change in [H+] and pCO2

62
Q

PCRs

A

found in carotid arteries and aortic arch, sensitive to changes in arterial pO2 and pH

63
Q

pCO2 levels impact on CCRs

A

directly impact CCRs and activate them causing hyper or hypoventilation

64
Q

what do PCRs detect

A

changes in pO2, decreased arterial O2 leads to hyperventilation (when pO2 is below 13.3 mmHg)

65
Q

what does the medulla have which control ventilation

A

Dorsal respiratory group (DRG) and Venrtal respiratory group (VRG)

66
Q

what is the DRG

A
  1. fibres innervate diaphragm and external intercostal muscles
  2. neurons switch on for 2s and off for 3 to causes rhythmic pattern
67
Q

what is the VRG

A
  1. fibres innervate abdominal muscles and internal intercostal muscles
  2. activity plays role in forced expiration
68
Q

what does the pneumotaxic centre (PONS) do

A
  1. transmits signals to DRG
  2. limits inspiration (inhibitory impulses to DRG)
  3. prevents overinflation of lungs
69
Q

what is the apneustic centre responsible for and what does it stimulate

A

prolonged respiratory gasps, prolongs DRG stimulation

70
Q

vagus nerve role in ventilation

A

sends afferent info from lungs to DRG, switches off inspiration

71
Q

cerebral cortex role in ventilation

A
  1. stimulates motor neurone of inspiratory muscles
  2. bypasses medullary centres when consciously controlling breathing
  3. limited ability to breathhold
72
Q

effects of high altitude

A
  1. hypoxia
  2. loss of appetite
  3. change in mental performance
  4. insomnia
73
Q

adaptations to mild hypoxia

A

increased ventilation, decrease pCO2. This increases CSF pH, increase in HCO3-

74
Q

how do choroid plexus cells correct CSF pH

A

export HCO3- from it