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20005 > gas exchange > Flashcards

gas exchange Flashcards

1
Q

what are anabolic reaction

A

actively transporting ions and maintaining gradients

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2
Q

what are catabolic reactions

A

energy from the brake down of large macromolecules releasing energy

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3
Q

what makes ATP

A

ADP+Pi+energy

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4
Q

what to catabolic reactions create

A
  • ATP
  • NADH
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5
Q

what is involved in oxidative phophorylation

A
  • electron transfer from NADH along a chain of molecules
  • O2 is final electron acceptor
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6
Q

how are H+ ions moved

A
  1. redox reaction generate energy, H+ pumped from mitochondrial matric through ATPase
  2. accumulation of H+ in inter membrane space
  3. generates H+ gradient
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7
Q

how is energy stored in the body

A
  • stored as macromolecules
  • ATP can’t be stored so neither can O2
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8
Q

how does partial pressure change affinity for oxygen

A

increase in PP decreases affinity of oxygen to haemoglobin

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9
Q

what is tissue hypoxia

A

when the tissue O2 demand is greater the supply

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10
Q

what are the 4 main mechanisms of tissue hypoxia

A
  1. lack of blood flow
  2. reduced number of Hb
  3. reduced unloading of O2 from Hb
  4. low Hb saturation due to low PaO2
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11
Q

oxygen unloading affinity

A

higher tissue pO2, reduces unloading and lower pO2 enhances unloading

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12
Q

how does oxygen unloading link to CO2

A
  • CO2 has a high affinity for Hb with slow binding
  • CO2 binding to Hb at same site causing O2 displacement
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13
Q

what is henry’s law

A

the amount of gas dissolved in a liquid depends on solubility of that gas in the liquid and pressure of the gas

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14
Q

how does oxygen treatment treat carbon monoxide poisoning

A

100% O2 makes half life of carbon monoxide decrease from 4 hours to 40 minutes

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15
Q

what are the limitations of pulse ox in carbon monoxide poisoning

A
  • HB-O2 and HbCO absorb red light similarly
  • pulse ox overestimate spO2 giving false positives
  • pt is hypoxaemic
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16
Q

what can cause falsely normal or elevated SpO2

A
  • CO poisoning
  • sickle cell anaemia vaso-occlusive crisis
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17
Q

what can cause falsely low SpO2

A
  • venous pulsations
  • excessive movement
  • IV pigmented dyes
  • finger nail polish
  • rare inherited Hb variants
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18
Q

what can cause falsely low or high SpO2

A
  • methemoglobinemia
  • sulfhemoglobinemia
  • poor probe positioning
  • sepsis and septic shock
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19
Q

what are the observations of cynosis

A

bluish colour of lips, tongue, gum, ears, nose, nails, fingers/ feet

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20
Q

what does a low arterial PaO2 show

A
  • low amount of dissolved O2
  • lower Hb-O2 saturation
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21
Q

what are the main mechanisms of low arterial PaO2

A
  • reduced alveolar PaO2
  • diffusion limitation
  • VQ scatter
  • Shunts
22
Q

how does hypoventilation reduce PaO2

A
  • reduced respiratory rate
  • reduced tidal volume
  • increased dead space
  • asphyxiation
23
Q

what is the diffusion limitation

A

rate of O2 diffusion at respiratory membrane is reduced when partial pressure gradient is reduced

24
Q

what factors affect the diffusion rate of O2

A
  • decreased surface area of diffusion
  • increased thickness
25
Q

what happens to diffusion during exersice

A
  • transit time in pulmonary capillaries is decreased
  • increased cardiac output
  • muscle need more O2
26
Q

what happens to diffusion when diffusion rate is reduced

A

longer duration will be required for equilibrium to be reached at rest

27
Q

what is deadspace in relation to VQ scatter

A

areas are better ventilated than perfusied

28
Q

what is shunt in relation to VQ mismatch

A

area are better perfused than they are ventilated

29
Q

how does increased VQ scatter reduce PaO2

A

increase in areas with low VQ decreases O2 content of blood from disassociation curve

30
Q

what is a shunt in gas exchange

A
  • blood not moving to where it is needed to be oxygenated
31
Q

what is the bodies response to supplemental O2 in hypoxemia

A
  • PaO2 needs to be managed and then underlying cause altered
  • high FiO2 needed to raise PaO2 in shunt
32
Q

where is CO2 produced in the cell cycles

A
  • TCA cycle in mitochondria
  • diffuses from cell to blood
  • CO2 binds to Hb releases H+ proton
33
Q

what is the Haldane effect

A

loss of affinity of Hb for CO2 and H+ when PaO2 increases

34
Q

how id CO2 transported from respiring tissue to the lungs

A
  • gas dissolved in plasma
  • bound to proteins
  • as bicarbonate after H2O reaction
35
Q

why are CO2 variations seen slowly

A
  • buffering systems slow it down
  • O2 has a rapid changed in arterial partial pressure
36
Q

what factors affect alveolar CO2

A
  • CO2 output
  • ventilation rate
  • inspired CO2 concentration
  • decreased diffusion capacity
37
Q

what is capnography used for

A
  • alveolar and arterial PCO2
  • look at expired CO2 changes according to phase of respiratory cycle
38
Q

what are the difference capnography phases

A
  1. inspiration and early exhalation
  2. transitional phase
  3. alveolar plateau
  4. inspiratory downslope
39
Q

what regulates ventialtion

A

medullar: dorsal respiratory group and ventral respiratory group

40
Q

what inputs modify ventilation

A
  • voluntary actions
  • involuntary actions
  • chemoreceptor activity
  • muscle and joint receptors
  • lung stretch receptors and lung irritant receptors
  • emotion
41
Q

where is the medullary dorsal respiratory group location

A

bilaterally in and around the nucleus tractus solitarius

42
Q

what activates the medullary dorsal respiratory group

A

neurones activated during inspiration

43
Q

how does the medullary dorsal group work

A
  • projecting to motor neurons in the spinal cord
  • projects to medullary ventral group
  • carry sensory efferent information from peripheral chemoreceptors
44
Q

what is the function of the medullary dorsal respiratory group

A

integration of sensory input to reflex alter the breathing pattern

45
Q

where is the medullary ventral respiratory group located

A
  • bilaterally in discreet regions
46
Q

what is the overall mechanism of the medullary ventral respiratory group

A
  • receives sensory info from DRG
  • has inspiratory and expiratory neurones
  • has interneurons, premotor neurons and motor neurons
47
Q

what is the caudal VRG

A
  • retro-ambigualis - expiratory upper motor neurone decussation
  • para-ambigualis - inspiratory neurones
48
Q

what is the rostral VRG

A
  • airway dilator
  • location of central pattern generator
  • expiratory neurones
49
Q

what is the chemical feedback regulation of ventilaton

A
  1. tigger, decrease O2 increase CO2
  2. sensor activation of peripheral chemoreceptors
  3. chemo sensitive neurones in medulla
  4. medullary respiratory group activated
  5. increased firing on somatic nerves
  6. contraction of primary and secondary respiratory muscle
50
Q

what do carotid chemoreceptors detect

A
  • arterial hypoxaemia
  • low ph
  • increased pCO2
51
Q

what do medullary central chemoreceptors detect

A

drop in ph in cerebrospinal fluid

52
Q

how to palpate accessory skeletal muscle use in respiration

A
  • posterior triangle of neck feel the contraction
  • sternomastoid, thumb and first finger draw back to feel contraction

20005 (29 decks)

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