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anatomy 1412 > respiratory physiology > Flashcards

respiratory physiology Flashcards

1
Q

what are the 3 processes in exchange of air

A
  1. pulmonary ventilation
    -inspiration
    -expiration
  2. external respiration
    3, internal respiration
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2
Q

pulmonary ventilation

A

the result of pressure gradients caused by changes in thoracic cavity volume
-boyles law
gas volume is inversely proportional to pressure

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3
Q

what pressures are involved in pulmonary ventilation

A

a. atmospheric pressure
b. intrapulmonary pressure
c. intrapleural pressure

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4
Q

what are the processes of pulmonary ventilation

A

a. quiet inspiration
- active process
at start Patm =P pul, no air moves in
b. forced inspiration
-active process
- diaphragm, external intercostals + sternocledomastoid
- increase volume of thoracic cavity
c. quiet expiration
-relax diaphragm, ext. intercostal
d. forced expiration
- laboured breathing
- relax diaphragm, ext.. intercostals +contract internal intercostals

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5
Q

what happens after no air moves in from Patm=Ppul

A

a. diaphragm contract, increase volume of thoracic cavity
b. lungs resist expansion
c. higher pressure difference between Ppul and Pip pushes lungs out
d. air moves down P gradient

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6
Q

stretch in lungs is determined by:

A

compliance: effort needed to stretch lungs
recoil: ability to return to resting size after stretch

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7
Q

lungs collapsing is prevented by

A

a. Pip is always below Ppul

b. presence of surfactant

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8
Q

respiratory distress syndrome

A
  • newborns < months gestation

- inadequate surfactant

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9
Q

lipoprotein/phospholipid mixture

A
  • in watery film coating alveoli

- allows easier stretch of lungs

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10
Q

F=(triangle)(P)/ R

A

f=air flow
(triangle)(P) = Patm - Ppul
R=airway resistance

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11
Q

how is resistance determined

A

by diameter of bronchi, bronchioles

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12
Q

how is airway resistance effected

A

asthma, bronchitis and emphysema increase airway resistance making it more difficult to expire than to inspire

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13
Q

what opens and closes the airways

A

inspiratory mechanics open airways

expiratory close airways

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14
Q

how are respiratory volumes measured

A

a spirometer

-1 respiration = 1 inspiration + 1 expiration

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15
Q

what are the different volumes in respiratory volumes

A
  1. tidal volume - inspired or expired air during quiet respiration
  2. inspiratory reserve volume - excess air over TV takin in on a max inspiration (~ 3000 ml)
  3. expriatory reserve volume - excess air over TV push out on max expiration (~1200 ml)
  4. residual volume - volume of air in lungs after maximal expiration
  5. minute respiratory volume = TV X respiratory rate
  6. forced expiratory volume in 1 second : volume expires in 1 second with max effort, following mac inspiration
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16
Q

lung capacities

A

2 or more volumes

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17
Q

inspiratory capacity

A

TV+IRV

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18
Q

vital capacity

A

TV+IRV+ERV

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19
Q

total lung capacity

A

max amount of air lungs can hold

20
Q

clinical applications

A

FEV1 is measured while measuring VC +expressed

21
Q

obstructive disorders

A

involve emphysema, asthma, cystic fibrosis

- hard to expire = increase resistance

22
Q

restrictive disorder

A

scoliosis, pneumothorax

  • restrict lung expansion
  • hard to inspire
23
Q

external respiration

A

O2 from alveoli to blood + C02 from blood to alveoli

24
Q

how is external respiration aided by

A

a. thin respiratory membrane
b. large surface area - capillaries, alveoli
c. blood velocity slow compared to gas diffusion (rbc can pick up and release gas)

25
Q

internal respiration

A

O2 from blood to cells + CO2 from cells to blood

26
Q

partial pressure of gases

A

the pressure exerted by a single gas in a mixture of gases

  • e.g. O2 = 21% or air
  • partial P = 0.21 x 760 mm Hg = 160 mmHg
27
Q

what promotes gas movements

A

pressure gradients

e.g. air to blood , blood to cells

28
Q

how is O2 carried

A
  1. dissolved in plasma (1.5%)

2. bound to hemoglobin (98.5%)

29
Q

bound to hemoglobin

A

each hemoglobin can bind 4 O2 molecules

30
Q

dissolved in plasma

A

a, at lung capillaries

  • O2 moves from high pressure to low pressure
    b. at tissue capillaries
  • arterial Po2 = 95mmHg
  • resting venous + ISF Po2 = 40mmHg
31
Q

what is the significance of the O2-Hb dissociation curve

A

a. plateau ( between 60-100 mmHg)
- if aveolar decreases little change in Hb saturation
b. steep portion
- at rest: ISF Po2 in tissues - O2 unloaded from Hb

32
Q

what are the shifts in O2 -Hb dissociation curve

A

a. shift to the right
- for a given Po2 get less Hb saturation i.e. unloads more easily/ loads less easily
b. shift to the left
- for a given P02 get more Hb saturation i.e. O2 loads more easily/unloads less easily

33
Q

when does a shift to the right occur on the O2-Hb dissociation curve

A
  1. increase Pco2
  2. decrease pH
  3. increase temp
  4. all occur when increase of cell metabolism e.g. exercise
34
Q

when does a shift to the left occur in the O2-Hb dissociation curve

A
  1. increase Pco2
  2. higher pH
  3. decrease in temp
    conditions at lung
35
Q

how is CO2 carried

A
  1. dissolved in plasma =8%
  2. bound to hemoglobin =20%
  3. as bicarbonate ions =72%
36
Q

dissolved in plasma

A

a. at the lungs
- alveolar PCO2 = 40 mmHg
- resting venous PCO2 = 45mmHg
- arterial PCO2 = 40 mmHg
b. at tissues
- arterial PCO2 = 4-mmHg
- ICF PCO2 >45 mmHg
- ISFPCO2 =45 mmHg
- resting venous PCO2 = 45 mmHg

37
Q

bound to hemoglobin

A

carbamino Hb = 20%

- CO2 binds to deoxyHb better than to oxyHb

38
Q

as bicarbonate ions

A

72%

a. inside RBC at tissues (increase CO2)
b. inside RBC at lungs

39
Q

control of respiration

A
  1. respiratory centres in medulla
    - set rate, depth of breathing
    - 2 groups of neurons - ventral (VRG) and dorsal (DRG) respiratory groups
    a. VRG = expiratory and inspiratory neurons
    b. DRG receives chemoreceptor input + modifies VRG output
  2. pontine respiratory centres
    - work with medullary centres to make breathing smooth, even
  3. other factors affecting breathing
    a. lung stretch receptors
    b. voluntary control
    c. chemical control
    d. other factors
40
Q

inspiratory neurons

A

impulses down spinal cord to

a. phrenic nerve (innervates diaphragm)
b. thoracic nerves (innervates external intercostals)

41
Q

expiratory neurons

A

fire to inhibit insp. neurons and expiration occurs passively

42
Q

quiet breathing VRG

A
  • insp. neurons active ~ 2 seconds =insp.
  • expir. neurons inhibit inspire. neurons output ~ 3 seconds = expir.
  • VRG also active for forced insp. and expir. to recruit the additional muscles
43
Q

voluntary control

A
  • 1 motor cortex to skeletal muscle - bpass medulla
  • if medulla damaged, must remember to breathe
  • hold breath - PCO2: medulla overrides voluntary control - breathe
44
Q

chemical control (chemoreceptor)

A
  1. peripheral chemoreceptors: carotoid and aortic bodies
    - weakly sensitive to PCO2
    - very sensitive to H+
    - PO2 stimulates receptor when PO2 reaches ~50-60 mmHg- emergency situation
  2. central chemoreceptors - medulla oblongata
    - responds indirectly to arterial PCO2
    - resting arterial PCO2 = 40 mmHg
    - CO2 crosses blood-brain easily H+, HCO3,
    - in CSF
    - only detect H+
    - CSF poorly buffered small change stimulates response
45
Q

clinical application

A
  1. hyperventilation
    - decrease arterial PCO2 leads to cerebral vasocon
  2. hypoventilation
    - increase arterial PCO2, increase H+ =acidosis leads to CNS confusion
  3. CO poisoning
    - CO : incomplete burning of gas, coal, wood, cigarettes
    - CO binds 210x more strongly to Fe than O2

anatomy 1412 (13 decks)

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