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Physiology > Physiology wk7 > Flashcards

Physiology wk7 Flashcards

1
Q

what is the primary purpose of the respiratory system

A

maintain arterial blood-gas homeostasis

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2
Q

how is arterial blood-gas homeostasis maintained

A
  1. Pulmonary ventilation
  2. Alveolar gas exchange
  3. Gas transport
  4. Systemic gas exchange
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3
Q

what are epiglottis

A

these are what seperates the upper and lower respiratory tracts

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4
Q

what is the membrane surrounding the lungs called

A

pleura

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5
Q

what is special about the pleura

A

intrapleural pressure < atmospheric pressure, and this prevents alveoli from collapsing

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6
Q

how many airway generations are there

A

there are 23

conduction zone:
traechea
bronchi
bronchioles
terminal brinchioles

respiratory zone:
respiratory bronchioles
alevolar ducts
alveolar sacs

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7
Q

where in the bronchi is the conduction zone

A

from the main bronchi (Z1) to the terminal bronchioles (Z16)

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8
Q

where does gas exchange occur in the lungs

A

in the ‘respiratory zone’ (Z17-23)
between respiratpry bronchioles and alveoli sacs

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9
Q

where does pulmonary gas exchange occur

A

pulmonary capillary

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10
Q

how does o2 and co2 move between air and blood

A

through simple diffusion (H to L)

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11
Q

what are the two types of alveolar cell (pneumocytes)

A
  1. Type 1 cells cover 95%, internal surface of the alveolus, critical for gas exchange
  2. type 2 cells release surfactant, this lowers surface tension
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12
Q

what is ficks law of diffusion

A

(surface area / thickness) x diffusion coefficent x (alveolar pressure - arterial pressure)

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13
Q

what are the 5 layers that gas needs to pass to enter blood

A
  1. surfactant
  2. alveolar epithelium - EP
  3. interstitium - IN
  4. capillary endothelium - EN
  5. plasma

SAICP

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14
Q

what are the 3 different mechanics of breathing

A
  • Contraction Length = change in volume
  • Contraction Velocity = change in flow
  • Contraction Force = change in pressure
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15
Q

what is inspiration

A

when the volume of thoracic cavity increases as muscles contract to lower pressure and allow air in

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16
Q

what is the bucket handle motion

A

ribs increases transverse (lateral) diameter of thorax in inspiration (they get wider)

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17
Q

what is the pump handle motion

A

the ribs increases the anteroposterior diameter of the thorax
chest pumps out

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18
Q

what is the diaphragm responsible for at rest

A

pulmonary ventilation (expiration is passive)

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19
Q

what happens to the diaphragm during exercise for inspiration

A

it is assisted by the external intercostal muscles, scalenes, sternocleidomastoid and this increases ventilation 10-20-fold above resting levels

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20
Q

how does expiration become an active process

A

by contraction of the rectus abdominis, internal intercostals and external obliques (RIE)

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21
Q

what is ohm’s law

A

Current = voltage/resistance, applied to breathing
Airflow is dependant upon a pressure gradient and airway resistance

volume per unit of time = (pressure 1 - pressure 2 )/ resistance

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22
Q

what is poiseuille’s law

A

Resistance is dependant upon the length and radius of the tube
Radius is raised to the fourth power, making it the major determinant of airway resistance

resistance = 8nl / (pie x r^4)

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23
Q

what is the formula for volume per unit of time

A

v = tidal volume x breathing freq

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24
Q

what is the formula for alveolar ventilation

A

(tidal volume - dead space) x breathing freq

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25
Q

what is dead space

A

air that doesnt participate in gas exchange, 150ml in healthy personal, doesn’t change during exercise

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26
Q

what are the effects of COPD

A

Higher end expiratory lung volume
Increased work of breathing
Increased breathing discomfort

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27
Q

what do the words volume and capacity refer to when looking at breathing frequency graph

A

volume = one segment
capacity = two segments

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28
Q

The ventilatory response to constant load steady state exercise occurs in 3 phases, what are they

A
  1. Immediate increase in Ventilation
  2. Exponential increase in ventilation
  3. Plateau
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29
Q

what is hyperpnoea

A

PaCO2 regulation due to proportional changes in alveolar ventilation (V^A) and metabolic rate (VCO2)

PaCO2 = (resistance x T? x VCO2) / alveolar ventilation

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30
Q

what happens to ventilation during incremental exercise

A

Ventilation increase linearly with intensity/workload until the ventilatory threshold (lactate/anaerobic threshold), this occurs at 50-75% of peak workload
After the threshold ventilation increases exponentially resulting in hyperventilation

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31
Q

what is exercise induced arterial hypoxaemia (EIAH)

A

reduction in PaO2 of >= 10mmHg from rest, occurs in highly trained males during heavy exercise and majority of females

occurs when ventilatory demand exceeds capacity

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32
Q

what are causes of EIAH

A
  • Limitation of diffusion
  • Volume/cardiac output mismatch
  • Relative hypoventilation
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33
Q

what influences ventilation during onset of exercise

A

ventilation changes are largely chieved by increasing tidal volume

34
Q

what influences ventilation change during heavy exercise

A

tidal volume plateaus and further increases in ventilation are caused by increasing breathing frequency

35
Q

what is the formula for work

A

force x volume (in breathing, work = pressure x volume)

36
Q

what if the formula for total work

A

sum of elastic, flow-resistive and inertial forces

37
Q

what is oesophageal pressure (poes)

A

an estimate of pleural pressure, used to calculate mechanical work of breathing

38
Q

what does the respiratoryy control centre rcc do

A

controls ventilation

39
Q

where are respiratory central pattern generators located

A

within the brainstem (pons and medulla)

40
Q

what are the three main groups of neurons

A
  1. Ventral respiratory group (inspiratory and expiratory)
  2. Dorsal respiratory group (inspiratory)
  3. Pontine respiratory group (modulatory)
41
Q

what is the central controller

A

brainstem (medulla and pons)

42
Q

what are the motor outputs

A
  • resistance muscles (cricoarytenoid)
  • pump muscles (diagram)
43
Q

what are the feedback inputs

A
  • peripheral chemoreceptors,
  • central chemoreceptors
44
Q

what are the feedforward inputs

A
  • muscle afferents (peripheral neurogenic)
  • co2 flow, (peripheral neurogenic)
  • central command (central neurogenic)
45
Q

where are peripheral chemoreceptors located

A

in the aortic arch and cartoid body

46
Q

what do peripheral chemoreceptors do

A

relay sensory information to the medulla via vagus and glossopharyngeal nerves, change in PaO2 = increase in ventilation

47
Q

what stimulates peripheral chemoreceptors

A

temp
adrenalin
co2
o2

48
Q

where are central chemoreceptors located

A

are in the ventral surface of the medulla, known as the retrotrapezoid nucleus (RTN)

49
Q

what is the RTN sensitive to

A

change in paCO2 and h+ io s

50
Q

what does an increase in paCO2 lead to

A

increase in ventilation

51
Q

what is the steps for chemoreceptor feedback

A
  1. detect error signals (disturbance to blood-gas homeostasis)
  2. central and peripheral chemoreceptors increase afferent input to brainstem
  3. premotor neurons in the dorsal respiratory group are activated
  4. inspiratory muscles contract, increase in ventilation
  5. increased ventilation causes changes to: PaO2, PaCO2 and pH.
  6. Blood-gas homeostasis is restored
52
Q

what is the difference between ventilatory response to o2 and co2

A

o2 is curvlinear and co2 is linear

53
Q

what do peripheral chemoreceptors do

A

fine tune breathing

54
Q

what happens during exercise above threshold

A

metabolites accumulate including: H+ and K+ which can stimulate breathing. PaCO2 actually falls and therefore inhibits breathing

55
Q

what chronic trainind adaptions improve aerobic capacity

A
  • Lower metabolite accumulation
  • Lower afferent feedback
  • Lower ventilatory drive
56
Q

what are 5 examples where pulmonary system limits performance

A
  1. Exercise-induced arterial hypoxaemia
  2. Exercise-induced laryngeal obstruction
  3. Expiratory flow limitation
  4. Respiratory muscle fatigue
  5. Intrathoracic pressure effects on cardiac output
57
Q

what is daltons law

A

total pressure of a gas mixture is equal to the sum of pressure that each gas would exert independently

P air = PN^2 + PO2 + PCO2

58
Q

what is the formula for partial pressure

A

Pgas = Fgas x Pbar

59
Q

what are the steps for pulmonary circulation

A
  1. Pulmonary artery carries deoxygenated blood from right ventricle to the lungs
  2. Gas exchange between the alveoli and pulmonary capillaries occurs
  3. Oxygenated blood is returned to the left atrium via the pulmonary vein
  4. Oxygenated blood is pumped around the systemic circulation to systemic cells
60
Q

what are two features that help pulmonary circulation

A

low pressure = low resistance
thin walled little smooth muscle

61
Q

what are the perfect conditions for gas exchange

A

ideal that ventilation matches bloodflow

62
Q

what does underperfused refer to

A

when ventilation is higher than blood flow

63
Q

what does overperfused refer to

A

when blood flow is higher than ventilation

64
Q

why does gas exchange improve during exercise

A

increased tidal volume
increased pulmonary artery pressure

65
Q

in what two forms is o2 carried

A

dissolved - 2
combined with HB - 98

66
Q

what is henrys law

A

amount dissolved is proportional to the partial pressure

67
Q

formula for total conc of o2 within the body

A

1.34 x Hb x saturation/100 + (0.003 x PO2)

68
Q

what is the bohr effect

A

causes a shift to the righ in how much o2 is released into the cells, caused by change in pH, co2 and body temp

69
Q

what is myoglobin and its function

A

o2 binding protein found in skeletal muscles
* Provides intramuscular o2 storage
* Shuttles o2 from muscle cell membrane to mitochondria

70
Q

what are the 3 ways that co2 is carried

A
  1. Dissolved – 10
  2. Bound to Hb – 20
  3. Bicarbonate – 70
71
Q

how does the cell maintain neutrality

A

Hco3- leaves the cell and CL- moves in

72
Q

how is carboamino Hb formed

A

H+ binds to Hb to form HHB which binds to Co2

73
Q

what are the muscles of inspiration

A

diaphragm
external intercostal
scalnes
sternaclosamastoid

74
Q

muscles in expiration

A

rectus abdominis
internal intercostal
external oblique

75
Q

what is the ventillation-perfusion ratio

A

gas exchange requires a matching of ventilation to blood flow

76
Q

what do you want to ventillation-perfusion ratio to be

A

1
>1 = underperfused (more air than blood)
1> = overperfused (less air than blood)

77
Q

why is blood flow lower in the apex (top) than in the base

A

due to gravity it is disproportionate

78
Q

why does the V/Q ratio improve during exercise

A

increased tidal volume
imcreased pulmonary artery pressure

could worsen during high intensity exercise

79
Q

what is the structure of the respiratory system

A

nose
nose cavity
pharynx
larynx
trachea
brochus
brochiole
terminal brochiole

80
Q

what is COPD

A

increased airway resistance and reduced FEV/FVC

Physiology (13 decks)

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