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Applied physiology > Respiration > Flashcards

Respiration Flashcards

1
Q

Purpose of respiratory system

A

maintain arterial blood-gas homeostasis

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2
Q

Respiratory system 4-step process

A

systemic gas exchange - CO2 into blood
gas transport
alveolar gas exchange - CO2 into alveoli
pulmonary ventilation - into atmosphere

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3
Q

Epiglottis

A

separate upper/lower respiratory tracts

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4
Q

Airways

A

trachea
bronchi
bronchioles
terminal bronchioles
respiratory bronchioles
alveolar ducts
alveolar sacs

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5
Q

Pulmonary gas exchange

A

across pulmonary capillary
diffusion high to low partial pressure

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6
Q

Type I alveolar cell

A

~95% of internal surface of alveolus
critical for gas exchange

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7
Q

Type II alevolar cells

A

release surfactant - a molecule that lowers surface tension
without = collapse

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8
Q

Fick’s law of diffusion

A

volume of gas proportional to surface area/thickness x diffusion coefficient x pressure gradient

proportional

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9
Q

Volume of gas dependent on

A

surface area
thickness
diffusion coefficient
pressure gradient (alveolar to arterial)

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10
Q

Why is the blood-gas barrier ideal for gas exchange?

A

very thin
vast surface

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11
Q

Mechanics of breathing

A

inspiration = volume thoracic activity increases as respiratory muscles contract
bucket hadle motion of ribs = increase lateral diameter of thorax
pump handle motion of ribs = increase anteroposterior diameter of thorax

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12
Q

Muscles of inspiration

A

diaphragm
external intercoastal muscles
scalenes
sternocleidomastoid
= increase pulmonary ventilation

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13
Q

Muscles of expiration

A

rectus abdominis
internal intercostal muscles
external oblique

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14
Q

Measure of diaphragmatic fatigue

A

bilateral phrenic nerve stimulation

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15
Q

Ohm’s law

A

current = voltage/resistance

flow directly proportional to pressure difference
inversely proportional to resistance

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16
Q

Poiseuille’s law

A

resistance dependent upon length and radius of tube

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17
Q

Exercise-induced asthma

A

flow limited during exercise
breath at high lung volume
end expiratory volume = higher at rest
resistance to flow becomes higer

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18
Q

Pulmonary ventilation equation

A

.v = vt x fb

v = volume
.v = volume per unit of time
t = tidal
fb = breathing frequency

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19
Q

Dead space

A

volume of air not particpiating in gas exchange (vd)
150mL in healthy individuals

Va = (vt - vd) x fb

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20
Q

Forced vital capacity

A

max volume air that can be forcefully expired after max inspiration

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21
Q

COPD

A

increased airway resistance
reduced forced vital capacity

sig reduced forced expiratory volume in one sec

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22
Q

Dynamic hyperinflation in COPD

A

increased end-expiratory lung volume
increased work of breathing
increased breathing discomfort

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23
Q

Respiratory muscle fatigue

A

not occur during prolonged heavy exercise

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24
Q

Ventilatory response to constant load steady-state exercise phases:

A

phase 1 - immediate increase in Ve
phase 2 - exponential increase in Ve
phase 3 - plateau - steady state

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25
Hyperpnoea
PaCO2 regulation due to proprtional changes in alveolar ventilation and metabolic rate insert equation
26
Ventilatory threshold
ventilation increases lineraly with exercise intensity until a point (Tvent) ~50-75% VO2 peak after Tvent - ve increase exponentially resting in hyperventilation (decrease PaCO2)
27
Exercise-induced arterial hypoxaemia
50% highly-trained males duirng heavy exercise majority females reduction in PaO2 of >/10 mmHg from rest occur because ventilatory demand exceeds capacity
28
EIAH caused due to:
diffusion limitation V/Q mismatch relative hypoventilation
29
Changes in breathing patterns during exercise
onset exercise - changes Ve achieved by increasing Vt heavy exercise - Vt plateaus and further increase in Ve achieved by fb insert diagram
30
Work equation
work = force x volume total work = sum of elastic, flow-resistive and inertial forces
31
Oesophageal pressure
estimate of pleural pressure used to calculate mechanical work of breathing during exercise
32
Respiratory central pattern generators loacted
within brainstem pons medulla
33
3 main groups of neurons
ventral respiratory group (inspiratory/expiratory) dorsal respiratory group (inspiratory) pontine respiratory group (modulatory)
34
Motor outputs
effectors resistance muscles pump muscles (diaphragm)
35
Feedback inputs
sensors peripheral chemoreceptors central chemorecptors
36
Feedforwards inputs
muscle afferents CO2 flow
37
Peripheral chemoreceptors
detects changes in PO2 of blood perfusing systemic and cerebral circulation located at aortic arch and cartoid body relays sensory info to medulla via vagus nerves decrease PaCO2 = increase Ve temp, adrenaline and CO2 stimulate peripheral chemoreceptors
38
Central chemoreceptors
loacted in ventral surface of medulla (RTN) sensitive to change in PaCO2/H+ of cerebral spinal fluid other areas sensitive - cerebellum
39
Chemoreceptor feedback
Chemoreceptors detect error signals (disturbances to blood- gas homeostasis)  Central and peripheral chemoreceptors respond to increasing PaCO2 or decreasing PaO2 or pH  Premotor neurons in the dorsal respiratory group are activated  Inspiratory muscle contract, increasing ሶ VE  Changes in ሶ VE elicit changes in PaO2, PaCO2 and pH, thus restoring blood-gas balance 
40
Ventilatory response to O2
curvilinear below ~65 mmHg
41
Ventilatory responses to CO2
linear changes in paCO2 elict much greater changes in Ve
42
Ventilatory control during moderate exercise
no change in mean paCO2 = primary stimulus is feedforward in origin central neurogenic peripheral neurogenic peripheral chemoreceptors - fine tune breathing
43
Ventilatory control during heavy exercise
PaCO2 falls = inhibit breathing Tvent metabolites accumulate = stimulate breathing feedforward - central neurogenic, peripheral neurogenic feedback - central chemorecptors, peripheral chemoreceptors increased body temp augmented muscle afferent input
44
Effects of endurance training on respiration
Ve 20-30% lower vs untrained decrease metabolite accumulation decrease afferent feedback decrease ventilatory drive
45
How do lungs adapt to training?
lungs/airways not adapt respiratory muscles stronger/more fatigue resistant maladaptive adaptations = airways hyperresponsivensss in skiers/swimmers
46
Pulmonary system limit max exercise performance?
Exercise-induced arterial hypoxaemia (EIAH)   Exercise-induced laryngeal obstruction (EILO)   Expiratory flow limitation   Respiratory muscle fatigue   Intrathoracic pressure effects on cardiac output  
47
Dalton law
total pressure of gas mixture is equal to some of pressure that each gas would exert independently Pair = Pn2 + Po2 + PCo2
48
Partial pressure of gas
Pgas = Fgas x Pbar 760mmHg sea level
49
Partial pressure of inspired O2 and CO2
159 0.3 mmHg
50
Gas exchange impairment
arterial PO2 (~100mmHg) slighlty less than alveolar PO2 (~105 mmHg)
51
Cellular respiration
O2 consumed and CO2 produced venous PO2 decreased to 40 mmHg venous PCO2 increased to 46 mmHg
52
Pulmonary circulation process
Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs   Gas exchange between the alveoli and pulmonary capillaries occurs   Oxygenated blood is returned to the left atrium via the pulmonary vein   Oxygenated blood is pumped around the systemic circulation to systemic cells  
53
Pulmonary circulation
low pressure low resistance thin walled, little smooth muscle accepts entire cardiac output not redistribute blood flow
54
Pulmonary vascular resistance
decreases during exercise due to recruitment of pulmonary capillaries
55
What does gas exchange require?
matching of ventilation to blood flow ideal V/Q is 1
56
Upright lung
blood flow increases disproportionatly more than ventilation from the top to bottom of lung due to effects of gravity
57
Upon exercise V/Q improves due to
increased tidal volume increased pulmonary artery pressure worsens during heavy exercise
58
How is oxygen carried in the blood?
dissolved (2%) combined with haemoglobin (98%)
59
Henry's law
amount dissolved O2 proportional to partial pressure
60
Haemoglobin
blood chemically bound to haemoglobin transport 4 molecules of O2 amount O2 transported as oxyhaemoglobin dependent upon Hb mass
61
Bohr shift
oxygen dissociation curve right shift due to rise in H+ ions, CO2 and body temp from exercise facilitates unloading of O2 in active tissue
62
Myoglobin
O2 binding protein in muscles high affinity O2 = unloads at very low PO2 shuttles O2 from muscle cell membrane to mitochondria for aeroic respiration provides intramuscular O2 storage
63
How is CO2 carried in the blood?
dissolved (10%) bound to haemoglobin (20%) bicarbonate (70%) 20x more soluble than O2
64
Carbon dioxide transport
HCO3- leaves cell and Cl- moves into cell to maintain neutrality (chloride shift) H+ binds to Hb to form HHb which binds to CO2 to create carboamino Hb most CO2 forms reversable reaction when bound with water CO2 + H2O <-> H2CO3 <-> H+ + HCO3-
65
Ventilation and acid base balance
CO2 + H2O <-> H2CO3 <-> H+ + HCO3- increase in CO2 during exercise = increase in H+ = decrease arterial pH = stimulate breathing via feedback loop
66
How is CO2 transported in arterial blood?
bicarbonate
67
Cartoid bodies
chemoreceptors sensitive to changes in arterial ph, PCO2 and PO2
68
Tidal volume
amount of gas moved per breath
69
FEV1/FVC pulmonary function test
ratio of forced expiratory volume in first second to forced vital capacity of lungs 0.60 = suggestive of airway obstruction normal = 0.75-85
70
Changes in ventilatory patterns during exercise
important to ensure optimal mechanics of breathing are realised to reduced risk of respiratory fatigue increased tidal volume = dead space ventilation remains small
71
Graded exercise test
ventilation during transition from rest to moderate exercise achieved by: increase breathing frequency increase tidal volume
72
Effect on ventilation
small increase arterial PCO2 = greater effect compared to small decrease in PO2
73
Ventilation-perfusion relationship
gas exchange requires a matching of ventilation to blood flow ideal = 1 above 1 = more air than blood below 1 = less air than blood
74
Upright lung
blood flow increases disproportionately more than ventilation from top to bottom of the lungs due to effects of gravity
75
Lungs
enclosed within membranes (pleura) intrapleural pressure < atmospheric pressure = prevent alveoli collapse

Applied physiology (24 decks)

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