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Exercise Physiology > Chapter 10: Respiration During Exercise > Flashcards

Chapter 10: Respiration During Exercise Flashcards

1
Q

what is the difference between pulmonary respiration and cellular respiration?

A

pulmonary ventilation (breathing): exchange of O2 and CO2 in the lungs
cellular respiration: O2 utilization and CO2 production by the tissues

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2
Q

purposes of the respiratory system during exercise

A

1) gas exchange between the environment and the body
2) regulation of acid-base balance during exercise

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3
Q

how does intrapulmonary pressure and atmospheric pressure compare during inspiration and expiration, respectively?

A

inspiration: intrapulmonary pressure < atmospheric
expiration: intrapulmonary pressure > atmospheric

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4
Q

how does the diaphragm and the volume of the lungs change during inspiration and expiration, respectively?

A

inspiration: diaphragm pushes downward, ribs lift outwards and the volume of the lungs increases
expiration: diaphragm relaxes, ribs pull downward and the volume of the lungs decreases

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5
Q

what is pulmonary ventilation (minute ventilation, Ve, V, MV)?

A

the amount of air moved in or out of the lungs per minute (L/min)

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6
Q

2 factors determining minute ventilation. equation?

A

tidal volume (Vt): amount of air moved per breath (L/breath)
breathing frequency (f): number breaths per minutes (breath/min)
Ve = Vt x f

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7
Q

pulmonary ventilation during rest and during maximal exercise?

A

rest = 7.5 L/min
max exercise = 120-175 L/min

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8
Q

breathing frequency at rest and at maximal exercise?

A

rest = 15 breaths/min
max exercise = 40-50 breaths/min

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9
Q

tidal volume at rest and during maximal exercise?

A

rest = 0.5 L/breath
max exercise = 3-3.5 L/breath

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10
Q

how is ventilation controlled at rest?

A

somatic motor neurons in the spinal cord and the respiratory control center in the medulla oblongata

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11
Q

2 inputs to the respiratory control center

A

neural input and humoral chemoreceptors

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12
Q

what is the neural input that is sent to the respiratory control center?

A

from motor cortex and skeletal muscle mechanoreceptors (stimulate muscle spindles, Golgi tendon organs, joint pressure receptors —> input to the RCC —> increased ventilation)

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13
Q

2 humoral chemoreceptors and their locations

A

central chemoreceptors: medulla
peripheral chemoreceptors: aortic and carotid bodies

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14
Q

what do central chemoreceptors detect change in?

A

PCO2 and H+ concentration in cerebral spinal fluid

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15
Q

what do peripheral chemoreceptors detect change in?

A

PO2, PCO2, H+, and K+ in the blood

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16
Q

primary mediator of ventilation during submaximal exercise

A

neural input

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17
Q

primary mediator of ventilation during maximal exercise?

A

humoral input

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18
Q

describe the pattern of blood flow in pulmonary circulation

A

pulmonary artery receives mixed venous blood from the right ventricle —> oxygenated blood is returned to the left atrium via pulmonary vein

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19
Q

rate of blood flow in pulmonary circuit is equal to __

A

rate of blood flow in the systemic circuit

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20
Q

during resting conditions (standing), where does most of the blood flow specifically go in the lungs? why?

A

base of the lung due to gravitational force

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21
Q

during upright exercise conditions, where in the lung does bloodflow increase?

A

blood flow increases to all parts of the lung; top of the lung (apex)

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22
Q

what does the ventilation/perfusion ratio (V/Q) indicate? ideal value?

A

if the rate of blood flow is matching ventilation
ideal: ~1.0 or above if blood flow is high

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23
Q

how does the V/Q compare at the apex and base of the lungs?

A

apex: (ventilation > blood flow) so underperfused relative to ventilation
base: (ventilation < blood flow) so overperfused relative to ventilation

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24
Q

what is exercise-induced asthma (bronchoconstriction) caused by?

A

contraction of smooth muscle around the airways (bronchospasms) and mucus in the airways during or after exercise

25
Q

symptoms of exercise-induced asthma

A

labored breathing (dyspnea), wheezing sound

26
Q

how common is exercise-induced asthma in elite athletes?

A

> 10% of elite athletes, but doesn’t impair performance if correctly managed

27
Q

describe how asthma affects the V/Q ratio

A

initially, there is reduced alveolar ventilation and excessive perfusion —> V/Q <1 —> decreased PO2 and increased PCO2 in the alveoli —> pulmonary arterioles serving these alveoli constrict —> reduced alveolar ventilation, reduced perfusion

28
Q

describe how a blood clot affects the V/Q ratio

A

initially, there is enhanced alveolar ventilation and inadequate perfusion —> V/Q > 1 —> pulmonary arterioles serving these alveoli dilate —> enhanced alveolar ventilation and enhanced perfusion

29
Q

how does low to moderate intensity exercise affect V/Q ?

A

improves V/Q

30
Q

how does high intensity exercise affect V/Q? why?

A

results in slight V/Q inequality
pulmonary capillary transit time: blood is moving through the capillary too quickly to fully saturate with oxygen

31
Q

99% of O2 transported in the blood is bound to ___

A

hemoglobin

32
Q

3 factors that determine how much O2 can be transported per unit of blood

A

1) Hb concentration
2) arterial oxygen saturation
3) amount dissolved in the plasma (minor contribution)

33
Q

the direction of the following rxn depends on what 2 factors:

deoxyhemoglobin + O2 —> oxyhemoglobin

A

1) PO2 of the blood
2) affinity between Hb and O2

34
Q

what happens to oxyhemoglobin association/ dissociation at the lung?

A

high PO2 —> formation of oxyhemoglobin (“loading”)

35
Q

what happens to oxyhemoglobin dissociation/association at the tissues (eg skeletal muscles)?

A

low PO2 —> release of O2 to tissues (“unloading”)

36
Q

how does pH affect the O2-Hb dissociation curve?

A

decreased pH (more H+ ions) lowers Hb-O2 affinity which results in a rightward shift of the curve & favors “offloading” of O2 to the tissues

37
Q

how does temperature affect the O2-Hb dissociation curve?

A

increased blood temperature lowers Hb-O2 affinity, which results in a “rightward” shift of the curve

38
Q

what is 2-3 DPG?

A

byproduct of RBC glycolysis

39
Q

how does 2-3 DPG affect the O2-Hb dissociation curve?

A

results in a rightward shift of the curve (during altitude exposure, not a major cause of rightward shift during exercise)

40
Q

mechanism of pH affecting O2-Hb dissociation curve

A

intense exercise —> increased blood H+ —> H+ ions bind to Hb —> reduces Hb capacity to transport O2

41
Q

mechanism of temperature affecting the O2-Hb dissociation curve

A

body temp increases during exercise —> increased temp weakens the bond between O2 and Hb —> assists unloading of O2 to working muscle

42
Q

how does arterial and venous O2 content change during exercise?

A

arterial O2 content remains relatively unchanged, (a-v)O2 diff at the tissues increases, so then venous O2 content decreases

43
Q

purpose of myoglobin

A

shuttles O2 from the cell membrane to the mitochondria of skeletal and cardiac muscle fibers

44
Q

how does myoglobin content vary in type I and type IIx fibers?

A

Mb content high in type I and low in type IIx

45
Q

which has a higher affinity for O2: hemoglobin or myoglobin? why?

A

myoglobin, this is important because it “takes” the O2 from Hb at the blood where PO2 is lower

46
Q

how does myoglobin contribute to oxygen deficit and EPOC?

A

during oxygen deficit: myoglobin O2 stores serve as an “O2 reserve” during transition periods from rest to exercise
during EPOC: O2 consumption is above rest in order to replenish the myoglobin O2 stores

47
Q

3 ways CO2 is transported in the blood

A

1) 10% dissolved CO2 in plasma
2) 20% bound to Hb
3) 70% as bicarbonate

48
Q

how does pulmonary ventilation remove H+ from the blood?

A

via the bicarbonate buffering reaction

49
Q

how does increased ventilation affect CO2 concentration?

A

increased ventilation results in CO2 exhalation —> reduces PCO2 and H+ concentration —> pH increases

50
Q

how does decreased ventilation affect CO2 concentration?

A

decreased ventilation results in buildup of CO2 —> increases PCO2 and H+ concentration —> pH decrease

51
Q

how do PO2 and PCO2 change during steady state exercise?

A

remain relatively unchanged

52
Q

how does ventilation change from onset of exercise to steady state?

A

ventilation increases rapidly then there is a slower rise towards steady state

53
Q

how do ventilation and blood gases change during prolonged exercise in hot environments?

A

little change in PCO2; ventilation tends to drift upward

54
Q

why does ventilation increase during prolonged exercise in a hot environment if PCO2 isn’t changing?

A

increased blood temperature affects respiratory control center

55
Q

how does ventilation change during graded exercise?

A

ventilation increases steadily until the ventilatory threshold is reached where ventilation begins to increase exponentially

56
Q

is the pulmonary system seen as a limitation during submaximal exercise?

A

no

57
Q

when might the pulmonary system be seen as a limitation during exercise?

A

in highly trained elite endurance athletes during graded, maximal exercise

58
Q

why might the pulmonary system limit performance in elite athletes at max exercise?

A

mechanical limitations of the lung & respiratory muscles fatigue during prolonged (>120 mins), high intensity (90-100% max) exercise

59
Q

how common is exercise-induced arterial hypoxemia? why does it occur?

A

40-50% of elite athletes; blood is moving too quickly past the lungs to be able to fully saturate with oxygen in the capillaries

Exercise Physiology (25 decks)

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