Exercise physiology

Question 1

what is cardiac output?

Answer 1

how much blood pumps through the circulatory system in one minute

Question 2

cardiac output equation

Answer 2

CO = SV x HR
cardiac output = stroke volume (end diastolic volume - end systolic volume) x heart rate (beats/min)

Question 3

how does the parasympathetic nervous system effect heart rate?

Answer 3

decreases heart rate by acetylcholine

Question 4

starlings law

Answer 4

the more ventricles fill with the blood the more they contract

Question 5

whats the effect of increased “preload” on cardiac output?

Answer 5

cardiac output increases

Question 6

what is afterload?

Answer 6

ventricles contract and push against arterial pressure

Question 7

describe starlings law (5)

Answer 7

1. increased filling pressure stretches heart
2. increases force of contraction
3. more blood expelled from L.ventricle
4. volume that enters ventricle more/less equal to blood that exits
5. cardiac output increases when preload increases

Question 8

how does the structure of blood vessels change as they increase in diameter?

Answer 8

mean wall thickness increases

Question 9

how is blood distribution controlled? (3)

Answer 9

1. vasoconstriction
2. vasodilation
3. pre-capillary sphincters

Question 10

vasoconstriction

Answer 10

narrowing of blood vessels when blood vessel’s wall contract

Question 10

vasodilation

Answer 10

widening of blood vessels when blood vessel’s muscle wall relaxes

Question 11

mean arteriole pressure equation

Answer 11

MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure)

Question 11

pre-capillary sphincters

Answer 11

can close of capillaries in response to local signals

Question 11

how do pre-capillary sphincters work?

Answer 11

• when sphincters relaxed, blood can flows through all capillaries in bed
• when sphincters constrict, blood flow bypasses capillaries and flows through metarterioles

Question 12

what does the mean arteriole pressure tell us? (2)

Answer 12

1. speed of how much the heart is pumping blood may be changing
2. average blood pressure in circulatory system

Question 13

how does the sympathetic nervous system effect the CVS?

Answer 13

releases adrenaline via sino-atrial node (left atrium + left ventricle). Promoting activation increasing heart rate and L.ventricle contraction

Question 14

how does the parasympathetic nervous system effect the CVS?

Answer 14

signal from vagus nerve releases acetylcholine via sino-atrial node reducing heart rate

Question 15

what is the haemoglobin saturation at different PO2 levels (3)

Answer 15

1. 0mmHg = 0%
2. 40mmHg = 75% (resting cell)
3. 100mmHg = 98% (alveoli)

Question 16

how does pH effect haemoglobin oxygen affinity? (2)

Answer 16

1. more basic (7.6) - higher oxygen affinity
2. more acidic (7.2) - lower oxygen affinity

Question 17

why is oxygen released more readily in anaerobically respiring skeletal muscle cells?

Answer 17

because they’re accumulating lactic acid, lowering the pH

Question 18

how does temperature effect haemoglobin oxygen affinity and why does this benefit active tissue? (2)

Answer 18

1.haemoglobin release oxygen more readily in higher temps
2. tissues that are more active produce more heat

Question 19

how does PCO2 effect haemoglobin oxygen affinity and how does this benefit respiring tissues? (2)

Answer 19

1. oxygen disassociates more readily at higher PCO2
2. tissues undergoing higher rates of cellular respiration produce more CO2

Question 20

what 3 factors cause oxygen to disassociate more readily? (3)

Answer 20

1. lower pH (more acidic)
2. higher temp
3. higher PCO2

Question 21

describe how the body signals for the body to breathe more air (CA) (5)

Answer 21

1. carbonic anhydrase - enzyme in red blood cells
2. converts CO2 + H20 into bicarbonate ion + H+ ion
3. makes blood pH slightly acidic
4. lowered pH (as well as elevated CO2 and reduced O2) detected by chemoreceptors - carotid bodies in arteries above aorta
5. carotid bodies send signal to medulla in brain -> activates SNS -> increase heart rate + simulate skeletal muscles to increase breathing rate