Exercise physiology Flashcards
what is cardiac output?
how much blood pumps through the circulatory system in one minute
cardiac output equation
CO = SV x HR
cardiac output = stroke volume (end diastolic volume - end systolic volume) x heart rate (beats/min)
how does the parasympathetic nervous system effect heart rate?
decreases heart rate by acetylcholine
starlings law
the more ventricles fill with the blood the more they contract
whats the effect of increased “preload” on cardiac output?
cardiac output increases
what is afterload?
ventricles contract and push against arterial pressure
describe starlings law (5)
- increased filling pressure stretches heart
- increases force of contraction
- more blood expelled from L.ventricle
- volume that enters ventricle more/less equal to blood that exits
- cardiac output increases when preload increases
how does the structure of blood vessels change as they increase in diameter?
mean wall thickness increases
how is blood distribution controlled? (3)
- vasoconstriction
- vasodilation
- pre-capillary sphincters
vasoconstriction
narrowing of blood vessels when blood vessel’s wall contract
vasodilation
widening of blood vessels when blood vessel’s muscle wall relaxes
mean arteriole pressure equation
MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure)
pre-capillary sphincters
can close of capillaries in response to local signals
how do pre-capillary sphincters work?
- when sphincters relaxed, blood can flows through all capillaries in bed
- when sphincters constrict, blood flow bypasses capillaries and flows through metarterioles
what does the mean arteriole pressure tell us? (2)
- speed of how much the heart is pumping blood may be changing
- average blood pressure in circulatory system
how does the sympathetic nervous system effect the CVS?
releases adrenaline via sino-atrial node (left atrium + left ventricle). Promoting activation increasing heart rate and L.ventricle contraction
how does the parasympathetic nervous system effect the CVS?
signal from vagus nerve releases acetylcholine via sino-atrial node reducing heart rate
what is the haemoglobin saturation at different PO2 levels (3)
- 0mmHg = 0%
- 40mmHg = 75% (resting cell)
- 100mmHg = 98% (alveoli)
how does pH effect haemoglobin oxygen affinity? (2)
- more basic (7.6) - higher oxygen affinity
- more acidic (7.2) - lower oxygen affinity
why is oxygen released more readily in anaerobically respiring skeletal muscle cells?
because they’re accumulating lactic acid, lowering the pH
how does temperature effect haemoglobin oxygen affinity and why does this benefit active tissue? (2)
1.haemoglobin release oxygen more readily in higher temps
2. tissues that are more active produce more heat
how does PCO2 effect haemoglobin oxygen affinity and how does this benefit respiring tissues? (2)
- oxygen disassociates more readily at higher PCO2
- tissues undergoing higher rates of cellular respiration produce more CO2
what 3 factors cause oxygen to disassociate more readily? (3)
- lower pH (more acidic)
- higher temp
- higher PCO2
describe how the body signals for the body to breathe more air (CA) (5)
- carbonic anhydrase - enzyme in red blood cells
- converts CO2 + H20 into bicarbonate ion + H+ ion
- makes blood pH slightly acidic
- lowered pH (as well as elevated CO2 and reduced O2) detected by chemoreceptors - carotid bodies in arteries above aorta
- carotid bodies send signal to medulla in brain -> activates SNS -> increase heart rate + simulate skeletal muscles to increase breathing rate
