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Flashcards about the cardiovascular system during exercise and recovery, covering heart rate (HR), stroke volume (SV), cardiac output (Q), and vascular shunt mechanism.
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What causes the anticipatory rise in heart rate?
Occurs before exercise due to adrenalin.
Why does heart rate increase rapidly at the start of exercise?
To cope with the increased demand for oxygen from muscles.
What are the 5 stages of heart rate change during exercise and recovery?
Anticipatory rise, fast increase at start, plateau, fast decrease at end, slower decrease during recovery.
Describe submaximal exercise intensity
Aerobic, long duration, endurance, below anaerobic threshold, low-moderate intensity.
Describe maximal exercise intensity
Anaerobic, short duration, short bursts, at or above anaerobic threshold, high intensity.
Why is no steady state reached during maximal exercise?
The oxygen supply never catches up with the demand from the muscles.
According to Starling's Law of the Heart, what does Stroke Volume depend on?
Venous return (VR) the volume of blood returning to the heart.
Explain the first stretch of Starling's Law of the Heart involving the Atria
More blood enters atria = stretch of atria walls. This stimulates the SA node causing it to increase firing rate = increased HR.
Explain the second stretch of Starling's Law of the Heart involving the Ventricles
More blood enters ventricles = stretch of ventricular walls. This causes a more forceful contraction of ventricular walls = increased SV.
What causes SV to increase at submaximal exercise intensity?
Increased venous return and Starling’s Law of the heart.
Why does Stroke Volume plateau and decrease during maximal exercise?
HR increases, not enough time for ventricles to fill, less blood in ventricles, less blood ejected, decreased SV.
Why does Stroke Volume remain elevated during recovery?
To maintain blood flow to the muscles in order to remove lactic acid and carbon dioxide.
Why does Cardiac Output increase at submaximal exercise intensity?
HR and SV are increasing, Q = HR x SV
Why does Cardiac Output plateau towards maximal exercise intensity?
HR continues to increase, SV decreases due to cardiovascular drift, so Q remains constant at its maximum value.
How do Heart Rate and Stroke Volume behave during recovery in relation to Cardiac Output?
HR decreases quickly but SV remains elevated.
What is vascular shunt mechanism?
The redistribution of Cardiac Output during exercise.
What is the role of chemoreceptors?
Monitor chemical changes in the body during exercise and recovery e.g. increase in lactic acid or decrease in O2.
What is the role of baroreceptors?
Monitor blood pressure increases during exercise and decreases during recovery.
What is the role of proprioceptors?
Monitor increase in muscle activity during exercise and decrease during recovery.
What is the vasomotor control centre and its function?
Situated in the brain and controls the vascular shunt mechanism, controls the diameter of arteriole and pre-capillary sphincter.
What is an arteriole?
A small artery that carries oxygenated blood to muscles and organs. It has a muscular middle layer to allow for vasoconstriction and vasodilation.
What is a pre-capillary sphincter?
A small ring-shaped muscle at the junction between arteriole and capillary. It can vasoconstrict and vasodilate.
What is vasodilation?
A decrease in sympathetic stimulation causes a widening of the diameter of the arteriole and pre-capillary sphincter.
What is vasoconstriction?
An increase in sympathetic stimulation causes a narrowing of the diameter of the arteriole and pre-capillary sphincter.
What are the 5 solutions to help with maintaining venous return during exercise?
Pocket valves, skeletal muscle pump, smooth muscle, respiratory pump, gravity.
What is the role of pocket valves in venous return?
Prevent backflow of blood.
How does the skeletal muscle pump aid venous return?
Lower leg muscles contract, press against vein walls, squeezing blood up towards the heart.
How does smooth muscle aid venous return?
Thin layer of smooth muscle in the vein walls allows for some venoconstriction to move blood up towards the heart.
How does the respiratory pump aid venous return?
During inspiration the diaphragm flattens, decreasing volume and increasing pressure in the abdomen to below pressure in the thoracic cavity, pulling blood up.
How does temperature regulate heart rate during recovery (intrinsic factor)?
A gradual decrease in temperature causes decreased speed of nerve transmissions, causing HR to decrease.
How do hormonal factors regulate heart rate during recovery?
Release of adrenalin inhibited, causing decrease in firing rate of SA node, causing HR to decrease.
How does venous return regulate heart rate during recovery (intrinsic factor)?
A gradual decrease in VR causes SV to decrease.
How do neural factors regulate heart rate during recovery?
The CCC uses the parasympathetic nervous system to decrease firing rate of SA node, causing HR to decrease.
What are the intrinsic, neural, and hormonal factors in regulation of heart rate during exercise?
Increased temperature, increased VR, neural factors, hormonal factors.