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Physiology Lecture 10- Cardiac Cycle And Cardiac Output Exam Study Guide, Exams of Physiology

Physiology Lecture 10- Cardiac Cycle And Cardiac Output Exam Study Guide

Typology: Exams

2024/2025

Available from 02/12/2025

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Physiology Lecture 10- Cardiac Cycle
And Cardiac Output Exam Study
Guide
phases of the cardiac output - Answer all events during a single heartbeat
phase 1: ventricular filling - Answer occurs during the mid to late diastole (ventricular
relaxation); blood flows into the atria, through the AV valves, and into the ventricles. At
this time, the semilunar valves are closed; toward the end of this phase, the atria
contract to drive more blood into the ventricles
phase 2: isovolumetric contraction - Answer occurs at the beginning of systole. the
pressure in the ventricle exceeds that in the atria and the AV valves close (generates
first sound of the heartbeat); however the pressure is not great enough to open
semilunar valves; thus, there is no blood flow into or out of the ventricle
phase 3: ventricular ejection - Answer ventricular pressure rises and blood is pushed
through the semilunar valves. now, ventricular pressure drops and the semilunar valves
shut (generates second sound of heartbeat); this ends systole
phase 4: isovolumetric relaxation - Answer as the ventricles enter the early stage of
diastole, the pressure is still too high to allow AV valves to open, and too low to push
semilunar valves open; thus, all valves are closed and no blood is moving through the
ventricles as they relax
aortic (arterial) pressure - Answer pressure is measured in millimeters of mercury
diastolic pressure - Answer at the end of phase 2, the pressure in the aorta is at its
minimum
systolic pressure - Answer during phase 3, as the ventricular pressure rises, the
semilunar valve opens, the aortic pressure rises to a maximum
at the end of phase 3 - Answer as the ventricle pressure is dropping, the aortic pressure
drops but remains higher and the difference causes the semilunar valve to close
mean arteriole pressure (MAP) - Answer the average arterial pressure based on the
following equation
MAP - Answer (systolic pressure + 2 diastolic pressure) / 3
end-diastolic volume (EDV) - Answer during phase 1 (ventricular filling) - the ventricular
volume is increasing and eventually reaches its maximum
end-systolic pressure (ESV) - Answer during phase 3 (ventricular systole) - the
ventricular volume is decreasing and eventually reaches its minimum
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Physiology Lecture 10- Cardiac Cycle

And Cardiac Output Exam Study

Guide

phases of the cardiac output - Answer all events during a single heartbeat

phase 1: ventricular filling - Answer occurs during the mid to late diastole (ventricular relaxation); blood flows into the atria, through the AV valves, and into the ventricles. At this time, the semilunar valves are closed; toward the end of this phase, the atria contract to drive more blood into the ventricles

phase 2: isovolumetric contraction - Answer occurs at the beginning of systole. the pressure in the ventricle exceeds that in the atria and the AV valves close (generates first sound of the heartbeat); however the pressure is not great enough to open semilunar valves; thus, there is no blood flow into or out of the ventricle

phase 3: ventricular ejection - Answer ventricular pressure rises and blood is pushed through the semilunar valves. now, ventricular pressure drops and the semilunar valves shut (generates second sound of heartbeat); this ends systole

phase 4: isovolumetric relaxation - Answer as the ventricles enter the early stage of diastole, the pressure is still too high to allow AV valves to open, and too low to push semilunar valves open; thus, all valves are closed and no blood is moving through the ventricles as they relax

aortic (arterial) pressure - Answer pressure is measured in millimeters of mercury

diastolic pressure - Answer at the end of phase 2, the pressure in the aorta is at its minimum

systolic pressure - Answer during phase 3, as the ventricular pressure rises, the semilunar valve opens, the aortic pressure rises to a maximum

at the end of phase 3 - Answer as the ventricle pressure is dropping, the aortic pressure drops but remains higher and the difference causes the semilunar valve to close

mean arteriole pressure (MAP) - Answer the average arterial pressure based on the following equation

MAP - Answer (systolic pressure + 2 diastolic pressure) / 3

end-diastolic volume (EDV) - Answer during phase 1 (ventricular filling) - the ventricular volume is increasing and eventually reaches its maximum

end-systolic pressure (ESV) - Answer during phase 3 (ventricular systole) - the ventricular volume is decreasing and eventually reaches its minimum

stroke volume - Answer the amount of blood ejected form the ventricle during one heartbeat

SV - Answer EDV - ESV

average stroke volume - Answer 70 ml

ejection fraction (EF) - Answer stroke volume / end-diasolic volume ; average: 54% ; when the ventricle is completely relaxed, it holds 130ml, the SV on average is 70ml, so that means 60ml was not ejected

cardiac output (CO) - Answer the amount of blood pumped by the heart in one minute

cardiac output (CO) (ml/min) - Answer stroke volume (ml/beat) x heart rate (beats/min) ; average: 5.25 liters

neural control of heart rate - Answer controlled by two branches of our autonomic nervous system; sympathetic and parasympathetic

sympathetic ANS - Answer neurons release epinephrine and norepinephrine, which bind to adrenergic receptors on the SA (pacemaker) cells; as a result, funny channels and T-type calcium channels are opened and the frequency of action potential generation is increased

parasympathetic ANS - Answer neurons release acetylcholine, which binds to muscarinic cholinergic receptors on the SA (pacemaker) cells; as a result, T-type calcium channels and sodium channels close and potassium channels open; thus, the cell hyperpolarizes and action potentials decrease

epinephrine - Answer released from the adrenal gland in large amounts when we're under stress; increases heart rate; hormonal control of heart rate

ventricular contractility - Answer extrinsic (external) influence

sympathetic influence on stroke volume - Answer it not only causes an increase in heart rate but it also causes an increase in calcium activity such that the cell's contractile is maximized

epinephrine from adrenal gland (changes in stroke volume) - Answer causes increased heart rate, increase in calcium activity (cell's contraction is maximized)

thyroid hormone, glucagon, and insulin - Answer can increase force of contraction

influence of end-diastolic volume on stroke volume - Answer an intrinsic (internal) influence

starling's law - Answer when the rate at which blood flows into the heart changes, the heart automatically adjusts its output to match the inflow

if EDV increases - Answer force of ventricular contraction increases, SV increases, CO