The Structure of the Heart Flashcards
What is the cardiac output?
The volume of blood pumped through each ventricle per minute.
What is the formula for cardiac output?
CO = HR x SV
What occurs during diastole?
Blood returning to the atria flows into the ventricles.
What does atrial systole do?
TRansfers the remainder of the blood through the atrioventricular valves to the ventricles.
What does ventricular systole do?
Closes the AV valves and pumps the blood out through the semilunar valves to the aorta and pulmonary artery.
What happens to the SL valves during diastole?
The higher pressure in the arteries closes them.
What is responsible for the heart sounds heard with a stethoscope?
The opening and closing of the AV and SL valves.
Where does the heartbeat originate?
In the heart itself.
What is the pacemaker?
The auto-rhythmic cells of the sino-atrial node (SAN).
What is the function of the SAN?
To set the rate at which the heart contracts.
Where is the sino-atrial node located?
In the wall of the right atrium.
What is the timing of cardiac muscle cell contraction controlled by?
Impulses from the SAN spreading through the atria causing atrial systole.
Where do the impulses from the SAN travel to?
The atrioventricular node, located in the centre of the heart.
What causes ventricular systole?
Impulses from the AVN travel down fibres in the central wall of the heart and then up through the walls of the ventricles.
What does an electrocardiogram detect?
Currents generated by impulses in the heart.
What should an interpretation of an electrocardiogram involve?
Calculations of the heart rate and linking of the waves to atrial systole, ventricular systole and diastole.
What does the medulla regulate?
The rate of the sinoatrial node through the antagonistic action of the autonomic nervous system.
What is the function of the sympathetic nerve?
To release noradrenaline which increases heart rate.
What is the function of the parasympathetic nerve?
To release acetylcholine which decreases the heart rate.
How does blood pressure change in the aorta during the cardiac cycle?
Blood pressure increases during ventricular systole and decreases during diastole.
What is used to measure blood pressure?
A sphygmomanometer.
Hoe does a sphygmomanometer work?
An inflatable cuff stops blood flow, in the artery, and deflates gradually. Blood starts to flow (detected by a pulse) at systolic pressure. The blood flows freely through the artery ( and a pulse is not detected) at diastolic pressure.
What is a typical blood pressure reading?
120/80 mmHg
What is hypertension a major risk factor for?
Coronary heart disease.
