KA 2.6 The structure and function of the heart

What is cardiac output & what is it determined by?

The volume of blood pumped through each ventricle per minute and is determined by heart rate and stroke volume

Complete sentnce-

The left and right ventricles pump the ___ volume of blood through the ____ and _________ artery.

The left and right ventricles pump the same volume of blood through the aorta and pulmonary artery.

What happens during diastole and what happens to valves?

During diastole, blood returning to the atria flows into the ventricles. In diastole, the higher pressure in the arteries closes the SL valves.

Describe atrial systole?

Atrial systole transfers the remainder of the blood through the atrio-ventricular (AV) valves to the ventricles.

Describe ventricular systole?

Ventricular systole closes the AV valves and pumps the blood out through the semi lunar (SL) valves to the aorta and pulmonary artery.

What is responsible for the heart sounds heard with a stethoscope?

The opening and closing of the AV and SL valves are responsible for the heart sounds heard with a stethoscope.

Where does your heartbeat originate?

The heartbeat originates in the heart itself.

How is the rate at which the heart contracts set?

The auto-rhythmic cells of the sino-atrial node (SAN) or pacemaker, located in the wall of the right atrium, set the rate at which the heart contracts.

Where do the impulses from the SAN then travel after causing atrial systole?

They then travel to the atrio-ventricular node (AVN), located in the centre of the heart.

Where do the impulses from the AVN travel to?

Impulses from the AVN travel down fibres in the central wall of the heart and then up through the walls of the ventricles, causing ventricular systole.

How can impulses in th heart be detected?

Impulses in the heart generate currents that can be detected by an electrocardiogram (ECG).

Which part of the brain regulates the rate of the sino-atrial node?

The medulla regulates the rate of the sino-atrial node through the antagonistic action of the autonomic nervous system (ANS).

Describe the role of the autonomic nervous system in controlling the heart rate?

A sympathetic nerve releases noradrenaline which increases the heart rate, whereas a parasympathetic nerve releases 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.

Describe how blood pressure is measured using a sphygomamnometer?

An inflatable cuff stops blood flow, in the artery, and deflates gradually. The 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 for a young adult

A typical blood pressure reading for a young adult is 120/80 mmHg.

What is the issue with having high blood pressure?

Hypertension (high blood pressure) is a major risk factor for many diseases including coronary heart disease.