KA6 - The Structure And Function Of The Heart

Question 1

What type of blood does the left side of the heart pump and where does it pump it to?

Answer 1

The left side of the heart pumps oxygenated blood to the body cells

Question 2

What type of blood does the right side pump and where does it pump it to?

Answer 2

The right side of the heart pumps deoxygenated blood to the lungs

Question 3

Name the 8 chambers of the heart

Answer 3

Right ventricle
Right atrium
Vena cava
Pulmonary artery
Aorta
Pulmonary vein
Left atrium 
Left ventricle

Question 4

State the names of the 2 valves and where they are found in the heart

Answer 4

AV valves are found between the atria and ventricles.

Semi lunar valves are found at the exit to the aorta and pulmonary artery.

Question 5

Why is the human circulatory system referred to as a double system?

Answer 5

Because it has the pulmonary circuit and the systemic circuit

Question 6

What is the pulmonary circuit?

Answer 6

The pulmonary circuit carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the heart

Question 7

What is the systemic circuit?

Answer 7

The systemic circuit carries oxygenated blood from the left ventricle to the aorta to the rest of the body and returns deoxygenated blood to the heart.

Question 8

What is heart rate?

Answer 8

The number of times a heart beats in one minute measure in beats per minute

Question 9

What is stroke volume?

Answer 9

The volume of blood ejected by each ventricle during contraction measured in millilitres

Question 10

What is cardiac output?

Answer 10

The volume of blood pumped by each ventricle per minute

Question 11

How is cardiac output calculated?

Answer 11

CO = HR XSV

Question 12

What are the 3 stages in the cardiac cycle?

Answer 12

1. Aerial and ventricular diastole
2. Atrial systole
3. Ventricular systole

Question 13

What is meant by systole ?

Answer 13

Contraction of the heart

Question 14

What is meant by diastole?

Answer 14

Relaxation of the heart

Question 15

Explain atrial and ventricular diastole

Answer 15

During this stage all chambers of the heart are relaxed and filling with blood.

The AV valves are open and the semi lunar valves are closed.

Blood returning to the atria flows into the ventricles.

Question 16

Explain atrial systole

Answer 16

During this stage, both atria contract.

The remaining blood in the atria is forced into relaxed ventricles through the open AV valve.

Question 17

Explain ventricular systole

Answer 17

AV valves close preventing back flow of blood into atria.

Ventricles contract.

Blood pumped out of the heart, through semi lunar valves into the aorta and pulmonary artery.

Semi lunar valves close when pressure in arteries exceeds pressure in ventricles. This prevents the back flow of blood into the ventricles.

Cardiac cycle begins again.

Question 18

Describe pressure changes during the cardiac cycle

Answer 18

Pressure is highest during ventricular systole

Question 19

Explain the sound of a heartbeat

Answer 19

The opening and closing of the AV and semi lunar valves creates the sound of the heart which are heard with a stethoscope

Question 20

What does the conducting system of the heart ensure?

Answer 20

That the heart contracts in a coordinated manner

Question 21

What 2 nodes are involved in the conducting system of the heart?

Answer 21

Sino atrial node(SAN)

Atrio ventricular node(AVN)

Question 22

Where is the SAN located?

Answer 22

The top wall of the right atrium

Question 23

Where is the AVN located?

Answer 23

The centre of the heart

Question 24

Explain the sino atrial node

Answer 24

The SAN sends out electrical impulses which are carried through the muscular walls of both atria. These impulses cause atrial systole.

Question 25

Explain the atrio ventricular node

Answer 25

The impulses from SAN travel to and are passed on to another node within the heart, the AVN. Impulses from the AVN then travel down fibres in the central wall of the heart. The impulse then splits and travels up the left and right ventricles causing them to contract simultaneously, ventricular systole.

Question 26

What is an electrocardiogram?

Answer 26

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

Question 27

In an electrocardiogram, what is the P wave?

Answer 27

The P wave corresponds to a wave of excitation spreading over the atrial walls causing atrial systole.

Question 28

In an electrocardiogram, what is the QRS wave?

Answer 28

The QRS wave corresponds to a wave of excitation spreading over the ventricle walls causing ventricular systole

Question 29

In an electrocardiogram, what is the T wave?

Answer 29

The T wave corresponds to electrical recovery of the ventricles

Question 30

What is the function of the medulla in the conducting system?

Answer 30

The medulla regulates the rate of SAN through antagonistic action of the autonomic nervous system

Question 31

What is the autonomic nervous system?

Answer 31

The autonomic nervous system varies the rate at which the heart contracts.

Question 32

What are the 2 antagonistic beaches involved in the autonomic nervous system?

Answer 32

Sympathetic pathway | Parasympathetic pathway

Question 33

What is the sympathetic pathway?

Answer 33

Sympathetic nerves release noradrenaline which increases heart rate

Question 34

What is the parasympathetic pathway?

Answer 34

Parasympathetic nerves release acetylcholine which decreases heart rate

Question 35

What is blood pressure?

Answer 35

Blood pressure is the force exerted by blood against walls of blood vessels

Question 36

What does blood pressure do during the cardiac cycle?

Answer 36

Changes the aorta

Question 37

What is used to measure blood pressure?

Answer 37

A sphygmomanometer in mmHg

Question 38

What happens to blood pressure during ventricular systole and diastole?

Answer 38

Blood pressure increases during ventricular systole and decreases during diastole

Question 39

What is a typical blood pressure reading for a hound adult?

Answer 39

120/80mmHg

Question 40

What are the two values used to measure blood pressure?

Answer 40

Systolic BP | Diastolic BP

Question 41

Explain how a sphygmomanometer is used

Answer 41

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.

Question 42

What can hypertension cause?

Answer 42

Hypertension is a major risk factor for many diseases including coronary heart disease.