The structure and function of the heart

Question 1

Through what vessel does de oxygenated blood return to the right atrium?

Answer 1

Vena cava

Question 2

What are the four chambers of the heart

Answer 2

• left and right atria
• left and right ventricles

Question 3

Explain the route of blood flow from it being brought back to the heart by the vena cava, to being pumped around the body by the aorta

Answer 3

1. deoxygenated blood enters the right atrium via the vena cava
2. blood passes into right ventricle and leaves the heart through the pulmonary artery where it travels to the lungs to be oxygenated
3. oxygenated blood returns to heart via pulmonary veins
4. blood then flows from left atrium to left ventricle and out to the rest of the body via the aorta

Question 4

Why is the left ventricle thicker than the right ventricle?

Answer 4

The left ventricle has to pump blood all around the body whereas the right ventricle only pumps blood to the lungs

Question 5

What are the two types of valves found in the heart?

Answer 5

• Atrioventricular valves (AV)
• Semi-lunar valves

Question 6

where are the AV valves found and what is their function?

Answer 6

• found between the atria and ventricles
• prevent back flow of blood from the ventricles to the atria

Question 7

Where are the semi lunar valves found and what is their function?

Answer 7

• between right ventricle and pulmonary artery
• between left ventricle and aorta

prevent back flow of blood into the ventricles

Question 8

what is heart rate?

Answer 8

number of heartbeats that occur per minute

Question 9

What is the stroke volume?

Answer 9

The volume of blood pumped out of each ventricle per heartbeat

Question 10

What is the cardiac output?

Answer 10

The volume of blood pumped out of each ventricle per minute

Question 11

How is the cardiac output calculated?

Answer 11

CO= HR x SV

CO= cardiac output
HR= heart rate
SV= stroke volume

Question 12

What is the cardiac cycle?

Answer 12

the processes of systole and diastole which occur during one complete heartbeat

Question 13

What occurs during diastole?

Answer 13

• period of relaxation for the heart - no contraction
• blood returns to the atria
• atrial pressure begins to be greater than ventricular pressure
• blood begins to enter the ventricles

Question 14

What occurs during atrial systole?

Answer 14

Atria contract and send remaining blood into the ventricles

Question 15

What occurs during ventricular systole?

Answer 15

contraction of the ventricles pumps blood into the aorta and pulmonary artery

Question 16

What part of the heart sets the heart rate?

Answer 16

Sino atrial node

Question 17

Explain the pathway of an electrical impulse after it is produced by the SA node

Answer 17

1. spreads across the muscle cells of the atria causing atrial systole
2. Impulse picked up at the atrioventricular node
3. Impulse passes from AVN to bundle of conducting fibres which divides into two branches
4. Impulse spreads to the ventricular muscle cells via these branches, leading to ventricular systole

Question 18

Where is the Sino atrial node located?

Answer 18

The upper part of the wall of the right atrium

Question 19

Where is the AV node located?

Answer 19

At the base of the atria

Question 20

What can be used to record the electrical activity of the heart

Answer 20

An electrocardiogram (ECG)

Question 21

Which part of the brain is involved in regulating the rate of the Sino atrial node?

Answer 21

The medulla

Question 22

What are the two branches of the autonomic nervous system?

Answer 22

sympathetic and parasympathetic

Question 23

What do the sympathetic and parasympathetic nervous systems do to the heart rate?

Answer 23

• sympathetic system increases heart rate
• parasympathetic system decreases heart rate

they are antagonistic of each other

Question 24

What neurotransmitter do sympathetic nerves release to increase heart rate?

Answer 24

Noradrenaline

Question 25

What neurotransmitter do parasympathetic nerves release to decrease heart rate?

Answer 25

Acetylcholine

Question 26

What happens to the heart rate when a person is in a state of ‘fight or flight’?

Answer 26

Sympathetic nervous system causes release of adrenaline which increases heart rate

Question 27

Define blood pressure and what is it measured in?

Answer 27

Force exerted by blood on blood vessel walls

measured in mmHg

Question 28

What equipment is used to measure blood pressure?

Answer 28

sphygmomanometer

Question 29

What is a normal blood pressure for a healthy adult?

Answer 29

120/80mmHg

Question 30

A person’s blood pressure is 120/80mmHg

what do these two numbers mean?

Answer 30

First number (120) = systolic blood pressure

second number (80) = diastolic blood pressure

Question 31

What is hypertension

Answer 31

prolonged elevation of blood pressure at rest

Question 32

what blood pressure value is considered to be hypertension?

Answer 32

above 140/90 mmHg

Question 33

Why is having prolonged hypertension bad?

Answer 33

major risk factor for coronary heart disease and strokes