Unit 2 (K6) - Structure and Function of Heart

Question 1

Name the 4 chambers of the heart.

Answer 1

1. Left Atria
2. Left Ventricle
3. Right Atria
4. Right Ventricle

Question 2

Where does blood coming from the body enter the heart?

Answer 2

Into the right atrium through the vena cava.

Question 3

Where does blood leave the heart to go to the lungs from?

Answer 3

From the right ventricle it goes to the lungs in the pulmonary artery.

Question 4

Where does blood go when it comes back from the lungs?

Answer 4

Into the left atrium through pulmonary vein.

Question 5

Where does blood leave the heart and go to the body?

Answer 5

From the left ventricle in the aorta.

Question 6

How is cardiac output calculated?

Answer 6

Stroke Volume x Heart Rate

Question 7

What is systole?

Answer 7

Contraction of the heart muscle.

Question 8

What is the relaxation of the heart muscle called?

Answer 8

Diastole.

Question 9

During the cardiac cycle what occurs during diastole?

Answer 9

1. During diastole, the return of the blood via the vena cava and pulmonary veins to the atria causes the volume of the blood in the atria to increase.
2. Eventually, atrial pressure exceeds that in the ventricles. The AV valves are pushed open and blood starts to enter the ventricles.

Question 10

During the cardiac style what occurs during atrial systole?

Answer 10

1. During atrial systole, the two atria contract simultaneously and send the remainder of the blood down in the ventricles through the open AV valves.
   2.The ventricles fill up and the SL valves remain closed.

Question 11

During the cardiac cycle what occurs during ventricular systole?

Answer 11

1. This involves the contraction of the ventricles and the closure of the AV valves.
   2.The pressure exerted on the blood in the ventricles soon exceeds the blood pressure in the arteries.
2. The SL valves are pushed open and blood is pumped out the heart and into the aorta and pulmonary arteries.

Question 12

What causes the atrio-ventricular (AV) valves to open and close?

Answer 12

1. AV valves open from pressure of blood flowing in from the vena cava and pulmonary vein during diastole.
2. AV valves close when the pressure changes during ventricular systole.

Question 13

What causes the semilunar valves to open and close?

Answer 13

1. Increased pressure from ventricular systole pushes open the semilunar valves.
2. In diastole, blood pressure in the arteries leaving the heart closes the semilunar valves.

Question 14

How can the electrical activity of the heart be monitored?

Answer 14

With an electrocardiogram (ECG).

Question 15

What is the proper name for the pacemaker part of the heart? and where is it?

Answer 15

1. The sino-atrial node.
2. It is in the wall of the right atrium.

Question 16

How is the heart rate regulated?

Answer 16

1. The medulla regulates the rate of the sino-atrial node through the autonomic nervous system.
2. Hormones also regulate the heart rate.

Question 17

What is the role of the sino-atrial node in heart contraction?

Answer 17

It is the pacemaker which sends impulses that coordinates the contraction of the heart muscle.

Question 18

Describe the electrical impulses that make a heart beat.

Answer 18

1. The sino-atrial node (AVN) sends out an impulse causing the atria to contract. This impulse is picked up by the atrioventricular node (AVN).
2. The AVN passes impulses through the ventricles causing them to contract.

Question 19

What does sympathetic nerves release?

Answer 19

Noradrenaline.

Question 20

What does parasympathetic nerves release?

Answer 20

Acetylcholine.

Question 21

What does Noradrenaline hormone do to heart rate?

Answer 21

Causes an increase in heart rate.

Question 22

What does acetylcholine hormone do to heart rate?

Answer 22

Causes a decrease in heart rate.

Question 23

How is blood pressure measured?

Answer 23

Using a sphymomanometer. The cuff is inflated round the arm to close both arteries and veins. Pressure in the cuff is gradually reduced until pulse is heard.

Question 24

What is hypertension?

Answer 24

High blood pressure/ prolonged elevated blood pressure when at rest.

Question 25

Why is hypertension best avoided?

Answer 25

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