5.4 Circulatory System I

Question 1

What is the circulatory system made up of?

Answer 1

Heart, blood vessels and blood.

Question 2

What is the role of the circulatory system?

Answer 2

To transport oxygen and nutrients to our body’s tissues.

Question 3

Describe what each circuit in the double circulatory system do?

Answer 3

• In the first one, the heart pumps deoxygenated blood to the alveoli in the lungs to take in oxygen. The oxygenated blood then returns to the heart.
• In the second one, the heart pumps oxygenated blood around all the other organs of the body. Here, the blood gives up its oxygen to the body cells. Here, the blood gives up its oxygen at the body cells. The deoxygenated blood then returns to the heart to be pumped out to the lungs again.
• As it is pumped around the body, the blood also travels through blood vessels near exchange surfaces - including the villi (where it picks up food molecules and water) and the kidneys (where it is filtered and urea is removed).

Question 4

What are the top chambers of a heart called?

Answer 4

Atria - a single one being called an atrium

Question 5

What are the bottom chambers of a heart called?

Answer 5

Ventricles

Question 6

What do we find between the chambers and the vessels in a heart?

Answer 6

Valves

Question 7

What do valves in a heart do?

Answer 7

Prevent the blood from flowing backwards, ensuring that it always flows in the right direction.

Question 8

Describe the path that blood takes in the heart (5)

Answer 8

1) Blood flows into the two atria from the vena cava and the pulmonary vein.
2) The atria contract, pushing the blood into the ventricles.
3) The ventricles contract, forcing the blood into the pulmonary artery and the aorta, and out of the heart.
4) The blood then flows to the organs, including the lungs, through arteries, and returns through veins.
5) The atria fill again and the whole cycle starts over.

Question 9

How does the heart keep the beat of the blood cycle steady?

Answer 9

There a group of cells in the right atrium that act as a pacemaker and these pacemaker cells produce small electrical impulses which spread through the muscular walls of the heart, causing them to contract

Question 10

What may a doctor do if a patient’s pacemaker cells don’t work properly?

Answer 10

They can implant an artificial pacemaker, which is a small device they place just under the skin above the heart and has a wire that can carry an electrical current down to the heart, telling it to contract regularly.

Question 11

What does the term ‘artery’ refer to?

Answer 11

Any vessel that carries blood away from the heart

Question 12

What does the term ‘vein’ refer to?

Answer 12

Any vessel that carries blood to the heart

Question 13

Which ventricle in the heart has a thicker wall?

Answer 13

Left ventricle

Question 14

Why does the left ventricle have a wall much thicker than the right ventricle?

Answer 14

It needs the greater pressure generated by the thicker muscle because it has to pump blood around the whole body, whereas the right ventricle only has to pump it to the lungs.

Question 15

The heart is made up of cardiac muscle. What type of cells are in them and what do they do?

Answer 15

Cardiac muscle cells. They contain lots of mitochondria to provide them with ATP. This releases the energy needed for the muscles to contract.

Question 16

What is blood supplied to the cardiac muscle by?

Answer 16

Two coronary arteries, which branch from the base of the aorta.

Question 17

What do the two coronary arteries do?

Answer 17

They allow the oxygen and glucose needed for the heart cells to respire to diffuse through the thick walls of the heart.

Question 18

Which blood vessel carries deoxygenated blood from the heart to the lungs?

Answer 18

Pulmonary artery

Question 19

The journey of blood around the body (arrows)

Answer 19

Body tissues -> vena cava -> right atrium -> right ventricle -> pulmonary artery -> lungs -> pulmonary vein -> left atrium -> left ventricle -> aorta -> body tissues

Question 20

Which blood vessel carries oxygenated blood from the heart to the body?

Answer 20

Aorta