Circulatory System (heart + blood vessels)

Question 1

What does the heart do?

Answer 1

An organ that pumps blood around the body in a double circulatory system.

• Right ventricle pumps blood through the pulmonary artery to the lungs where gas exchange takes place.
• Left ventricle pumps blood through the aorta to the rest of the body.

Question 2

What is the circulatory system made up of?

Answer 2

Heart, blood and vessels.

Question 3

What is a double circulatory system?

Answer 3

Two circuits joined together.

Question 4

How does the first circuit work in a double circulatory system?

Answer 4

• Heart pumps deoxygenated blood (without oxygen) to the lungs. Blood picks up oxygen in the lungs.
• Oxygenated blood then returns to the heart.

Question 5

How does the second circuit work in a double circulatory system?

Answer 5

• Heart pumps oxygenated blood around all the other organs of the body. This delivers oxygen to body cells.
• Deoxygenated blood returns to the heart to be pumped out to the lungs again.

Question 6

How many chambers does the heart have?

Answer 6

Has 4 chambers made of muscle tissue - this tissue is used to pump blood around the body.

Question 7

How does the heart pump blood around the body?

Answer 7

1) Blood flows into the two atria from the vena cava and the pulmonary vein.
2) The ventricles pump the blood out of the heart.
3) The blood then flows to the organs through arteries, and returns through veins.
4) The atria fills again - whole cycle starts over.

Question 8

What do the valves in the heart?

Answer 8

Stop blood from flowing backwards.

Question 9

Where does the heart get oxygenated blood from?

Answer 9

Heart needs its own supply of oxygenated blood.

Gets it from arteries called coronary arteries. These branch of the aorta and surround the heart.

Question 10

What is the heart’s pacemaker?

Answer 10

Group of cells in the right atrium wall control our natural resting heart rate - tells the heart when to pump blood so acts as a pacemaker.
The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker

Question 11

What are the 3 different types of blood vessel?

Answer 11

Arteries
Veins
Capillaries

Question 12

Explain how the structure of arteries relates to its function.

Answer 12

Carries blood away from the heart.

• Artery walls are strong and elastic as the heart pumps out blood at high pressure.
• Have thick layers of muscle to make them strong.
• Have elastic fibres to allow them to stretch and spring back.
• The lumen is the hole down the middle.

Question 13

Explain how the structure of capillaries relates to its function.

Answer 13

Arteries branch out into capillaries - too tiny and small to see.

• Carry the blood really close to every cell in the body to exchange substances.
• Have gaps in their walls so substance can diffuse in and out.
• Supply food + oxygen, and take away waste like CO2.
• Walls are one cell thick so diffusion is very fast as short distance for molecules to travel.

Question 14

Explain how the structure of veins relates to its function.

Answer 14

Capillaries join up to form veins.

• Blood is at low pressure in the veins so walls don’t have to be thick like artery walls.
• Veins have a bigger lumen than arteries to help the blood flow despite the low pressure.
• Have valves as well to help keep the blood flowing in the right direction.