7.2

Question 1

Describe the circulatory system

Answer 1

circulatory system: a system of blood vessels with a pump and valves to ensure one-way flow of blood

Question 2

How is blood pumped in our bodies?

Answer 2

Blood is pumped away from the heart into arteries and returns to the heart in veins

Question 3

Investigate and state the effect of physical
activity on pulse rate

Answer 3

The heart rate increases with exercise.
This is because more oxygen is needed by the muscles for respiration.

Resting heart rate can be affected by age.

Question 4

Describe the structure and functions of arteries

Answer 4

Arteries
- Carry blood at high pressure away from the heart
- Carry oxygenated blood (other than the pulmonary artery)
- Have thick muscular walls containing elastic fibres
- Have a narrow lumen
- Speed of flow is fast

Question 5

Describe the structure and functions of veins

Answer 5

Veins
- Carry blood at low pressure towards the heart
- Carry deoxygenated blood (other than the pulmonary vein)
- Have thin walls
- Have a large lumen
- Contain valves
- Speed of flow is slow

Question 6

Describe the structure and functions of capillaries

Answer 6

Capillaries
- Carry blood at low pressure within tissues
- Carry both oxygenated and deoxygenated blood
- Have walls that are one cell thick
- Have ‘leaky’ walls
- Speed of flow is slow

Question 7

List the components of blood

Answer 7

The components of blood: red blood cells, white blood cells, platelets and plasma

Question 8

State the functions of the red blood cells

Answer 8

red blood cells: transport oxygen, contains hemoglobin, carries oxygen in the form of oxyhemoglobin

Question 9

State the functions of the white blood cells

Answer 9

white blood cells: carries out phagocytosis, produces antibodies, (so they can defend our body against infection)

Question 10

State the functions of the platelets

Answer 10

Platelets: helps the blood to clot

Question 11

State the functions of the plasma

Answer 11

plasma: transports blood cells, carbon dioxide, ions, nutrients, and carbon dioxide

Question 12

Describe double circulation

Answer 12

Double circulation: circulation to the lungs and circulation to the body tissues in mammals

• This means that for every one circuit of the body, the blood passes through the heart twice.
• The right side of the heart: receives deoxygenated blood and pumps it to the lungs
  (called the pulmonary circulation).
• The left side of the heart: receives oxygenated blood from the lungs and pumps it to the body
  (called the systematic circulation)

Question 13

Explain the advantages of a double circulation

Answer 13

Blood travelling through the small capillaries in the lungs loses a lot of pressure that was given to it by the pumping of the heart, meaning it cannot travel as fast.

By returning the blood to the heart after going through the lungs its pressure can be raised again before sending it to the body,

this means cells can be supplied with the oxygen and glucose they need for respiration faster and more frequently

Question 14

Describe the functioning of the heart

Answer 14

• deoxygenated blood is brought into the heart by the vena cava
• it then travels through the right atrium and through the right ventricle
• then it goes to the lung via the pulmonary arteries and is pumped back in via the pulmonary veins
• since the blood is now oxygenated, it is brought through the left atrium and left ventricle
• it exists the heart into the rest of the body via the aorta

Question 15

Describe coronary heart disease

Answer 15

It is the blockage of coronary arteries.

Possible risk factors:

diet: too much fat, could lead to fatty plaque buildup

stress: (stress) could lead to increased blood pressure

smoking: (smoking) causes blood vessels become narrower, increases blood pressure

genetic predisposition: it can be in your genetics

age and gender: risk gets higher as you age, males more likely to get it than female s

Question 16

how to Investigate for the effect of physical activity on the pulse rate

Answer 16

• record the pulse rate at rest for a minute.
• Immediately after they do some exercise, record the pulse rate every minute until it returns to the resting rate.
• This experiment will show that during exercise the heart rate increases and may take several minutes to return to normal.

and will prove that,
When a person exercises, their pulse rate increases.

Question 17

Explain how the structures of arteries, veins and capillaries are adapted for their functions

Answer 17

Arteries:
- thick muscular walls containing elastic fibres to withstand high pressure of blood and maintain blood pressure
- Have a narrow lumen to maintain high pressure

Veins:
- large lumen as blood pressure is low
- valves to prevent the backflow of blood as it is under low pressure

Capillaries:
- walls are one cell thick so that substances can easily diffuse in and out of them
- ‘leaky’ walls so that blood plasma can leak out and form tissue fluid surrounding cells