The Circulatory System

Question 1

How does blood travel around the body?

Answer 1

Arteries
Veins
Capillaries

Question 2

Describe the functions of the heart in the pumping of blood

Answer 2

• the right side of the heart pumping blood to the lungs

- the left side of the heart pumping blood to the rest of the body

Question 3

Where is blood under high pressure?

Answer 3

In the arteries which is under higher pressure than blood in the veins

Question 4

Explain in terms of pressure difference why blood flows from one area to another?

Answer 4

It is this pressure difference that causes blood to flow around the body

Question 5

Explain the advantage of the double circulatory system in mammals

Answer 5

Higher pressures

Therefore greater rate of flow to the tissues

Question 6

Explain how the adaptations of arteries, veins and capillaries relate to their functions

Answer 6

• Thick muscular and elastic wall in arteries to cope with high pressure
• Large lumen and presence of valves in veins to prevent the back flow of blood
• Permeability of capillaries to allow the exchange of substances between cells and blood

Question 7

Explain how the structure of a red blood cell is adapted to its function in terms of the small size providing a large surface area to volume ratio

Answer 7

• small and flexible so they can pass through narrow blood vessels
• shape of the cells increases their surface area for transferring oxygen

Question 8

Describe how haemoglobin in red blood cells reacts with oxygen in the lungs to form oxyhemoglobin and how the reverse of this reaction happens in the tissues

Answer 8

When the cells reach the lungs, oxygen diffuses from the lungs into the blood. The haemoglobin molecules in the red blood cells bind with the oxygen to form oxyhemoglobin.

Haemoglobin + oxygen ⇌ oxyhemoglobin

Question 9

Explain why the left ventricle has a thicker muscle wall than the right ventricle

Answer 9

Because it has to pump blood around the whole body

Question 10

Describe the function of plasma

Answer 10

Transports:

• carbon dioxide from the cells to the lungs
• glucose and other digested food products from the small intestine to the cells
• waste products from the liver to the kidneys
• hormones to the target organs
• antibodies around the body to fight disease

Question 11

Describe how the parts of the circulatory system work together to bring about the transport of the substances around the body

Answer 11

• arteries transporting blood away from the hesrt
• veins transporting blood to the heart
• capillaries exchanging materials with tissues

Question 12

Identify the names and positions of the parts of the heart and functions

Answer 12

• left and right ventricles to pump blood
• left and right atria to receive blood
• semilunar , tricuspid and bicuspid valves to prevent back flow
• four main blood vessels of the heart

Question 13

Describe the functions of components of the blood:
Red blood cells
White blood cells
Platelets

Answer 13

Red blood cells - transport oxygen from the lungs to the tissues
White blood cells - protect the body against disease
Platelets - clump together when a blood vessel becomes damages and form a meshwork of fibres to produce a clot