B3.2.2 The blood

Question 1

What is blood and what does it contain?

Answer 1

A tissue made up of plasma, red blood cells, white blood cells and platelets.

Question 2

What are red blood cells?

Answer 2

Tiny, nucleus-free cells which carry oxygen from the lungs to tissues.

Question 3

How are red blood cells adapted to efficiently transport oxygen?

Answer 3

• There are huge numbers of red blood cells
• They are tiny so they can pass through capillaries
• They have a high surface area due to their biconcave disc shape
• They contain haemoglobin

Question 4

What does haemoglobin do?`

Answer 4

Combines with oxygen in the lungs to form oxyhaemoglobin.

Oxyhaemoglobin splits up into haemoglobin and oxygen in other organs.

Question 5

What does bright red blood indicate?

Answer 5

The blood is oxygenated.

Question 6

What does dark red blood indicate?

Answer 6

The blood is deoxygenated.

Question 7

What are white blood cells?

Answer 7

Cells that contain a nucleus and make up part of the body’s defence against microorganisms.

Some can engluf pathogens
Some create antibodies
Some create antitoxins

Question 8

What is blood plasma + what does it transport?

Answer 8

A straw-coloured liquid which makes up about 55% of blood.

Transports:

• hormones
• antibodies
• nutrients - such as water, glucose, amino acids, minerals and vitamins
• waste substances - such as carbon dioxide and urea

Question 9

What are platelets?

Answer 9

Small fragments of cells which have no nucleus. Platelets help blood to clot at the site of a wound.