Human Transport

Question 1

Describe the composition of blood

Answer 1

Red blood cells: transports oxygen
White blood cells: defence against disease
Platelets: helps form blood clots
Plasma: liquid part of blood, transport of substances

Question 2

What is the role of plasma

Answer 2

Transport of carbon dioxide, digested food, urea, hormones and heat energy

Question 3

What adaptations do red blood cells have to make them suitable for the transport of oxygen

Answer 3

• biconcave shape for efficient exchange of oxygen in + out of cell
• no nucleus so more space for more haemoglobin so more oxygen can be transported
• contains haemoglobin to carry oxygen
• high SA:Volume ratio so large area for diffusion
• thin shape so short diffusion distance to the centre of the cell

Question 4

How does the immune system respond to disease using white blood cells

Answer 4

Phagocytes: engulf + digest the pathogen
Lymphocytes: release antibodies specific to the pathogen

Question 5

How do vaccinations work

Answer 5

• vaccine exposes body to dead/weakened pathogens in small quantities
• antibodies are produced to destroy the pathogens
• memory cells are produced and left behind
• the memory cells recognise the pathogen at a secondary response so can produce more antibodies at a faster rate

Question 6

How are platelets involved in blood clotting

Answer 6

• if skin is cut, exposure to air stimulates platelets + damaged tissue to produce a chemical
• the chemical causes soluble plasma protein fibrinogen to change into insoluble fibres of another protein fibrin
• The fibrin forms a network across the wound in which red blood cells get trapped
• This forms a clot, which prevents further loss of blood + entry of microorganisms that may be pathogens

Question 7

Describe the structure of the heart

Question 8

Describe how the heart functions

Question 9

Explain how heart rate changes during exercise and under the influence of adrenaline

Question 10

How do factors increase risk of heart disease

Answer 10

• heredity (inherit it)
• high blood pressure (more strain on heart)
• diet (cholesterol levels)
• smoking (raise blood pressure, blood clots more likely to form)
• stress (raise blood pressure)
• lack of exercise (higher blood pressure, weaker heart)

Question 11

Structure of arteries

Question 12

Structure of veins

Question 13

Structure of capillaries

Question 14

General structure of the circulatory system