Transport in Humans

Question 1

What is plasma?

Answer 1

Plasma is the yellow liquid part of the blood. It transports carbon dioxide, digested food, urea, hormones and heat energy around the body

Question 2

What do red blood cells do?

Answer 2

Red blood cells carry oxygen around the body. They contain haemoglobin (containing iron) which bonds with oxygen in the lungs to form oxyhaemoglobin. In body tissues, the reverse reaction happens to release oxygen to the cells.

Question 3

How are red blood cells adapted for transporting oxygen?

Answer 3

• don’t have a nucleus, freeing up space for haemoglobin so they can carry more oxygen
• they’re biconcave to give a large surface area for absorbing and releasing oxygen
• there are no mitochondria as the cells respite anaerobically do the cells don’t use any oxygen

Question 4

What are the two types of white blood cells?

Answer 4

Phagocytes and lymphocytes

Question 5

What do phagocytes do?

Answer 5

They ingest pathogens

- they detect foreign things to the body and engulf and digest them

Question 6

What do lymphocytes do?

Answer 6

They produce antibodies
- when they come across a foreign antigen, they produce antibodies, marking them out for destruction by other white blood cells

Question 7

How do vaccinations work?

Answer 7

• dead or inactive pathogens are injected into the body
• the antigens carried by the pathogen will trigger an immune response - lymphocytes will produce antibodies
• some of the lymphocytes will remain in the blood as memory cells
• if live pathogens of the same type ever appear, antibodies will kill them sooner, faster and in greater quantity

Question 8

How does the heart function?

Answer 8

Deoxygenated blood from the body is received by the right atrium through the vena cava. The blood flows through the tricuspid valve into the right ventricle, then through a semi-lunar valve into the pulmonary artery, pumping it to the lungs.
Oxygenated blood from the lungs is received by the left atrium through the pulmonary vein. The blood flows through the bicuspid valve into the left ventricle, then through a semi-lunar valve into the aorta, which pumps it all around the body.

Question 9

Why does the wall of the left ventricle have more muscle?

Answer 9

The wall of the left ventricles is thicker because it has to pump blood all around the body, not just to the lungs

Question 10

Why does heart rate go up during exercise?

Answer 10

When you exercise, your muscles need to respire more in order to gain more energy. You need to get more oxygen to your cells and remove more carbon dioxide. For this to happen, your blood must flow faster which means your heart rate increases.

Question 11

How does adrenaline affect heart rate?

Answer 11

• when an organism is threatened, adrenaline is released by the adrenal glands on top of the kidneys
• the adrenaline binds to adrenegic receptors in the heart
• this causes the cardiac muscle to contract more frequently and with more force, so that the heart rate increases and the heart pumps more blood

Question 12

What are the four main components in blood?

Answer 12

• plasma
• red blood cells
• white blood cells
• platelets

Question 13

What are the three types of blood vessels?

Answer 13

Arteries, veins and capillaries

Question 14

What does an artery do?

Answer 14

It carries blood away from the heart

Question 15

What does a vein do?

Answer 15

It carries blood to the heart

Question 16

What does a capillary do?

Answer 16

It is involved in the exchange of materials at the tissues

Question 17

What are some characteristics of an artery?

Answer 17

• they have strong and elastic walls which contain thick muscle - this is because blood is pumped at high pressure
• the walls are thick compared to the size of the lumen

Question 18

What are some characteristics of veins?

Answer 18

• they have a large lumen to help blood flow - this is because blood is pumped at low pressure
• they don’t have very thick walls
• they have valves to prevent back flow

Question 19

What are some characteristics of capillaries?

Answer 19

• they have permeable walls
• their walls are one cell thick which increase the rate of diffusion by decreasing the diffusion distance
• the lumen is the same width as a red blood cell (shorter distance)