B3e

Question 1

What is plasma?

Answer 1

• a pale yellow liquid
• the liquid part of blood
• carries almost everything that needs transporting around your body

Question 2

What does plasma carry?

Answer 2

• red blood cells, white blood cells and platelets (used in blood clotting)
• water
• digested food products like glucose and amino acids from the gut to body cells
• carbon dioxide from body cells to lungs
• urea from the liver to the kidneys (where it’s removed in the urine)
• hormones:chemical messengers
• antibodies:proteins in a immune response

Question 3

How are red blood cells adapted to their function?

Answer 3

• small and bioconcave shape to give large surface are to volume ration for absorbing and releasing oxygen
• contains haemoglobin, which gives blood its colour–it contains iron
• no nucleus to have more space for haemoglobin, so they can carry more oxygen
• very flexible to pass easily through the tiny capillaries

Question 4

What are the three blood vessels?

Answer 4

• arteries to carry blood away from the heart
• capillaries are involved in the exchange of materials at the tissues
• veins carry blood to the heart

Question 5

What is the structure of arteries?

Answer 5

• carry blood under high pressure so the walls are strong and elastic
• walls are thick compared to the size of the lumen
• the walls contain thick layers of muscle to make them strong

Question 6

What is the structure of veins?

Answer 6

• capillaries eventually join up to form veins
• the blood pressure is lower in the veins so the walls are not as thick as artery walls
• bigger lumen than arteries to help blood flow despite the low pressure
• valves to keep blood flowing in the right direction

Question 7

What is the structure of capillaries?

Answer 7

• arteries branch into capillaries
• too small to see
• carry blood really close to every cell in the body to exchange substances with them
• permeable walls, so substances diffuse in and out
• supply food and oxygen, take away wastes like CO2
• walls usually one cell thick, this increases the rate of diffusion by decreasing the distance over which it occurs

Question 8

What is a double circulatory system?

Answer 8

• mammals have this
• the first system, heart pumps deoxygenated blood to the lungs to take in oxygen
• the blood returns to the heart
• the second system, heart pumps oxygenated blood to the rest of the body

Question 9

What are the advantages of a double circulatory system?

Answer 9

• blood returning to the heart after picking up oxygen means it can be pumped around the body at much higher pressure
• this increases rate of blood flow to the tissues (blood can be pumped around the body much faster), so more oxygen can be delivered to cells
• this is important because mammals use up a lot of oxygen maintaining their body temperature

Question 10

How does blood travel through the heart?

Answer 10

• vena cava
• right atrium
• right ventricle
• plumonary artery
• lungs
• pulomonary vein
• left atrium
• left ventricle
• aorta
• whole body

Question 11

What does haemoglobin do?

Answer 11

• combine with oxygen in the lungs to become oxyhaemoglobin

- in body tissues they do the reverse to release oxygen into the cells

Question 12

Why does the left ventricle have a thicker wall than the right ventricle?

Answer 12

-because it has to pump blood to the whole body, whereas the right ventricle only has to pump blood to the lungs

Question 13

What are the valves in the heart and what do they do?

Answer 13

• semilunar, tricuspid, bicuspid

- prevent backflow of blood