Blood and the circulation

Question 1

What is the vena cava and does it do?

Answer 1

vein

carries deoxygenated blood to the heart from the body

Question 2

What does the pulmonary vein do?

Answer 2

carries oxygenated blood to the heart from the lungs

Question 3

What is the aorta and does it do?

Answer 3

artery

the heart pumps out oxygenated blood to the body through this

Question 4

What does the pulmonary artery do?

Answer 4

carries deoxygenated blood to the lungs

Question 5

what does the coronary artery do

Answer 5

supply the heart muscle with oxygenated blood

Question 6

What do capillaries do?

Answer 6

allow substances needed by the cell to pass out of the blood.

Question 7

What are the adaptations of capillaries?

Answer 7

• walls are only 1 cell thick: increases rate of diffusion by decreasing the distance over which it occurs
• permeable walls: so substances can move across

Question 8

What are the adaptations of arteries?

Answer 8

• heart pumps the blood out at high pressure so the artery walls are strong, thick and elastic
• elastic fibres allow them to stretch

Question 9

Describe oxygenated blood flows in the heart and gets pumped out to the rest of the body?

Answer 9

oxygenated blood flows into the left atrium from the pulmonary vein

the atrium contracts, pushing the blood into the ventricles

the ventricles contract, forcing the blood into the aorta and out of the heart

the aorta takes the blood around the body

Question 10

Describe deoxygenated blood flows in the heart and gets pumped out to the lungs?

Answer 10

deoxygenated blood flows into the right atrium from the vena cava.

the atrium contracts, pushing the blood into the ventricles

the ventricles contract, forcing the blood into the pulmonary artery and out of the heart

the pulmonary artery takes the blood to the lungs

Question 11

What happens during gas exchange?

Answer 11

1) blood, in the capillaries, passing next to the alveoli is deoxygenated, and has a lot of CO2 (has just come from the pulmonary vein)
2) oxygen diffuses out of the alveolus down the concentration gradient into the capillary bloodstream (low conc. of oxygen)
3) CO2 diffuses down its concentration gradient from the blood to the alveolus to be breathed out
4) when blood reaches body cells oxygen diffuses down the CG from the red blood cells to the boy cells
5) at the same time, CO2 diffuses down the concentration gradient from the body cells into the blood and is carried back to the lungs

Question 12

How are alveoli are adapted for gas exchange?

Answer 12

• large, moist surface area
• capillaries provide a rich, large blood supply, maintaining the concentration gradient
• close to the blood capillaries, the distance for gases to diffuses is small
• thin walls, short diffusion pathway

Question 13

What does blood contain?

Answer 13

plasma in which, red blood cells, white blood cells and platelets are suspended.

Question 14

what are the substances that plasma transports?

Answer 14

products of digestion, hormones, antibodies, urea and carbon dioxide

Question 15

What is the job of the red blood cells?

Answer 15

to carry oxygen from the lungs to all the cells in the body, which need it for respiration

Question 16

Red blood cells adaptions

Answer 16

• contain haemoglobin, which binds to oxygen
• biconcave disc gives the red blood cell a larger surface area for absorbing oxygen
• the don’t have a nucleus, so there’s more room for haemoglobin
• they are very small, so they can fit through the tiny capillaries

Question 17

what are platelets and what do they do?

Answer 17

fragments of cells, which collect at wounds and trigger blood clotting