2 Blood and circulation page 70-79, 81-83

Question 1

What does blood transport?

Answer 1

• Oxygen from the lungs to all other parts of the body.
• Carbon dioxide from all parts of the body to the lungs.
• Nutrients from the gut to all parts of the body.
• Urea from the liver to the kidneys.

Question 2

What is a single circulatory system?

Answer 2

The blood is pumped from the heart to the gas exchange organ and then directly to the rest of the body.

Question 3

What is a double circulatory system?

Answer 3

The blood is pumped from the heart to the gas exchange organ, back to the heart and then to the rest of the body.

Question 4

How is the heart adapted to its function?

Answer 4

• The left ventricle pumps blood to the whole body while the right ventricle pumps only to the lungs. This requires more pressure so the wall of the left ventricle is much thicker due to the pressure.
• Valves prevent the backflow of blood.
• Walls of the heart are made with cardiac muscle, so it can contract and relax continuously without getting fatigued.
• Walls of the atria are thin and can be stretched to receive blood and can also contract enough to push the blood out.

Question 5

What do arteries do?

Answer 5

Carry blood away from the heart.
Pulmonary artery, aorta

Question 6

What do veins do?

Answer 6

Carry blood to the heart.

Question 7

What do capillaries do?

Answer 7

Carry blood through organs, through the organs. Linking arteries and veins.

Question 8

What is coronary heart disease caused by?

Answer 8

Blocked coronary arteries (saturated fats).

Question 9

What factors make coronary heart disease more likely?

Answer 9

• Heredity.
• High blood pressure.
  (Puts more strain on the heart)
• Diet
• Stress.
• Lack of exercise.

Question 10

What happens to our heart rate when we exercise?

Answer 10

It increases.

Question 11

Why does this happen?

Answer 11

When exercising, our cells need more oxygen to respire. So the heart pumps more blood around the body to deliver this energy.

Question 12

Why does this happen (nerves)?

Answer 12

The receptors in the aorta and carotid artery detect this increase in carbon dioxide and send nerve impulses to the medulla. The medulla responds by sending nerve impulses along the accelerator nerve.

Question 13

What does the accelerator nerve do?

Answer 13

Increases the heart rate and makes it beat with more force.

Question 14

What happens to out heart rate when we are afraid or scared?

Answer 14

It increases.

Question 15

Why does this happen?

Answer 15

It supplies extra blood to the muscles, enabling them to release extra energy through aerobic respiration. This is apart of the bodys’ ‘fight or flight’ response to danger. It is triggered by the secretion of the hormone adrenaline from the adrenal glands.

Question 16

Who are these changes in heart rate controlled?

Answer 16

Through the medulla in the brain.

Question 17

How are arteries adapted?

Answer 17

• Thick muscular walls, helps to control the blood flow by dilating and constricting.
• Elastic tissue, allows them to recoil and spring back into shape by maintaining the high blood pressure.

Question 18

How are veins adapted?

Answer 18

• They contain valves which prevent the backflow of blood.
• They don’t have as thick walls as they don’t have such high pressure in them when they are carrying around blood.

Question 19

How are capillaries adapted?

Answer 19

• They are very small in order to fit between cells and allow materials to pass through their walls easily.
• One cell thick so the diffusion of materials into and out of the blood can be easier- proving a shorter distance.
• Oxygen can diffuse out of them very easily as the red blood cells are very close to the capillaries walls.

Question 20

What is the composition of the blood?

Answer 20

• Plasma.
• Red blood cells.
• White blood cells.
• Platelets.

Question 21

What are examples of white blood cells?

Answer 21

• Phagocytes.
• Lymphocytes.

Question 22

What is plasma?

Answer 22

Liquid part of blood, mainly water.

Question 23

What is plasmas function?

Answer 23

Carries the blood cells around the body; carries dissolved nutrients, hormones, carbon dioxide and urea; also distributes heat around the body.

Question 24

What are red blood cells?

Answer 24

Biconcave disk-like cells with no nucleus so more blood can bind to them.

Question 25

What are red blood cells function?

Answer 25

They transport oxygen. They contain mainly haemoglobin, which loads oxygen in the lungs and unloads it in other regions of the body.

Question 26

What are lymphocytes?

Answer 26

About the same size as red blood cells with a large spherical nucleus.

Question 27

What are lymphocytes function?

Answer 27

Produce antibodies to destroy microorganisms. Some persistent in our blood after infection and give us immunity to specific diseases.

Question 28

What are phagocytes?

Answer 28

Much larger than red blood cells, with a large spherical or lobed nucleus.

Question 29

What are phagocytes function?

Answer 29

Digest and destroy bacteria and other microorganisms that have infected our bodies.

Question 30

What are platelets?

Answer 30

The smallest cells - are really fragments of other cells

Question 31

What are platelets function?

Answer 31

Release chemicals to make blood clot when we cut our cells.

Question 32

How are red blood cells adapted?

Answer 32

• No nucleus, so more haemoglobin can be packed into each red blood cell so that the maximum amount of blood can be transported.
• Biconcave shape allows for efficient exchange of oxygen as it has a high surface area: volume ratio allowing for a large area of diffusion.
• Thin shape of the cell allows for a short diffusion distance to the center of the cell.

Question 33

How does phagocytosis work?

Answer 33

They encircle the microorganism and grow pseudo-podia which are extensions of their cytoplasm.
The microorganism is now stuck inside a vacuole and the phagocyte secretes enzymes which slowly break it down.

Question 34

What do lymphocytes do?

Answer 34

Their function is to make antibodies.
These antigens are markers which are recognised by phagocytes.
These antibodies are then recognised by phagocytes so they can digest and break them down.

Question 35

How do the antibodies destroy pathogens?

Answer 35

• Causing bacteria to stick together, so that phagocytes can ingest them more easily.
• Acting as a ‘label’ ion the pathogen, so that it is more easily recognised by a phagocyte.
• Causing bacterial cells to burst open.
• Neutralising poisons (toxins) produced by pathogens.

Question 36

What is the production of antibodies following the the first exposure to a foreign antigen called?

Answer 36

The first immune response.