Circulation

Question 1

What is the function of red blood cells?

Answer 1

Transports oxygen around the body

Question 2

What are the adaptations of the red blood cells?

Answer 2

Have a biconcave disc shape → this provides a large surface area for diffusion of oxygen
Contain haemoglobin → that oxygen binds to
No nucleus → therefore there is more space to carry haemoglobin

Question 3

What is the function of white blood cells?

Answer 3

protects the body against diseases

Question 4

What are the adaptations of the white blood cells?

Answer 4

There are 2 types of white blood cells:
Lymphocytes → produce antibodies
Phagocytes → engulf and digest microorganisms by phagocytosis

Question 5

What is the function of a platelet?

Answer 5

Help clot the blood

Question 6

Explain how platelets help reduce blood loss

Answer 6

They convert Fibrinogen (soluble) into Fibrin (insoluble)
Fibrin forms a mesh to trap the blood and helps to form scabs
This reduces blood loss (after injury)

Question 7

What is the function of plasma?

Answer 7

Yellow liquid part of the blood that helps to transport:
Blood cells / Food molecules / Carbon dioxide / Hormones (e.g. insulin) & Urea (waste)

Question 8

What is the blood made up of?

Answer 8

Red blood cells, White blood cells, Platelets and Plasma

Question 9

Explain why arteries have thicker muscular walls and more elastic fibres than veins

Answer 9

Thicker muscle → as the arteries are under high pressure (as they are close to the heart)

Elastic fibres → allows the artery to expand and recoil as blood pushes through

Question 10

Explain why the vein has a large lumen and contains valves

Answer 10

Large Lumen → prevents friction and helps move the blood along

Valves → prevents the backflow of blood as the veins are under low pressure (ensure the blood moves in one direction)

Question 11

Explain why a capillary is one cell thick and permeable

Answer 11

One cell thick → creates a short diffusion distance for molecules to be transported e.g. oxygen

Permeable → allows exchange between blood and body cells (e.g. diffusion of oxygen from red blood

Question 12

Why is it a benefit for capillaries to be under lower pressure than the arteries?

Answer 12

To allow time for the molecules (e.g. glucose and oxygen) to diffuse out into the surrounding cells

Question 13

What does the Hepatic vein contain?

Answer 13

Hepatic vein → carries glucose and amino acids from the liver to the body and carbon dioxide back to the lungs

Question 14

What blood vessel bring blood to the kidney?

Answer 14

Renal artery

Question 15

What blood vessel bring blood to the Liver?

Answer 15

Hepatic artery

Question 16

What blood vessel takes blood away from the kidney and back to the heart?

Answer 16

Renal vein

Question 17

What blood vessel takes blood from the small intestine to the Liver?

Answer 17

Hepatic portal vein

Question 18

What is cardiac output?

Answer 18

CARDIAC OUTPUT = volume of blood pumped by the heart per minute

Question 19

What is recovery rate?

Answer 19

RECOVERY RATE = the time it takes for the pulse or heart rate to return to normal

Question 20

What are the effects of exercise on the heart?

Answer 20

-Exercise strengthens the heart (as it would any muscle) and increases cardiac output
-During exercise our muscles need more energy as they are contracting more often
-The heart has to pump more blood to our muscles so that they get more oxygen and glucose for respiration
-Increased cardiac output during exercise increases blood pressure and therefore increases blood flow to the muscles

Question 21

What is double circulation?

Answer 21

the blood travels through the heart twice for each complete circuit of the body

Question 22

What is a unidirectional pump?

Answer 22

The heart ensures that the blood is pumped in one direction

Question 23

Why are the ventricles thicker than the atria?

Answer 23

The ventricles are thicker than the atria → as they require more pressure to pump the blood to either the lungs or the rest of the body

Question 24

Why is the left ventricle thicker than the right?

Answer 24

As it requires more pressure to pump the blood to the whole body and not just to the lungs like the right

Question 25

Which arteries supply the heart muscle with blood (containing oxygen and glucose)

Answer 25

Coronary arteries

Question 26

What lifestyle factors can cause Coronary Heart Disease (CHD)?

Answer 26

Diet high in fat
Smoking
Lack of exercise or obesity
Stress
High blood pressure
Drinking too much alcohol

Question 27

How does a heart attack occur? [6 marks]

Answer 27

-Buildup of cholesterol or fat in the coronary arteries (which forms a plaque)
-This causes the coronary arteries to narrow and makes it more difficult for blood to flow through them
-It may become so narrow that a blockage forms a clot
-Blood carrying oxygen and glucose cannot get through to muscle tissue in the heart
-The heart cannot respire or produced energy
-The heart cells die and cannot contract (i.e. the heart stops beating) causing a heart attack