B4. Blood, blood vessels and the heart

Question 1

What is the structure of blood plasma?

Answer 1

• Straw yellow liquid

- Made up of water and dissolved substances.

Question 2

What is the function of blood plasma?

Answer 2

• Plasma transports many dissolved substances around the body.
• Examples include digested foods (e.g. glucose), gases (e.g. carbon dioxide), wastes (e.g. urea) and hormones (e.g. insulin), antibodies, anti-toxins.
• Plasma also transports heat around the body.

Question 3

What is the structure of red blood cells?

Answer 3

• Very small in size. This provides a large surface area to volume ratio.
• They contain Haemoglobin - this is a red pigment that binds oxygen –> oxyhaemoglobin.
• They are shaped like discs –(biconcave) but are thicker at the edges.
• They have NO nucleus (so there is more space for haemoglobin)

Question 4

What is the function of red blood cells?

Answer 4

• To transport oxygen to all the body cells for respiration.

- Haemoglobin binds oxygen molecules forming oxyhaemoglobin.

Question 5

What is the structure of white blood cells?

Answer 5

• Much bigger than red blood cells.
• Much fewer in number than red blood cells.
• They HAVE a nucleus.
• They have no definite shape

Question 6

What is the function of white blood cells?

Answer 6

The fight disease in the body.

Question 7

Name the 2 types of white blood cell and explain how they fight disease.

Answer 7

• Phagocytes – engulf (‘eat’) pathogens.

- Lymphocytes – create antibodies which destroy pathogens.

Question 8

What is the structure of platelets?

Answer 8

• These are tiny fragments of cells
• They have NO nucleus
• They cause blood to clot

Question 9

What is the function of platelets?

Answer 9

Their function is to help form blood clots. This helps seal wounds (and prevent blood loss) when we cut ourselves

Question 10

What is meant by humans having a ‘double circulatory system’?

Answer 10

The heart is an organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle pumps blood around the rest of the body.

Question 11

Describe the structure of an artery.

Answer 11

• Thick collagen, elastin & muscle wall.

- Narrow lumen

Question 12

Describe the structure of a vein?

Answer 12

• Thin muscle & elasin wall
• Wide lumen
• Have valves

Question 13

What is the function of valves in veins?

Answer 13

Valves prevent the back-flow of blood.

Question 14

What type of blood do arteries (usually) carry?

Answer 14

Oxygenated blood

Question 15

What type of blood do veins (usually) carry?

Answer 15

Deoxygenated blood

Question 16

Describe the structure of a capillary.

Answer 16

• Very small blood vessel

- Endothelium wall is just one cell thick

Question 17

What is the function of capillaries?

Answer 17

allow fast exchange/diffusion of substances e.g. glucose, oxygen - out of the blood into the body cells/tissues.

Question 18

Describe the pathway of blood through the heart.

Answer 18

(RHS) Vena cava –> right atrium –> right ventricle –> pulmonary artery (pumps blood to the lungs) –> (LHS) Pulmonary vein –> left atrium –> left ventricle –> aorta (pumps blood all around the body)

Question 19

What are the 2 top chambers of the heart called?

Answer 19

Left and right atria (singular atrium)

Question 20

What are the 2 bottom chambers of the heart called?

Answer 20

Left and right ventricles

Question 21

Which blood vessel carries deoxygenated blood into RHS of the heart?

Answer 21

Vena cava

Question 22

Which blood vessel carries oxygenated blood into the LHS of the heart?

Answer 22

Pulmonary vein

Question 23

What are the coronary arteries?

Answer 23

These are the arteries that supply the heart muscle with oxygen and glucose for respiration.

Question 24

How can blocked coronary arteries lead to heart disease?

Answer 24

In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle.

Question 25

Name the 3 main ways of treating heart disease?

Answer 25

• Drugs: e.g. statins
• Mechanical devices: stents, artificial valves, artificial pacemakers
• Heart transplant

Question 26

What is a stent?

Answer 26

A wire mesh (‘balloon’) which is inserted into a (blocked) coronary artery to widen the artery and allow more blood to flow.

Question 27

What are statins?

Answer 27

Are drugs taken to reduce blood cholesterol levels, which slows down the rate of fatty deposit build up in the coronary arteries.

Question 28

What is an artificial valve?

Answer 28

• Valves in the heart prevent backflow of blood.
• If the valve becomes faulty this could prevent the valve from opening fully, or the heart valve might develop a leak.
• Faulty heart valves can be replaced using biological or mechanical valves.

Question 29

What is an heart transplant?

Answer 29

Replacement of a faulty/diseased heart with that of one donated by another person.

Question 30

What is a pacemaker?

Answer 30

The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker. Artificial pacemakers are electrical devices used to correct irregularities in the heart rate.

Question 31

What is an artificial heart?

Answer 31

If donor organs are not available doctors may insert an artificial heart.-

• It is a mechanical device that can pump blood for a person who has a failed heart.
• They are used as a temporary fix to keep someone alive until they can have a heart transplant.