Chapter 4

Question 1

How are lungs adapted for gas exchange

Answer 1

• Large surface area
• Walls in the lungs are thin = short diffusion pathway
• Good blood supply = Maintain a high concentration gradient

Question 2

The heart

Answer 2

• Atrium
• Ventricle
• Pulmonary veins
• Aorta
• Vena cava
• Muscular heart wall
• Valves

Question 3

Coronary arteries

Answer 3

Supply the heart with blood

Question 4

Pacemaker

Answer 4

Resting heart rate is controlled by a group of cells

- Irregular heart beats can be controlled using an artificial pacemaker

Question 5

Arteries, veins and capillaries

Answer 5

• Arteries carry high pressure blood away from the heart. They have smaller lumen and no valves.
• Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and have valves to prevent backflow of blood.
• Capillaries have thin walls (one cell thick) to allow glucose and oxygen to pass through. Also used to connect arteries to veins.

Question 6

Four parts of blood

Answer 6

• RED BLOOD CELLS – contain haemoglobin and carry OXYGEN around the body. They have no NUCLEUS and a large surface area.
• PLATELETS – small bits of cells cause BLOOD CLOTTING when you are cut (for a scab).
• WHITE BLOOD CELLS – kill invading MICROBES by producing ANTIBODIES or engulfing the microbe.
• These three are all carried around by the PLASMA. Plasma also transports Co2 and GLUCOSE as well as taking away waste products to the KIDNEYS.

Question 7

Cause of coronary heart disease

Answer 7

Fatty material can build up inside the coronary arteries, leading to coronary heart disease which can be treated with statins or stents

Question 8

Treatments for the heart

Answer 8

Heart valves that may not open and close properly or they leak can be repaired with biological valves which only last 15 years or mechanical valves which last a long time but medication is needed to stop blood clotting.
Artificial hearts are sometimes used while someone is waiting for a transplant.