Energy for life: The Heart

Question 1

How does the structure of veins relate to their function? [4 points, excluding explanation]

Answer 1

• transport blood at low pressure
• wide lumen > low resistance to blood flow
• valves > prevent the backflow of blood
• thin muscle layer in wall > contracts to keep blood flowing

Question 2

How does the structure of arteries relate to their function? [3 points, excludin explanation]

Answer 2

• transport blood at high pressure
• thick muscle layer in wall > can contract to maintain pressure
• thick elastic layer in wall > can stretch and recoil to prevent bursting

Question 3

What is the function of the septum?

Answer 3

divides the left and right side of the heart, preventing mixing of oxygenated and deoxygenated blood

Question 4

What factors increase the risk of developing coronary heart disease? List three.

Answer 4

Any from the following list:
- smoking
- diet high in saturated fat and cholesterol,
- lack of exercise
- obesity
- high blood pressure
- high salt levels in diet

Question 5

Why is the left ventricle wall thicker than the right ventricle wall?

Answer 5

to generate a higher pressure on the left side, to push blood round the entire body

Question 6

What is plasma? [2 points]

Answer 6

• yellow liquid
• carries proteins and other subtances like CO2.
• Temperature control

Question 7

What are the function of red blood cells?

Answer 7

They carry oxygen from the lungs to cells int he body.

Question 8

Name an adaptation of red blood cells

Answer 8

no nucleus for larger are to carry haemoglobin

Question 9

What are the 3 things required in the circulatory system?

Answer 9

liquid (blood)
pump (heart)
series of pipes (blood vessels)

Question 10

What is pulmonary circulation in the human DC system? [2 points]

Answer 10

deoxygenated blood is pumped to the lungs and oxygenated blood returns back to the heart

Question 11

what is Systemic circulation in the human DC circulation? [2 points]

Answer 11

oxygenated blood is pumped to all the other organs of the body and deoxygenated blood returns back to the heart.

Question 12

Name the 4 chambers the heart is divided into [2 points]

Answer 12

2 atria and 2 ventricles

Question 13

what are the right and left sides of the heart sepearted by?

Answer 13

The septum

Question 14

Why is the left ventricle wall much thicker than the right ventricle wall? [2 points]

Answer 14

allows it to pump blood at higher pressures so that the blood can travel around the whole body.

Question 15

How does the heart pump blood? [2 points]

Answer 15

The two sides of the heart contract and relax at the same time to pump blood.
The atria contracts, emptying blood into the ventricles. The ventricles then contract, pushing blood into the arteries.
Valves close to ensure blood flows in the correct direction.

Question 16

how many times, on average, does the human heart beat at rest?

Answer 16

70 times

Question 17

why does the rate our heart beats change when we excercise?

Answer 17

muscles need more glucose and oxygen for aerobic respiration.

Question 18

Where are the changes in heart rate controlled?

Answer 18

from a part of the brain called the medulla

Question 19

how does excercise increase heart rate? [6-7 points]

Answer 19

When exercise starts the muscles produce more carbon dioxide in aerobic respiration. Sensors in the aorta and carotid artery detect this increase.
They send nerve impulses to the medulla.
The medulla responds by sending nerve impulses along the accelerator nerve.
The accelerator nerve increases the heart rate.
More blood is supplied to the muscles to meet the demands of increased aerobic respiration.

Question 20

what is the name of the nerve that sense electrical impulses to the heart at rest?

Answer 20

decelerator nerve

Question 21

what colour is plasma?

Answer 21

straw-coloured

Question 22

what is plasma?

Answer 22

liquid that transports blood cells etc.

Question 23

list 3 things that plasma transports

Answer 23

aftf:
blood cells
dissolves nutrients (glucose and animo acids)
dissolved waste products (urea and CO2)
hormones
proteins

Question 24

what are red blood cells? [2 points]

Answer 24

small red cells that transport oxygen which binds to haemoglobin

Question 25

give 3 adaptations of the red blood cells and why [6 points]

Answer 25

- contains haemoglobin (a protein which combines with oxygen to form oxyhaemoglobin), which transports oxygen to respiring cells. - No nucleus so more haemoglobin can be packed into each cell and more oxygen can be transported - biconcave shape which increases

Question 26

How does blood clotting occur? [7 points]

Answer 26

Platelets are fragments of larger cells. If the platelets are exposed to oxygen (because of a cut) they release chemicals which start the clotting process. These chemicals cause the soluble plasma protein fibrinogen to be changed into the insoluble fibrous protein fibrin. The fibrin forms a network of fibres across the cut, which trap platelets and red blood cells. This forms a clot, or scab, which prevents further loss of blood. It also acts as a barrier to prevent the entry of pathogens.

Question 27

where do arteries carry blood away from?

Answer 27

the heart

Question 28

where do veins carry blood to?

Answer 28

the body

Question 29

what do capillaries do?

Answer 29

carries blood through all the tissues and are the site of exchange of materials by diffusion

Question 30

give the 3 structures in the atreries and explain what their functions are [6 points]

Answer 30

thick outer wall to transport blood at high pressure without bursting thick layer of elastic tissue to allow artery to stretch and recoil to keep blood flowing at a high pressure thick layer of muscular tissue to help control blood flow by widening (dilating) and narrowing (constricting)

Question 31

give the 3 structures in the veins and explain what they're for [6 points]

Answer 31

thin outer wall because blood pressure is lower thin layer of muscle and elastic tissue so the wall can contract to keep the blood flowing semilunar valves to prevent the blood form flowing backwards

Question 32

why do veins have semilunar valves?

Answer 32

to prevent backflow of blood

Question 33

why does arteries have thick outer walls?

Answer 33

to help transport blood at high pressures without bursting

Question 34

what is the name of the adaptation of the veins that prevents blood backflow?

Answer 34

semilunar valves

Question 35

what do the conorary arteries do?

Answer 35

supply the heart with blood

Question 36

what happens if you have CHD? [6 points]

Answer 36

If you have a lot of saturated fats in your diet, fatty deposits will build up in the artery walls. The fatty deposits narrow the lumen (space) of the artery. The fatty deposits cause the heart muscle cells to receive less blood. This means that the heart muscle cells receive less oxygen (and glucose) for aerobic respiration. As a result aerobic respiration reduces and anaerobic respiration increases in the heart muscle cells. Lactic acid will build up due to the increase in anaerobic respiration, poisoning the heart muscle cells and causing heart attacks.