Circulatory system and heart

Question 1

Describe the path of deoxygenated blood from the body to the lungs

Answer 1

Body - vena cava - RA - tricuspid valve - RV - semi lunar valve - pulmonary artery - Lungs

Question 2

Describe the path of oxygenated blood from the lungs to the body

Answer 2

Lungs - aorta - LA - bicuspid valve - LV - semi lunar valve - pulmonary vein - Body

Question 3

Describe arteries

Answer 3

Carry oxygenated blood from heart to body. Thich, muscular and elastic walls

Question 4

Describe veins

Answer 4

Carry deoxygenated blood back to heart under low pressure. Wide lumen and valves

Question 5

Describe capillaries

Answer 5

Involved of gas exchange. Short diffusion pathway. Thin and high in number

Question 6

What is tissue fluid?

Answer 6

A substance made from small molecules that leave blood plasma and surrounds cells in tissue

Question 7

Describe the process of pressure filtration

Answer 7

At the start of the capillary bed (nearest arteries) the hydrostatic pressure inside the capillaries is greater than that in the tissue fluid.
Differences in hydrostatic pressure means an overall outward pressure forces fluid out out of capillaries into the spaces around cells and tissue fluid forms.
The fluid leaves and the hydrostatic pressure reduces in the capillaries (lower at venule end).
Due to fluid loss and the increased concentration of plasma proteins the water potential at venule end is lower than in the tissue fluid.
Some water re-enters capillaries from tissue fluid at venule end by osmosis.
Excess tissue fluid drained into lymphatic system.

Question 8

Why is the left ventricle thicker than the right ventricle?

Answer 8

It needs to contract powerfully to pump blood all round the body

Question 9

Why are ventricles thicker than atriums?

Answer 9

They need to push blood out of the heart

Question 10

What do AV valves do?

Answer 10

Link atria to ventricles.
Stop blood flowing back to the atria when the ventricles contract

Question 11

What do SL valves do?

Answer 11

Stop blood flowing back into the heart when ventricles contract

Question 12

When are valves forced open?

Answer 12

When there is an increase in pressure behind a valve

Question 13

When are valves forced close?

Answer 13

When there is an increase in pressure in front of a valve

Question 14

What are the 3 stages of the cardiac cycle?

Answer 14

Atrial systole
Ventricular systole
Diastole

Question 15

Explain atrial systole

Answer 15

Ventricles relax whilst atria contract, causing a decrease in volume and an increase in pressure. This pushes blood into ventricles. SL valves = closed
AV valves = open

Question 16

Explain ventricular systole

Answer 16

Atria relax whilst ventricles contract causing an increasing in pressure.
AV valves = shut
SL valves = open

Question 17

Explain diastole

Answer 17

Both ventricles and atria relax
SL valves = shute
AV valves = open

Question 18

How does atheroma form?

Answer 18

Damage occurs to endothelium causes white blood cells and lipids to clump together to form fatty streaks. A build up of these will harden to form fibrous plaque (atheroma). This plaque will partially block the lumen and restrict blood flow (high BP)

Question 19

How does a heart attack occur?

Answer 19

When coronary arteries become completely blocked meaning heart is completely cut off from its blood supply

Question 20

What factors increase the risk of cardiovascular diseases?

Answer 20

Increase in blood cholesterol
Poor diet
Cigarette smoking
High blood pressure