2 - Circulatory System

Question 1

what is tissue fluid and what is it made up of?

Answer 1

fluid that bathes cells in tissues

made up of water, oxygen, glucose and mineral ions

contains the waste products released from cells, like carbon dioxide, water and urea

Question 2

Formation of Tissue Fluid

Answer 2

At the arteriole end of a capillary, high hydrostatic pressure pushes fluid out into tissues.

Large proteins remain in the blood, creating a water potential gradient.

At the venule end, lower pressure allows some water to move back into the capillary.

Overall, more fluid leaves than returns, forming tissue fluid around cells.

High blood pressure (hypertension) increases fluid loss, leading to oedema (swelling).

Question 3

Atrial Systole

Answer 3

atria contract
ventricles relax.

decreases the volume inside the atria which increases the pressure

increased pressure forces the atrioventricular valves open and pushes blood into ventricles

Question 4

Ventricular systole

Answer 4

ventricles contract
atria relax

decreases the volume inside the ventricles which increases the pressure

forces atrioventricular valves closed and causes semi-lunar valves to open.

The closure of the AV valve prevents the back-flow of blood into the atria.

Blood is forced out of the ventricles and into the arteries (the aorta and the pulmonary artery).

Question 5

Diastole

Answer 5

Both atria and ventricles are relaxed so the pressure is low in both chambers.

Since the pressure is higher in the arteries than in the heart chambers, the semi-lunar valves are forced closed which prevents blood flowing backwards into the ventricles.

Blood is returned to the heart and the atria fill with blood.

Question 6

Atheroma

Answer 6

process in which the artery lining becomes hard due to the build-up of fatty material in the artery wall

increases the risk of aneurysm (high blood pressure from weakened artery pushes on artery lining , causing artery to balloon out)

Question 7

Myocardial infarction

Answer 7

heart attack

The atheroma ruptures and bursts through the endothelium of the artery, damaging the artery wall

This triggers blood clotting (thrombosis) which can cause complete blockage

prevents blood flow so lack of oxygen

cells within the tissue cannot carry out aerobic respiration and will start to die

Question 8

how structure of vein allows it to pump blood even though blood is at low pressure

Answer 8

valves to prevent backflow
Large lumen so less resistance to flow
Thin walls that can be compressed