circulatory system

Question 1

arteries

Answer 1

carry blood away from the heart to the body. Accommodate large volumes of blood. Have thick walls, consisting of many muscle fibres and elastic fibres (collagen and elastin). Can withstand high pressures. The peak pressure is at systolic (contraction) pressure. It works with vasoconstriction (reduces the lumen and circumferences and increases blood pressure to the part of the body they supply)

Question 2

veins

Answer 2

Carry blood from capillary to the heart
Prevent backflow of blood when blood pressure is slow, using valves
Flexible when squeezed
Thin walls (few muscle and elastic fibres)
Low pressure

Question 3

capillaries

Answer 3

1 cell thick
Think walls of endothelial cells
Close to cells for nutrient and gas exchange
Receives waste from cells to bring to blood
Slow blood flow
Has a lot of branches (large total length)
Low pressure

Question 4

the heart

Answer 4

Consists of cardiac muscle tissue, which contracts involuntarily
Needs a lot of mitochondria
Cells are connected by cytoplasmic bridges

Question 5

single cardiac cycle

Answer 5

divided into two phases: systole and diastole
Consists of relaxation(diastole) and contraction (systole)
Single circulatory system: blood passes through heart only once (e.g. fish)
Double circulation: humans, blood passes through heart twice
Advantages: higher pressure, greater blood flow rate to tissues

Question 6

atherosclerosis

Answer 6

Slow build up of materials in the arteries (called plaque, which is composed of lipids, cholesterol, cell debris and calcium(
The build up of this material causes the arteries to become hard and less flexible
The blockage in the coronary arteries causes a portion of the heart muscle to be deprived of an oxygen supply, which is what happens during atherosclerosis: leads to partial or complete occlusion
OCCLUSION: condition of plaque build up where the blood vessel can no longer supply healthy volume of blood
EFFECT: CAN LEAD TO A HEART ATTACK

Question 7

coronary heart disease

Answer 7

-fat blocked artery

Question 8

cancer

Answer 8

• proliferation of cells on heart (TUMOR)

Question 9

control of heart rate

Answer 9

• its myogenic (no nervous system)

- use of pacemaker cells; control heart rate with electrical impulses

Question 10

process of heart rate control

Answer 10

1. wave of depolarization spreads from SAN (in right atria) over atria
2. Atria depolarize, contract and pump blood into ventricles
3. wave reaches AVN, where there is a 0.1 second delay
4. wave transmitted along purkinje fibres into ventricles
5. ventricles depolarize and contract and pump blood into arteries
6. atria and ventricles depolarize and relax
7. Atria fill with blood from vena cava and pulmonary vein

Question 11

influenzes of heart rate

Answer 11

• excersize
• stress
• chemicals (adrenaline or epinprine)