Biology Unit 1 Booklet 5

Question 0

Roles of valves in control of blood flow (3)

Answer 0

Atrioventricular valves prevent back flow of blood when ventricular pressure exceeds atrial pressure (1)
Semi lunar valves prevent back flow when recoil action of arteries creates greater pressure than in ventricles (1)
Pocket valves in the veins ensure blood flows back to the heart when veins are squeezed e.g. During muscle contractions (1)

Question 1

Events of the cardiac cycle (11)

Answer 1

Atria contracts (atrial systole) (1)
Increased pressure in the atria (1)
Atrioventricular valves open (when pressure in atria is higher than pressure in ventricles) (1)
Blood flows into ventricles (1)
Atrioventricular valves shut ( when pressure in the ventricles is higher than the pressure in the atria) (1)
Ventricles contract (ventricular systole) (1)
Increased pressure in ventricles ( biggest difference) (1)
Semi lunar valves open ( when pressure in the ventricles is greater than the pressure in the arteries ) (1)
Blood moves into the arteries fast at first ( rapid ejection) and then more slowly (1)
Semi lunar valves close ( when pressure in the arteries is higher than the pressure in the ventricles ) (1)
Diastole ( heart relaxes and atria accepts more blood from the veins) (1)

Question 2

Coordinating heartbeats (7)

Answer 2

Sino atrial node (1)
Sends out a wave of electrical activity causes atria to contract (1)
Electrical activity is delayed by atrioventricular node (1)
To allow blood to move into ventricles (1)
Before they contract. Electrical activity passed down he bundle of His (1)
So ventricles contract from bottom up (1)
To ensure all blood is ejected from ventricles (1)

Question 3

What is antheroma (2)

Answer 3

Build up of lipoproteins, white blood cells and cholesterol (1)
In artery wall under endothelial lining (1)

Question 4

Why may antheroma lead to blood clots (2)

Answer 4

Narrows arteries (1)
Causes uneven blood flow (1)

Question 5

How does antheroma lead to an aneurysm (3)

Answer 5

Weakens artery wall (1)
So that it bursts (1)
When under high blood pressure (1)

Question 6

How high blood pressure affects arteries (2)

Answer 6

Muscle in artery wall becomes thicker (1)

Can lead to an aneurysm (1)

Question 7

How antheroma is caused and how it may rule in myocardial infarction (6)

Answer 7

Antheroma forms in artery wall (Ldl’s, white blood cells, cholesterol under endothelial lining) (1)
Antheroma may narrow lumen of artery (1)
Antheroma promotes clotting and increase blood pressure (1)
Blood clot may lodge in coronary artery (1)
There is a reduced blood supply to heart muscle (1)
Reduced oxygen or glucose supply leads to cells death due to cells inability to respire aerobically (1)

Question 8

How smoking increases risk of developing coronary heart disease (4)

Answer 8

Smoking increases risk of clotting (1)
Nicotine causes platelets to stick together (1)
Carbon monoxide is associated with the risk of plaque formation (1)
Which reduces the elasticity of the arteries (1)

Question 9

How high blood cholesterol increases the risk of devolving coronary heart disease (4)

Answer 9

Fatty deposits on wall of arteries (1)
Damages endothelium (1)
Narrows lumen (1)
Can lead to blood clots (1)