The Heart

Question 1

Flow of blood inside the heart

Answer 1

Deoxygenated blood returns from the body in the vena cava and enters the right atrium

The blood then passes through an atrioventricular valve into the right ventricle and then out through the semi lunar valve into the pulmonary artery

The blood now passes through a second atrioventricular valve into the left ventricle and then through the semi lunar valve into the aorta, and then onto respiring body tissues

Question 2

Pressure in the heart chambers

Answer 2

The atria fill with blood as the pressure in them increases

The atria systole pushing the atrioventricular valves open and pushing blood into the ventricles

High pressure in the ventricles causes the atrioventricular valves to shut

The ventricles systole pushing the semilunar valves open, pushing blood out of the heart

The deoxygenated blood travels to the lungs via the pulmonary artery and the oxygenated blood travels to the body via the aorta

Question 3

What do systole and diastole mean?

Answer 3

Systole- contraction of heart muscle

Diastole - heart muscle relaxes

Question 4

Aneurysm

Answer 4

When the artery becomes blocked, blood flow through the area is restricted

The blood pressure builds up in front of the blockage and presses on the artery wall

This pressure causes the wall to weaken and it starts to bulge outwards

This is known as an aneurysm. The vessel may rupture, causing internal bleeding

Question 5

Atherosclerosis

Answer 5

Process of atheroma formation

Plaque builds up under artery walls until it blocks half of the artery lumens, due to artery damage and lipid accumulation

Question 6

Thrombosis

Answer 6

Plaque breaches epithelium, causing a blood clot

If the thrombus can move it can cause blockages elsewhere which can lead to apoptosis (cell death)

Question 7

Myocardial infarction (heart attack)

Answer 7

Plaque builds up and completely covers artery

This causes a heart attack as cells cannot respire.

Question 8

Artery adaptations

Answer 8

Thick muscular wall - helps to withstand high pressure

Elastic fibers - helps them to stretch and recoil

Arterioles - slow the flow of blood as capillaries are delicate but also to give time for substance exchange

Question 9

Vein features/adaptations

Answer 9

Easily ruptured

Less muscle - less pressure to withstand

Large lumen - less pressure so veins push blood through as quickly as possible

Question 10

Capiliary

Answer 10

One cell thick - short diffusion distance

Squamous (flattened cells). SA:V

Narrow lumen increases time for gas exchange

Question 11

Calculating cardiac output

Answer 11

Cardiac output = stroke volume x heart rate

Question 12

Why would heart rate need to increase/decrease?

Answer 12

Decrease:high blood pressure
To remove waste products from respiration
Lactic acid from anaerobic respiration needs to be delivered to the liver to be broken down
During fight/flight/exercise

Question 13

Non modifiable risk factors for cardiovascular disease

Answer 13

Age
Gender
Race and ethnicity
Genetics

Question 14

Modifiable risk factors for cardiovascular disease

Answer 14

high BP
smoking
physical activity
obesity
high blood cholesterol

Question 15

The cardiac cycle - Diastole

Answer 15

Atria and ventricular muslces relax
Blood enters the atria via the vena cava and pulmonary vein
Blood flowing into atria increases pressure within atria

Question 16

The cardiac cycle - Atrial systole

Answer 16

The atria muscular walls contract, increasing the pressure further
This causes the atrioventricular valves to open and blood to flow into the ventricles
The ventricular muscular valves relax - ventricular disastole

Question 17

The cardiac cycle - Ventricular systole

Answer 17

• After a short delay the ventricular muscular valves contract, increasing the pressure beyond that of the atria
• This causes the atrioventricular valves to close and the semi lunar valves to open
• The blood is pushed out of the ventricles into the ateries (pulmonary and aorta)