Topic 1- Lifestyle, Health And Risk

Question 1

Why do many animals have a heart and circulation?

Answer 1

Mass transport to overcome limitations of diffusion in meeting the requirements of organisms

Question 2

Why is water as a solvent important in transport

Answer 2

Water is dipolar which means it is cohesive and a solvent. This means it can transport molecules effectively

Question 3

What does water being cohesive mean?

Answer 3

Cohesion is the attraction between molecules of the same type- water molecules can stick together as they are dipolar. This helps the water to flow

Question 4

Why is water a good solvent?

Answer 4

Water is dipolar so the slightly positive end is attracted to the slightly negative ion and vice versa. This means the ions will get totally surrounded by water molecules and will dissolve easily

Question 5

How does the structure of a capillary relate to its function?

Answer 5

Function- where metabolic exchange occurs
Large network of capillaries increases surface area
Walls are one cell thick which speeds up diffusion

Question 6

How does the structure of an artery relate to its function?

Answer 6

Function- carry blood from the heart to the rest of the body
Thick walls, muscular, elastic tissue in walls to cope with high pressure
Narrow lumen to maintain high pressure
Smooth endothelium reduces resistance to blood flow

Question 7

How does the structure of a vein relate to its function?

Answer 7

Function- take blood back to the heart
Large lumen, thin walls with little elastic or muscle tissue as bod is under lower pressure
Valves to stop the blood flowing backwards

Question 8

Describe stage one of the cardiac cycle

Answer 8

Ventricular diastole, atrial systole
Ventricles are relaxed. Atria contract, decreasing volume of chambers and increasing pressure inside chambers. This pushes the blood into the ventricles. There’s a slight increase in ventricular pressure and chamber volume as the ventricles receive the ejected blood from the contracting atria

Question 9

Describe stage 2 of the cardiac cycle

Answer 9

Ventricular systole, atrial diastole
The atria relax. The ventricles contract, decreasing their volume and increasing their pressure. The pressure becomes higher in the ventricles than the atria which forces the AV valves shut to prevent back flow. The pressure in the ventricles is also higher than in the aorta and pulmonary artery, which forces open the SL valves and blood is forced out into these arteries

Question 10

Describe stage 3 of the cardiac cycle

Answer 10

Cardiac diastole
The ventricles and the atria both relax. The higher pressure in the pulmonary artery and aorta closes the SL valves to prevent back flow into the ventricles. Blood returns to the heart and the atria fill again due to the higher pressure in the vena cava and pulmonary vein. In turn this starts to increase the pressure of the atria. As the ventricles continue to relax, their pressure falls below the pressure of the atria and so the AV valves open. This allows blood to flow passively into the ventricles from the atria. The atria contract and the whole process begins again

Question 11

How does the structure of the heart relate to its function?

Answer 11

Left ventricle has thicker, more muscular walls than the right because it needs to contract powerfully to pump blood all the way around the body, right only goes to lungs which are near.
Ventricles have thicker walls than atria because they push blood out of the heart whereas atria just go to ventricles.
AV valves link atria to ventricles and stop blood flowing back into the atria when the ventricles contract.
SL valves link the ventricles to the pulmonary artery and aorta, and stop blood flowing back into the heart after ventricles contract

Question 12

How can the relationship between heart structure and function be investigated practically?

Answer 12

Dissections
External- four main blood vessels, atria, ventricles and coronary arteries
Internal- atria, ventricles, AV valves and SL valves

Question 13

How is an atheroma formed?

Answer 13

Endothelium wall is damaged
This causes an inflammatory response
Plaque formations
Raised blood pressure

Question 14

Describe the clotting cascade

Answer 14

Thromboplastin is released from a damaged blood vessel
Thromboplastin and calcium ions trigger the conversion of prothrombin into thrombin
Thrombin catalyses the conversion of fibrinogen into fibrin
Fibrin fibres tangle together and form a mesh in which platelets and RBCs get trapped- this forms the blood clot

Question 15

How do blood clots causes heart attacks?

Answer 15

The heart muscle is supplied with blood by the coronary arteries.
This blood contains the oxygen needed by the heart muscle cells to carry out respiration.
If a coronary artery becomes completely blocked by a blood clot an area of the heart muscle will be totally cut off from its blood supply, so it won’t receive any oxygen.
This causes a heart attack (myocardial infarction).
A heart attack can cause damage and death of the heart muscle.
Symptoms include pain in the chest and upper body, shortness of breath and sweating.
If large areas of the heart are affected complete heart failure can occur, which is often fatal

Question 16

How does diet affect risk of CVD?

Answer 16

A diet high in sat fat increases risk of CVD. This is because it increases blood cholesterol level which increases atheroma formation. Atheromas can lead to the formation of blood clots which can cause a heart attack, stroke or DVT. A diet high in salt will also increase the risk of CVD because it increases the risk of high blood pressure

Question 17

How does high blood pressure increase risk for CVD?

Answer 17

Increases risk of damage to artery walls, which increases the risk of atheroma formation which can lead to CVD. Excessive alcohol consumption, stress and diet can all increase blood pressure

Question 18

How does smoking increase risk of CVD?

Answer 18

CO in cigarette smoke binds to haemoglobin and reduces the amount of oxygen transported in the blood. This reduces the amount of oxygen available to tissues. If the heart muscle doesn’t receive enough oxygen it can lead to a heart attack and if the brain doesn’t receive enough oxygen it can lead to a stroke.
Nicotine makes platelets sticky, increasing the chance of blood clots forming which increases the risk of CVD.
Smoking decreases the amount of antioxidants in the blood- these are important for protecting cells from damage. Fewer antioxidants means cell damage in the artery walls is more likely, and this can lead to atheroma formation which increases the risk of CVD

Question 19

How does exercise affect CVD?

Answer 19

Lack of exercise increases risk of CVD as it increases blood pressure

Question 20

How do genetics increase risk of CVD?

Answer 20

Some people inherit particular alleles that make them more likely to have high blood pressure or high blood cholesterol so they are more likely to suffer from CVD

Question 21

How does age increase the risk of CVD?

Answer 21

The risk of developing CVD increases with age. This is partly because plaque can build up very slowly over time, which can eventually lead to CVD

Question 22

How does gender increase risk of CVD?

Answer 22

Men are three times more likely to suffer from CVD than pre-menopausal women. This may be due to their different levels of hormones.
E.g. oestrogen which is higher in females, increases HDL. Low level of oestrogen in men can lead to higher levels of total blood cholesterol and increase the risk of CVD

Question 23

Factors that lead to overestimation of risk

Answer 23

Misleading information in the media
Overexposure to information
Personal experience of the associated risk
Unfamiliarity with the event 
The event causing severe harm

Question 24

Factors that cause underestimation of risk

Answer 24

Lack of information
Misunderstanding of factors that increase the risk
Lack of personal experience of the associated risk
Unfamiliarity with the event
The harm being non-immediate