CVD

Question 1

Cardiovascular Diseases - CVD

Answer 1

One of the main processes leading to CVD are Atherosclerosis and Hypertension
Cardiovascular disease is a group of diseases of the heart and blood vessels. The main examples include:-
Peripheral Vascular Disease
Angina
Myocardial infarction (heart attack)
Stroke

Question 2

Atherosclerosis

Answer 2

Atherosclerosis is the accumulation of fatty material (consisting mainly of cholesterol), fibrous material and calcium forming an atheroma or plaque beneath the endothelium

Question 3

Atheromas=Plaque

Answer 3

As the atheroma grows the artery thickens and loses its elasticity. The diameter of the artery’s lumen becomes reduced and blood flow becomes restricted resulting in increased blood pressure

Question 4

Reactions which form a clot

Answer 4

Damage to cell = clotting factors released by the cell.
Prothrombin = an inactive enzyme present in blood plasma.
Clotting factors convert prothrombin into its active form = thrombin.
Thrombin turns a soluble plasma protein = fibrinogen into threads of insoluble protein called fibrin.
Fibrin threads interweave = platelets stick to the fibrin threads = Blood clot/thrombus
Wound sealed and scar tissue forms.

Question 5

Thrombosis

Answer 5

Atheromas make the surface of the inner artery uneven = restrict blood flow
-Atheromas enlarge and eventually burst through the endothelium and damage it.
-Platelets can attach to rough inner surface of an artery caused by atherosclerosis and release clotting factors.
-This causes a thrombus (blood clot).
-The formation of a clot is referred to as a thrombosis.

Question 6

Thrombosis pt2

Answer 6

-In some cases a thrombus may break loose forming an embolus and travel through the bloodstream until it blocks a blood vessel.
-A thrombosis in a coronary artery may lead to a heart attack (MI).
-A thrombosis in an artery in the brain may lead to a stroke.
-Cells are deprived of oxygen leading to death of the tissues

Question 7

Peripheral Vascular Disorders

Answer 7

Peripheral arteries = those other than coronary arteries, carotid arteries (going to brain) and aorta.

-Peripheral vascular disease is narrowing of the arteries due to atherosclerosis of arteries other than those of the heart or brain.
-The arteries to the legs are most commonly affected.
-Pain is experienced in the leg muscles due to a limited supply of oxygen.

Question 8

Deep Vein Thrombosis

Answer 8

A DVT is a blood clot that forms in a deep vein most commonly in the leg, and can break off and result in a pulmonary embolism.

Question 9

Cholesterol

Answer 9

Cholesterol is a type of LIPID FOUND IN cell membranes
It is also used to make the sex hormones, testosterone, oestrogen and progesterone.

Cholesterol is synthesised by all cells, although 25% of total production takes place in the liver.
A diet high in saturated fats or cholesterol causes an increase in cholesterol levels in the blood.

Question 10

Lipoproteins

Answer 10

Molecules made of lipid and protein.

Present in blood plasma.

Transport lipids [including cholesterol] around the body.

2 Main groups = Low–Density Lipoproteins [LDL’s] Bad Cholesterol and High-Density Lipoproteins [HDL’s] Good Cholesterol.

Question 11

Low Density Lipoprotein

Answer 11

-LDL transports cholesterol from the LIVER to the BODY CELLS
-Most cells have LDL receptors ON THEIR CELL MEMBRANES that take LDL into the cell where it releases cholesterol.
-Cholesterol used within the cell (CELL MEMBRANES/SEX HORMONES)

Question 12

When a cell has sufficient Cholesterol

Answer 12

Once a cell has sufficient cholesterol a negative feedback system INHIBITS the synthesis of new LDL receptors =
LDL circulates in the blood where it may deposit cholesterol in the arteries forming an atheroma = BAD

Question 13

High Density Lipoproteins

Answer 13

-HDL transports excess cholesterol from the body cells to the liver for elimination.
-This prevents accumulation of cholesterol in the blood.
HDL cholesterol does not build up in the artery walls as it is not taken in.
-Regular physical activity tends to raise HDL levels.
-Dietary changes aim to reduce the levels of total fat in the diet and to replace saturated with unsaturated fats.

Question 14

Once cholesterol levels rise

Answer 14

Once a cell has sufficient cholesterol a negative feedback system inhibits the synthesis of new LDL receptors.

LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas

Question 15

Maintaining a healthy Lipoprotein balance

Answer 15

-Normally HDL molecules carry 20-30% of blood cholesterol with LDL molecules carrying 60-70%
-A higher ratio of HDL to LDL molecules = decrease in blood cholesterol = reduced risk of atherosclerosis
-The reverse of this is true with a lower HDL to LDL ratio.

Question 16

Statins

Answer 16

-Statins help to reduce the level of cholesterol in the blood.
-They inhibit an enzyme [competitive inhibition] that is essential for the synthesis of cholesterol in the liver.
-Statins also increase the number of LDL receptors made by liver cells = more LDL [bad cholesterol] removed from the bloodstream.

Question 17

Blood glucose levels and vascular disease

Answer 17

Normal blood plasma = 5 mmol/l of glucose.
Person with untreated diabetes = blood glucose level rises to 30 mmol/l. This is an abnormal and chronic level.

Question 18

Microvascular disease

Answer 18

-Chronic elevation of blood glucose levels leads to the endothelium cells taking in more glucose than normal, damaging the blood vessels.
-Atherosclerosis may develop leading to cardiovascular disease, stroke or peripheral vascular disease.
-Small blood vessels damaged by elevated glucose levels may result in haemorrhage of blood vessels in the retina, renal failure or peripheral nerve dysfunction.

Question 19

Regulating blood glucose levels

Answer 19

All living cells require a supply of glucose for respiration.
The liver can store up to 100 grams of glucose in the form of glycogen.
Glucose can be removed from the liver if the body’s cells demand it.
2 important hormones are produced to help control blood glucose levels = insulin and glucagon

Question 20

The role of insulin

Answer 20

Pancreatic receptors respond to raised blood glucose levels by increasing secretion of insulin from the pancreas.

Insulin activates the conversion of glucose to glycogen in the liver decreasing blood glucose concentration.

Question 21

Glucagon

Answer 21

Pancreatic receptors respond to lowered blood glucose levels by increasing secretion of glucagon from the pancreas.
Glucagon activates the conversion of glycogen to glucose in the liver increasing blood glucose concentration.

Question 22

Glucose levels during exercise

Answer 22

During exercise and fight or flight responses, glucose concentrations in the blood are raised by adrenaline, released from the adrenal glands, stimulating glucagon secretion and inhibiting insulin secretion.

Question 23

Diabetes

Answer 23

A person with diabetes is unable to control their blood glucose levels.
Normal levels = 5 mmol/l
Untreated = 10-30 mmol/l
Two types of diabetes.

Question 24

Type 1 diabetes

Answer 24

Type 1 diabetes usually occurs in childhood. A person with type 1 diabetes is unable to produce insulin and can be treated with regular doses of insulin.

Question 25

Type 2 diabetes

Answer 25

Type 2 diabetes typically develops later in life. The likelihood of developing type 2 diabetes is increased by being overweight. In type 2 diabetes, individuals produce insulin but their cells are less sensitive to it. This insulin resistance is linked to a decrease in the number of insulin receptors in the liver, leading to a failure to convert glucose to glycogen

Question 26

Diabetes problems

Answer 26

In both types of diabetes, individual blood glucose concentrations will rise rapidly after a meal. The kidneys will remove some of this glucose, resulting in glucose appearing in urine.
Testing urine for glucose is often used as an indicator of diabetes.

Question 27

Glucose Tolerance Test

Answer 27

Glucose tolerance =capacity of the body to cope with ingested glucose by producing correct levels of insulin.

T-he Glucose tolerance test is used to diagnose diabetes.
-The blood glucose concentrations of the individual are initially measured after fasting.
-The individual then drinks a glucose solution and changes in their blood glucose concentration are measured for at least the next two hours.
-The blood glucose concentration of a diabetic usually starts at a higher level than that of a non-diabetic.
-During the test a diabetic’s blood glucose concentration increases to a much higher level than that of a non-diabetic and takes longer to return to its starting concentration.

Question 28

Patient 1

Answer 28

Glucose concentration rises to maximum at 30 minutes then quickly drops to initial level within 2.5 hours.
Insulin production normal.
Process so effective that blood glucose level dips below initial fasting level for a short time towards end of test.

Question 29

Patient 2

Answer 29

Glucose concentration starts at normal fasting level but keeps rising to a maximum around 60 minutes before beginning to decrease.
Delay in insulin response = mild type 2 diabetes.
Careful diet will sort this out and won’t require insulin treatment.

Question 30

Patient 3

Answer 30

Even after fasting, glucose concentration abnormally high.
Following ingestion of glucose, concentration rises for 60 minutes then decreases a little.
It does not return to initial high level.
Severe diabetes [type 1] due to no insulin production.
Regular insulin injections and careful diet essential to control this condition.

Question 31

Obesity

Answer 31

Obesity is characterised by excess body fat in relation to lean body tissue [muscle]

It is a major risk factor for cardiovascular disease and type 2 diabetes.

Question 32

Role of diet and exercise in reducing obesity and cardiovascular disease (CVD).

Answer 32

Obesity is linked to high fat diets and a decrease in physical activity.

The energy intake in the diet should limit fats and free sugars, as fats have a high calorific value per gram and free sugars require no metabolic energy to be expended in their digestion.

Question 33

Causes of Obesity

Answer 33

Factors which contribute to obesity include genetic, psychological, environmental, metabolic and dietary.

Most common cause is excessive consumption of food rich in fats and free sugars, combined with a lack of physical activity.

Question 34

Causes of Obesity

Answer 34

Exercise increases energy expenditure and preserves lean tissue.

Exercise can help to reduce risk factors for CVD by keeping weight under control, minimising stress, reducing hypertension and improving blood lipid profiles.

Question 35

BMI

Answer 35

BMI = Body Mass Index. This is a calculation based on the idea that every person has an ideal body mass.
-Body mass index (BMI) is commonly used to measure obesity but can wrongly classify muscular individuals as obese.
-BMI = body mass divided by height squared. A BMI greater than 30 is used to indicate obesity.

Question 36

Limitations of BMI as an indicator of obesity

Answer 36

Certain individuals [body builders, front row rugby players] have a relatively low percentage of body fat and an unusually high percentage of muscle bulk.

They would be wrongly classified as obese by the BMI method.

Measuring body density is a more accurate way of measuring body fat.

Question 37

Effect of exercise on body composition

Answer 37

Weight loss = total energy intake has to be less than total energy used.

Intensity of exercise also affects speed and amount of weight loss.