Extended-Response Question -Pathology of Cardiovascular Disease

Blood Glucose Levels & Obesity - type 1 & type 2 diabetes (3 marks)

Thrombosis - what it is & its effects on the body

Control of Cholesterol Levels in the Body - what it is & its effects on the body

Glucose Tolerance Test

Atherscelerosis

Build-up of fatty material underneath the endothelium (such as fibrous material, cholesterol and calcium)

This accumulation forms an atheroma

As an atheroma continues to build-up a number of things happen:

artery loses its elasticity

the restricted blood flow increases blood pressure

the blockage restricts blood flow due to the decreased diameter of the lumen

Blood Clotting

If an atheroma ruptures it can damage the endothelium of the artery, resulting with events leading to a blood clot

3. thrombin causes the plasma proteins finbrinogen to form threads of fibrin

3. fibrin threads mesh together clotting the blood and sealing the wound

2. clotting factors convert the enzyme prothrombin to thrombin

5. scar tissue forms on the scaffold creating a clot

1. damage to endothelium releases clotting factors

Thrombosis

The term given to the formation of a blood clot (thrombus) inside a blood vessel

If a thrombus breaks lose it forms an embolus where is travels in the bloodstream where it may block a blood vessel completely

If an embolus blocks a coronary artery it may lead to a heart attack

If an embolus blocks an artery supplying the brain with oxygen it may lead to a stroke

In either case, tissue death can occur due to a lack of oxygen

Deep Vein Thrombosis

Peripheral Vascular Disease (PVD) is caused by the narrowing of arteries that are not connected to the heart nor the brain

Arteries in the legs are commonly affected by PVD

Pain in legs may be felt due to lack of oxygen reaching muscle cells

Deep Vein Thrombosis is a blood clot that forms in a deep vein, commonly in the leg

The blood clot can break off to form an embolus and can cause a pulmonary embolism

Is a type of lipid found in the cell membrane

And it is also used to synthesise sex hormones

Too much cholesterol in the blood can cause conditions like CVD

Increased levels can be as a result of a diet in high in saturated fats, or cholesterol

All body cells produce cholesterol but 25% of it comes from the liver

There are 2 types of cholesterol carrying proteins:

HDL

LDL

low-density lipoproteins

high-density lipoproteins

transport excess cholesterol from the rest of the body to the liver for eliminations

transport excess cholesterol from the liver to the rest of the body and deposit cholesterol inside the arteries

Cholesterol levels are also controlled by negative feedback system:

1. cells have LDL receptors on their surface which allow cholesterol to be deposited inside the cells by LDLs

2. once there is enough cholesterol inside the cell, synthesis of new LDL receptors are inhibited which reduces the amount of cholesterol absorbed into the cells

3. excess LDL carried cholesterol is deposited inside the arteries, lining the endothelium, causing an atheroma to form

Controlling cholesterol levels

A higher ratio of HDL to LDL will result in lower blood cholesterol levels and will reduce chances of developing atherosclerosis

A low diet in saturated fats and regular physical activity will raise HDL levels

Cholesterol can also be managed with Statins which reduce blood cholesterol levels by inhibitting cholesterol synthesis in the liver

Insulin

a hormone produced in the pancreas which regulates glucose concentrations in the blood

if blood glucose is too high the pancreas produces insulin to move the glucose from the blood into cells, where it is stored

or the liver converts it to glycogen for storage

either as body fat

Blood Glucose Regulation

Too high

liver converts glucose to glycogen

blood glucose goes down

pancreas secretes insulin

Too low

pancreas secretes glucagon

glycogen is converted to glucose

blood glucose goes up

Adrenaline stimulates the liver to break down glycogen into glucose to provide energy to respond to "fight or flight"

Diabetes

Type 1

Type 2

Unable to produce insulin

Treated with regular insulin injections and a careful diet

Occurs in early childhood

Able to produce insulin

Cells have a decreased number of insulin receptors on their surface, making them less sensitive to insulin - can't convert glucose to glycogen

Treated with exercise, diet control, weight loss and in some cases insulin

Occurs in adulthood

Obesity

Term for a person with high excess body fat

At greater risk of type 2 diabetes, heart disease and some types of cancer

BMI

BMI = m/h^2

25-30 is overweight & 30+ is obese

Patients drink glucose solution - glucose levels are monitored

A diabetics blood glucose will increase more than a non-diabetic and will take longer to return to normal