Cardiovascular Disease, Diabetes and Obesity Higher Human Biology

Learning Intentions Explain the process of atherosclerosis and its effect on arteries and blood pressure Explain the link between atherosclerosis and cardiovascular disease

Lesson starter What is atherosclerosis? What is an atheroma? Describe three effects atherosclerosis has on arteries

Lesson starter What is atherosclerosis? The build up of fatty material (mainly cholesterol), Fibrous material and calcium What is an atheroma? Formed from atherosclerosis in the epithelium. AKA plaque Describe three effects atherosclerosis has on arteries Blocks the narrow cavity in the artery, which decreases diameter and restricts blood flow causes an increase in blood pressure causes the artery to lose elasticity

Coronary Heart Disease Heart disease is a major problem in Scotland, especially in more deprived areas.

Atherosclerosis Also known as ’hardening of the arteries’, atherosclerosis is the build up of fatty material (mainly cholesterol), and calcium. The absolute scenes. This forms an (or plaque) under the epithelium lining the artery. Fibrous material atheroma

Atherosclerosis As the plaque builds up, it: Blocks the narrow cavity in the artery, which decreases diameter and restricts blood flow causes an causes the increase in blood pressure artery to lose elasticity Video

How does CHD start and progress? Normal artery walls are elastic to allow blood to flow at high pressures 1. Part of the lining (endothelium) of an artery is damaged by a plaque 2. Over time more plaques stick to the artery wall in the plaque-damaged region 3. The plaque is rigid – so elasticity of the artery is 4. Stress or exercise can cause the accumulated plaque to crack 5. enters the crack and gets trapped there, platelets are activated so a blood clot is formed reduced Blood animation

Consequences Atherosclerosis can lead to the development of various cardiovascular diseases like: Coronary heart disease (including angina) Strokes Heart attacks Peripheral vascular disease

Atherosclerosis Summary Atherosclerosis is the accumulation of fatty material (consisting mainly of cholesterol), fibrous material and calcium forming an atheroma (or plaque) beneath the endothelium. As the artheroma grows the artery thickens and loses its elasticity. The diameter of the artery becomes reduced and blood flow becomes restricted resulting in increased blood pressure. Atherosclerosis is the root cause of various cardiovascular diseases including angina, heart attack, stroke and peripheral vascular disease.

Learning Intention Explain what is meant by thrombosis and give the role of prothrombin, thrombin, fibrinogen and fibrin Explain the effects of thrombosis in arteries

Blood Clotting The atheroma can rupture, which damages the endothelium. 2. This activates clotting factors which causes a cascade of reactions that convert prothrombin (inactive enzyme) to thrombin (active enzyme) Prothrombin Thrombin Clotting factors

Blood Clotting 3. Thrombin promotes the conversion of molecules of fibrinogen to threads of fibrin. 4. The threads of fibrin form a mesh network that clots the blood and seals the wound. This provides a scaffold for scar tissue. Thrombin Fibrinogen Fibrin

Blood Clotting

Thrombosis Atheromas on the inside lining of an artery make the surface uneven and disrupt the flow of blood. As the atheroma becomes larger, it can burst through the endothelium and damage it. Thrombosis may occur (thrombosis is the formation of a blood clot in a vessel).

Thrombosis

Embolus If the thrombus breaks loose from the site of formation (embolus), it travels along the blood stream until it reaches an artery too narrow to allow it to get through.

Effects of an embolus If the blood clot blocks a coronary artery it may lead to a heart attack.

Stroke If a blood clot blocks an artery supplying the brain, this can lead to a stroke. In both heart attack and stroke, tissue death can occur due to a lack of oxygen.

Thrombis Summary Atheromas may rupture damaging the endothelium. The damage releases clotting factors that activate a cascade of reactions resulting in the conversion of the enzyme prothrombin to its active form thrombin. Thrombin then causes molecules of the plasma protein fibrinogen to form threads of fibrin. The fibrin threads form a meshwork that clots the blood, seals the wound and provides a scaffold for the formation of scar tissue.

Thrombis Summary Cont’d The formation of a clot (thrombus) is referred to as thrombosis. 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 (myocardial infarction). A thrombosis in an artery in the brain may lead to a stroke. Cells are deprived of oxygen leading to death of the tissues.

Learning Intention Explain what is meant by peripheral vascular disease Explain how different areas of the body are affected by peripheral vascular disease

Peripheral Vascular Disease Caused by narrowing of the arteries other than those of the heart or brain You may not know that you have the condition. If you do get symptoms, the most common is pain or cramp in your calf. The pain will come on after exercise as oxygen supply to the cells will be restricted. Video

Deep Vein Thrombosis A DVT is a blood clot that forms in a deep vein most commonly in the leg. The leg can become swollen with blood and if the clot breaks off this can result in a pulmonary embolism.

This can be treated using anticoagulant drugs Pulmonary Embolism ECG game Video This can be treated using anticoagulant drugs

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

Deep Vein Thrombosis Summary A deep vein thrombosis (DVT) is a blood clot that forms in a deep vein most commonly in the leg. If the clot breaks off and travels through the bloodstream it may result in a pulmonary embolism.

Discuss how cardiovascular disease occurs................. Results of cardiovascular disease include angina, stroke, heart attack, hypertension and peripheral vascular disease. Atherosclerosis is build-up of cholesterol, calcium and fibrous material in an artery. LDLs transport cholesterol to the arteries. A plaque (atheroma) forms beneath the endothelium of artery and artery hardens, loses elasticity and narrows. This causes blood pressure to increase (hypertension develops). Atheromas can rupture and clotting factors are released, and there is formation of a clot (thrombus occurs). The clot can break loose forming an embolus which can block arteries (causing a stroke/heart attack). This means cells are deprived of oxygen. A deep vein thrombosis (DVT) is a clot in a vein.

Learning Intention Explain the role of LDL and HDL in negative feedback control of cholesterol Explain the ratio of LDL to HDL in maintaining health Explain how blood cholesterol can be lowered Explain how FH can be screened for and treated

Cholesterol Cholesterol is a type of lipid and is an important molecule because: It is a component of the cell membrane It is a precursor for steroids Not the steroids you’re thinking of – certain hormones, bile salts etc It’s presence in the bloodstream at an appropriate level is important to maintain health and wellbeing. REMEMBER!

Cholesterol Cholesterol is made in the liver cells from saturated fats present in the diet. Too much cholesterol can cause health problems like CVD.

Higher ratio of HDL to LDL will result in lower cholesterol and reduced chance of atherosclerosis  Found in eggs and dairy 2 Types of cholesterol -carrying proteins (HDL, LDL) HDL- gathers Cholesterol from body cells for elimination by liver – bye  Cholesterol Low-density Lipoproteins (LDL) - bad cholesterol  LDL- carries Blood cholesterol from liver to body cells – Hello  As level of HDL Increases, risk of CHD decreases  High-density Lipoproteins (HDL) - good cholesterol 

HDLs (High density lipoproteins) HDLs transport cholesterol from the rest of the body to the liver Remove cholesterol from inside blood vessels including the coronary arteries Referred to as ‘Good cholesterol’

LDLs (Low density lipoproteins) LDLs transport cholesterol from the liver to parts of the body Deposit cholesterol inside the arteries including coronary arteries Referred to as ‘Bad cholesterol’

HDL vs LDL If there is a higher ratio of HDL to LDL, this reduces the risk of atherosclerosis and CHD

HDL & LDL foods HDL Olive oil. (The type of heart-healthy fat found in olives and olive oil can increase your HDL and lower the inflammatory impact of LDL cholesterol on your body) Beans and legumes. Like whole grains, beans and legumes are a great source of soluble fibre Whole grains Certain fruits Fatty fish Flax. Nuts. Chia. LDL Butter. Ghee. Hard margarines. Lard and goose fat. Fatty meat and meat products such as sausages. Full fat cheese, milk, cream and yogurt. Coconut and palm oils and coconut cream.

HDL and LDL

HDL and LDL

LDL liver cells HDL

Negative Feedback Cholesterol levels are controlled by negative feedback: Cell has adequate supply of cholesterol Synthesis of new LDL receptors is inhibited Less LDL-cholesterol is absorbed by cells LDL-Cholesterol is taken up by endothelial cells lining the inside of an artery Cholesterol is deposited in an atheroma in the wall of the artery.

Familial Hypercholesterolaemia Familial Hypercholesterolaemia (FH) is an inherited disorder (which is dominant). It is caused by a defect in a gene which controls the way cholesterol is handled in the body. The level of low-density lipoprotein (LDL) cholesterol in the blood is higher than normal from birth.

FH As a result of the defect, LDL receptor number is reduced or the structure altered. This stops the LDL from unloading its cholesterol into the cell. LDL cholesterol is not broken down properly and builds up in the bloodstream. Affected individuals suffer CVD at a younger age.

Screening and Treatment Genetic screening can be used to test for FH. If an individual tests positive for the condition, it can be treated by adopting a modified lifestyle and taking medication such as statins.

Staying Healthy The level of cholesterol in the blood can be reduced by medication like statins which inhibit the enzyme needed to synthesise cholesterol. Regular physical exercise raises HDL levels and lowers the risk of CVD.

Staying Healthy HDL levels can be raised by replacing saturated fat with unsaturated fat and consuming less fat overall.

Cholesterol Summary Most cholesterol is synthesised by the _________ from saturated fats in the diet. Cholesterol is a component of cell membranes and a precursor for _________ synthesis. High-density lipoprotein (HDL) transports excess __________ from the body cells to the liver for elimination. This prevents accumulation of cholesterol in the _________. Low-density lipoprotein (LDL) transports cholesterol to ________ cells. Most cells have LDL receptors that take LDL into the cell where it releases cholesterol. Once a cell has sufficient cholesterol a ___________ feedback system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit cholesterol in the arteries forming ______________. A higher ratio of HDL to LDL will result in __________ blood cholesterol and a reduced chance of atherosclerosis.

Cholesterol Summary Most cholesterol is synthesised by the liver from saturated fats in the diet. Cholesterol is a component of cell membranes and a precursor for steroid synthesis. High-density lipoprotein (HDL) transports excess cholesterol from the body cells to the liver for elimination. This prevents accumulation of cholesterol in the blood. Low-density lipoprotein (LDL) transports cholesterol to body cells. Most cells have LDL receptors that take LDL into the cell where it releases cholesterol. Once a cell has sufficient cholesterol a negative feedback system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas. A higher ratio of HDL to LDL will result in lower blood cholesterol and a reduced chance of atherosclerosis.

Learning Intention Explain how chronic elevated blood glucose levels can cause disease Explain the role of cell receptors and hormones in the negative feedback control of blood glucose levels

Blood Glucose Levels and Vascular Disease Normal blood glucose levels 5 mmol/l If a person has untreated diabetes blood glucose levels become elevated Chronic level of 30mmol/l

Blood Glucose and Vascular Disease Endothelial cells lining blood vessels absorb far more glucose than normal. This causes damage to the blood vessels and can lead to peripheral vascular disease, CVD or stroke. When this happens in small blood vessels, it can cause microvascular disease.

Microvascular 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.

Blood Glucose and Vascular Disease Summary 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 cardio vascular 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.

Blood Glucose Levels Blood glucose levels in the body must stay at a constant level so that there is always enough glucose in the blood to be delivered to cells for respiration. 2 hormones produced by the pancreas control blood glucose levels – INSULIN and GLUCAGON.

Insulin Insulin Glucose Glycogen This is produced by the pancreas. It is carried in the blood to the target organ - liver. Insulin causes the liver to take up glucose from the blood and convert it to a storage carbohydrate called glycogen and therefore reduces the levels of glucose in the blood. Insulin Glucose Glycogen

Glucagon This is also produced by the pancreas. It is carried in the blood to the target organ - liver. Glucagon causes the liver to convert the storage carbohydrate glycogen to glucose and therefore increases the levels of glucose in the blood. Glucagon Glycogen Glucose

Eating Less glucose in blood More glucose in blood Exercise Pancreas makes MORE INSULIN and LESS GLUCAGON Glucose in the blood increases which pancreas detects Insulin tells the liver to convert more glucose into glycogen Eating Less glucose in blood Normal level of glucose in the blood Normal level of glucose in the blood More glucose in blood Exercise Glucagon tells the liver to convert more glycogen to glucose Pancreas makes LESS INSULIN and MORE GLUCAGON Glucose in the blood decreases which pancreas detects

Epinephrine During exercise and ‘fight or flight’ responses, glucose levels are raised by ephinephrine (adrenaline). Ephinephrine is released from the adrenal glands and stimulates glucagon secretion while inhibiting insulin secretion.

Regulation of Blood Glucose Summary Pancreatic receptors respond to high blood glucose levels by causing secretion of insulin. Insulin activates the conversion of glucose to glycogen in the liver decreasing blood glucose concentration. Pancreatic receptors respond to low blood glucose levels by producing glucagon. Glucagon activates the conversion of glycogen to glucose in the liver increasing blood glucose level.

Regulation of Blood Glucose Summary Cont’d During exercise and fight or flight responses glucose levels are raised by adrenaline (epinephrine) released from the adrenal glands stimulating glucagon secretion and inhibiting insulin secretion.

Learning Intentions Explain the difference between type 1 and type 2 diabetes. Describe how diabetes can be diagnosed

Type 1 Diabetes Type 1 diabetes usually develops early in life and is the most common type of diabetes in children. It occurs when the body is unable to produce any insulin. Type 1 diabetes is treated with insulin injections, or by using an insulin pump. About 15% of people with diabetes have type 1.

Type 2 Diabetes Type 2 diabetes is the most widespread form of the condition and usually develops later in life. This develops when the body is unable to make enough insulin, or when the insulin that is produced does not work properly (known as insulin resistance). Type 2 diabetes can be treated with diet and physical activity alone, or combining these with tablets which lower glucose levels in the blood.

Comparing Diabetes Type 1 Diabetes Type 2 Diabetes Stage of life at which condition normally occurs Childhood or early teens Adulthood Ability of pancreatic cells to produce insulin Unable to produce insulin Able to produce insulin Sensitivity of cells to insulin Cells have the normal number of insulin receptors on their surface. They respond to the presence of insulin. Cells have a decreased number of insulin receptors on their surface, making them less sensitive to insulin. This means they can’t convert glucose to glycogen Treatment Regular injections of insulin and a careful diet Exercise, diet control, weight loss (in some cases insulin)

Diabetes In both types of diabetes, individual blood glucose levels will rise rapidly after a meal and the kidneys are unable to cope. This results in glucose being lost in the urine. Testing urine for glucose is often used as an indicator for diabetes.

Glucose Tolerance Test The glucose tolerance test is used to test for diabetes. The patient fasts, drinks 250-300ml glucose solution and then their blood glucose levels are measured.

Glucose Tolerance Test diabetic dog game

Learning Intentions State what is meant by the term ‘obesity’ and explain how to characterise obesity Describe the link between obesity and cardiovascular disease Explain how exercise can reduce risk of cardiovascular disease

Obesity-Risk Factor Obesity is a major risk factor for cardiovascular disease and type 2 diabetes

Obesity The most common cause of obesity is the excessive consumption of foods rich in fats and free sugars, combined with a lack of physical exercise. Obesity is characterised by excess body fat in relation to lean body tissue (muscle). BMI can be used to measure body composition. A BMI greater than 30 is used to indicate obesity

Body Mass Index (BMI) Classification BMI (kg/m2) Associated health risks Underweight Less than 18.5 Low Normal 18.5 - 24.9 Average Overweight Moderate Obese class 1 Obese class 2 Obese class 3 Greater than 25.0 25.0 – 29.9 30.0 – 34.9 35.0 – 39.9 Greater than 40.0 Increased Moderate increase. Severe increase. Very severe increase.

Limitations of BMI Some individuals, e.g. body builders, would be classified as obese using BMI. To measure body fat accurately, body density needs to be measured.

Treatment Affected inidivduals should limit consumption of fat (which is high in calories) and free sugars (which do not use any metabolic energy in their digestion. They should also take regular exercise to expend more energy.

Benefits of Exercise As well as aiding weight loss, exercise also brings about: A reduction in risk of CVD An increase in the level of HDL cholesterol in the blood A decrease in high blood pressure and stress