Higher Human Biology Unit 2 Physiology Health KEY

Higher Human Biology Unit 2 Physiology & Health KEY AREA 8: Blood Glucose Levels and Obesity

Higher Human Biology We are going to build on the knowledge and skills that you developed during N 5 and will learn about the following Physiology & Health key areas : - Key Area 1 – Reproductive Organs Key Area 2 –Hormonal Control of Reproduction Key Area 3 – Biology of Controlling Fertility Key Area 4 – Ante- and Postnatal Screening Key Area 5 – Structure and Function of Arteries, Capillaries and Veins Key Area 6 – Structure and Function of the heart Key Area 7 – Pathology of Cardiovascular Disease (CVD) Key Area 8 – Blood Glucose Levels and Obesity

N 5 Revision - What is Homeostasis? Homeostasis is the control of the internal environment in the body Homeostasis is important so that body cells can function properly Homeostasis controls water concentration in the blood (osmoregulation). This prevents cells from bursting or shrinking due to osmosis Homeostasis controls body temperature (thermoregulation). This ensures enzymes are working at an optimum temperature Homeostasis controls glucose concentration in the blood. This ensures that cells receive the correct levels of glucose required for respiration

Physiology & Health Learning Intentions KEY AREA 8 – Blood Glucose Levels and Obesity a)Chronic Elevated Blood Glucose Levels b)Obesity linked to CVD and Diabetes

8 a) Regulation of blood glucose levels

8 b) Chronic elevated blood glucose levels When blood glucose levels remain too high (elevated) over a long period of time (chronic), the endothelium cells take in more glucose than normal This leads to damage of the blood vessels, it can lead to atherosclerosis which leads to further complications such as: CVD, 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

8 c) Controlling Blood Glucose Levels The pancreas monitors the concentration of glucose in the blood Receptor cells in the pancreas detect changes in blood glucose concentration When blood glucose INCREASES(above the norm) - Pancreatic receptor cells respond by increasing the secretion of the hormone insulin - Insulin travels in the blood to the liver - Insulin activates the conversion of glucose to glycogen (an insoluble storage carbohydrate) - Blood glucose concentration decreases(returning to the norm) When blood glucose DECREASES (below the norm) - Pancreatic receptor cells respond by increasing the secretion of the hormone glucagon - Glucagon travels in the blood to the liver - Glucagon activates the conversion of glycogen to glucose in the liver - Blood glucose concentration increases (returning to the norm)

8 c) Controlling Blood Glucose Levels During exercise and fight or flight responses, the body needs additional supplies of glucose to provide energy quickly The adrenal glands secrete the hormone adrenaline Adrenaline stimulates secretion of glucagon and inhibits insulin secretion, thus promoting the breakdown of glycogen to glucose Once the situation is over, adrenaline levels return to a minimum and the normal homeostatic control of blood glucose control resumes

8 d) Diabetes is a condition whereby sufferers are unable to control their blood glucose levels If untreated, blood glucose levels can rise to 10 -30 mmol/l compared with the normal blood glucose concentration of around 5 mmol/l Type 1 Diabetes Type 2 Diabetes % of all cases of diabetes 5 -10% 90 -95% First occurrence Childhood/Early teens Adulthood Typical body mass of sufferer Normal/underweight Overweight/obese Ability of pancreatic receptors to produce insulin ABSENT PRESENT Sensitively of cells to insulin Sensitive Cells have normal number of insulin receptors on their surface & respond to insulin Less Sensitive Cells have a decreased number of insulin receptors in the liver leading to a failure to convert glucose to glycogen Treatment Regular doses of Insulin (careful diet) Exercise, weight loss & diet (insulin in some cases)

8 e) Testing for Diabetes is a condition whereby sufferers are unable to control their blood glucose levels 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 in the urine, therefore testing urine for glucose is often used as an indicator of diabetes The glucose tolerance test is used to diagnose diabetes - the blood glucose levels are measured after a period of fasting (~8 hours) - the individual then drinks a glucose solution and changes in their blood glucose concentration are measured for at least the next 2 hours - the blood glucose concentration of a diabetic usually starts at a higher level than that of a non-diabetic - the blood glucose concentration of a diabetic also takes longer to return to normal/its starting concentration - (see figure 13. 15 pg 190)

8 f) Obesity is a major risk factor for Cardiovascular Disease and for Type 2 Diabetes Obesity is characterised by excess body fat in relation to lean body tissue (muscle) A body mass index (BMI) is commonly used to measure obesity BMI= Body Mass (kg) divided by height squared (m 2) A BMI greater than 30 is used to indicate obesity BMI does not take in account muscle mass so some people are wrongly classified when using this method (e. g. muscular individuals can be classed as obese)

8 g) Treatment of Obesity The most common cause of obesity is a high fat diet and decreased physical activity (others such as genetics, psychological, environmental factors also contribute) Treatment of obesity involves reducing energy intake and increasing energy expenditure The energy intake in the diet should limit fats (as fats have a high calorific value per gram) and free sugars (as they require no metabolic energy to be expended to digest them) 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 - improving blood lipid profiles

Physiology & Health Questions KEY AREA 8 – Blood Glucose Levels & Obesity 1. Testing Your Knowledge 2 Page 195 Q’s 1 -3 2. What you should know Page 195 Q’s 1 -16 Applying knowledge & Skills Page 196 Q’s 1 - 10 3.