Advanced Higher Biology

1. Advanced Higher Biology Course Contents Section 1 Exercise and the cardiovascular system 1.1 Structure and function of the cardiovascular system 1.2 Pathology of cardiovascular diseases (CVD) 1.3 Role of exercise in prevention and treatment of CVD Section 2 Exercise and Metabolism 2.1 Energy 2.2 Body composition & Weight Control 2.3 Diabetes Mellitus 2.4 Osteoporosis Physiology Health & Exercise

2. BHF Survey, 2007 Scottish Stats

3. Deaths from CHD

6. Advanced Higher Biology The CVS is subject to disease processes e.g. Atherosclerosis & hypertension are disease processes that lead to the development of : atherosclerosis Cardiovascular Disease - diseases of the heart and blood vessels hypertension

7. Advanced Higher Biology Structure & Function of the Cardiiovascular system

8. Structure/ Function of CVS • 2 parts: • Pump • Vessels

9. Heart Heart external view BICUSPID (mitral) VALVE TRICUSPID VALVE SEMILUNAR VALVE • Double pump • Right side – pumps to lungs (pulmonary circulation) • Left side – pumps to body (systemic circulation • Left side > right side • Heart Valves prevent backflow of blood • Coronary arteries supply heart muscle with blood (food & oxygen)

10. Heart & Blood Supply • Pulmonary artery – deoxygenated blood • Pulmonary vein – oxygenated • Coronary arteries – supply heart • Coronary veins – drain into the right atrium • Aorta - blood to body (from L. ventricle) • Vena cava (sup./ inf.) - drain body (into R atrium) N.B. Hepatic Portal Vein does not return blood to heart. Supplies liver with products of digestion. Important in first pass metabolism – allowing toxins to be broken down before systemic circulation

11. Heart Beat • Heart beat is endogenous (continues to beat if removed from body) • Rhythmical contraction of muscles • Under nervous/ hormonal control • Influence strength & frequency of contraction • Heart beat originates in SinoAtrial node • Max. rate limited (refractory period) • AV node collects signal and initiates ventricular contraction via Bindle of His after a short delay. • In disease, arrythmia can develop in damaged tissue • Extra heart beat can occur initiated by damaged tissue • Heart beat signal propagated through heart by bundle of His (atria – ventricles), & Purkinje fibres (nerves through muscle tissue)

12. Heart Sounds • Stethoscope • Listen to heart sounds • Lub dub (closing of valves) • Lub – closure of AV valves • Dub – closure of semilunar valves • Diagnostic of valvular disease • Leaky – indistinct lub/ dub

13. Heart & ECG • ECG is a record of the electrical signals producing the heart beat • ECG= ElectroCardioGram • Used diagnostically to show heart problems

14. Cardiac Cycle • DIASTOLE (relaxed phase) • Venous filling of atria • Atria distend • Some passive flow into ventricles • SYSTOLE (contractile phase) • SA initiates atrial contraction • Blood expelled from atria into ventricles • Bundle of His conducts excitation to ventricles/ propagated rapidly by Purkinje fibres • Ventricle contracts expels blood into arteries • Contraction ends, relaxes (refractory period)

15. Blood Vessels • Arteries • Must withstand high pressure • Thick walled • Mainly elastic fibres near heart • Stretch to absorb pressure of blood expelled by heart • At diastole stretched arteries relax so maintain blood flow (120/80 mmHg) • Arteries more distant from heart less elastic fibres/ more muscle (under nervous control) • Muscles regulate blood flow into capillary beds • Arteries lead to arterioles • Can have pre-capillary sphincters to completely close blood flow e.g to skin in cold

16. Blood Vessels • Capillaries • Wall single cell thick • Allows exchange of soluble substances • No cell more than few cell widths from a capillary • Diffusion rapid over these short distances

17. Blood vessels • Veins • Less muscle/ elastic fibre than arteries • Floppy • Low pressure in vein – requires valves to stop backflow • Muscle pumping in calves helps venous return (Economy Class Syndrome)

18. Blood Pressure • High arterial blood pressure (80-120 mmHg (systolic/ diastolic) • Rapid fall in BP in arterioles/ capillaries • Very low BP in veins

19. Blood Pressure • BP quoted as Systolic / diastolic • Measure with a sphygmomanometer • Block all blood flow • Slowly release pressure • Systoliic BP = pressure when sound of artery closing (snap) is heard • Diastolic BP = pressure when all noises stop

20. Summary of Structure

21. Cardiovascular Disease • CVD s Coronary Heart disease Angina pectoris Myocardial infarction Cerebrovascular disease Stroke (cerebrovascular accident (CVA))

22. Cardiovascular disease pathology • Two major pathological processes lead to CVD • Atherosclerosis • Narrowing & hardening of arteries (claudication/ angina) • Damage to endothelium • promotes blood clot formation • blocking arteries – thrombosis/ embolism • Hypertension • Prolonged, elevated blood pressure • Primary – no known cause • Secondary – caused by pathology • Kidney disease • Phaeochromacytoma (excess epinephrine produced)

23. Atherosclerosis • Typically starts in childhood, progresses in adulthood. • Damage to the arterial wall caused by e.g. • elevated levels of cholesterol and triglyceride in the blood • high blood pressure. • tobacco smoke • diabetes 

24. Atherosclerosis • Fat accumulates under inner lining of arteries • As disease progresses, fibrous material / calcium/ lipids (inc. cholesterol) accumulates (atheroma) • Bulges into lumen of vessel • Starts to reduce diameter of artery • Restricts blood flow • Reduces elasticity of arterial wall • Can lead to high blood pressure

25. Atherosclerosis • Progression accelerated by: • High blood cholesterol (especially LDL or "bad" cholesterol over 100 mg/dL) • Cigarette smoking and exposure to tobacco smoke • High blood pressure • Diabetes mellitus • Obesity • Physical inactivity

26. Cholesterol & CVD • Cholesterol – steroid • Cell membranes, hormones, bile salts • Most cholesterol in blood is synthesised by liver • Dietary cholesterol acts to suppress liver biosynthesis • Dietary cholesterol NOT important risk factor for CVD (overall cholesterol should be less than 200mg/dl) • Saturated fats (animal) are used by liver to produce cholesterol • High dietary saturated fat INCREASES blood cholesterol levels!!

27. Cholesterol & CVD • Cholesterol – insoluble in blood • Transported attached to a protein LIPOPROTEIN • Two types of LIPOPROTEIN • HDL – High density lipoprotein • LDL – Low density lipoprotein • HDL – transports cholesterol to liver for destruction GOOD • LDL – transports cholesterol to body cells for deposition BAD • In abnormal circumstances LDL will deposit cholesterol in arteries

28. Cholesterol & CVD • LDL (bad) – 60-70% blood cholesterol • As LDL increases risk of atherosclerosis increases • HDL (good) – 20-30% blood cholesterol • AS HDL increases risk of atherosclerosis decreases • Risk of CHD is predicted from HDL:LDL ratio • High HDL (40mg/dl or more):LDL is GOOD • Exercise, low fat diet, not smoking improve HDL:LDL ratio

29. Atherosclerosis – Heart - AP • Narrowing of coronary arteries leads to ischaemia (inadequate blood flow) • Pain - angina pectoris (AP) due to ischaemia in heart muscle • AP only during exertion of heart (when O2 needs are high) • Glycerol trinitrite tablets release Nitric oxide (dilates blood vessels) • Angioplasty/ Stents • Bypass surgery

30. Atherosclerosis – Embolism • Clots • thrombus-attached • embolus-travelling • Embolus/ thrombus can cause blood supply to a region of the heart muscle (myocardium) to become blocked, causing myocardial infarction • Thrombosis/ embolus may occur in cerebral artery – stroke (cerebrovascular accident-CVA) • or lungs pulmonary embolus

31. Myocardial Infarction • Myocardial infarction – MI (death of heart tissue) • Caused by a sudden blockage to a coronary artery. • Due thrombosis/ embolis • Atherosclerosis (may cause angina symptoms) leads to increased likelihood that thombosis will occur. • Causes pain (15 min) in arm, neck, jaw; nausea. • If large artery blocked – collapse, sudden death • Tissue dies forming a scar, can cause: • Heart failure (weak pumping action) • Arrythmia, irregular contraction • Cardiac arrest – ventricular fibrillation

32. Hypertension • Persistently high resting blood pressure e.g. diastolic >90mmHg (normal 120/80; high 140/90) • Often caused by atherosclerosis leading to narrowing of arteries or loss of elasticity • Risk factor for majority of CVDs (incl. CHD)

33. Diet (high salt (Na+), high fat) Smoking Obesity Genetic predisposition Stress Nicotine (vasoconstrictor) Hypertension – risk factors

34. Risk Factors for CVD- SQA • Modifiable • Diet, Smoking, Activity, Obesity • Non modifiable • Age, Gender, Race, Heredity

35. Risk factors Summary • What other factors contribute to heart disease risk? • The risk of heart disease in people who drink moderate amounts of alcohol (an average of one drink for women or two drinks for men per day) is lower than in nondrinkers. One drink is defined as 1-1/2 fluid ounces (fl oz) of 80-proof spirits (such as bourbon, Scotch, vodka, gin, etc.), 1 fl oz of 100-proof spirits, 4 fl oz of wine or 12 fl oz of beer. It's not recommended that nondrinkers start using alcohol or that drinkers increase the amount they drink. • Diabetes mellitus —  • Diabetes seriously increases your risk of developing cardiovascular disease. • risks are even greater if blood sugar is not well controlled. • About three-quarters of people with diabetes die of some form of heart or blood vessel disease. • Obesity and overweight — • People who have excess body fat — especially if a lot of it is at the waist — are more likely to develop heart disease and stroke even if they have no other risk factors. • Excess weight increases the heart's work. It also raises blood pressure and blood cholesterol and triglyceride levels, and lowers HDL ("good") cholesterol levels. • It can also make diabetes more likely to develop. Many obese and overweight people may have difficulty losing weight. But by losing even as few as 10 pounds, you can lower your heart disease risk. Physical inactivity Regular, moderate-to-vigorous physical activity helps prevent heart and blood vessel disease. The more vigorous the activity, the greater your benefits. Physical activity can help control blood cholesterol, diabetes and obesity, as well as help lower blood pressure in some people. High blood pressure High blood pressure increases the heart's workload, causing the heart to thicken and become stiffer. It also increases your risk of stroke, heart attack, kidney failure and congestive heart failure. When high blood pressure exists with obesity, smoking, high blood cholesterol levels or diabetes, the risk of heart attack or stroke increases several times. High blood cholesterol As blood cholesterol rises, so does risk of coronary heart disease. When other risk factors (such as high blood pressure and tobacco smoke) are present, this risk increases even more. A person's cholesterol level is also affected by age, sex, heredity and diet. • Tobacco smoke  • Smokers' risk of developing coronary heart disease is 2–4 times that of nonsmokers. • risk factor for sudden cardiac death: about twice the risk of nonsmokers. • Exposure to other people's smoke increases the risk of heart disease even for nonsmokers.

36. Exercise & CVS • Cardiovascular system (CVS) delivers oxygen & nutrients to body tissues, removes wastes • During exercises more O2 & nutrients required by exercising tissues (muscles), wastes removed • Exercise effects Cardiovascular system function • Cardiac output increased • Circulation redistributed to important tissues

37. Cardiac Output • Cardiac output (C.O.) = volume of blood pumped per min. by the heart • Regulated by: • Heart rate (H.R.) • Stroke volume (S.V.) • C.O. = H.R. x S.V.

38. Exercise effects on Heart • Exercise causes HR & SV to increase i.e. CO • Meets needs of muscles

39. Athlete’s Heart • Regular exercises strengthens heart muscle • Ventricular mass (echocardiography) increases (210-300g) • Force of contraction , more blood expelled per beat (SV ) • Ventricular volume also increases (100-180ml)(SV ) • Consequently HR at rest of a trained athlete  • (Bjorn Borg – 32bpm, Miguel Induraine, 29bpm) • CO of trained heart increased so more O2 and food delivered at max. HR • Therefore max. level of activity greater

40. Redistribution of Blood flow • During exercise blood flow directed away from non-essential needs (gut, kidney) • Redirected to heart, muscles, skin (cooling) • Vasodilation/ vasoconstriction of supplies to these tissues.

41. Exercise & Blood Pressure • Cardiac Output increased (HR/ SV) • Tends to increase BP • Vasodilation of blood supply to muscles • Increases volume of vascular system • Peripheral vascular resistance reduced • Tends to reduce BP • Overall slight increase in BP • Systolic increase > diastolic

42. Exercise & Hypertension • Regular exercise, produces long term, moderate fall in BP • Offsets age related hardening of arteries • Acutely, a fall in BP is also found following exercise.

43. Role of exercise- in preventing CVD • Decreases a number of risk factors: • HDL , LDL  • Resting HR  • Arterial blood pressure  • Body fat  (i.e. obesity ) • Reduces development of atheroma • Reduces stress • Moderate exercise 3-5 times per week lasting more than 20mins

44. SCOTLAND

45. Exercise testing - Introduction • Monitor recovery from MI • Monitor improvement in athletic training programme • Measure aerobic capacity • Assess performance of respiratory and cardiovascular systems in delivering oxygen

46. Exercise testing - Principles • Oxygen required by body to work • Maximum work rate – determined by body’s ability to deliver oxygen to body • VO2max – maximal oxygen uptake • Higher the VO2max, the greater the aerobic fitness • Measure by exercising to exhaustion and directly measure O2 uptake and CO2 ouput

47. Exercise testing – Direct Method • Treadmill/ bicycle ergometer • Using online gas analysis • Progressively increase workload until no further increase in O2 consumption • i.e. exercise to exhaustion • Oxygen consumption at that point = VO2max • Suitable for fit people

48. Exercise testing – Indirect Method • Shuttle test • Run between two cones (20m apart) • Rate determined by a tape (beep) • Subject continues until they can’t maintain pace • Number of completed shuttles can be used to predict VO2max

49. Exercise Testing – Sub maximal • If exercise to exhaustion clinically contra-indicated • Submaximal testing used • Patient O2 consumption measured at various levels of work intensity (submaximal) • Graph of O2 consumption vs. HR plotted • Theoretical max. HR calculated (220-age) • Graph extrapolated to estimate theoretical max. O2 consumption

50. Exercise Testing – Sub maximal • Assumptions: • Direct relation between HR and O2 consumption and intensity of exercise • Sources of error: • HR affected by other factors: • Emotion • Temperature • Anxiety • Predicted HR may be inaccurate for a given individual