AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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thebiotutor.com

AS Biology Unit 1

Heart & Cardiac Cycle

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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Structure of the heart (label and colour oxygenated areas in red)

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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The cardiac cycle Stages: Atrial and ventricular diastole (relaxation) - PASSIVE FILLING Atrial systole (contraction) – FORCED FILLING Ventricular systole – FORCED EXPULSION

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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How do the valves work? Explain the action and function of the atrioventricular (AV)valves (bicuspid and tricuspid) and the semi-lunar (SL)valves (pocket valves) and what makes the ‘lub, dub’ sound. Pressure changes

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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mark the following events on the pressure graph below Atrial /ventricular diastole (D) Atrial systole (A) Ventricular systole (V) Atrioventricular valve closure (X) Semi-lunar valve closure (Y)

Control of the cardiac cycle

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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Myogenic contraction Role of the SAN (sino-atrial node) Role of the non-conducting tissue Role of the AV node (atrio-ventricular node) Role of purkinje (purkyne) fibres Interpreting an ECG P excitation of the atria Q, R ,S excitation of the ventricles T diastole

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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CHD is a disease of the coronary arteries which damages or causes malfunctions of the heart. It is caused by atherosclerosis. Atheroscleosis the process of deposition of fatty materials (notably

cholesterol) in the lining of arteries to from atheroma. It leads to arteriosclerosis (hardening of the arteries)

Atheroma and plaque formation

AQA as revision notes Trevor Chilton Topic 4: Heart and cardiac cycle

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Summary of atherosclerosis How may atherosclerosis result in a coronary thrombosis or stroke? Cholesterol, HDLs, LDLs and atherosclerosis Cholesterol is a fat but not a triglyceride. It is found in many foods and usually associated with saturated fats in meat, eggs and dairy products. It is needed for

Stabilising cell membranes Making steroid (fat based) hormones Making bile in the liver

Transport of cholesterol around the body It is carried around the blood system in a combined form with lipoproteins.

HIGH DENSITY LIPOPROTEINS (HDLs) are made with unsaturated fats LOW DENSITY LIPOPROTEINS (LDLs) are made with saturated fats

Good or bad? Saturated v unsaturated fats in the diet. Why are HDLs good and LDLs bad? (explain the role of lipoprotein receptors on the surface membranes of liver and adipose (fat) tissue cells)