Option D.4 The Heart https://media.giphy.com/media/oStBM1ANst52U/giphy.gif

Understandings D.4.U1: Structure of cardiac muscle cells allows propagation of stimuli through the heart wall. D.4.U2: Signals from the sinoatrial node that cause contraction cannot pass directly from atria to ventricles. D.4.U3: There is a delay between the arrival and passing on of a stimulus at the atrioventricular node. D.4.U4: This delay allows time for atrial systole before the atrioventricular valves close. D.4.U5: Normal heart sounds are caused by the atrioventricular valves and semilunar valves closing causing changes in blood flow. D.4.U6: Conducting fibres ensure coordinated contraction of the entire ventricle wall. D.4.A1: Use of artificial pacemakers to regulate the heart rate. D.4.A2: Use of defibrillation to treat life-threatening cardiac conditions. D.4.A3: Causes and consequences of hypertension and thrombosis. D.4.S1: Measurement and interpretation of the heart rate under different conditions. D.4.S2: Interpretation of systolic and diastolic blood pressure measurements. D.4.S3: Mapping of the cardiac cycle to a normal ECG trace. D.4.S4: Analysis of epidemiological data relating to the incidence of coronary heart disease. D.4.NOS: Developments in scientific research followed improvements in apparatus or instrumentation—the invention of the stethoscope led to improved knowledge of the workings of the heart.

6.2.1 – Be able to draw and label a human heart Right atrium Left atrium Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle Left ventricle

6.2.2 The heart is supplied with nutrients / oxygen from coronary arteries: The heart is made of muscle cells which need fuel

6.2.3 Heart blood flow The heart collects blood in the atrium(s) Valves open and close sequentially to maintain a ‘one way’ flow Valves are divided into two or three sections

D.4.U1: Structure of cardiac muscle cells allows propagation of stimuli through the heart wall. Cardiac muscles are linked by intercalating discs and are also branched These connections allow for increased blood flow and ability contract simultaneously Skeletal muscle

The SAN receives signals from medulla oblongata (or epinephrine) D.4.U2: Signals from the sinoatrial node that cause contraction cannot pass directly from atria to ventricles. D.4.U3: There is a delay between the arrival and passing on of a stimulus at the atrioventricular node. The SAN receives signals from medulla oblongata (or epinephrine) These cells cause atrial systole(contraction) and stimulation of AVN AVN sends signal from atrium, down center of the heart and causes ventricular systole

D.4.U4: This delay allows time for atrial systole before the atrioventricular valves close. D.4.U5: Normal heart sounds are caused by the atrioventricular valves and semilunar valves closing causing changes in blood flow. Important to make sure atrial valves are closed when ventricular valves are open and vice versa

D.4.U6: Conducting fibers ensure coordinated contraction of the entire ventricle wall. The signal travels from SAN to AVN to fibers which contract the ventricles

D.4.A1: Use of artificial pacemakers to regulate the heart rate. Problems with signal conduction (too fast or to slow) can be regulated by a pacemaker Also used after heart attacks if heart rate is not coordinated properly

D.4.A2: Use of defibrillation to treat life-threatening cardiac conditions. Used to restart or correct a heart that is not beating sufficiently Delivers an electronic pulse between two electrodes

D.4.A3: Causes and consequences of hypertension and thrombosis. Thrombosis is the formation of a blood clot in blood vessels. Causes blockage, may break free and travel to other areas Caused by being overweight or immobility among other things

D.4.A3: Causes and consequences of hypertension and thrombosis. Hypertension is high blood pressure caused by narrower blood vessels, which makes the heart work harder Can lead to heart attacks Caused by: stress, overweight alcohol, dietary

D.4.S1: Measurement and interpretation of the heart rate under different conditions.

D.4.S2: Interpretation of systolic and diastolic blood pressure measurements. Systolic pressure is the pressure created by each contraction of the heart, diastolic is the lower pressure during relaxation

D.4.S3: Mapping of the cardiac cycle to a normal ECG trace. P wave represents the atrial contraction (systole) QRS wave represents ventricular contraction The T wave represents ventricular relaxation (diastole) Can show signs of a heart attack

Heart Sounds are caused by the opening and closing of valves, not by muscles contracting

D.4.S4: Analysis of epidemiological data relating to the incidence of coronary heart disease. What causes differences in coronary hear deaths? Diet, lifestyle, genotype…