Grade 8 Biology - Circulatory System PDF

Circulatory System  Learning Points The circulatory The heart Heart disease system The circulatory system Structures & functions of arteries and veins - Blood vessel Human double circulation Blood Vessel Blood Vessel  Double Circulation  The Heart Healthy/...

Circulatory System  Learning Points The circulatory The heart Heart disease system The circulatory system Structures & functions of arteries and veins - Blood vessel Human double circulation Blood Vessel Blood Vessel  Double Circulation  The Heart Healthy/normal person - Heart beats 70 times a minute - normal activities never become tired (fatigued) controlled by a pacamaker  The Heart The signals from the pacemaker will ensure: a. The atria contract just before the ventricles b. The hearbeat is fast enough to meet the demands of the tissue - O2, nutrients, & waste removal Artificial pacemaker  The Heart provides the pressure that forces the blood through arteries, capillaries, and veins Squeeze - muscle - contracts - rhythmcally A double pump  The Heart The heart sound https://www.youtube.com/watch?v=zNHI-l_c-ls  Group work A doctor listening to the heartbeat through a stethoscope hears two sounds as the blood flows through the heart: ‘lup-dup lup-dup lup-dup’. a. From your knowledge of the working of the heart, suggest how these two sounds are produced. b. The doctor records 72 beats per minute. How long a period would there be between two consecutive ‘lup’ sounds? Explain your answer.  Group work Lup: The first sound (S1), caused by the closure of the AV valves (tricuspid and mitral valves) at the start of systole. Dup: The second sound (S2), caused by the closure of semilunar valves (aortic and pulmonary valves) at the beginning of diastole 72 beats per minute means one complete heartbeat cycle (lup-dup). takes 60s/72beats≈0.83. means the time between two consecutive “lup” sounds is 0.83s  Coronary heart The heart muscle requires a supply of O2, glucose & other nutrients Heart muscle has its own blood supply through coronary arteries Family history, diet, lifestyle may affect the effeciency of coronary arteries coronary heart disease is one of the major causes of death Coronary heart Checking the heart activity ECG (Electrocardiogram) Measuring pulse rate Heart sounds Coronary heart disease (CHD) Heart attack - poor diet, poor lifestyle, genetic factors Coronary heart disease (CHD) Coronary heart disease (CHD)