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A LEVEL BIOLOGY

Explore the internal and external features of the heart, its circulatory system, and the cardiac cycle. Discover how the structure of the heart relates to its function and the significance of blood flow. Learn about the control of the heart rate and the mechanisms that regulate it. Engage with practical activities and tutorials to deepen your understanding of this vital organ.

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A LEVEL BIOLOGY

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  1. A LEVEL BIOLOGY • 8 TOPICS • 12 REQUIRED PRACTICALS • 3 EXAMS

  2. Lesson Aims How is the structure of the heart related to its function? How much blood does the human body contain? 5.6 litres

  3. The Heart Where is it? • Between the two lungs • Enclosed by the PERICARDIUM • Pericardial fluid is secreted between them to aid movement • The pericardium protects the heart from over expansion

  4. Internal Features Semi-lunar valves (bicuspid valve) Septum Pericardial membranes

  5. Watch this Video • Blood flow through the heart How far does your blood travel in one day? nearly 12,000 miles

  6. Blood flow through the heart • Blood comes into the heart from the body • It then has to pass to the lungs to collect oxygen • This is called a double circulatory system • After it returns to the heart it leave again to be transported to the body. Task: Draw a flow diagram to show the flow of blood through the heart. You should start and finish with the body.

  7. Atrium- receives blood from veinsVentricle- pumps blood into arteries Body Left Vena cava Oxygenated blood Deoxygenated blood atrium Right atrium Bicuspid valve Tricuspid valve Pulmonary vein Left ventricle Right ventricle aorta Pulmonary artery body lungs

  8. Activity Drag the labels to the right place to complete the diagram and the key

  9. External Features

  10. Your sheep’s heart A B What external features can you identify? C D How much blood does the heart pump in a lifetime? a million barrels of blood E F

  11. External Features FRONT BACK Apex

  12. The Circulatory System

  13. The Cardiac Cycle • Cardiac muscle contracts without nervous or hormonal stimulation these are MYOGENIC contractions. • The muscle cells work together to produce the heartbeat (cardiac cycle)

  14. Systole (contraction) • Atrial systole • Atria contract • Semi-lunar valves closed • Blood forced from the atria into the ventricle • Ventricular systole • Ventricle contracts • Blood is forced into arteries • Bicuspid and tricuspid valves closed

  15. Diastole (relaxation) • Heart relaxes and fills with blood from the veins. • Semi-lunar valves closed to blood entering through arteries. • Cardiac Cycle Tutorial • Task: Order the diagrams of the cardiac cycle and annotate.

  16. HEARTRATE • What effects heart rate??

  17. Control of the heart beat • Although the heart has its own rhythm it is also regulated by the nervous and hormonal systems. • Sensory receptors in the walls of heart and blood vessels are sensitive to changes in blood pressure • These send impulses to the CARDIORESPIRATORY CENTRE in the medulla oblongata • A vagus nerve branch leads to the SA node. • The vagus nerve is part of the Parasympathetic Nervous System and so is an inhibitory nerve, impulses slow the heart rate.

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