1. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) Topic: Transport in Mammals( Part 1) At the end of lesson, you should be able to:  Identify the main blood vessels to and from the heart, lungs, liver and kidney.  Describe the structure & function of the heart in terms of muscular contraction and the working of valves.  Outline the cardiac cycle in terms what happens during systole and diastole.

2. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) Double Circulation Pulmonary Circulation Systemic Circulation

3. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) Type of Circulation: Pulmonary Circulation Systemic Circulation (i) PressureLowHigh (ii) Destination of blood flow from heart to LungThe rest of the body (iii) Walls of the ventricle Walls of the right ventricle are thinner and less muscular. Walls of the left ventricle are thicker and more muscular. (iv) BloodDeoxygenatedOxygenated

4. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) How does the heart pumps blood? When both atrium contract, the oxygenated blood in left atrium is pumped into the left ventricle while the deoxygenated blood in right atrium is pumped into right ventricle. When the left ventricle contracts, the aorta carrries oxygenated blood to the rest of the body. Simultaneously, the deoxygenated blood flows out of right ventricle to the lungs through the pulmonary artery when the right ventricle contracts.

5. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) Deoxygenated blood from vena cava. Right atriumLeft atrium Left ventricleRight ventricle Pulmonary arteryAorta Lung enters The rest of the body Oxygenated blood from pulmonary vein. enters When both atrium contract, blood is pumped into ventricles. When both ventricles contract, blood is pumped out of the heart.

6. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) Events of a Cardiac Cycle A cardiac cycle is a complete heartbeat. It contains 2 main phases: systole and diastole, which are defined by whether the ventricles are contracted or relaxed. During the cycle, valves open and close, producing the familiar “lub-dub” sound.

7. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) 3 After a short pause, the ventricles contract. This is called ventricular systole. The increase in blood pressure forces the bicuspid and tricuspid valves to close, preventing backflow of blood into the atria. This produces a loud ‘lub’ sound. When the pressure in the left ventricle becomes higher than the pressure in the aorta, the semilunar valves are forced open. Oxygenated blood flows from the left ventricle into the aorta. As the ventricles contract, the atria relax. right ventricle 2 left ventricle right ventricle 1 pulmonary vein left ventricle left atrium vena cava right atrium aortic arch 3 pulmonary arch bicuspid valve tricuspid valve The Cardiac Cycle

8. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) The pressure in the ventricles changes during the cardiac cycle. When the pressure of blood in the ventricles is high, it forces the semilunar valves to open. It also forces the tricuspid and bicuspid valves to close. semilunar valves tricuspid & bicuspid valves

9. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) The pressure in the aorta changes during the cardiac cycle. When the left ventricle contracts, the semilunar opens and the blood rushes into the aorta. The pressure of the aorta increases. semilunar valves aorta

10. Prepared By, Mrs Yap-Wong Fui Yen (HKSS) Parts of the Circulatory System 4 artery blood flowing from the heart Veins The blood vessels that carry blood back to the heart are called veins. heart arteries arterioles capillaries venules veins blood flowing back to the heart vein a capillary network links arteries and veins 3 Blood capillaries The microscopic thin-walled (one cell thick) blood vessels that carry blood from a small artery (arteriole) to a small vein (venule) are called capillaries. The thin walls of the capillaries also allow certain substances to diffuse rapidly through the capillary walls. 2 Arteries The blood vessels that carry blood away from the heart are called arteries. 1 The heart The heart is a muscular organ which drives the blood around the body.