JWSS Biology Chapter 6 Transport in Humans

3G3 Science (Biology) Chapter 6 Notes 1 JURONG WEST SECONDARY SCHOOL SECONDARY THREE – SCIENCE BIOLOGY Chapter 6: TRANSPORT IN HUMANS Learning Outcomes: Candidates should be able to: (a) name (label) the main blood vessels to and from the heart, lungs, liver and kidney (b) state the functions of blood •red blood cells – haemoglobin and oxygen transport • white blood cells – phagocytosis, antibody formation and tissue rejection • platelets – fibrinogen to fibrin, causing clotting • plasma – transport of blood cells, ions, soluble food substances, hormones, carbon dioxide, urea, vitamins, plasma proteins (c) relate the structure of arteries, veins and capillaries to their functions (d) describe the structure and function of the heart in terms of muscular contraction and the working of valves (histology of the heart muscle, names of nerves and transmitter substances are not required) Describe and explain the pathway of blood through the heart. (e) describe coronary heart disease in terms of the occlusion of coronary arteries and list the possible causes, such as diet, stress, smoking, and the possible preventative measures ACTIVITY: Remember in Secondary two you learnt all about parts of the heart? Let’s see how many can you remember! Label the heart with the following labels provided. 1. right atrium 2. right ventricle 3. left atrium 4. left ventricle 5. pulmonary arteries 6. aorta 7. vena cava 8. pulmonary vein

3G3 Science (Biology) Chapter 6 Notes 2 Why the need for circulatory system? • Unicellular organisms do not need a transport system for exchange or distribution of materials. They rely on diffusion and active transport for movement of substances • No part of the cell is far from environment outside. • Exchange of materials occurs easily by diffusion. • What about multicellular organisms like us?’ • In multicellular organisms, numerous cells are situated deep in the body, far from external environment. • Simple diffusion alone CANNOT bring enough oxygen and food into the cells, and CANNOT remove waste products. • So we need a transport system to transport these efficiently. Functions of the circulatory system 1. Transporting substances around the body. These include oxygen, glucose, carbon dioxide, nutrients, water and waste products (urea). 2. Controlling body temperature. More blood can flow to the surface of your skin and release heat. 3. Protecting the body. Blood contains cells and anti-bodies that fight infection and clotting agents to stop bleeding. The double circulatory system The pulmonary circulation carries: • deoxygenated blood from the heart to the lungs • oxygenated blood back from the lungs to the heart, ready to be pumped out to the body. The systemic circulation carries: • oxygenated blood to the rest of the body through the arteries • deoxygenated blood back to the heart through the veins. Commented [PLX1]: In multicellular organisms, numerous cells are situated deeps in the body, far from external environment. Simple diffusion alone CANNOT bring enough oxygen and food materials into the cells, and CANNOT remove waste products. So we need a transport system.

3G3 Science (Biology) Chapter 6 Notes 3 The circulatory system Components of the Circulatory System 1. The Human Heart 2. The Blood Vessels 1. The Human Heart • Located in the thoracic cavity, between the two lungs and slightly to the left. • About the size of a clenched fist. • Weighs around a ½ pound • Made up of a special type of muscle i.e. cardiac muscle, which contracts rhythmically. • The four chambers of the heart have special names: o An upper chamber is called an atrium (plural: atria). o A lower chamber is called a ventricle. Oxygenated blood from the lungs returns to the heart through the pulmonary vein. Oxygenated blood is pumped at high pressure from the ventricle to the body through the aorta. Deoxygenated blood is pumped from the heart to the lungs through the pulmonary artery. Deoxygenated blood returns to the heart from all parts of the body through the vena cava.

3G3 Science (Biology) Chapter 6 Notes 4 • Here are some other important parts of the heart: Test yourself! 1 What is the consequence of having a hole in the septum? Deoxygenated blood will mix with oxygenated blood. Not enough oxygen transported to body cells. Respiration occurs slower. Lesser energy released. → feel tired / die 2 The left ventricle has the thickest walls. Why? To generate and withstand high pressure in order to pump blood from the heart to the rest of the body, which is a longer distance compared to transporting blood to the lungs

3G3 Science (Biology) Chapter 6 Notes 5 Pathway of blood through the heart 1. Deoxygenated blood from various parts of the body is returned to the right atrium via the superior vena cava and inferior vena cava. 2. Muscles of the right atrium contracts. Pressure in the right atrium is higher than the right ventricle. Tricuspid valve opens. Blood is pumped from the right atrium into the right ventricle. 3. Muscles of the right ventricle contracts. Tricuspid valve closes because pressure in the right ventricle is higher than pressure in the right atrium. This prevents the backflow of blood from the right ventricle back into the right atrium. 4. Blood is pumped into the pulmonary arch, which divides into two pulmonary arteries, semi-lunar valves open. 5. Semi-lunar valves in the pulmonary arch prevents the backflow of blood back into the right ventricle. 6. Blood enters the lungs for gaseous exchange. Deoxygenated blood becomes oxygenated (more details in the chapter of Respiration) 7. Oxygenated blood is brought back to left atrium via the pulmonary veins. 8. Muscles of the left atrium contracts, Pressure in the left atrium is higher than the left ventricle. bicuspid valve opens. blood is pumped into the left ventricle. 9. Muscles of the left ventricle contracts, bicuspid valve closes because pressure in the left ventricle is higher than pressure in the left atrium. This prevents the backflow of blood from the left ventricle back into the left atrium. 10. Blood is pumped out from the left ventricle into the aorta. 11. Semi-lunar valves in aorta prevent backflow of blood back into left ventricle. 12. Blood is distributed to the rest of the body via the aorta. Blood is distributed to the rest of the body via the aorta.

3G3 Science (Biology) Chapter 6 Notes 6 Questions: 1. Does the whole heart pump together? Or does it have a order to which part of the heart contracts first? No, the atria muscles will contract first, followed by the ventricle muscles. ………………………………………………………………… ………………………………………………………………… ………………………………………………………………… 2. What do we call the blood vessels that are supplying oxygen to the heart muscles? Coronary artery ……………………………………………. 3. The figure on the right shows an external view of the heart. State the name and function of the tissue that makes up the part labelled L. Name: Cardiac muscle tissue of the left ventricle Function: cardiac muscles can contract, which creates a force to move the blood in the left ventricle of the heart out of the aorta and then to the rest of the body. ……………………………………………………………….. ………………………… …………………………………….. ……………………………………………………………….. Commented [PLX2]: Name: Cardiac muscle tissue of the left ventricle Function: it can contract, which creates a force to move the blood in the ventricle of the heart out of the aorta.

3G3 Science (Biology) Chapter 6 Notes 7 Blood Pressure changes in The Heart Blood pressure is the FORCE that blood exerts on the walls of blood vessels. Refer to Fig. 1.4. What can you deduce about this graph? What can you conclude? Fig. 1.4 BSSB: A: Bicuspid, B: Semi-lunar,