Multicellular Organisms Sub-Topic 2.6 Transport Systems in Animals On completion of this sub-topic I will be able to state that: In mammals a transport system is required to deliver essential substances to cells and take waste materials away from cells In mammals, nutrients, oxygen and carbon dioxide are transported in the blood The blood contains plasma, red blood cells and white blood cells Red blood cells are specialised by having a biconcave shape and no nucleus Red blood cells contain haemoglobin which allows them to transport oxygen efficiently in the form of oxyhaemoglobin White blood cells are part of the immune system and are responsible for destroying invading pathogens There are two main types of white blood cells phagocytes and lymphocytes Phagocytes carry out phagocytosis by engulfing pathogens Some lymphocytes produce antibodies which destroy pathogens Antibodies are specific to one pathogen The heart is made up of four chambers, the right and left atria and the right and left ventricles Valves which prevent the backflow of blood are located between the atria and ventricles and also found in the pulmonary artery and aorta Blood vessels associated with the heart include the aorta, vena cava, pulmonary arteries, pulmonary veins and coronary arteries Deoxygenated blood comes back to the heart from circulating around the body and flows into the vena cava, then flows through the right atrium and right ventricle before leaving the heart through the pulmonary artery to go to the lungs Duncanrig Secondary School 2017 Page 1 of 13
In the lungs the blood becomes oxygenated and returns to the heart via the pulmonary vein, then flows through the left atrium and left ventricle leaving the heart through the aorta to circulate around the body Blood leaves the heart in arteries, exchanges materials through capillaries and returns to the heart in veins Arteries have thick, muscular walls, a narrow central channel and carry blood under high pressure away from the heart Veins have thinner, muscular walls, a wide central channel and carry blood under low pressure. Veins have valves to prevent the backflow of blood and carry blood towards the heart Capillaries form networks at organs and tissues. They are thin walled and have a large surface area, allowing exchange of materials. Duncanrig Secondary School 2017 Page 2 of 13
Transport Systems in Animals The Need for a Transport System in Animals Each of our cells needs a constant supply of nutrients and oxygen for respiration and other cell processes. Cells must also be able to get rid of wastes which would become toxic if built up. In mammals the blood transports materials to and from cells. The cells of a multicellular organism are located close to a blood supply. The blood is a transport system which supplies the substances needed and provides a means of removing waste. A transports system is needed since it would take years for these substances to move through the body by any other means (e.g. diffusion). The Circulatory System The circulatory system consists of i. Blood vessels - tubes ii. The heart - a pump iii. Blood - liquid The circulatory system transports - Nutrients from where they are obtained to where they are needed e.g. amino acids and glucose. Wastes from where they are produced to where they are excreted e.g. urea, carbon dioxide. Hormones so that different areas of the body can communicate e.g. ADH, insulin. Heat so that all areas of the body are kept close to the optimum temperature of 37 o C. Gases to and from the lungs e.g. Oxygen and Carbon Dioxide. Duncanrig Secondary School 2017 Page 3 of 13
Blood Blood is made up of the following: Plasma (55%) Plasma is a watery, yellowish fluid which contains various dissolved substances such as glucose and amino acids. It is responsible for transporting these substances around the body so they can be delivered to cells that need them. Waste materials such as carbon dioxide also dissolve in the plasma. Blood cells (45%) of which there are three types o Red blood cells which transport oxygen o White blood cells which are involved in defending the body against disease o Platelets which are tiny cell fragments involved in clotting Red Blood Cells Red blood cells (RBCs) are very small and extremely numerous (approximately 5.5 million per mm 3 of blood). RBCs are shaped like a biconcave disc and transport oxygen around the body. They contain a cytoplasm filled with a red pigment called haemoglobin (the oxygen carrying pigment) and they lack a nucleus, which makes them very efficient at carrying oxygen. Whilst in the lungs, haemoglobin within the RBCs combines with oxygen to form oxyhaemoglobin. When the RBCs reach their target cells the oxyhaemoglobin releases the oxygen for the cells to use and the pigment once again becomes haemoglobin. Duncanrig Secondary School 2017 Page 4 of 13
Activity 1 Collect: BIOVIEWER Slide & information card labelled Human Blood Working in pairs use the BIOVIEWER and the slides in the information pack labelled Human Blood to examine: 1. Human Blood unstained, magnified (900x) 2. A Human Blood Smear stained, magnified (900x) 3. Blood Platelets stained, magnified (900x) Draw what you observed in the boxes below. If there is time you can have a look at slides 4, 5 and 6 which show white blood cells. Slide 1 Slide 2 Slide 3 Duncanrig Secondary School 2017 Page 5 of 13
White Blood Cells Our immune system is a network of cells, tissues and organs that work together to defend the body against attack by disease causing micro-organisms known as pathogens. These are organisms such as bacteria, viruses, and fungi that can cause infections. Pathogens White blood cells are part of the immune system and are responsible for destroying invading pathogens. There are two main types of white blood cells, phagocytes and lymphocytes. Phagocytes Phagocytes carry out phagocytosis (cell eating) by engulfing pathogens. They identify the microbes as being foreign, engulf the microbe by creating a vacuole around the pathogen. Powerful digesting enzymes within the vacuole then digest the pathogen. Duncanrig Secondary School 2017 Page 6 of 13
Use information from the notes and class resources to complete the diagrams showing the mechanism of action of phagocytes and lymphocytes. Summary of the Action of Phagocytes: 1. 2. 3. 4. Duncanrig Secondary School 2017 Page 7 of 13
Lymphocytes Some lymphocytes produce specific Y shaped proteins called antibodies. Each lymphocyte produces a specific type of antibody that can destroy one particular pathogen. Pathogens have proteins on their surface called antigens, the body can recognise these antigens as being foreign. When a lymphocyte with the appropriate antibody meets its specific antigen, the lymphocytes reproduces quickly and makes copies of the antibody that neutralises the effect of the pathogen. Use the words provided in the word bank to label the diagram showing the binding of an antibody to its antigen. Word Bank: antibody antigen pathogen antibody attached to antigen Duncanrig Secondary School 2017 Page 8 of 13
Pathway of Blood The circulatory system is a double circulation where the blood flows twice through the heart for each complete circuit. Blood flows from the heart to the lungs, back to the heart, then all round the body. Lungs Right atrium Left atrium Right ventricle Left ventricle Body Duncanrig Secondary School 2017 Page 9 of 13
The Heart The heart is a muscular pump that is divided into two separate sides as shown in the diagram. Each side has 2 hollow chambers. Right atrium Right ventricle Left atrium Left ventricle The Four Chambers of the Heart There are two atria 1. The right atrium (RA) 2. The left atrium (LA) There are two ventricles 3. The right ventricle (RV) 4. The left ventricle (LV) The diagram shows the four heart chambers viewed from the front of the person. The right hand side of the heart is therefore on the left of the diagram and vice versa. The Major Blood Vessels of the Heart These carry blood into and out of the heart. They connect to all parts of the body. The veins (pulmonary vein and vena cava) return blood under low pressure back to the heart. The arteries (pulmonary artery and aorta) take blood under high pressure away from the heart. Duncanrig Secondary School 2017 Page 10 of 13
Label the following diagram of the major blood vessels of the heart using the information on the previous page to help you. Pathway of Blood Through the Heart Blood low in oxygen (deoxygenated blood) is brought back to the heart from the body via the vena cava. It enters the right atrium and then flows down into the right ventricle. From the right ventricle the blood is pushed out of the heart through the pulmonary artery to the lungs where it picks up oxygen. Blood returning from the lungs (oxygenated blood) enters the heart by the pulmonary vein. It enters the left atrium and then flows down into the left ventricle. From the left ventricle the blood is pushed out of the heart through the aorta to the rest of the body. Demonstration 1 Watch carefully as your teacher dissects a sheep s heart, paying particular attention to the different chambers and blood vessels that you see. Duncanrig Secondary School 2017 Page 11 of 13
The Coronary Blood Vessels The heart muscle requires its own blood supply which is provided by the coronary blood vessels. These can be seen on the outside of the heart. Coronary arteries branch off the aorta Coronary veins join the vena cava Label the following diagram: Blood Vessels Arteries An artery is a vessel which carries blood away from the heart. It has a thick muscular wall and a narrow central channel to carry blood under high pressure away from the heart. Each time the heart beats, blood is forced along the arteries at high pressure and this can be felt as a pulse. Capillaries When an artery reaches a tissue it divides into very narrow vessels called capillaries which are in close contact to all cells of the body. Capillaries are thin walled and have a large surface area which allows diffusion to easily take place. They form networks at tissues and organs to allow efficient exchange of materials. Capillaries join up into a vein to carry blood away from a tissue. Duncanrig Secondary School 2017 Page 12 of 13
A tissue Capillaries Artery Vein (note: arteries and veins are like motorways between cities; capillaries are like streets within the city) Veins A vein is a vessel which carries blood back to the heart. Although muscular, its wall is thinner and they have wider channels than that of an artery since blood flows along a vein at low pressure. They have valves to prevent the backflow of blood. Use the information on blood vessels from Pages 7 and 8 to complete the following table: Blood Vessel Function Features Artery Capillary Vein Duncanrig Secondary School 2017 Page 13 of 13