Need for Transport System

Transport in humans Need for transport system Question: What are the two transport systems in humans? [Recall what you have learnt in the absorption process in S.3] Circulatory system Lymphatic system Human circulatory system A. Blood Blood is a tissue composed of blood cells suspended in plasma. Question: What type of tissue does blood belong to? Connective tissue Question: What does plasma consist of? Circle the components. carbon dioxide lipid hormone urea glucose amino acid starch glycogen antibody fibrinogen Question: What is the difference between plasma and serum? The portion of plasma without fibrinogen is called serum. Remarks: When blood clots, fibrinogen in plasma forms an insoluble network that traps blood cells to form a clot. 1 Transport in humans The structures and functions of different blood cells: Question: Identify the cell types below. Red blood cells White blood cells Blood platelets Two major types: Very small pieces of cell fragments Shape Bioconcave disc shape Irregular shape Irregular shape Colour Red due to the pigment haemoglobin Colourless Colourless Nucleus No nucleus when mature Large round or lobed No nucleus Site of production In bone marrow of bones like limb bones, ribs and vertebrae In bone marrow and spleen; mature in lymph nodes In bone marrow Site or method of destruction In the liver and spleen; haemoglobin is broken down into iron and bile pigment Some are killed by germs or passed out of the body in faeces In the liver and spleen Function Contain haemoglobin to carry oxygen Protect our body against diseases by killing germs Ability for penetrating through capillaries Cannot penetrating through capillary Can penetrating through capillary (changing the shape of cell membrane) Involved in blood clotting to prevent further blood loss and entry of germs into our body Cannot penetrating through capillary Question: Match the photomicrographs of human blood smear showing (A) normal condition (B) anaemia (C) leukaemia (B) anaemia (A) normal condition (C) leukaemia 2 Transport in humans B. Blood vessels There are three types of blood vessels: arteries, veins and capillaries. Question: Draw arrows to show the direction of blood flow. Question: The walls of both the artery and the vein consists of four layers of tissues. Label the tissues in the photomicrographs and diagrams below. Refer to Fig 8.10 in textbook Chapter 8 Page 10.  Differences between arteries and veins: Artery Vein Remarks: Direction of • Artery has a thicker wall to withstand the high blood pressure • The wall of arteries has thicker layer of muscle. The muscles contract or relax to change the size of the lumen, so that the amount of blood flow to different parts of the body can be regulated. • The wall of artery contain more elastic tissue which allows the elastic recoil to maintain a continuous blood flow. • The lumen of vein is larger so as to reduce the resistance to the blood flow inside the vein. away from the heart towards the heart Usually deep inside the body Relatively close to the body surface blood flow Location 3 Transport in humans Nature of oxygenated blood (except in the pulmonary Deoxygenated blood (except in the blood carried artery and the umbilical arteries) pulmonary veins and the umbilical vein) Driving force Provided by the pumping action of the Provided by the contraction of the for blood heart skeletal muscles that squeeze on the veins Wall Thicker, with more elastic tissue Thinner, with less elastic tissue Lumen Smaller Larger (resistance to blood flow is reduced) Presence of Not present (except in the pulmonary artery Valves are present to prevent the valves and the aorta which have valves at their backflow of blood flow base) Question: Which of the following is/are the function(s) of the walls of arteries/arterioles?  layers of muscles in the walls of arteries contract and squeeze blood forward for maintaining a continuous blood flow ✓ thick walls of the arteries allow the arteries to withstand high blood pressure due to the pumping action of the heart ✓ when the heart relaxes, the elastic tissue of arteries recoil due to the elasticity of their walls for maintaining a continuous blood flow ✓ layers of muscles in the arterioles contract and relax to change the size of lumen which helps regulate the amount of blood flow to different parts of the body (a) Skeletal muscles contract (b) Skeletal muscles relax Question: Explain how the blood flow in vein is maintained. Contraction of the skeletal muscles lying next to the veins squeezes on the veins. The valves help prevent the backflow of blood. 4