HKDSE Biology Ch.8 Transport in humans Worksheet Answers PDF

HKDSE Biology Ch.8 Transport in humans 8.1 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 8.2 Human circulatory system A. Blood Blood is a tissue composed of blood...

HKDSE Biology Ch.8 Transport in humans 8.1 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 8.2 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 urea glucose amino acid lipid starch glycogen hormone 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  HKDSE Biology Ch.8 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 Colourless Colourless haemoglobin Nucleus No nucleus when mature Large round or lobed No nucleus Site of In bone marrow of bones In bone marrow and spleen; In bone marrow production like limb bones, ribs and mature in lymph nodes vertebrae Site or method In the liver and spleen; Some are killed by germs or In the liver and spleen of destruction haemoglobin is broken down passed out of the body in into iron and bile pigment faeces Function Contain haemoglobin to Protect our body against Involved in blood clotting carry oxygen diseases by killing germs to prevent further blood loss and entry of germs into our body Ability for Cannot penetrating through Can penetrating through Cannot penetrating penetrating capillary capillary (changing the through capillary through shape of cell membrane) capillaries Question: Match the photomicrographs of human blood smear showing (A) normal condition (B) anaemia (C) leukaemia (B) anaemia (A) normal condition (C) leukaemia 2  HKDSE Biology Ch.8 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: 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. Direction of away from the heart towards the heart blood flow Location Usually deep inside the body Relatively close to the body surface 3  HKDSE Biology Ch.8 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 flow 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 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  HKDSE Biology Ch.8 Transport in humans Question: With reference to the structures and Question: Why do we need to grasp and squeeze an locations of artery and vein, should blood be object during blood donation? drawn from artery or vein for blood donation? Explain your answer. The muscles in the arm contract when we squeeze the object. This muscle contraction squeezes the veins and Blood should be drawn from vein for blood forces blood to flow out of the arm. donation. - Veins are close to the surface of skin/ - The blood pressure in veins is lower than that in arteries. - The wall of veins are thinner and less innervation – less hurt and pain - Veins have larger lumen and hold more blood – faster and easier collection of blood. Capillaries In the body tissues, arterioles branch into networks of capillaries, forming capillary bed for exchange of materials between the blood and body cells. The lumen of capillaries is only slightly larger than the diameter of a red blood cell. The capillary wall is made up of one-cell thick endothelium. It is differentially permeable and has no muscle layer.  Adaptation of capillaries for exchange of materials between blood and body cells: Feature Adaptation Highly branched capillary bed Provides a large surface area for rapid exchange of materials between the blood and body cells Large total cross-sectional area Blood flows (slowly) in the capillaries, thus allowing a longer time for exchange of materials One-cell thick capillary wall Provides a short distance for rapid diffusion of materials 5  HKDSE Biology Ch.8 Transport in humans Blood pressure and rate of blood flow along different blood vessels Blood pressure Rate of blood flow  In arteries ◼ (High) due to the ◼ (High) in the arteries due to the pumping action of the heart pumping force of the heart and ◼ Changes periodically as the heart ◼ Decreases in the arterioles as the total arterioles contracts and relaxes cross-sectional area of arterioles increases  In ◼ Drops significantly because the small ◼ Drops to nearly zero because the total diameter of the capillaries results in a cross-sectional area is the greatest capillaries high resistance to blood flow ◼ As fluid is forced out of the blood at the arterial end of capillaries, the blood volume in the capillaries decreases, leading to the drop in blood pressure  In veins ◼ Drops to nearly zero because the blood ◼ Increases due to contraction of and venules has overcome great resistance of the skeletal muscles lying next to the blood vessel walls after travelling a veins and the veins are squeezed to long distance force blood to flow towards the heart. Question: With reference to the photomicrograph on the right, identify the blood vessels P and Q. Explain your answer. P is artery while Q is vein. The wall of P is thicker than that of Q. / The lumen of Q is larger than that of P. Question: Identify which curve in Fig 2 indicates changes in blood pressure and which curve indicates changes in rate of blood flow. Changes in blood pressure : Curve X Changes in rate of blood flow: Curve Y Question: Match blood vessels I, II and III in Fig 1 with blood vessels P, Q and R in Fig 2. Blood vessel 1: R Blood vessel 2: Q Blood vessel 3: P Question: With reference to the observable features in Fig 1, explain how blood vessels I and III adapt to the changes in the rate of blood flow. Blood vessel I: Blood vessel I has large lumen which Blood vessel III: Blood vessel III has a thick wall. reduces the resistance to blood flow. The elastic tissue in the thick wall distends and recoils to maintain a continuous blood flow. 6  HKDSE Biology Ch.8 Transport in humans C. The heart ◼ It is surrounded by a membrane called the pericardium filled with the pericardial fluid. The fluid reduces friction within the pericardium. 2 Structure of the heart The heart is mainly made up of cardiac muscles. Question: What will happen if the coronary arteries are blocked? The supply of nutrients and oxygen to the cardiac muscles will be reduced, and the heart fail to pump blood properly which lead to coronary heart disease. Questions: (i) Identify the left and right side of the heart. (ii) Label the four chambers of the heart. Arrange the thickness of the muscular walls of chambers in descending order: left ventricle > right ventricle > left atrium = right atrium What is the significance of the thick wall of the left ventricle and aorta? Left ventricle: provides a great force to pump blood to all the parts of the body except the lungs. Aorta: allows it to withstand high blood pressure. (iii) Label the septum (a thick muscular wall separating two sides of the heart). (iv) Label the blood vessels that contain oxygenated blood. Label : *aorta, *pulmonary vein (v) Label the blood vessels that contain deoxygenated blood. Label: # pulmonary artery, # vena cava (not shown in the diagram) (vi) Label the valves between atria and ventricles (label: bicuspid valve and tricuspid valve) and the valves at the base of blood vessels. (label: semi-lunar valves) (vii) Label the heart tendons. What is the function of heart tendons? Heart tendons can hold the valve in place to prevent them from turning inside out when the ventricles contract. 7  HKDSE Biology Ch.8 Transport in humans Practical 8.4 Dissection and examination of a pig heart Water run into What happens venae cavae Water comes out from the pulmonary arteries. pulmonary artery Water cannot enter and no water comes out from any vessels. pulmonary vein Water comes out from the aorta. aorta Water cannot enter and no water comes out from any vessels. Question: Bicuspid valve prevents backflow of blood from the left ventricle into the left atrium when ventricle contracts. Tricuspid valve prevents backflow of blood from the right ventricle into the right atrium when ventricle contracts. Question: What is the function of semilunar valves? Semi-lunar valves prevent the backflow of blood from the aorta or pulmonary artery into the left and right ventricles respectively. Question: What is the control mechanism for the opening and closing of valves? By pressure difference. Valves can only be opened in one direction. 8  HKDSE Biology Ch.8 Transport in humans Question: Draw blue arrows to indicate the direction of blood flow from venae cavae to the lungs and draw red arrows to indicate the direction of blood flow from pulmonary veins to the rest of body (except the lungs). Question: Calculate the heartbeat rate. 75 beats / min Question: The blood pressure in the heart chambers may increase during the cardiac cycle. State the causes for the increase in blood pressure. Cause 1: contraction of heart chambers (atria/ventricles) Cause 2: increase in volume of blood in the heart chambers Question: Fill the space below: I II III Duration 0.1s 0.3s 0.4s State of left atrium Contracting Relaxing Relaxing State of left Relaxing Contracting Relaxing ventricle Direction of blood From the left atrium aorta pulmonary veins flow to the left ventricle Bicuspid valve Open and then close Close Close and then open Semilunar valve Close Open Close 9  HKDSE Biology Ch.8 Transport in humans 8.3 Blood circulation When blood flows throughout our body in one complete loop, it passes through the heart twice. This type of circulation is called a double circulation. Pulmonary circulation Systemic circulation Right atrium → right ventricle → Left atrium → left ventricle pulmonary artery → lung → pulmonary → aorta Pathway vein → left atrium → all parts of the body except the lungs → vena cava → right atrium Change of blood Becomes oxygenated Becomes deoxygenated Question: Some people have a hole on the septum. What is the consequence of this defect to body tissues? Explain your answer. The oxygen content of the blood in the left atrium and ventricle is lowered because the blood is mixed with the deoxygenated blood in the right atrium. The body tissues would not receive enough oxygen from the blood pumped out from the left ventricle. Question: In some animals, blood passes through the heart only once as blood throughout the body in one complete loop which is called single circulation (Textbook P.22). What are the advantages of double circulation over single circulation? Allows blood to be pumped to the body cells faster to meet the needs of respiration. The blood pressure in the blood vessels in the lungs can remain low and safe. Question: In a type of heart disease, bicuspid valve cannot close properly. A man suffering from this disorder may faint easily when he performs vigorous exercise. How would you explain this? If bicuspid valve does not close properly, some oxygenated blood in the left ventricle will flow back to the left atrium when the ventricle contracts. (1) This reduces the amount of oxygenated blood pumped out of the heart in each beat. (1) During vigorous exercise, the oxygen consumption of the skeletal muscles is very high. (1) This increases the risk of insufficient oxygen supply to the brain, thus the person would faint easily. (1) Questions: Which blood vessel carries blood with (i) the lowest urea content? Renal vein (ii) the highest glucose content after a starchy meal? Hepatic portal vein (iii) the lowest blood pressure? Vena cava Question: Which blood vessel branches into capillaries at both ends? Hepatic portal vein Question: By means of a flowchart, show the route by which a red blood cell from the small intestine reaches the lung. Indicate the major blood vessels and organs involved. (small intestine) → hepatic portal vein → liver → hepatic vein → vena cava → heart → pulmonary artery → (lung) 10  HKDSE Biology Ch.8 Transport in humans B. Exchange of materials between blood and body cells Question: Use arrows to indicate the direction of Question: Draw a red blood cell in the lumen of the blood flow in the Diagram A. blood vessel in diagram B. (arrow showing the direction from left (artery with a Size of red blood cell is smiliar to the lumen of thicker wall) to left (vein with a larger lumen) capillary. Question: According to the observable features in Diagram A and Diagram B, explain how capillary is adapted for exchange of materials. Diagram A: The numerous branches of the capillary network provide a large surface area for diffusion. Diagram B: The capillary wall is one-cell thick which provides a short distance for diffusion. Question: Circle the area where tissue fluid is formed. (Circle the arterial end of capillary bed). Question: Why do some components of the plasma (e.g. water, minerals, sugars) move out of the capillary walls to form tissue fluid? At the arterial end of capillary bed, the pressure of blood in the capillaries is higher than the pressure of the fluid surrounding the body cells. This forces some components out of the capillary walls top form tissue fluid. Question: Why do plasma proteins, red blood cells and blood platelets remain in the blood but are not found in tissue fluid? They are too large to pass through the capillary wall. Question: At the venule end of the capillaries, why do water in tissue fluid return to blood? As plasma proteins remain in the blood, the water potential of the blood at the venule end of the capillaries is lower than that of tissue fluid. Thus, water in the tissue fluid is drawn into the capillaries by osmosis. Question: What’s the fate of excess tissue fluid? Most tissue fluid returns to the blood at the venule end of the capillaries. Some tissue fluid drains into the lymph capillaries along the pressure gradient. Question: Identify the major causes of fluid flow represented by P, Q and S. S (At the arterial end of capillary): difference between the hydrostatic pressure of blood and tissue fluid (The hydrostatic pressure of blood [i.e., blood pressure] is higher than that of tissue fluid) P: difference between the hydrostatic pressure of tissue fluid and lymph (The hydrostatic pressure of tissue fluid is higher than that of lymph) Q (At the venule end of capillary): difference between water potential of blood and tissue fluid leading to osmosis / water potential gradient between blood and tissue fluid leading to osmosis (The water potential of tissue fluid is higher than that of blood leading to osmosis) 11  HKDSE Biology Ch.8 Transport in humans 8.4 Human lymphatic system A. Components of lymphatic system ◼ The spleen filters damaged cells and lymph vessels join to two large veins germs in the blood ◼ The spleen and the thymus produce right atrium and store white blood cells which kill germs and destroy dead cells in the lymph vessel blood small intestine lymph node ◼ The white blood cells in tonsils guard against germs that enter the mouth or nose Key: direction of lymph flow Question: Compare the composition of blood and lymph. Note: The composition of lymph is similar Blood Lymph to blood, except for the absence of red Plasma proteins ✓ × blood cells, blood platelets and plasma proteins. Red blood cells ✓ × Blood platelets ✓ × Glycogen × × Amino acid ✓ ✓ Urea ✓ ✓ Question: The lymphatic system has no pumping mechanism. With reference to the photomicrograph below, explain how the lymph flow along the lymph vessels (towards the veins) can be maintained. The lymph is kept flowing slowly by: Contraction of skeletal muscles squeezes on the lymph vessels. Valves are present in the lymph vessels to prevent the backflow of the lymph. Question: What is the function of lymph nodes? White blood cells which accumulate in lymph nodes kills the germs in the lymph. Question: What are the functions of lymphatic system? Put a ‘✓’ in the correct box(es). ✓ It collects and returns excess tissue fluid to the blood circulation. ✓ It protects us against diseases.  It transports vitamins B and C. (Note: It transports lipid-soluble vitamins (e.g. A, D, E, K) only ✓ It transports lipids. 12  HKDSE Biology Ch.8 Transport in humans Question: Explain why the blockage of lymph vessels leads to swelling of the legs. (3 marks) Due to the blockage of lymph vessels, tissue fluid in the legs cannot return to the blood circulation. (1) On the other hand, tissue fluid formed continuously. (1) Tissue fluid accumulates in the legs leads to swelling. (1) Question: Draw arrows ( →) between the boxes to show the direction of flow of fluids between the circulatory system and the lymphatic system. 13