HWA CHONG INSTITUTION (HIGH SCHOOL) SECONDARY 3 BIOLOGY 2012 NOTES. Name:... ( ) Class: 3... Date:...

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1 Name:... ( ) Class: 3... Date:... Topic: Transport in Humans Learning Outcomes: Students should be able to: Describe the circulatory system as a system of tubes with a pump and valves to ensure one-way flow of blood Describe the double circulation in terms of a low pressure circulation to the lungs and a high pressure circulation to the body tissues and relate these differences to the different functions of the two circuits Describe the structure and function of the heart in terms of muscular contraction and the working of valves *State that heart action is initiated at the pacemaker (sino-atrial node) Outline the cardiac cycle in terms of what happens during systole and diastole with involvement of the heart valves (Histology of the heart muscles, names of nerves and transmitter substances are not required) Describe the effect of exercise on heart rate and its significance Identify the main blood vessels to and from the heart, lungs, liver and kidney Relate the structure of arteries, veins and capillaries to their functions and be able to recognize these vessels from photomicrographs *State the origin of blood pressure *Describe how blood pressure is measured *Describe how a pulse is generated State the functions of various blood components: 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 Identify red and white blood cells as seen under the microscope on prepared slides, and in diagrams and photomicrographs Explain the role of haemoglobin in the transport of oxygen *Explain the significance of the Bohr shift in the oxygen dissociation curve List the different ABO blood groups and all possible combinations for the donor and recipient in blood transfusion *Differentiate between the innate and adaptive immune systems in the generation of an immune response Describe the transfer of materials between capillaries and tissue fluid Describe coronary heart disease in terms of the occlusion of coronary arteries and list the possible causes, such as diet, stress and smoking, stating the possible preventive measures *Explain the cause of deep vein thrombosis and its prevention 1

2 ABO blood typing system Blood typing involves the two types of molecules called: Antigen Protein or polysaccharide, that stimulates the immune system to react, such as to produce antibodies Antibody Protein produced in response to the presence of antigen Each antibody combines with a specific antigen. The most common system for typing blood is the ABO system In the ABO system, the presence or absence of type A and type B antigens on red blood cells determines a person s blood type For example: A person has type A blood, the A antigen is on his/her red blood cells This molecule is not a foreign antigen to this individual, although it can be an antigen to a recipient who does not have type A blood There are four types of blood: A, B, AB and O Within the plasma, there are antibodies to the antigens that are not present on the person s red blood cells These antibodies are called anti-a and anti-b It is reasonable that type A blood would have anti-b and not anti-a antibodies in the plasma If anti-a antibodies were present in the plasma, agglutination, or clumping of red blood cells would occur Antigens on an erythrocyte (Red blood cell) A red blood cell (RBC) has three different antigens on the surface of its membrane The antigens are glycoproteins with unique molecular shapes They have molecular weights of 200,000 to 300,000 2

3 Three different types of blood antibodies that circulate in the plasma Each antibody has two combining sites where it attaches to the complimentary antigen on the surface of a red blood cell (RBC) membrane Anti-A and Anti-B antibodies are glycoproteins with a molecular weight of about 900,000 Anti-Rh antibodies are smaller glycoproteins with a molecular weight of about 150,000! Type A erythrocyte Red blood cells (RBCs): Type A Positive (left) and type A Negative (right). Both types have the A antigen, but only the A Positive (left) has the Rh antigen. Type B erythrocyte Red blood cells (RBCs): Type B Positive (left) and type B Negative (right). Both types have the B antigen, but only the B Positive (left) has the Rh antigen. 3

4 Type AB erythrocyte HWA CHONG INSTITUTION (HIGH SCHOOL) Red blood cells (RBCs): Type AB Positive (left) and type AB Negative (right). Both types have A and B antigens, but only the AB Positive (left) has the Rh antigen. Type O erythrocytes Red blood cells (RBCs): Type O Positive (left) and type O Negative (right). Both types are without A and B antigens, but the O Positive (left) have the Rh antigen. Type O Negative (right) has none of the antigens (A, B or Rh) on its membrane. Agglutination (clumping) Agglutination (clumping) of type A red blood cells (RBCs) by anti-a antibodies The antibodies have two combining sites and are able to attach to the A antigens on adjacent RBCs, thus causing the RBCs to bond together Agglutination of red blood cells can cause blood to stop circulating in small blood vessels, and this can lead to organ damage It is also followed by hemolysis, which may cause the death of the individual Blood transfusion For a recipient to receive blood from a donor, the recipient's plasma must not have an antibody that causes the donor s cells to agglutinate Important to determine each person s blood type Blood that is of good quality and free of infectious agents 4

5 Blood typing kit Using the antibodies derived from plasma (antibodies are immobilized onto the blood typing kit) to determine the blood type If clumping occurs after a sample of blood is exposed to a particular antibody; the person has that type of blood Rhesus system (Rh system) - For Enrichment Another important antigen in matching blood type is the Rh factor. Rh+ (Rh positive) Antigen is present on the red blood cells. Rh- (Rh negative) Antigen is not present on the red blood cells. Individuals normally do not have antibodies to the Rh factor, but they may make them when exposed to the Rh factor. Anti Rh antibodies are used for blood testing When Rh+ blood is mixed with anti Rh antibodies, agglutination occurs Hemolytic disease of the newborn During pregnancy, if the mother is Rh- and the father is Rh+, there is a possibility that the child is Rh+. The Rh+ red blood cells may begin leaking across the placenta into the mother s cardiovascular system, as placental tissues normally break down before and at birth. The presence of these Rh antigens causes the mother to produce anti Rh antibodies. In this or a subsequent pregnancy with another Rh+ baby, the anti Rh antibodies produced by the mother may cross the placenta and destroy the child s red blood cells. The Rh problem is prevented by giving the Rh- women an Rh immunoglobulin injection either midway through the pregnancy or no later than 72 hours after giving birth to any Rh+ child. Injection contains anti Rh antibodies that attack any of the baby s red blood cells in the mother s blood before these cells can stimulate her immune system to produce her own antibodies. 5

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7 Component of Blood HWA CHONG INSTITUTION (HIGH SCHOOL) The red blood cells (erythrocytes) Small, biconcave disks that lacks a nucleus when mature Occurs in great quantities 4 6 million red blood cells per mm 3 of whole blood Absence of a nucleus provides more space for the pigment haemoglobin Respiratory pigment because it transports oxygen A red blood cell contains about 200 million haemoglobin molecules If this much haemoglobin is suspended within the plasma rather than enclosed within the cells, blood would be so viscous; the heart would have difficulty pumping it 7

8 The iron portion of haemoglobin carries oxygen, a molecule that cells require for cellular respiration Hb + O2 HbO2 Haemoglobin, which is combined with oxygen, is called oxyhaemoglobin Formed in the lungs and has a bright red colour Haemoglobin, which has given up oxygen to tissue fluid, is called de-oxyhaemoglobin Dark purplish colour The life cycle of an erythrocyte HWA CHONG INSTITUTION (HIGH SCHOOL) In infants, red blood cells are produced in the red bone marrow of all bones In adults, production primarily occurs in the red bone marrow of the skull bones, ribs, sternum, vertebrae and pelvic bones All blood cells, including erythrocytes, are formed from special red bone marrow cells called stem cells A stem cell is ever capable of dividing and producing new cells that differentiate into specific cell types. As red blood cells mature, they lose their nucleus and acquire haemoglobin Due to the lack of nucleus, red blood cells live only for 120 days As they age, they are destroyed in the liver and spleen where they are engulfed by macrophages Macrophages large phagocytic cells that originated from monocytes Engulf and digest cell debris or foreign particles 2 million red blood cells are destroyed per second An equal number must be produced to keep the red blood cell count in balance When red blood cells are broken down, the haemoglobin is released The globin portion of the haemoglobin is broken down into its component amino acids, which are recycled by the body The iron is recovered and returned to the bone marrow for reuse The heme portion undergoes chemical degradation and is excreted as bile pigments by the liver into bile Bile pigments bilirubin and biliverdin (contributes to the colour of faeces) Chemical breakdown of heme is also what causes a bruise of the skin to change from red/ purple to blue to green to yellow 8

9 Anemia The number of red blood cells produced increases whenever arterial blood carries a reduced amount of oxygen E.g. when an individual first takes up residence at a high altitude (acclimatisation) or loses red blood cells or full use of their lungs. Kidneys accelerate their release of erythropoietin, a hormone that is carried in blood to red bone marrow Speeds up the maturation of cells that are in the process of becoming red blood cells Liver and other tissues also produce erythropoietin Mass produced through biotechnology Sometimes abused by athletes in order to raise their red blood cell counts and thereby increase the oxygen carrying capacity of their blood When there is an insufficient number of red blood cells or the cells do not have enough haemoglobin, the individual suffers from anemia Tired, run down feeling Diets do not contain enough iron or folic acid Whole grain cereals (rich in iron and folic acid) Pernicious anemia Digestive tract is unable to absorb enough vitamin B12, found in diary products, fish, eggs and poultry Essential for proper formation of red blood cells Immature red blood cells tend to accumulate in the bone marrow in large quantities Special diet and administration of vitamin B12 by injection is an effective treatment Hemolytic anemia (Hemolysis rupturing of red blood cells) Increased rate of red blood cells destruction 9

10 Sickle cell disease Hereditary condition in which the individual has sickle-shaped red blood cells that tends to rupture as they pass through the narrow capillaries. Leukocytes (White blood cells) Leukocytes differ from erythrocytes in that they are: Usually larger Have a nucleus Lack haemoglobin There are only 5000 to per mm 3 of blood Fight infection Leukocytes are derived from stem cells in the red bone marrow Undergo several maturation stages Production of leukocytes increases whenever the body is invaded by pathogens Hormones called colony stimulating factors are released by white blood cells, and circulate back to the bone marrow, stimulating an increased production Red blood cells are confined to the blood, but leukocytes are able to squeeze through pores in the capillary walls Therefore, they are found in tissue fluid and lymph When there is an infection, leukocytes greatly increase in number 10

11 Types of leukocytes - For Enrichment Leukocytes are classified into the granular leukocytes and the agranular leukocytes Both types of cells have granules in the cytoplasm surrounding the nucleus, but the granules are more visible upon staining in granular leukocytes Granules contain various enzymes and proteins, which help leukocytes, defend the body Three types of granular leukocytes and two types of agranular leukocytes Differ by the size of the cell and shape of the nucleus Differ in their functions 11

12 Granular leukocytes Neutrophils, eosinophils and basophils are granular leukocytes Neutrophils Most abundant of the white blood cells Multilobed nucleus joined by nuclear threads Also called polymorphonuclear First type of leukocytes to respond to an infection and they engulf pathogens during phagocytosis What is phagocytosis? The process of engulfing and ingesting foreign particles, such as bacteria, by the leukocytes is known as phagocytosis A phagocyte first engulfs the bacteria by flowing over them and enclosing them The phagocyte then ingests the bacteria The ingested bacteria will be digested by the phagocyte In the process of fighting with the bacteria at the site of the wound, some of the phagocytes are killed These dead phagocytes, together with the dead bacteria, form pus 12

13 Eosinophils HWA CHONG INSTITUTION (HIGH SCHOOL) Bilobed nucleus Increase in number when there is a parasitic worm infection or in the case of allergic reactions Basophils U shaped or lobed nucleus Basophils enter the tissues and are believed to become mast cells, which release the histamine associated with allergic reaction Histamine dilates blood vessels and causes contraction of smooth muscle Agranular leukocytes Monocytes Monocytes and lymphocytes are agranular leukocytes Responsible for specific defense to particular pathogens and their toxins (poisonous substances) Pathogens have molecules called antigens that allow the immune system to recognize them as foreign Kidney shaped nucleus Largest of the leukocytes After taking residence in the tissues, they differentiate into even larger macrophages Phagocytose pathogens, old cells and cellular debris Stimulate other leukocytes to defend the body 13

14 Lymphocytes Spherical shaped nucleus 2 types B lymphocytes and T lymphocytes B lymphocytes protect us by producing antibodies T lymphocytes protect us by destroying any cell that has foreign antigens. 14

15 *Innate vs Adaptive Immunity - For Enrichment (Non - SMTP) 15

16 Model of Immune Response: Speed and Specificity Response Innate immune response Adaptive immune response time after infection 16

17 Defence mechanisms of the body Inflammation HWA CHONG INSTITUTION (HIGH SCHOOL) Production of antibodies - humoral immunity Antibodies protect our bodies against disease by: Destroying the bacteria by attaching to them, causing the bacterial surface membrane to rupture Causing the bacteria to clump together or agglutinate so that they can be easily ingested by the phagocytes Neutralising the harmful substances (toxins) produced by the bacteria Attaching to viruses, making them unable to bind to the host cell Antibodies may stay in the blood long after the disease has been overcome Thus, a person who has recovered becomes immune or resistant to that infection Some types of dead bacteria are sometimes injected into the bodies if certain animals to induce the formation of antibodies in the blood Antibodies are extracted from the animal s serum and injected into human beings to protect them from the same disease Antibody production may also be directly induced in the human body immunisation/vaccination Some of the lymphocytes become memory cells Geared to provide a faster and more vigorous defence should the same invader attack a second time 17

18 Cell mediated immunity When antibody mediated immunity is ineffective When foreign organisms have successfully invaded and are multiplying inside the cells of the body Infected cells display the foreign antigens on their surface Lymphocytes cytotoxic cells (N K cells) produce proteins which create holes in the infected cell Protein from the cytotoxic cells will enter the infected cell and trigger programmed cell death 18

19 Test yourself Name the leukocytes! Leukemia Abnormally large number of immature leukocytes that fill the red bone marrow Prevents erythrocytes development Anemia results and the immature leukocytes offer little protection from disease Type of cancer Blood platelets (thrombocytes) Not true cells Membrane bound fragments of cytoplasm from certain bone marrow cells Play a part in clotting of blood Blood clotting When blood vessels are damaged, damaged tissues and blood platelets release an enzyme known as thrombokinase Thrombokinase converts the protein prothrombin, normally present in the plasma, into thrombin Calcium ions must be present before this can take place Thrombin is also an enzyme. It catalyses the conversion of soluble protein fibrinogen to insoluble threads of fibrin Fibrin threads entangle blood cells and the whole mass form a clot In undamaged blood vessels, the blood does not clot Presence of an anti clotting substance called heparin Produced in the liver Thrombokinase neutralizes the action of heparin so that clotting can take place When blood clots, a yellowish liquid called serum is left behind Serum has the same composition as plasma except that it lacks the clotting factor 19

20 thrombokinase 20

21 Real world application - warfarin Warfarin (Coumadin ) is the most commonly used prescription medication for preventing harmful blood clots from forming or from growing larger. Warfarin belongs to a class of drugs called anticoagulants, which simply means medications that prevent the blood from clotting. People often call these drugs "blood thinners." 21

22 It is vital that our bodies can form blood clots to control bleeding. However, many medical conditions and inherited factors can make a person more likely to form abnormal blood clots. Abnormal blood clots are dangerous because they can block the flow of blood to parts of the body like the heart, lungs, or brain. Some conditions that are treated with warfarin on a short-term or long-term basis include: Irregular heartbeat Heart valve replacement Previous heart attack or stroke Blood clot in a vein (venous thrombosis or deep vein thrombosis) Blood clot in the lung (pulmonary embolism) Certain orthopedic surgeries, such as knee or hip replacement Inherited blood clotting disorders, such as Factor V Leiden Haemophilia HWA CHONG INSTITUTION (HIGH SCHOOL) Inherited clotting disorder due to deficiency in a clotting factor Slightest bump can cause the affected person to bleed into the joints Normal clotting mechanism is greatly impaired Slight injuries may cause a person to bleed to death or die of internal bleeding 22