Chapter 11. Oxygen, nutrients, wastes, carbon dioxide, hormones and more. Body temperature, water-salt balance and body ph

Transcription

1 Chapter 11 FUNCTIONS OF BLOOD 1. Transportation Oxygen, nutrients, wastes, carbon dioxide, hormones and more 2. Defense Against invasion by pathogens 3. Regulatory functions Body temperature, watersalt balance and body ph COMPOSITIONS OF BLOOD Plasma 92% of water and 8% of salts and organic molecules Strawcoloured liquid that makes up about 55% of blood Plasma protein: dissolved substance in the blood Help balance water flow between blood and the cells Albumins Most abundant and important for plasma s osmotic pressure as well as the transport of other molecules Globulins Transports lipids and fatsoluble vitamins Some are antibodies Fibrinogen Important for the formation of blood clots the process for the blood stem cells differentiating into these descendants is called hematopoiesis

2 Formed elements Red blood cells / erythrocytes white blood cell/ leukocytes Formed by the red bone marrow The sponge like framework supports fat cells but also supports the undifferentiated cells called blood stem cells Platelets Also called thrombocytes, essential for blood clotting Made from fragments of large cells called megakaryocytes made in the red bone marrow Makes 200 billion/day Blood proteins named thrombin and fibrinogen are important for blood clotting by generating fibrin threads that catch red blood cells Disorders involving platelets Thrombocytopenia Thromboembolism A disorder in which the # of platelets is too low due to not enough born in the bone marrow or the breakdown outside the marrow When a clot forms(thrombus) and breaks off from its site of origin (embolus) and plugs another vessel Hemophilia A genetic disorder that results in a deficiency of a clotting factor so that when a person damages a blood vessel they are unable to properly clot their blood both internally and externally

3 BLOOD CLOTTING 4 main things Platelets Clotting factors (special proteins) Fibrin (a mesh of special kinds of clotting factors) Other cells red and white Steps 1. When a blood vessel is broken, the nearby platelets becomes sticky and stick to each other and the hole of the blood vessel 2. Clotting factors that float by the tear reinforces the platelet plug Converts inactive blood protein to prothrombin activator, which then coverts prothrombin (plasma protein made by liver) to an active form, thrombin Thrombin causes changes in other plasma proteins produced by the liver called fibrinogen, then it forms long strand of fibrins 3. Fibrins, a web acts like glue and forms a blood clot 4. Other cells float by and sticks to the clot Red blood cell Also called erythrocytes Picks up oxygen from the lungs and ferry it to all the cells of the body Red blood cells and hemoglobin The shape of the cell, dented on both sides maximizes the surface area for gas exchange

4 Each red blood cell is packed with hemoglobin, the oxygenbinding pigment that is responsible for the cells red colour Contains about 280 million hemoglobin molecules and each hemoglobin molecules binds 4 O2 It lacks a nucleus and few organelles The hem group contains an iron ion that actually binds to the oxygen and is then called oxyhemoglobin Life cycle of red blood cells Take about 6 days to make red blood cell 1. Very immature cells become a factory for hemoglobin molecules, and after the cell is packed with hemoglobin, the nucleus is pushed out 2. A structural metamorphosis occurs culminating in a mature red blood cell with a typical biconcave shape 3. Once this occurs, the cell leaves the bone marrow and enter the blood stream It lives for about 120 days, but travels a lot It lives so short because of its lack of nucleus Without a nucleus, protein synthesis needed to replace key enzymes can t take place, causing the cell to be rigid and fragile Liver and spleen are the graveyard where worn out red blood cells are removed from circulation Production of red blood cell Controlled by negative feedback When there is a loss of blood, it triggers a homeostatic mechanism that speeds up the rate of red blood cell production Certain cells in kidney sense the in oxygen, so they respond by producing the hormone erythropoietin (EPO) Initiated by a in the oxygen supply to the body s cells Excreted by the kidney The EPO travels to the red marrow where it steps up both the division rate of the stem cells and the maturation rate of immature red blood cells

5 Disorders of red blood cells Anemia: blood s ability to carry oxygen is which can result from too little hemoglobin, too few red blood cells or both Anemic person s heart beat faster to compensate for the blood s ability to carry oxygen Iron deficiency anemia: insufficiency of iron in the body, which leads to inadequate hemoglobin production Sicklecell anemia: genetic disease that causes red blood cells to be sickle shaped that tend to rupture when the blood s oxygen is too low Pernicious anemia: red blood cell # drop when the production of red blood cells are halted or impaired Depend on supply of vitamin B12 which is absorbed by the small intestine but produced by the stomach lining Hemolytic disease of the newborn: a condition with incompatible blood types that leads to rupturing blood cells in a baby before and continuing after birth WHITE BOLD CELLS Also called leukocytes removes wastes, toxins, and damaged or abnormal cells Serve as a warrior in the body s fight against disease Produced in red bone marrow Production is regulated by colonystimulating factor (CSF) Marge blood cells that have nucleus Can leave the circulatory system and move to sites of infection around by squeezing in between neighbouring cells Some live days and other live months and years unlike red blood cells Granulocytes Contain noticeable granules, lobed nuclei Sacs containing chemicals that are used as weapons to destroy invading pathogens, bacteria 1. Neutrophil Not stained by dyes About 5070% of WBC

6 Multi lobed nucleus Most abundant of all white blood cells, and blood cell soldiers on the front line Arriving at the infection site 1st, it begins to engulf microbes by phagocytosis, thus curbing the spread of infection After eating 12 bacteria, it dies, but while dying, it releases chemicals that attract more neutrophils After it dies, it becomes pus 2. Eosinophil Stained by eosin and turns red Small % of WBC Contain a bilobed nucleus Contains substances that are important in the body s defense against tape work and hookworm Lessen the severity of allergies by eating antibodyantigen complexes and inactivating inflammatory chemicals 3. Basophil Stained by basic dye and turns blue Small % of WBC Ushaped or lobed nucleus Release histamine, a chemical that attracts other white blood cells to the site of infection and cause blood vessel to dilate to blood flow to the infection area Arganulocytes Lack cytoplasmic granules Nonlobed nuclei Classified as monocytes and lymphocytes 1. Monocytes Largest of all formed elements WBC with horseshoe shaped nucleus Leaves the bloodstream and enter various tissues and then develops into macrophages

7 Phagocytic cells that eat invading microbes, dead cells and cellular debris 2. Lymphocytes About 2535% of all WBC Large nucleus that takes up most of the cytoplasm B lymphocytes Give rise to plasma cells that produces antibodies which is called antigens that on the surface of invading microbes or other foreign cells T lymphocytes Specialized WBC that play role in the body s defence mechanism Disorders of white blood cells Infectious mononucleosis Also known as kissing disease The infection causes an in lymphocytes that have atypical appearance Spread by person to person contact or by using the same utensils Causes fatigue, sore throat and swollen lymph nodes Leukemia A group of cancers that affect WBC in which the cells divide uncontrollably Abnormal cell that remains immature and are therefore unable to defend the body against infectious organisms They take over bone marrow, preventing the development of normal blood cells, like RBC, WBC and platelets Severe combined immunodeficiency disease (SCID) An inherited disease in which stem cells of WBC s lack of enzymes that allow them to fight any infection BLOOD TYPING Antigen: a foreign substance, often a polysaccharide or a protein that stimulates an immune response Antibody: proteins made in response to an antigen in the body and binds to that antigen and help to eliminate it from the body

8 Very specific and our bodies make enormous # of different antibodies to respond to a large # of potential antigens ABO blood types Type A: RBC with only antigen A on their surface Type B: RBC with only antigen B on their surface Don t have antigen A & B Type O: RBC with no antigen A or B on their surface Have antibodies against A antigen Type AB: RBC with antigen A&B on their surface Have antibodies against B antigen Have antibodies against A and B antigens If 2 different blood types are together, it will agglutinate (clump together) clumped cells can get stuck in small blood vessels and block blood flow to body cells can also break open and release hemoglobin which then clogs the filtering system in the kidney, causing death Rh factor the Rh factor is often included when expressing a blood type by naming it positive or negative people with Rh factor are positive and those without it are negative Rh antibodies only develop in a person when they are exposed to the Rh factor from another s blood (usually a fetus)

9 Hemolytic disease of newborn can happen during pregnancy under these condition: Mon : Rh Dad: Rh + Baby: Rh + How to prevent hemolytic disease Rh women are giving an injection of antirh antibodies no later than 72 hours after birth of an Rh+ baby These antibodies attack fetal RBC in the mother before the mother s immune system can bake antibodies This will have to be repeated if an Rh mother has another Rh+ baby