Chapter 19: Blood

(Blood) Chapter 19 Blood · blood is a fluid connective tissue that contains cells suspended in a fluid matrix · blood represents 8% of total body weight Whole blood: · average volume of blood ↳ 5 liters in women - hematocrit 42% ↳ 5.5 liters in men - hematocrit 45% (Extracellular matrix) Components of Blood · whole blood can be separated into plasma, buffy coat, (Specialized cells) and red blood cells (hematocrit) · plasma proteins include: ↳ albumins: plasma osmolarity, osmotic pressure, and transport (most abundant) ↳ globulins: antibodies (immunoglobulins), transport (Leukocytes) Everything but plasma ↳ fibrinogen: blood clotting, helps form serum ↳ all are made in the liver Hematocrit · percentage of blood occupied by cells · average range: ↳ females 38-42% (42%) ↳ males 40-54% (45%) · anemia: not enough RBC or hemoglobin, therefore not enough oxygen · polycythemia: too many RBC (over 65%) ↳ dehydration, tissue hypoxia, blood doping in athletes (Erythrocytes) Erythrocytes · red blood cells (RBC) · no nucleus, no organelles, or ribosomes ↳ short life span of 120 days · bioconcave discs ↳ greater surface area for diffusion ↳ thinness allows for faster diffusion ↳ flexible membrane so can bend and flex w/o rupturing ↳ form stacks to smooth blood flow · contain hemoglobin → used to carry oxygen Hemoglobin (Hb or Hgb) · primary role to transport O2 and CO2 · pigment containing iron ↳ appears reddish when oxygenated (oxyhemoglobin) ↳ appears bluish when deoxygenated (deoxyhemoglobin) · Molecule consists of two parts: ↳ globin portion -protein composed of four highly folded polypeptic chains ↳ heme groups -four iron containing nonprotein groups -each is bound to one of the polypeptides · Hemoglobin also binds to: ↳ carbon dioxide ↳ acidic hydrogen-ion portion (H+) of ionized carbonic acid ↳ carbon monoxide ↳ nitric oxide Erythrocyte Enzymes · glycolytic enzymes: RBC rely on glycolysis for ATP formation (anaerobic) because they cannot produce their own · carbonic anhydrase ↳ critical CO2 transport ↳ catalyzes reaction that leads to conversion of metabolically produced CO2 into bicarbonate ion (HCO3-) - primary form in which CO2 is transported in blood Erythropoeisis · production of RBC · Site: prenatal-yolk sac, liver, spleen, bone marrow ↳ In adults this occurs only in myeloid tissue (red bone marrow) · differentiate from pluripotent stem cells · erythropolitin hormone → stimulates proerythroblast → produces hemoglobin → bunch of steps happen → reticulocyte is formed → ejects nucleus and enters blood stream to mature · spleen removes old erythrocytes from circulation Explanation: · Kidneys detect reduced oxygen carrying capacity in blood and stimulate the release of erythropoietin into blood stream ↳ goes to red bone marrow and stimulates stem cells to divide and mature faster · increased RBC and oxygen carrying capacity reduces erythropoietin Hematopoiesis: The differentiation and maturation of ALL blood cells is known as hematopoiesis. The differentiation and maturation of RED blood cells is erythropoiesis. Hence, erythropoiesis is a type of hematopoiesis. WBC production and differentiation is called leukopoeisis White Blood Cells · all WBCs (leukocytes) have a nucleus but no hemoglobin · granular or agranular classification: ↳ granulocytes: neutrophils, eosinophils, and basophils ↳ agranulocytes: monocytes and lymphocytes · granulocytes and monocytes are produced in bone marrow, lymphocytes are produced in lymphoid organs (lymph nodes and tonsils) · WBC help the body against invasion and remove toxins, wastes, and damaged cells Complete blood count (CBC): RBC + WBC level + platelets (numbers) CBC differential: looks at WBC count and which are present Neutrophils Eosinophils · most abundant by exocytosis · phagocytic specialists · attack objects coated in antibodies · functions: · increase in number during: ↳ allergic reactions ↳ first defenders, call for help with leukotrines ↳ internal parasite infections ↳ inflammatory response (release prostaglandins) ↳ scavenge to clean up debris Basophils Monocytes · similar to mast cells · in bone marrow = monocyte · least numerous, poorly understood · synthesizes and stores histamine and heparin · baby macrophages · in tissues = macrophages · macrophages are aggressive phagocytes Lymphocytes · highly mobile · provide immune defense for specifically programmed targets · types of lymphocytes: ↳ B lymphocytes - produce antibodies Terms to know: · leukocytosis → too many WBC · leukopenia → too little WBC · neutrophilia → increase in - antibody-mediated, humoral immunity neutrophils - destroys cells by releasing cytotoxins that punch holes lymphocytes - targets cells invaded by viruses and cancer cells monocytes ↳ T lymphocytes - cell-mediated immunity ↳ Natural Killer cells (NK) - immune surveillance (detect + destroy) · lymphocytosis → too many · monocytosis → too many Medical Uses of Growth Factors · synthetic erythropoietin used for decreased RBC production of end- stage kidney disease, anemic individuals, or as a blood alternative · colony stimulating factors (CSF) given to stimulate WBC formation in cancer patients who recieve chemotherapy · thrombopoietin helps prevent platelet depletion during chemotherapy Platelets (Thrombocytes) · the hormone thrombopoietin stimulates thrombopoiesis ↳ thrombopoietin produced in liver · platelets form in bone marrow · no nucleus, contains SER · disc-shaped, 2-4 micron cell fragment · megakaryocytes in red bone marrow manufacture structural proteins, enzymes, and membranes Functions of Platelets · Hemostasis (the stopping of bleeding) · platelet plug formation · steps in the process of blood clotting: 1. platelet adhesion 2. Platelet release reaction 3. platelet aggregation Blood Clotting Process ① Vascular phase · contraction of blood vessel (vascular spasm) decreases diameter of the vessel at the site of injury (30 min) ② Platelet Phase ④ Clot Retraction · releases chemicals like ADD, PAF, vWF (von Willebrand closer together, reducing the size of the · platelet adhesion/aggregation that forms a plug factor) etc. ③ Coagulation phase · clot formation after 30 sec · coagulation factors · coagulation cascade (explained later) · platelets in clot contract and pulls damaged area ⑤ Clot Destruction · removes the clot through fibrinolysis so it doesn't restrict blood flow Clotting Cascade · series of steps involving 12 plasma clotting factors that leads to final conversion of fibrinogen into a stabilized fibrin mesh · Extrinsic pathway ↳ requires contact with external tissue factors ↳ tissue thromboplastin released from damaged tissue activates factor X · Intrinsic pathway ↳ seven separate steps ↳ factor XII is activated by contact with collagen, then activates factor X · Common pathway ↳ begins when factor X activates from one of the pathways, then process speeds up when both pathways are activated ↳ Factor X activates prothrombin activator, which converts prothrombin to thrombin. Thrombin then activates and turns fibrinogen to fibrin. Fibrin then forms the clot. Understand this process (generally) Fibrinolysis used in clot destruction ABO Blood Groups · plasma membranes have surface antigens made of glycolipids on RBC: ↳ A, B, and Rh · certain blood types do not react well with each other b/c they have antibodies to some antigens eg. B blood has anti-A antibodies, and if introduced to A blood it will agglutinate (clump together) · RH blood groups do not naturally contain anti-Rh antibodies ↳ antibodies only form after exposure to Rh +/- (ie. during blood transfusion or certain type of pregnancy with negative mom and positive fetus) · if you have the Rh antigen you are Rh+, if you don't have it you are Rh↳ there is no specific antigen for Rh- just the lack of Rh Hemolytic Disease of the Newborn · mother is RhD- and baby is RhD+ · first pregnancy: baby develops separate from mother, but blood merges after birth and the mother produces an immune response to the RH+ antigen from the babies blood · second pregnancy: RH+ antibody is now present in the mother, which will attack the baby (memory cells) ↳ RhoGAM is used to prevent this Universal Recipient = AB blood Universal Donor = O blood