Blood Chapter 12

Functions of Blood Considered a type of connective tissue Deliver O2 and nutrients to all body cells Transport waste products from cells for elimination Transport hormones Maintain body temp (distribute heat) Maintain pH (carry buffers) Maintain fluid volume Prevent blood loss (clotting) Prevent infection (WBCs, antibodies)

Blood Components Plasma (55%) Water (90%), ions, proteins, gases, nutrients, wastes, hormones Hematocrit (45%) RBCs, WBCs, platelets Develop from stem cells in bone marrow

Blood Volume Average about 5 liters Depends upon Body size Fluid and electrolytes Fat tissue

Erythrocytes Red blood cells (RBCs) Transport O2 in blood Biconcave discs Anucleate (no nucleus) Leaves room for hemoglobin Hemoglobin: iron-containing protein, binds to O2 Oxyhemoglobin – oxygen combined with hemoglobin Bright red Cyanosis - Blue coloration near surface of skin due to the build-up of deoxygenated blood Life span: 100-120 days

Red Blood Cell Count Male 4.6 - 6.2 mill/mm3 Female 4.2 - 5.4 mill/mm3 Linked to O2 capacities Used for disease diagnosis Evaluate course of disease

Destruction of RBC’s RBC’s become fragile due to passing through capillaries Macrophages conduct phagocytosis (in liver & spleen) Hemoglobin broken down into heme and globin Heme decomposed into iron and biliverdin Iron recycled and stored in liver Biliverdin converted into bilirubin Excreted as bile as bile pigments Jaundice Bilirubin accumulates Yellowing of skin and eyes

Jaundice

Blood Cell Formation Hematopoiesis: blood cell formation Embryo and fetus – occurs in yolk sac, liver, and spleen Adults - occurs in red bone marrow Hemocytoblast: stem cell for RBC, WBC, platelets

RBC Hematopoiesis Dietary requirements: Iron for hemoglobin Vitamin B12 and folic acid for DNA synthesis of all cells Iron for hemoglobin Anemia: decrease in oxygen-carrying ability of blood Low RBC count or deficient hemoglobin content Sickle-Cell Disease: abnormal hemoglobin Genetic disorder Carriers of 1 allele are resistant to malaria in Africa Heterozygote advantage

Negative Feedback Mechanism Erythropoietin Hormone released in response to low oxygen concentration (hypoxia) Detected by kidneys and liver Travels to red bone marrow for RBC production

Leukocytes White blood cells (WBCs) Types: neutrophils, eosinophils, basophils, lymphocytes, monocytes Defend body against infection and tumors Phagocytosis Many lysosomes Neutrophils and monocytes Antibodies (Immunity) Lymphocytes Locate areas of tissue damage by responding to chemicals

WBC Counts Normal: 5,000-10,000/mm3 Differential WBC count lists %’s of types of leukocytes present Leukocytosis > 10,000/mm3 Appendicitis, leukemia (acute and chronic) Leukopenia < 5,000 /mm3 Typhoid fever, flu, measles, mumps, polio, AIDS

WBC Counts Leukemia: bone marrow becomes cancerous  huge numbers of WBCs Treatment: chemotherapy, radiation, stem cell transplant

Types of WBC Agranulocytes Monocyte – phagocytic Lymphocyte – key players in immune response Granulocytes Neutrophils – phagocytic Eosinophils – moderate allergic reactions and regulate parasitic infections Basophils – release histamine to promote inflammation and heparin to inhibit blood clotting during tissue damage

Platelets Cell fragments of megakaryocytes Large cells in marrow that shatter 130,000 - 360,000/mm3 normal count Functions Close breaks in vessels Initiate formation of blood clots

Plasma Plasma proteins Clear, straw-colored, liquid portion of blood ~ 92% is H20 Functions: Transport nutrients, gases, and vitamins Fluid and electrolyte balances Maintaining pH (~ 7.45) Plasma proteins Albumin – maintain osmotic pressure Globulins – transport lipids and fat-soluble vitamins Fibrinogens – role in blood coagulation

Hemostasis = stoppage of bleeding Vascular spasm Constrict damaged blood vessels Serotonin causes smooth muscle contraction Platelet plug forms Platelets stick and bind to damaged site Release chemicals to attract more platelets Coagulation Blood clotting Fibrin threads forms mesh that traps RBCs Time: blood clot normally forms within 3-6 min.

Hemostasis - Coagulation Prothrombin Vitamin K needed to make prothrombin Converted to thrombin in the presence of calcium Thrombin fragments catalyze a reaction to convert: Fibrinogen into fibrin which sticks to the vessel walls and traps cell and platelets Positive feedback mechanism Original action stimulates more of the same action

Disorders Thrombus: clot in unbroken blood vessel Coronary thrombosis = heart attack Embolus: thrombus breaks away from vessel wall and floats freely Cerebral embolus = stroke Hemophilia: hereditary bleeding disorder, lack clotting factors

Human Blood Groups Antigen (agglutinogens): foreign substance (invader) that immune system recognizes Antibodies (agglutinins): Y-shaped proteins secreted by WBC’s that attach to antigens Agglutination: clumping caused by antibodies binding to antigens on RBCs RBC surface proteins: A antigen B antigen Rh antigen

ABO Blood Groups 43% 42% 12% 3% Type A: has A antigen on surface of RBC Type B: has B antigen Type AB: has both A & B antigens Type O: has no antigens on surface Rh antigen found on RBC’s in Rhesus monkeys (1940)

Rh Factor in Pregnancy Rh+ Have antigens Rh- Do not have antigens Problem occurs when female is Rh- and baby is Rh+ Problem is with future pregnancies Erythroblastosis fetalis can develop in newborn Treated with RhoGAM shots

Blood Typing Analysis Blood sample mixed with 3 antibodies If blood clumps, antigens are present If no clumps, no antigens are present Anti-A antibody test Rh antibody test Anti-B antibody test

Blood Typing Identifying the antigens Finding out if A, B, or Rh are present Why? Transfusions Serious reactions may occur