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Transcript
Unit III: Homeostasis Blood Chapter 17 pp. 575-585 Review 1. The most effective buffer in the intracellular fluid is: a.) phosphate; b.) protein; c.) bicarbonate; d.) carbonic acid 2. A blood pH of 7.2 caused by inadequate pulmonary ventilation would be classified as _________. 3. Tubular secretion of hydrogen ions would cease if the acidity of the tubular fluid fell below a value called the _________. 4. (T/F) The bicarbonate system buffers more acid than any other chemical buffer. 5. Acids ____________ hydrogen ions in a solution, whereas, bases _______ them. Functions of Circulatory System • Fundamental purpose: transport substances from place to place • Transport – O2, CO2, nutrients, wastes, hormones, and stem cells • Protection – Inflammation, WBCs, antibodies, and platelets • Regulation – fluid regulation, buffering, and heat Presence of Potassium in Blood Hypokalemia <2 mEq/L in blood: • muscular weakness •paralysis Hyperkalemia Normal potassium levels in serum (3.5–5.5 mEq/L) Factors Promoting Hypokalemia Diuretics (Lasix) Aldosteronism ↑ volume of urine overstimulates sodium produced retention & potassium loss >8 mEq/L in blood • cardiac arrhythmias Factors Promoting Hyperkalemia Chronically low body fluid pH Kidney failure Several drugs promote diuresis by blocking Na reabsorption at the kidneys. Blood Composition • Adults have 4-6 L of blood • Plasma – – Water, proteins, nutrients, electrolytes, nitrogenous wastes, gases, and hormones Withdraw blood (Table 18.2 p. 687) • Serum – Lacks fibrinogen Centrifuge Plasma (55% of whole blood) Buffy coat: leukocytes and platelets (<1% of whole blood) Erythrocytes (45% of whole blood) Formed elements Plasma Proteins • 3 major categories of plasma proteins: – albumins - most abundant • contributes to viscosity and osmolarity influences blood pressure, flow and volume – globulins (antibodies) • provide transport, clotting, and immunity • alpha, beta and gamma globulins – fibrinogen • precursor of fibrin help form blood clots • Plasma proteins formed by liver – except gamma globulins (produced by plasma cells) Formed Elements of Blood •Erythrocytes •Platelets •Leukocytes –Granulocytes Neutrophils Eosinophils Basophils –Agranulocytes Lymphocytes Monocytes Properties of Blood • Viscosity – whole blood 5 times as viscous as water • Osmolarity (total molarity of dissolved particles that can’t pass through blood vessel wall) – high blood osmolarity • raises blood pressure – low blood osmolarity • lowers blood pressure Properties of Blood • Hematocrit – (packed cell volume) – Females: 37-48% – Males: 45-52% • pH: 7.35 - 7.45 • RBC count: – Females: 4.2-5.4 million/µL – Males: 4.6-6.2 million/µL • Total WBC count: 5000 – 10,000 /µL • Volume/Body weight: 80-85 mL/kg – Female: 4-5L – Male: 5-6L Erythrocytes (RBCs) • Disc-shaped cell with thick rim • Gas transport – increased surface area/volume ratio • due to loss of organelles during maturation • increases diffusion rate of substances – 33% of cytoplasm is hemoglobin (Hb) • O2 delivery to tissue and CO2 transport to lungs • Carbonic anhydrase (CAH) Erythrocytes and Hemoglobin • Common measurements: – Hematocrit (packed cell volume) – Red blood cell count – hemoglobin concentration of whole blood • men 13-18g/dL; women 12-16g/dL • Values are lower in women – androgens stimulate RBC production – women have periodic menstrual losses – Hematocrit is inversely proportional to % body fat Erythropoiesis • 2.5 million RBCs/sec (hematocrit value of 20mL of RBC/day) • Development takes 3-5 days – reduction in cell size, increase in cell number, synthesis of hemoglobin and loss of nucleus Events Occurring in the Red Bone Marrow Multipotent stem cells Start Proerythroblasts stimulated by erythropoietin (EPO) Macrophages in liver, spleen, and bone marrow Fe2+ Amino Heme acids 90% Biliverdin Bilirubin 10% Fe2+ transported in circulation by transferrin Average life span of RBC is 120 days RBC formation Erythroblast Roughly four days of differentiation Hemolysis Ejection of nucleus New RBCs released into circulation Retilculocytes remain in the bone marrow for 2 more days Erythrocyte Homeostasis • Negative feedback control – drop in RBC count causes kidney hypoxemia – EPO production stimulates bone marrow – RBC count in 3 - 4 days • Stimulus for erythropoiesis – hemorrhaging, blood loss – low levels O2 – abrupt increase in O2 consumption – loss of lung tissue in emphysema Anemia •Inefficient amount of red blood cells •Causes: inadequate erythropoiesis •Kidney failure •Iron-deficiency •Vitamin B12 deficiency blood loss RBC destruction •Consequences: Hypoxia Decreased blood osmolarity Decreased blood viscosity Erythrocyte Disorders Sickle Cell Disease and Thalassemia • Hereditary Hb ‘defect’ of African Americans and Mediteraneans – recessive allele modifies hemoglobin structure – sickle-cell trait - heterozygous for HbS • individual has resistance to malaria – sickle-cell disease - homozygous for HbS • individual has shortened life – low O2 concentrations sickle shape – stickiness agglutination blocked vessels – intense pain; kidney and heart failure; paralysis; stroke Antigens and Antibodies • Antigens (agglutinogens) – unique molecules on all cell surfaces • used to distinguish self from foreign • Antibodies (agglutinins) – secreted by plasma cells – Appear 2-8 months after birth; reach maximum at 10 yr. – Transfusion reaction • Agglutination : RBC Surface antigens Opposing antibodies Antigen-antibody complex Hemolysis ABO Blood Groups • Your ABO blood type is determined by presence or absence of agglutinogens on RBCs and agglutinins in blood plasma. Type A RBCs with antigen A only. Surface antigen A Type B RBCs with antigen B only. Type AB RBCs with both A and B antigens. Type O RBCs lacking both A and B antigens. Surface antigen B Plasma contains anti-B Plasma contains anti-A antibodies, which will attack antibodies. Type B surface antigens. Plasma contains both Plasma has neither anti-A nor anti-B antibodies. anti-A and anti-B antibodies. • most common/universal donor - type O • Rarest/universal recipient - type AB ABO Group Genetics • A and B alleles are dominant over O; but codominant to each other Genotype AA AO BB BO AB OO Antigen A A B B A and B Neither Phenotype A A B B AB O A AB AB AB B A A B B Rh Group • 3 antigens: C, D, E • Rh (D) agglutinogens – Rh+ blood type has D agglutinogens on RBCs – Rh frequencies vary among ethnic groups • Anti-D agglutinins not normally present – form in Rh- individuals exposed to Rh+ blood • no problems with first transfusion Hemolytic Disease of the Newborn Rh– mother First Pregnancy of an Rh– Mother with an Rh+ infant Rh+ fetus Maternal blood supply and tissue Rh+ fetus These antibodies destroy fetal RBCs dangerous anemia. Placenta Fetal blood supply and tissue Exposure to fetal red blood cell antigens generally occurs during delivery. Second Pregnancy of an Rh– Mother with an Rh+ Infant Maternal anti-Rh antibodies present. During First Pregnancy Very few fetal cells enter the maternal circulation. Rh– mother Need for blood cells ↑ During Second Pregnancy Maternal Leave bone marrow underdevelopment. Maternal antibodies Hemorrhaging at Delivery Maternal Fetal Hemolysis of fetal RBCs Fetal Rh antigen on fetal red blood cells A woman’s first infant Maternal Antibody Production is not affected. Maternal antibodies Maternal to Rh antigen Results of blood typing tests on blood samples from four individuals Anti-A Anti-B Anti-D Blood type A+ B+ AB+ O–