A&P II: Advanced Physiology Study Guide for Exam 3 (questions and explained answers)

Advanced Phys Study Guide Exam 3 1. Where do blood cells arise from during embryonic development? • yolk sac in vertebrate embryo produce stem cells that colonize fetal bone marrow, liver, spleen & thymus • liver stops producing blood cells at birth, but spleen and thymus remain involved with WBC production • red bone marrow (myeloid hematopoiesis) produces RBCs, WBCs and platelets 2. Role of hemacytoblasts (stem cells)? What are the major cell lines they can follow to mature into blood cells? • Hemacytoblasts give rise to intermediate progenitors of various blood cell types o Proerythroblasts: Develop into red blood cells o Myeloblasts: Develop into basophils, neutrophils, eosinophils o Lymphoblasts: Develop into lymphocytes o Monoblasts: Develop into monocytes o Megakaryoblasts: Develop into platelets 3. Steps in development of RBCs - Development takes 3-5 days & involves reduction in cell size, increase in cell number, synthesis of hemoglobin & loss of nucleus blood loss speeds up the process increasing reticulocyte count • Steps: o Uncommitted stem cells become committed to the erthyroid line and become proerthyroblasts (erythropoietin helps process) o Proerythroblast loses nucleus and becomes a normoblast o Hemoglobin synthesis occurs o Termed a reticulocyte when a large, nonnucleated immature cells that has remnants of the golgi apparatus mitochondria, and other cytoplasmic organelles o Stays in bone marrow before becoming mature erythrocyte o Reticulocyte reabsorbs the reticulum and then becomes a mature erythrocyte. It obtains the biconcave disk shape now. 4. Anemia- hemoglobin deficiency in blood that is caused by too few RBCs or too little hemoglobin in cells Effects of anemia: • tissue hypoxia and necrosis (short of breath & lethargic) • low blood osmolarity (tissue edema) • low blood viscosity (heart races & pressure drops) 5. WBCs and their functions: • Eosinophils – granulocyte - pink-orange granules & bilobed nucleus, o (­ in parasitic infections or allergies) o phagocytosis of antigen-antibody complexes, allergens o decrease inflammation o release enzymes destroy parasites such as worms • Basophils – granulocyte - abundant, dark violet granules (1%), large U- to S-shaped nucleus hidden by granules o (­ in chicken pox, sinusitis, diabetes) o Similar to mast cells (in tissues) o secrete histamine (vasodilator) o secrete heparin (anticoagulant) o important in allergic reactions • Neutrophils – granulocyte - multilobed nucleus (60-70%), fine reddish to violet granules in cytoplasm o (­ in bacterial infections) o phagocytosis of bacteria o release antimicrobial chemicals o most common • Monocytes – agranulocyte - kidney- or horseshoe-shaped nucleus (3-8%), large cell with abundant cytoplasm o (­ in viral infections & inflammation) o differentiate into macrophages o phagocytize pathogens and debris o “present” antigens to activate other immune cells • T cells (lymphocytes)-agranulocytes - leave bone marrow unfinished, go to thymus to complete their development (T cells), round, uniform dark violet nucleus (25-33%) variable amounts of bluish cytoplasm o o o o o • B cells o (­ in diverse infections & immune responses) destroy cancer & foreign cells & virally infected cells “present” antigens to activate other immune cells coordinate actions of other immune cells secrete antibodies & provide immune memory (lymphocytes) Antibody production 6. Properties of WBCs • 1. Margination- white blood cells leave the main blood stream and migrate toward vessel walls • 2. Diapedesis- neutrophils and monocytes squeeze through pores of blood capillaries • 3. Ameboid Motion- neutrophils and macrophages can send out cytoplasmic “feet” which allows them to move through tissues to reach invaders • 4. Chemotaxis- neutrophils and macrophages can follow a chemical “scent” produced by inflamed/infected tissues • 5. Phagocytosis 7. Vitamins and minerals needed for RBC production • Vitamin B12 o Needed for synthesis of DNA and RNA in RBCs • Iron -lost daily through urine, feces, and bleeding, men 0.9 mg/day and women 1.7 mg/day o low absorption rate requires consumption of 5-20 mg/day o dietary iron in 2 forms: ferric (Fe+3) & ferrous (Fe+2) o stomach acid converts Fe+3 to absorbable Fe+2 o gastroferritin from stomach binds Fe+2 & transports it to intestine o absorbed into blood & binds to transferrin to travel o bone marrow uses to make hemoglobin, muscle used to make myoglobin and all cells use to make cytochromes in mitochondria o liver binds surplus to apoferritin to create ferritin for storage o needed for production of heme • Folate- for rapid cell division, needed for synthesis of DNA and RNA, promotes RBC maturation • Vitamin C- cofactors for enzymes synthesizing RBCs • Copper - cofactors for enzymes synthesizing RBCs 8. Erythropoietin • increases RBC production; main producers are peritubular interstitial cells of kidneys, 9. in renal failure EPO release slows and RBC production is inadequate, stimulus for secretion is hypoxia, androgens What happens to old RBCs? • RBCs live for 120 days o membrane fragility -- lysis in narrow channels in the spleen • Macrophages in spleen and liver o digest membrane bits o separate heme from globin o hydrolyze globin (amino acids) o remove iron from heme o convert heme to biliverdin o convert biliverdin to bilirubin § becomes bile product in feces Hematopoietic growth factors: • Erythropoietin: increases RBC production; main producers are peritubular interstitial cells of kidneys. • Thrombopoietin: hormone produced by liver that stimulates formation of platelets. • M-CSF: produced by macrophages and fibroplasts to stimulate macrophage production. • GM-CSF: produced by T cells, macrophages and fibroblasts to stimulate neutrophil, macrophage and philphil production. • G-CSF: produced by macrophages and fibroblasts to stimulate neutrophil, eosinophil, and basophil production.