Ch 11 Blood

Functions of Blood Deliver O2 Remove metabolic wastes Maintain temperature, pH, and fluid volume Protection from blood loss- platelets Prevent infection- antibodies and WBC Transport hormones

Plasma-55% Buffy coat-<1% Red Blood Cells -45% Composition of Blood

Figure 11.1 on page 305 in our book

Formed Elements of the Blood Erythrocytes (red blood cells) Leukocytes (white blood cells) Platelets (thrombocytes) Formed elements: cells and

Blood Plasma Components-55% 90% Water 8% Solutes: Proteins Albumin (60 %) Globulins (38%) Fibrinogens (4%) Gas Electrolytes Albumin: Osmotic pressure, transport molecules Globulins: immune system, transport molecules Fibrinogens: blood clots

Blood Plasma Components Organic Nutrients Carbohydrates Amino Acids Lipids Vitamins Hormones Metabolic waste CO2 Urea

Buffy Coat- <1% Platelets Leukocytes (WBC)

Platelets Small fragments of megakaryocytes Formation is regulated by thrombopoietin Blue-staining outer region, purple granules Granules contain serotonin, Ca2+, enzymes, ADP, and platelet-derived growth factor (PDGF) Platelets

Developmental pathway Stem cell Developmental pathway Hemocyto- blast Promegakaryocyte Megakaryoblast Megakaryocyte Platelets Figure 17.12

Red Blood Cells -45% Erythrocytes (red blood cells)

Erythrocytes

Erythrocyte7.5m in dia ·   Anucleate ·   Function- transport respiratory gases ·  Life span 100-120 days and then destroyed in spleen (RBC recycling center)

Hemoglobin Four globin protein chains Four heme molecules with an Iron atom: Iron attracted to oxygen

Hematopoiesis Erythropoiesis The process of blood cell formation Location: red bone marrow of axial skeleton Erythropoiesis Process of red blood cell formation

Hematopoiesis: Blood Cell Production Hormones and growth factors push the cell toward a specific pathway of blood cell development Hemocytoblasts

Erythropoiesis Phases in development Ribosome synthesis Hemoglobin accumulation Ejection of the nucleus and formation of reticulocytes Reticulocytes then become mature erythrocytes Committed cell Developmental pathway Stem cell Phase 1 Ribosome synthesis Phase 2 Hemoglobin accumulation Phase 3 Ejection of nucleus Proerythro- blast Early erythroblast Late erythroblast Reticulo- cyte Erythro- cyte Hemocytoblast Normoblast

Regulation of Erythropoiesis Too few RBCs leads to tissue hypoxia Hypoxia: low oxygen levels Too many RBCs increases blood viscosity Viscosity: Thick, Sticky, semifluid Balance between RBC production & destruction depends on: Hormonal controls Adequate supplies of iron, amino acids, and B vitamins

Regulation of Erythropoiesis Causes of tissue hypoxia: Hemorrhage or increased RBC destruction Insufficient hemoglobin (e.g., iron deficiency) Reduced availability of O2 (e.g., high altitudes) Hypoxia: low oxygen levels

Hormonal Control of Erythropoiesis Erythropoietin (EPO) Stimulates erythropoiesis Released by kidneys in response to hypoxia

Hormonal Control of Erythropoiesis Effects of EPO More rapid maturation of committed bone marrow cells Increased circulating reticulocyte count in 1–2 days Testosterone also enhances EPO production, resulting in higher RBC counts in males

Formation & Destruction of RBCs

Leukocytes

Types of Leukocytes 4,000-11,000 cells/mm 3 Never let monkeys eat bananas Granulocytes: granules in cytoplasm Neutrophils- 40-70% Eosinophils- 1-4% Basophils- <1% Agranulocytes: no granules in cytoplasm Monocytes- 4-8% Lymphocytes- 20-45%

Neutrophil Eosinophil Basophil Lymphocyte Monocyte