Chapter Notes - Week 2

1.The cardiovascular system consists of the blood, heart, and blood vessels. 2. Blood is a liquid connective tissue that consists of cells and cell fragments surrounded by a liquid extracellular matrix (blood plasma). 19.1 Functions and Properties of Blood 1. Blood transports oxygen, carbon dioxide, nutrients, wastes, and hormones. 2. It helps regulate pH, body temperature, and water content of cells. 3. It provides protection through clotting and by combating toxins and microbes through certain phagocytic white blood cells or specialized blood plasma proteins. 4. Physical characteristics of blood include a viscosity greater than that of water; a temperature of 38°C (100.4°F); and a pH of 7.35–7.45. 5. Blood constitutes about 8% of body weight, and its volume is 4–6 liters in adults. 6. Blood is about 55% blood plasma and 45% formed elements. 7. The hematocrit is the percentage of total blood volume occupied by red blood cells. 8. Blood plasma consists of 91.5% water and 8.5% solutes. Principal solutes include proteins (albumins, globulins, fibrinogen), nutrients, vitamins, hormones, respiratory gases, electrolytes, and waste products. 9. The formed elements in blood include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets. 19.2 Formation of Blood Cells 1. Hemopoiesis is the formation of blood cells from hemopoietic stem cells in red bone marrow. 2. Myeloid stem cells form RBCs, platelets, granulocytes, and monocytes. Lymphoid stem cells give rise to lymphocytes. 3. Several hemopoietic growth factors stimulate differentiation and proliferation of the various blood cells. 19.3 Red Blood Cells 1. Mature RBCs are biconcave discs that lack nuclei and contain hemoglobin. 2. The function of the hemoglobin in red blood cells is to transport oxygen and some carbon dioxide. 3. RBCs live about 120 days. A healthy male has about 5.4 million RBCs/μL of blood; a healthy female has about 4.8 million/μL. 4. After phagocytosis of aged RBCs by macrophages, hemoglobin is recycled. 5. RBC formation, called erythropoiesis, occurs in adult red bone marrow of certain bones. It is stimulated by hypoxia, which stimulates the release of erythropoietin by the kidneys. 6. A reticulocyte count is a diagnostic test that indicates the rate of erythropoiesis. 19.4 White Blood Cells 1. WBCs are nucleated cells. The two principal types are granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes). 2. The general function of WBCs is to combat inflammation and infection. Neutrophils and macrophages (which develop from monocytes) do so through phagocytosis