Human Anatomy Chapter 18: Blood PDF

Human Anatomy Chapter 18 Blood Dr. Kim Blood Circulation Circulatory system is divided into Cardiovascular system Lymphatic system Blood Transport medium for o Nutrients o Signaling molecules o Respiratory gases o Waste products Bloo...

Human Anatomy Chapter 18 Blood Dr. Kim Blood Circulation Circulatory system is divided into Cardiovascular system Lymphatic system Blood Transport medium for o Nutrients o Signaling molecules o Respiratory gases o Waste products Blood Circulation Powered by the pumping action of the heart Oxygen and nutrients diffuse across capillary walls to body tissues Transports hormones from endocrine glands Conveys cells of immune system Regulates body temperature Composition of Blood Blood has cellular and liquid components Is a specialized connective tissue o Blood cells - formed elements o Plasma - liquid portion of blood Composition of Blood Hematocrit Is the percentage of the blood volume that consists of red blood cells (RBCs) Buffy coat Is portion of blood composed of leukocytes and platelets o Present at junction of plasma and RBCs Major Components of Whole Blood Blood Plasma Straw-colored, sticky fluid portion of blood Approximately 90% water Contains more than 100 kinds of molecules Ions - Na+ and Cl− Nutrients o Sugars, amino acids, lipids Wastes o Carbon dioxide, urea, ammonia Proteins Blood Plasma Three main proteins Albumin o Prevents water from diffusing out of blood vessels Globulins o Include antibodies and blood proteins that transport lipids, iron, and copper Fibrinogen o One of the molecules involved in chemical reactions for blood clotting Formed Elements Blood cells Erythrocytes, leukocytes, and platelets Staining of blood cells Acidic dye - eosin; stains pink Basic dye - methylene blue; stains blue and purple Blood Cells Erythrocytes - Red Blood Cells (RBCs) Oxygen-transporting cells - 7.5 µm in diameter (diameter of capillary 8 - 10 mm) Most numerous of the formed elements Have no organelles or nuclei Are the ideal measuring tool for estimating sizes of nearby structures Erythrocytes - Red Blood Cells (RBCs) Are packed with oxygen-carrying hemoglobin Hemoglobin molecule bears four chains of amino acids o Each amino acid chain bears an iron atom o These are the binding sites for oxygen molecules Oxidation of iron atoms of hemoglobin molecules o Gives blood its red color Erythrocytes - Red Blood Cells (RBCs) Pick up O2 at lung capillaries Release O2 across other tissue capillaries Structural characteristics contribute to respiratory function Biconcave shape → 30% more surface area 97% hemoglobin Lack mitochondria o Do not consume O2 they pick up Structure of Erythrocytes Leukocytes - White Blood Cells (WBCs) Protect the body from infectious microorganisms Function outside the bloodstream in loose connective tissue Diapedesis - circulating leukocytes leave the capillaries Originate in bone marrow Leukocytes - White Blood Cells (WBCs) Two types of leukocytes Granulocytes (neutrophils, eosinophils, and basophils) Agranulocytes (lymphocytes and monocytes) Mnemonic: “Never Let Monkeys Eat Bananas” Neutrophils, lymphocytes, monocytes, eosinophils, basophils Can help you remember the relative abundance of leukocytes, from the most abundant to the least abundant Relative Percentages of the Different Types of Leukocytes Granulocytes Neutrophils Most numerous WBC - granules pick up acidic and basic stains Nucleus - has two to six lobes Attracted by bacterial products and are first line of defense in inflammatory response Phagocytize and destroy bacteria o Also release enzymes into extracellular matrix of infected tissue Leukocytes Granulocytes Eosinophils Represent 1 - 4% of all WBCs Granules are large and stain red o Granules contain enzymes active during allergic reactions and parasitic infections Play a role in ending allergic reactions by phagocytizing allergens Secrete enzymes that degrade histamines Leukocytes Granulocytes Basophils - about 0.5% of all leukocytes Nucleus - usually two lobes Granules secrete histamines Function in inflammation mediation Direct later stages of inflammation in allergies and parasitic infections Leukocytes Agranulocytes Lymphocytes - comprise 20 - 45% of WBCs The most important cells of the immune system Nucleus - stains dark purple Effective in fighting infectious organisms Act against a specific foreign molecule (antigen) Leukocytes Agranulocytes Two main classes of lymphocyte T cells - attack foreign cells directly B cells - differentiate and produce antibodies o Mark the foreign cell for destruction by macrophages Agranulocytes Monocytes - compose 4 - 8% of WBCs The largest leukocytes Nucleus: kidney-shaped Transform into macrophages o Phagocytic cells Leukocytes Platelets Cell fragments Break off from megakaryocytes Function in clotting of blood Summary of Formed Elements of the Blood Summary of Formed Elements of the Blood Blood Cell Formation Hematopoiesis - process by which blood cells are formed 100 billion new blood cells formed each day Bone Marrow as the Site of Hematopoiesis Bone marrow Red marrow - actively generates new blood cells o In adults, red marrow is located ▪ The axial skeleton ▪ Girdles ▪ In proximal epiphyses of humerus and femur Bone Marrow as the Site of Hematopoiesis Tissue framework of bone marrow Reticular connective tissue Fibroblasts covering and secreting the fiber network Blood sinusoids run throughout the reticular tissue Mature blood cells enter the blood stream through endothelial cells of sinusoids Red Bone Marrow Cell Lines in Blood Cell Formation All blood cells originate in bone marrow All originate from one cell type Hemopoietic blood stem cell (pluripotential hematopoietic stem cell) Produces lines of progenitor cells o Lymphoid stem cells ▪ Give rise to lymphocytes o Myeloid stem cells ▪ Give rise to all other blood cells