Transcript Blood
The Circulatory System: Blood 3 Functions of Blood 1. Transport – transports CO2 & O2 – Nutrients – metabolic waste (urea & lactic acid) – hormones – enzymes – plasma proteins 3 Functions of Blood 2. Regulation • body temperature • pH in body tissues • fluid & electrolyte balance 3 Functions of Blood 3. Protection • prevents excessive bleeding • antibodies detect foreign material • prevents infection (WBC) Composition of Blood • Blood – made of plasma and formed elements • 8% of body wgt • pH = 7.4 • 5x more viscous than water Blood Composition Separated by Centrifugation Hematocrit Blood Plasma plasma → nonliving fluid part; straw-colored • 90% water; plasma proteins (8%) • Albumin –shuttles molecules through blood; buffer; helps maintain plasma’s osmotic pressure • Fibrogen – helps repair damaged tissue • Dissolved solutes (nutrients, gases, hormones, wastes, ions, proteins, etc.) (2%) • 55% of blood volume Blood Plasma Formed Elements in Blood Formed elements → living blood cells -45% of blood -platelets (thrombocytes) → clotting -red blood cells (RBC; erythrocytes) →carry oxygen; -white blood cells (WBC; leukocytes) →fight infection Blood cell formation • Hematopoiesis (aka hemopoiesis) • Occurs in: • Red bone marrow stem cells »Vertebrate, ribs, hips, sternum, skull »Lymph tissue in nodes, tonsils, spleen & thymus make small amounts Erythrocytes (RBCs) • Plasma membrane; anucleate • Hemoglobin- protein that transports oxygen/CO2 • Erythropoiesis • EPO • Hemolysis – 120 days • Phagocytocis Erythrocytes (RBCs) Excessive RBC • polycythemia – abnormal excess of erythrocytes that increases blood viscosity – Blood thickens, flows sluggishly Leukocytes (WBCs) • Complete cells (nuclei & organelles) 5 Types of WBC: Granulocytes – contain granules Types– neutrophils, basophils, & eosinophils 2. Agranulocytes – lack granules Types– lymphocytes and monocytes Leukocytes (WBCs) Platelets (Thrombocytes) • Essential for clotting; occurs in plasma when blood vessels are ruptured or injured • Form plug that helps seal break when they stick to damaged site • Megakaryocytes in bone marrow • Thrombopoietin Platelets (Thrombocytes) Coagulation (blood clotting) • Hemostasis • Procoagulants (clotting factors) – enhance clot formation • Anticoagulants – factors that inhibit clotting; heparin Hemostasis 4 phases: 1. Constrict blood vessel; reduce blood loss 2. Platelet plug hole & attract more platelets 3. Platelet plug injury and coagulate; thrombin and fibrogen form fibrin mesh - traps blood cells, seals hole until blood vessel can be fully repaired 3. Blood clot formation and retraction Coagulation (blood clotting) Blood Type • antigen –chemical that stimulates cells to produce antibodies • antibody –protein immune system produces in presence of nonself antigen; reacts with antigen – antibodies made limit receiving blood from certain types – Rh factor: + or - Rh – exposure forms antibodies to it Blood Type A B Antigen A Antibody anti-B B anti-A AB A and B *neither anti-A nor anti-B O **neither A nor B Both anti-A and anti-B *AB is universal recipient **O is universal donor RBC Disorders • anemia – blood has extremely low oxygen-carrying capacity due to low number of RBCs, low hemoglobin content, or abnormal hemoglobin Leukocyte Disorders • leukemia – (“white blood”) = rapid, uncontrolled production of clones of cancerous leukocyte; impairs normal bone marrow function Named after: – Abnormal cell type involved (i.e. lymphocytic leukemia = lymphocytes) – Speed it advances: acute – quickly advances (blast-type cells) chronic – slowly advances (later cell stages) Leukocyte Disorders • Infectious mononucleosis – EpsteinBarr virus; makes excessive atypical agranulocytes – No cure; with rest, virus runs its course and recovers in a few weeks