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: Constrict blood vessel; reduce blood loss Platelet plug hole & attract more platelets 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 Antigen Antibody A A anti-B B B anti-A AB A and B *neither anti-A nor anti-B O **neither Both anti-A A nor B 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 – Epstein-Barr virus; makes excessive atypical agranulocytes No cure; with rest, virus runs its course and recovers in a few weeks