T HE C ARDIOVASCULAR S YSTEM : B LOOD

F UNCTION Transportation-hormones, gasses, nutrients, ions, heat Regulation- pH, temperature, water balance in cells Protection- clotting, white cells interferons, complement

C OMPOSITION Connective tissue-Two parts Plasma = soluble materials (~55%) Remove the clotting proteins in plasma= serum Formed Elements = cells (~45%) Percent occupied by red blood cells (RBC) = hematocrit (Hct) White blood cells (WBC) ~1%

F IGURE 14.1 A

F IGURE 14.1 B

P LASMA ~ 91% water, 7% proteins, 1.5 % other solutes Proteins: Albumin (54%)- osmosis and carriers; Globulins (38%)- antibodies Fibrinogen (7%)- clotting Other: Electrolytes, nutrients, gases, hormones, vitamins & waste products

F ORMED E LEMENTS I. Red Blood Cells II. White blood cells A. Granular Leukocytes 1. Neutrophils 2. Eosinophils 3. Basophils B. Agranular leukocytes 1. T & B lymphocytes & natural Killer cells 2. monocytes III Platelets- thrombocytes

F ORMATION OF B LOOD C ELLS Called hemopoiesis Just before birth and throughout life occurs in red bone marrow Contains pluripotent stem cells In response to specific hormones these develop through a series of changes to form all of the blood cells

F IGURE 14.2 A

F IGURE 14.2 B

E RYTHROCYTES (RBC S ) Hemoglobin- carries oxygen Also carries some CO 2 Male has ~ 5.4 million cells/µl; Female has ~4.8 million membrane, no nucleus, flexible structure use glucose for ATP production to maintain ionic composition No mitochondria Wear out fast- live ~120 days

RBC C YCLING Cleared by macrophages (liver & spleen) Fe- recycled in bone marrow Carried in blood on transferrin Heme  bilirubin and excreted (bile) Globin  A.A. recycled.

F IGURE 14.3

RBC S YNTHESIS Called erythropoiesis From stem cells: hemocytoblasts Released as reticulocytes Mature to erythrocytes in 1-2 days Production & destruction is balanced Low O 2 delivery (hypoxia)  erythropoietin release (EPO) from kidney  Stimulates erythropoiesis

F IGURE 14.4

L EUKOCYTES (WBC) Defenses: phagocytes, antibody production and antibacterial action Phagocytes: Neutrophil- first responders Monocytes  macrophages (big eaters) Eosinophil- phagocitize antibody-antigen complexes Involved in suppressing allergic responses Immune response: Lymphocytes T-cells, B-cells& natural killer (NK) cells *Basophil- intensify allergic reactions (not a phagocyte)

WBC L IFE S PAN ,00 WBC /µl blood Limited number of bacteria can be eaten Life span is a few days During active infection may be hours Leukocytosis = increased WBC numbers  response to stresses Leukopenia = decreased WBC numbers

P LATELETS Myeloid stem cells  megakaryocytes  fragments = platelets Plug damaged blood vessels Promote blood clotting Life span 5-9 days

H EMOSTASIS Hemostasis = the stoppage of blood 1. Vascular reactions (spasm) Response to damage Quick reduction of blood loss 2. platelet plug formation Become sticky when contact damaged vessel wall 3. blood clotting (coagulation) Series of chemical reactions involving clotting factors Clotting in unbroken vessel= thrombosis

C OAGULATION Extrinsic pathway  common steps tissue factor(TF) from damaged cells  1 Intrinsic Pathway  common steps Materials “intrinsic” to blood  1 1. prothrombinase which causes 2. prothrombin  thrombin  causes 3. fibrinogen  fibrin  clot

C LOT R ETRACTION & V ESSEL R EPAIR Clot plugs ruptured area Gradually contracts (retraction) Pulls sides of wound together Fibroblasts replace connective tissue epithelial cells repair lining

C ONTROL M ECHANISMS Fibrinolysis : dissolving of clot by activated plasmin enclosed in clot Clots can be triggered by roughness on vessel wall = thrombosis Loose clot = embolus and can block a small vessel = embolism

F IGURE 14.5

B LOOD T YPES Surface antigens- react with antibodies Divided into groups based on antigens > 24 blood groups and > 100 different antigens We will deal with ABO and Rh groups

ABO G ROUP Two antigens = A & B Type A- if have only A Type B- if have only B Type AB- both antigens Type O- if neither then Blood usually has antibodies that can react with antigens e.g. anti-A antibody or anti-B antibody You don’t react with your own antigens Thus: type A has anti-B and vice versa

F IGURE 14.6

R H B LOOD G ROUP Antigen discovered in rhesus monkey If have antigen- Rh + Normally don’t have antibodies antibodies develop after the first exposure from transfusion

T RANSFUSIONS If mismatched blood given antibodies bind to it and hemolyze cells Type AB has no AB antibodies so can receive any ABO type blood called Universal recipients Type O have neither antigen so can donate to any other ABO type called Universal donors Misleading because of many other blood groups that must be matched