The Cardiovascular System: Blood Chapter 14

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

Composition Connective tissue-Two parts Plasma = soluble materials (~55%) Formed Elements = cells (~45%) Percent occupied by red blood cells (RBC) = hematocrit (Hct) White blood cells (WBC) ~1%

Figure 14.1a

Figure 14.1b

Plasma ~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

Formed Elements I. Red Blood Cells II. White blood cells III Platelets A. granular Leukocytes Neutrophils Eosinophils Basophils B. Agranular leukocytes T & B lymphocytes & natural Killer cells monocytes III Platelets

Formation of Blood Cells 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

Figure 14.2a

Figure 14.2b

Erythrocytes (RBCs) Hemoglobin package- carries oxygen Also carries some CO2 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 Cycling cleared by macrophages (liver & Spleen) Fe- recycled in bone marrow Carried in blood on transferrin Heme bilirubin and excreted (bile) Globin A.A. recycled.

Figure 14.3

RBC Synthesis called erythropoiesis From stem cells: hemocytoblasts Released as reticulocytes Mature to erythrocytes in 1-2 days Production & destruction is balanced Low O2 delivery (hypoxia)  erythropoietin release (EPO) from kidney Stimulates erythropoiesis

Figure 14.4

White Blood Cells 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 Basophil- intensify allergic reactions Immune response: T-cells, B-cells& natural killer (NK) cells

WBC Life Span 5000-10,00 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

Platelets Myeloid stem cells  megakaryocytes  2000 -3000 fragments = platelets Plug damaged blood vessels Promote blood clotting Life span 5-9 days

Hemostasis Hemostasis = stationary 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

Coagulation 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

Clot Retraction & Vessel Repair Clot pugs ruptured area Gradually contracts (retraction) Pulls sides of wound together Fibroblasts replace connective tissue epithelial cells repair lining

Control Mechanisms 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

Figure 14.5

Blood Types 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 Group Two antigens = A & B If have only A –type A If have only B –type B If neither then Type O 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

Figure 14.6

Rh Blood Group Antigen discovered in rhesus monkey If have antigen- Rh+ Normally don’t have antibodies antibodies develop after the first exposure from transfusion

Transfusions 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