Blood

I. Functions: 1. Transport molecules to + from capillaries where exchange occurs (RBC’s, plasma) 2. Help guard against microbes (WBC’s) 3. Prevent life-threatening blood loss by clotting (platelets etc)

II. Composition 55% Plasma (inorganic + organic substances dissolved in water  includes plasma proteins) 45% “FORMED ELEMENTS” ( cellular compound) a) erythrocytes (RBC’s) b) leukocytes (WBC’s) c) thrombocytes (platelets)

a) Red Blood Cells Continuously manufactured in red bone marrow (in ribs, vertebrae, ends of long bones) SHAPE: Biconcave discs Each cell has ~ 200million hemoglobin molecules (Hb) - 4 separate proteins (α + β) globins “Quaternary structure” - Hb increases the O 2 – carrying capacity of blood box+ - also helps transport CO 2

(RBC continued) - RBC’s have no nucleus – they last ~120days (destroyed in liver + spleen  heme portion is broken down into bile pigments + the iron gets recycled) - RBC production ↑ at high altitudes

b) White Blood Cells (WBC’s) - Main function is to fight infection x larger than RBC’s - Less numerous than RBC’s 2 MAIN TYPES:

GRANULARAGRANULAR Neutrophils 55 – 70% Phagocytize+digestbacteria Eosinophils + Basophils Involved in inflammatory + allergic response Polymorphonuclear (many-lobed nucleus) Monocytes - very large + phagocytic (2 – 8%) - Indented nucleus Lymphocytes - matured in lymph thymus + bone marrow - responsible for immunity - Procedure antibodies Mononuclear ( have circular or indented nucleus)

c) Platelets - Cell fragments of huge cells called megakaryocytes (from bone marrow) - Involved in blood clotting along with some plasma proteins - Produce 200,000,000,000 per day * If blood doesn’t clot, you may have HEMOPHILIA

Blood Clotting ① Blood vessel breaks; platelets + injured tissues release the enzyme PROTHROMBIN ACTIVATOR Prothrombin ② PROTHROMBIN  THROMBIN (from liver, requires VIT.K) activator ③ FIBRINOGEN  FIBRIN (from liver)(makes up the mesh of the clot; fibrin threads wind around platelets + RBC’s, making a plug. Eventually, the clot will be destroyed by the enzyme PLASMIN  prevents thromboembolism)

Blood Clotting (continued) Plasma Proteins - all of them help maintain blood PH (buffers) and blood osmotic pressure/ viscosity - specifically, some are for clotting, some are for the transport of large organic molecules (such as cholesterol, hormones, vitamins) and some for fighting infection (eg. Globulins, which are a type of antibody)

III TRANSPORT and EXCHANGE of O 2 + CO 2 a) - O 2 : most is carried by Hb inside RBC’s (O 2 is carried on heme portion of Hb) -O 2 binds with Hb in lungs, where it is cool + neutral ptt -O 2 released from Hb at body tissues, where it is warmer + slightly acidic lungs Hb + O 2 ↔ HbO 2 (oxy hemoglobin-bright red) (deoxyhemoglobin tissues – dark purple)

(continued) b) CO2: Carbon dioxide – carried 2 ways -a small amount is carried by Hb Hb + CO2 ↔ HbCO2  carbamino hemoglobin - most CO2 dissolves in the blood plasma, forming BICARBONATE ION! : tissues CO 2 + H 2 O ↔ H 2 CO 3 ↔ H + + HCO 3 - lungs lungs Bicarbonate ion H + + Hb  HHb ↑ reduced hemoglobin

O2/ CO2 exchange: -Blood always has a greater concentration of O 2 + nutrients than tissue fluid, so O 2 + nutrients diffuse out of a capillary into the tissues. - Tissue fluid always has a greater concentration of CO 2 + wastes than blood, so CO 2 + wastes diffuse into a capillary from the tissues

Fluid Exchange

Fluid Exchange (cont.) -At arterial end, blood pressure > osmotic pressure 40mmHg>25mmHg Therefore, water exits capillary (RBC’s + plasma proteins are too big to leave!)

Fluid Exchange (cont.) -At the venous end, blood pressure < osmotic pressure 10mmHg <25mmHg Therefore, water enters the capillary

(cont.) NOTE: osmotic pressure is created by the presence of salts and plasma proteins in the blood. - the water exchange is not equal – some H2O is not returned to the capillary. The excess tissue fluid is picked up by the lymph capillaries and is returned to the systemic venous blood at the subclavianvein.

IV BLOOD TYPING Antigen (Ag) – a marker on a cell or virus that is recognized by an antibody (Ab) - a specific Ab will react with a specific antigen, usually neutralizating the substance. - our own cells have antigens (“markers”), but we don’t make antibodies for them. However, if our cells are placed in someone else’s body, that person’s antibodies may destroy them - this is called TISSUE REJECTION. - blood cells have antigens Aor B NOTE: An ANTIBODY is a protein made by the body, designed to combat a foreign protein.

Blood type

Fetal Erythroblastosis : (death of body) - If a mother (Rh-) has an Rh+ baby, (ie. Father = Rh+) some leakage of baby’s blood occurs from baby to mom during birth (thru placenta)  therefore, mom makes Rh antibodies (during of just after birth) If mom has another Rh+ child; she already has Rh Ab’s that will attack the second baby’s RBC’s at birth.  to prevent this, mom is injected with RhoGAM shortly after the birth of first baby.  this destroys fetal cells present before the mom’s baby starts producing Rh antibodies (therefore, timing is important)

(cont.) Blood TypeAntigensAntibodies A B AB O