BLOOD River of Life

A. INTRODUCTION “River of life” transports everything that must be carried from one place to another Only fluid tissue in human body; 8% body weight Considered connective tissue made of Living cells: formed elements Non-living matrix: plasma GOODBADNEUTRAL Oxygen (O 2 )Carbon dioxide (CO 2 )Heat Nutrients (glucose, amino acids, fatty acids, vitamins) Urea, uric acid HormonesLactic acid

B. COMPOSITION & FUNCTION Sticky, metallic (due to Fe), salty, opaque fluid, pH , 38 °C Bright red (O 2 rich) to dark red (O 2 poor) in appearance Appears homogeneous but actually living solids (formed elements) are suspended in non-living watery liquid (plasma) O2O2O2O2

1. PLASMA Straw-colored fluid 90% water Solvent to carry all other substances mentioned below Absorbs heat Salts (electrolytes) Na +1, K +, Ca +2, Mg +2, Cl -, HCO3 - pH buffering, osmotic balance, regulating membrane permeability Proteins Mostly made by liver Albumin (pH buffer, osmotic balance), fibrinogen (clotting), globulins (antibodies) Nutrients Glucose, fatty acid, amino acids, vitamins Wastes Urea, uric acid (from metabolism) Gases CO2, O2 Hormones 77 different types secreted by endocrine glands

Plasma composition varies dozens of times each day Blood proteins regulated by liver During acidosis (too acidic) or alkalosis (too basic), respiratory system and excretory system regulate pH constantly redirecting heat to areas as needed

2. FORMED ELEMENTS

a. ERYTHROCYTES Red blood cells (RBCs) Most abundant at 4-6 million per mm 3 (1 drop = 50 mm 3 ) No nucleus ( anucleate ) Few organelles (no mitochondria) 1 RBC = 250 million hemoglobin molecules! Each hemoglobin carries 4 O 2 Men have more than women Function: carry O 2 to all cells

b. LEUKOCYTES white blood cells (WBCs) 4,000 – 11,000/mm 3 (<1% total blood volume) Only complete cells (nuclei, all organelles, hence DNA fingerprinting) Able to slip in & out of blood vessels to tissues & back (called diapedesis ) Locate tissue damage through chemical signals (called chemotaxis ) & move via ameboid motion Once activated for motion, body produces ~2x as many >11,000 = leukocytosis (sign of infection) <4,000 = leukopenia (Rx drugs, anticancer agents)

Leukocytes divided into 2 major categories: Granulocytes (“the phils”) Contain granules Agranulocytes (“the cytes”) No granules

i. NEUTROPHIL Multi-lobed nucleus (usually 3) 40-70% of WBC (3,000- 7,000/mm 3 ) Active phagocytes – foreign invader EATERS Destroy bacteria and viruses via phagocytosis During short-term infection, numbers increase rapidly to fight off invaders Granulocyte

ii. EOSINOPHILS Bi-lobed nucleus 1 – 4% of WBC (100 – 400/mm 3 ) Kills parasitic worms (tapeworms, flatworms, pinworms) Increase in number during allergy attacks May phagocytize antigen-antibody complexes thereby inactivating inflammatory chemicals Granulocyte

iii. BASOPHILS U or S-shaped nucleus 0 - 1% of WBCs (20 – 50/mm 3 ) Granules contain chemical histamine which initiates inflammation response makes blood vessels dilate & permeable (leaky) & attracts other WBCs to inflammatory site Granulocyte

iv. LYMPHOCYTES No granules, large round nucleus 20 – 45% of WBCs (1,500 – 3,000/mm 3 ) Aggregate around lymphatic tissues such as lymph nodes, tonsils, spleen Part of immune system; three types: B cells (from bone) produces antibodies T cells (from thymus) activates more B cells, Natural killer (NK) cells recognize abnormal cells (tumors and virus-infected) to kill them Agranulocyte

v. MONOCYTES 4 – 8% of WBCs ( /mm 3 ) Largest of all WBCs Irregular shaped cell fragments When migrate into tissues, become activated macrophages (large phagocytes) for long-term infections (like tuberculosis) Agranulocyte

c. PLATELETS Also known as thrombocytes 250,000 – 500,000/mm 3 Not real cells – just fragments of multinucleated cells called megakaryocytes Necessary for normal blood clotting ( coagulation ) Initiate clotting by clinging to ruptured blood vessel

C. HEMOSTASIS From Latin “blood standing still,” hemostasis is process of stopping blood flow Involves 3 major phases: 1. platelet plug formation 2. vascular spasms 3. coagulation (blood clotting) Whole process takes 3- 6 min