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 (11,000 = leukocytosis (sign of infection)