Chapter 6 Body Systems

Anatomy – structure Physiology – function Homeostasis – stable internal environment

Circulatory System Pumps blood throughout body, delivering oxygen and nutrients to cells; carbon dioxide and wastes away from body Made of: heart, blood, arteries, & veins

Two pathways Systemic circulation - heart pumps oxygenated blood away thru arteries to cells - cells absorb O 2 ; release CO 2 & other wastes - some waste – eliminated by kidneys, etc - carries blood back to heart

Pulmonary circulation - heart pumps deoxygenated blood, CO 2 & wastes to lungs - blood releases CO 2, wastes; picks up O 2 - oxygenated blood flows back to heart to enter systemic circulation

Blood Fn: distribute heat, transport O 2 and wastes Made of: red blood cells, white blood cells, platelets, & plasma

RBCs = erythrocytes Large surface area – efficient gas exchange Hemoglobin binds to oxygen & transports it Form in bone marrow; live ~120 days Formation depends upon oxygen levels

WBCs = leukocytes Protect body against infection; fight viruses & bacteria Healthy – 5,000 – 10,000 WBCs per mL blood Infection – 10,500+ (ex. appendicitis) Immune system suppressed – below 3,500 (ex. HIV, flu)

Platelets = thrombocytes = cell fragments surrounded by cell membrane Form blood clots (release clotting factors)

Plasma – liquid portion of blood 92 % water, rest = salts, nutrients, enzymes, proteins, dissolved gases, etc Transports nutrients, vitamins, and gases Regulates pH, maintains fluid balance, controls body temp

Path of blood thru Heart Heart – 2 atria (top), 2 ventricles (bottom) Capillaries – smallest vessels Alveoli – tiny air sacs in lungs Arteries - away from heart Veins – to heart

Deox blood to right atrium To right ventricle thru tricuspid valve Pumped into pulmonary artery to lungs Gas exchange - CO 2 from caps into alveoli; O 2 from alveoli into caps Ox. blood to left atrium thru pulmonary vein To left ventricle thru bicuspid valve To aorta to body

Path