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 O2 ; release CO2 & other wastes- some waste – eliminated by kidneys, etc- carries blood back to heart

• Pulmonary circulation- heart pumps deoxygenated blood, CO2 & wastes to lungs- blood releases CO2, wastes; picks up O2

- oxygenated blood flows back to heart to enter systemic circulation

Blood

• Fn: distribute heat, transport O2 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 - CO2 from caps into alveoli; O2

from alveoli into caps• Ox. blood to left atrium thru pulmonary vein• To left ventricle thru bicuspid valve• To aorta to body

• Path