Circulatory System

Figure 24.01

Transports materials throughout body: Nutrients Metabolic wastes Gases (O 2 & CO 2 ) Hormones [regulate body processes] Antibodies Circulatory System Function

Components of Circulatory System: Blood –transport medium; –consists of cells suspended in liquid (plasma) Heart –Pumps the blood through the vessels Blood vessels –tubes that carry blood –including arteries, veins, capillaries

Components of Blood Plasma: (yellowish), contains water, minerals, salts, proteins, vitamins, hormones, dissolved gases and fats Red blood cells: carry oxygen White blood cells: destroy pathogens (disease-causing organisms) bacteria, viruses Platelets: blood clotting factor

Accounts for ~ 7% body weight Totals ~ 5 liters (a little over a gallon) in volume Blood

Heart Four Chambers Right Atrium Right Ventricle Left Atrium Left Ventricle Pumps Blood Through Vessels Septum – divides ventricles

Blood Flow Through Heart 1.Blood arrives in the atria of the heart 2. Blood flows from atria to ventricles 3. Blood leaves the heart from the ventricles

Blood Flow Through Heart Valves in the heart make sure the blood only flows in one direction Tricuspid Aortic Semilunar Pulmonary Semilunar Bicuspid or Mitral

Circulatory System Pathways: Three Branches: –Pulmonary circulation (feeding the lungs) –Coronary circulation (feeding the heart) –Systemic circulation (feeding the remaining tissue)

Arteries, Capillaries, Veins Blood Vessels

Carry blood away from heart Thick-walled Elastic Blood under high pressure receives blood from heart Arteries

Carry blood towards heart Thinner-walled Lower pressure [further from heart] Valves keep blood moving upwards towards heart [against gravity] Veins

Exchange materials with surrounding tissue cells by diffusion Capillaries Only one cell thick materials diffuse or transported through the lining

At the Capillaries All exchanges of materials occur through the capillaries

Varicose Veins Veins with defective valves (allow the blood to flow backward) become enlarged or dilated to form varicose veins

Blood flows from arteries to arterioles to capillaries to venules to veins

Important arteries and veins of the circulatory system Systemic Circulation Aorta: largest artery brings blood from the heart (left ventricle) to the rest of the body Inferior vena cava: vein brings blood from the legs and abdominal cavity to the heart (right atrium) Superior vena cava: vein that brings blood from the head and the arms to the heart (right atrium) Inferior Vena Cava Aorta Superior Vena Cava

Important arteries and veins of the circulatory system Pulmonary Circulation Pulmonary arteries: bring blood from the heart (right ventricle) to the lungs Only artery with low oxygen Pulmonary veins: bring blood from the lungs to the heart (left atrium) Only vein with high oxygen Pulmonary Artery Pulmonary Vein

Major Arteries and Veins Aorta Pulmonary Arteries Pulmonary Trunk Pulmonary Veins Inferior Vena Cava Superior Vena Cava

Stages in the cardiac cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. superior vena cava right atrium inferior vena cava c. aorta pulmonary arteries atrioventricular valves b. semilunar valves a. pulmonary vein left atrium left ventricle right ventricle aorta Atria contract Ventricles Contract Atria and Ventricles relax

Control of Heartbeat The Pacemaker Electrical impulse starts at the sino- atrial node and spreads across the atria, causing them to contract Impulse transferred to atrio- ventricular node, spreads across ventricles, causing them to contract

Brain/nervous system - Monitor blood circulation - maintain constant blood pressure -Send signals to heart, blood vessels, endocrine glands Bone Marrow - Site of new blood cell manufacture Spleen - Breaks down old red blood cells - Stores red blood cells - Recycles Valuable constituents, such as iron Kidneys - Metabolic waste products removed from blood - Balance of minerals and fluids Supporting Organs Spleen