Transcript File
Circulatory System Circulatory System Consists of: Heart Blood vessels Blood 5 Functions of the Circulatory System 1. Carries nutrients from the digestive system to cells. 2. Carries O2 from lungs to cells. 3. Carries waste products to the urinary system. 4. Carries CO2 from cells to lungs 5. Carries immune cells that help fight disease. The Heart • Located near the center of the chest • Composed almost entirely of muscle • About the size of a clenched fist • Contracts about 72 times per minute and pumps 70ml of blood with each contraction Pericardium The heart is enclosed in a protective sac called the pericardium Myocardium Thick layer of muscle Contractions of the myocardium pump blood through the circulatory system Septum Divides the right and left sides of the heart On each side of the septum are two chambers Prevents mixing of oxygen-rich and oxygenpoor blood Atrium Upper chambers of the heart Right atrium receives oxygen- poor blood from body Left atrium receives oxygen-rich blood from the lungs Ventricle Lower chambers of the heart Pumps blood out of the heart Oxygen-rich blood leaves the left ventricle Total of 4 chambers Circulation Through the Body The heart functions as two separate pumps Pulmonary Circulation Oxygen-poor blood from the right side of the heart goes to the lungs. In the lungs... Carbon dioxide leaves the blood and goes into the alveoli of lungs. Oxygen is absorbed into the blood on red blood cells (hemoglobin) Systemic Circulation Oxygen-rich blood from the left side of the heart goes to the rest of the body. After cycling through the body Oxygen-poor blood returns to the right side of the heart and the cycle starts over. STOP HERE! Superior Vena Cava 4 1 Pulmonary Artery 8 4 4 Pulmonary Veins 5 Pulmonary 5 Veins 6 Pulmonary Valve Tricuspid Valve Inferior Vena Cava Mitral Valve 2 3 7 Aortic Valve Veins bring O2 poor blood from upper part of body O2-poor blood to right lung 4 Brings O2-rich blood from left ventricle to entire body 1 8 4 4 5 O2-rich blood O2-rich blood 5 from right lung from left lung 6 O2-poor blood enters the right atrium then right ventricle Veins bring O2poor blood from lower part of body O2-poor blood to left lung Lt. Ventricle pushes O2-rich blood to aorta and body 2 3 7 Rt. Ventricle pushes O2poor blood to right & left lung STOP HERE! Valves Flaps of connective tissue between atria and ventricles. Allows for one direction of blood flow. Heartbeat - SA Node Sinoatrial node (SA) = Pacemaker Small group of cardiac muscle cells Starts the wave of heart muscle contraction “Sets the pace” Heartbeat - AV Node Atrioventricular node (AV) Bundle of fibers Picks up impulses from the SA node and transmits to network of fibers in the ventricles Heartbeat Heartbeat depends on body’s need for oxygen-rich blood Increase heart beat: Sympathetic nervous system Decrease heart beat: Parasympathetic nervous system Blood Pressure • Contraction of the heart produces a pressure within the circulatory system • The force of blood on the wall of the arteries is known as blood pressure Measuring Blood Pressure • The BP cuff is wrapped around the upper portion of the arm and pumped with air until blood flow in the artery is blocked. • As the pressure is released, 2 numbers are recorded: Systolic pressure Diastolic pressure Blood Vessels 3 types of Blood Vessels Arteries Capillaries Veins Arteries • Large vessels • Carry blood from heart to tissues of body • Thick walls - need to handle the high pressure Capillaries • Smallest blood vessels • Walls only one cell thick • Bring nutrients and O2 to tissues and absorbs CO2 and waste from tissues Veins • Carry blood from tissues back to heart • Blood in veins do not have oxygen • Walls of veins contain connective tissue and smooth muscle Walls of Blood Vessels Connective Tissue - elastic, allows for expansion Smooth Muscle - regulates diameter Endothelium - layer of cells nearest blood Valves of the Veins Valves in large veins, prevents backflow of blood Located near or between skeletal muscles Skeletal muscle contraction forces blood through veins Prevents blood from accumulating in limbs Lack of exercise - Veins •Veins get out of shape •Valves weaken •Blood pools in veins = varicose veins STOP HERE! Disorders of the Circulatory System - Atherosclerosis • Fatty deposits in walls of arteries • Obstruct blood flow and raise blood pressure • Increase risk of blood clots Disorders of the Circulatory System - Heart Attack • Caused by blocked arteries • Blood cannot get to the heart muscle • Heart muscle begins to die due to lack of O2 Disorders of the Circulatory System - Stroke • Blood clot breaks free and blocks a vessel leading to the brain • Brain cells starved of O2 and nutrients • May cause paralysis, loss of ability to speak or death Disorders of the Circulatory System - High Blood Pressure • Blood pressure is the measure of force exerted by the blood on the wall of the arteries • Too much pressure can cause health problems such as heart disease STOP HERE!