The Circulatory System “ A Transport Service”

Circulatory System Consists of… Heart Blood Vessels Blood

HEART: The Vital Pump On average, the heart contracts 72 times a minute, pumping about 5 quarts of blood.

Structure and Function Keeps blood moving Large organ composed of –cardiac muscle, –rich in mitochondria –Enclosed by a PERICARDIUM sac

Structure of Heart (cont) Four chambers : –Two upper (Atria) –Two lower (Ventricles)

Right Ventricle Right Atrium Left Atrium Inferior Vena Cava Vein that brings oxygen-poor blood from the lower part of the body to the right atrium Tricuspid Valve Prevents blood from flowing back into the right atrium after it has entered the right ventricle Pulmonary Valve Prevents blood from flowing back into the right ventricle after it has entered the pulmonary artery Pulmonary Veins Bring oxygen-rich blood from each of the lungs to the left atrium Superior Vena Cava Large vein that brings oxygen-poor blood from the upper part of the body to the right atrium Aorta Brings oxygen-rich blood from the left ventricle to the rest of the body Pulmonary Arteries Bring oxygen-poor blood to the lungs Aortic Valve Prevents blood from flowing back into the left ventricle after it has entered the aorta Mitral Valve Prevents blood from flowing back into the left atrium after it has entered the left ventricle Left Ventricle Septum Structures of the Heart

Blood Flow Through the Heart ©COPY 1997 HeartPoint

Blood Flow Through the Heart Both Atria fill at same time –Right atrium receives oxygen POOR blood from body through vena cava –Left atrium receives oxygen RICH blood from lungs through four pulmonary veins After filled with blood atria contract, pushing blood into ventricles STEP 1 STEP 2

Both ventricles contract Right ventricle contracts and pushes oxygen-poor blood toward lungs, -against gravity -through pulmonary arteries STEP 3 Left ventricle contracts and forces oxygen rich blood out of heart through aorta (largest vessel) This creates the “lub” sound of the heartbeat.

STEP 4 As the ventricles relax, the valves snap shut. Blood start filling the atria, and the cycle begins again. This creates the “dub” sound, finishing the heartbeat.

Heart - as two separate pumps: Circulation of blood between the heart and the lungs- PULMONARY circulation Circulation of blood between the heart and the rest of the body- SYSTEMIC circulation

Circulatory System BLOOD VESSELS

Blood Vessels: Pathway of Circulation 3 types of vessels –Arteries –Capillaries –Veins

Arteries: carry blood Away from heart –Large –Thick-walled, Muscular –Elastic –Oxygenated blood Exception -Pulmonary Artery –Carried under great pressure –Steady pulsating

Capillary Connective tissue Smooth muscle Endothelium Valve Venule Endothelium Arteriole Vein Artery Capillaries - Smallest vessels –Microscopic –Walls one cell thick –Nutrients and gases diffuse here

Veins: Carry blood to heart –Carry blood that contains waste and CO 2 Exception -pulmonary vein –Blood not under much pressure –Valves to prevent much gravity pull

Circulatory System BLOOD

The Blood Body contains 4-6 L Consists of –Water –Red Blood Cells –Plasma –White blood cells and platelets

Whole Blood Sample Red blood cells White blood cells Platelets Plasma Sample Placed in CentrifugeBlood Sample That Has Been Centrifuged

Parts of the Blood

Blood: Fluid Transport Liquid Portion Carries Blood cells –red blood cells –white blood cells Platelets (non cellular particles) Proteins –Enzymes –Hormones – Endocrine System Nutrients - Digestive System Gases - Respiratory System Inorganic salts

Carbon Dioxide in the Blood CO 2 is a waste product of cellular work 70% of CO 2 combines with water The rest travels to the lungs

RBC Transporters of –Oxygen –Carbon Dioxide RBC –Lack a nucleus –Contain hemoglobin –Disk-shaped RBC are produced in red bone marrow of –ribs, –humerus, –femur, –sternum, and other long bones Lives for 120 days Old RBC are destroyed in liver and spleen

WBC WBC fight infection –Attack foreign substances Less abundant Large cells Some live for months –Most just a few days Several types ALL contain nuclei

Platelets PLATELETS are for CLOTTING blood Cell fragments Produced in bone marrow Short life span (1 week) Fibrin (sticky network of protein fibers) –Form a web trapping blood cells

Blood Clotting Break in Capillary Wall Blood vessels injured. Clumping of Platelets Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin.. Clot Forms Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..

Blood Types Massive loss of blood requires a transfusion Four Types –A –B –AB –O Inherited from your parents

Blood Pressure Blood against the blood vessel’s walls –The systolic pressure refers to the pressure recorded while the ventricles pump the blood. –The diastolic pressure refers to the pressure recorded as the ventricles fill with blood. A normal blood pressure is 120/80

Disorders (cont) Hypertension –High blood pressure –Hearts works harder than necessary –Increases risk of heart attack or stroke

Disorders (cont) Heart Attack –Atherosclerosis in coronary artery –Heart muscle begins to die Symptoms –Nausea –Shortness of breath –Severe chest pain IMMEDIATE MEDICAL ATTENTION NECESSARY

Disorders (cont) Stroke –Blood clot gets stuck in blood vessels leading to brain –Brain cells die due to lack of oxygen Or blood vessel burst –Can lead to paralysis, loss of ability to speak death

Current PREVENTION Recommendations Regular exercise Weight control Well balanced diet Do not smoke Diet low in saturated fat