Circulatory System Circulatory System Consists of Heart Blood

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 O 2 from lungs to cells. 3. Carries waste products to the urinary system. 4. Carries CO 2 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 70 ml 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 oxygen-poor 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.

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Superior Vena Cava 4 1 Pulmonary Artery 8 4 4 Pulmonary Veins 5 Pulmonary Valve Tricuspid Valve Inferior Vena Cava Pulmonary 5 Veins 6 2 Mitral Valve 3 7 Aortic Valve

Veins bring O 2 poor blood from upper part of body O 2 -poor blood to right lung 4 Brings O 2 -rich blood from left ventricle to entire body 1 8 4 4 5 O 2 -rich blood 5 from right lung O 2 -poor blood enters the right atrium then right ventricle Veins bring O 2 poor blood from lower part of body O 2 -poor blood to left lung from left lung 6 2 Lt. Ventricle pushes O 2 -rich blood to aorta and body 3 7 Rt. Ventricle pushes O 2 poor blood to right & left lung

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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 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 O 2 to tissues and absorbs CO 2 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

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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 O 2

Disorders of the Circulatory System - Stroke • Blood clot breaks free and blocks a vessel leading to the brain • Brain cells starved of O 2 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

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