CARDIOVASCULAR SYSTEM

INTRODUCTION: AKA: the circulatory system Consists of the heart and a closed system of vessels called arteries, veins, and capillaries

Two Pathways Pulmonary Circulation Systemic Circulation Carries blood to lungs and back Systemic Circulation Carries blood to body and back

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

Capillaries Smallest vessel Microscopic Walls one cell thick Nutrients and gases diffuse here

Veins: Carries blood to heart Carries blood that contains waste and CO2 Exception pulmonary vein Blood not under much pressure Valves to prevent much gravity pull

Varicose Veins Damaged Valves in Veins

Artery vs. Vein

SIZE,SHAPE & LOCATION OF HEART 4 chambered muscular organ Shaped/sized roughly like a person’s closed fist Lies in the mediastinum 2/3 of heart located on left side of the midline and 1/3 on the right.

Structure of the Heart Covering PERICARDIUM is a loose-fitting sac and consist of two parts: Fibrous portion tough, loose, and inelastic sac around the heart Serous portion consist of two layers

Serous portion -layers PARIETAL LAYER: lining inside of the fibrous pericardium VISCERAL LAYER: is also known as the EPICARDIUM -It attaches to the large blood vessels at the top of the heart PERICARDIAL SPACE is a space between the visceral layer (epicardium) and the parietal layer Lubricating fluid secreted by the serous membrane known as PERICARDIAL FLUID

Wall of the Heart Three layers of tissue make up the heart wall: Epicardium Myocardium Endocardium

Epicardium Outer layer Meaning “on the heart” Is actually the visceral layer of the pericardium

Myocardium Makes up the bulk of the heart wall Is the thick, contractile middle layer of cardiac muscle cells Cardiac muscles do not fatigue

Endocardium The lining of the interior of the myocardial wall Composed of a layer of endothelial tissue, which line the heart and blood vessels

Chambers of the Heart Interior is divided into 4 chambers (cavities) ATRIA (ATRIUM) Two upper chambers VENTRICLES Two lower chambers SEPTUM the left chambers is separated form the right chambers by this heart wall

Atria Often called the “receiving chambers” They receive blood from vessels termed veins Myocardium is not as thick here

Ventricles The lower chambers Receive blood from the atria and pump blood out of the heart into arteries “primary pumping chambers” Myocardium is thicker here

Valves of the heart Are mechanical devices that permit the flow of blood in one direction only Two Atrioventricular valves (AV) Guard the opening between the atria and the ventricles Two Semilunar valves (SL) Located where the pulmonary artery (right ventricle) and the aorta (left ventricle) arise

Atrioventricular Valves Tricuspid valve: consists of three flaps (cusps). The free edge of each flap is anchored to the papillary muscles by several cordlike structures termed chordae tendineae Bicuspid (or mitral valve): the left atrioventricular valve guards the left opening Only has two flaps. Both allow blood to flow from atria into ventricles but prevents it from flowing back.

Semilunar Valves Consist of half-moon shaped flaps Pulmonary semilunar valve Aortic semilunar valve

Blood Flow Through the Heart

Blood Pressure 2 types of pressure Systolic- measures the pressure in the arteries when the heart beats (when the heart muscle contracts). The top number, which is also the higher of the two numbers.   Diastolic- measures the pressure in the arteries between heartbeats (when the heart muscle is resting between beats and refilling with blood). The bottom number, which is also the lower number. A normal blood pressure is 120/80

Heart Rate Or pulse, is the number of times your heart beats per minute. Normal heart rate varies from person to person. To get the most accurate reading, put your finger over your pulse and count the number of beats in 60 seconds. The normal resting adult human heart rate ranges from 60–100 bpm.

Cardiac Output Cardiac output is the volume of blood pumped by one ventricle in a given period of time. It is calculated by multiplying the stroke volume by the heart rate (HR). CO= HR X SV Stroke volume (SV) - the amount of blood pumped by one ventricle during a contraction Calculated by subtracting the amount of blood after a contraction from the amount of blood in the ventricle before the contraction. EDV − ESV = SV. (End Diastolic Volume) - (End Systolic Volume)

Echocardiogram a graphic outline of the heart's movement. During an echo test, ultrasound (high-frequency sound waves) from a hand-held wand placed on your chest provides pictures of the heart's valves and chambers and helps evaluate the overall function of the heart.

Heartbeat Regulation The heart beats due to a small electrical current by the cardiac conduction system. It has 5 major components: 1. The sinoatrial node (SA node): Known as the heart's "pacemaker", causes the heart to beat.

Heartbeat Regulation 2. The atrioventricular node (AV node): the electrical "relay station" between the upper and lower heart chambers. 3. The bundle of His: muscle fibers that conduct the electrical impulses that regulate heartbeat. 4. Bundle branches: Connected to the bundle of His, these lead to the lower ventricles. 5. Purkinje fibers: conduct impulses through the heart.

Cardiac Conduction System

How it works! Special cells, produce electricity in the body by rapidly changing their electrical charge. When the heart is relaxed the cells have a negative charge. Outside of the cells are positive. Cells depolarize as some of their negative atoms move through the cell membrane, and it's this depolarization that causes electricity in the heart.

How it works -continued Once one cell depolarizes it sparks a chain reaction and electricity flows from cell to cell. When cells return to normal it's called repolarization, and the process is repeated with every heartbeat.