CARDIOVASCULAR SYSTEM CARDIOVASCULAR SYSTEM

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

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

Arteries: carries blood A way 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 CO 2 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 organ4 chambered muscular organ Shaped/sized roughly like a person’s closed fistShaped/sized roughly like a person’s closed fist Lies in the mediastinumLies in the mediastinum 2/3 of heart located on left side of the midline and 1/3 on the right.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:PERICARDIUM is a loose-fitting sac and consist of two parts: Fibrous portion tough, loose, and inelastic sac around the heartFibrous portion tough, loose, and inelastic sac around the heart Serous portion consist of two layersSerous portion consist of two layers

Serous portion -layers PARIETAL LAYER: lining inside of the fibrous pericardiumPARIETAL 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 heartVISCERAL 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 layerPERICARDIAL SPACE is a space between the visceral layer (epicardium) and the parietal layer Lubricating fluid secreted by the serous membrane known as PERICARDIAL FLUIDLubricating fluid secreted by the serous membrane known as PERICARDIAL FLUID

Wall of the Heart Three layers of tissue make up the heart wall:Three layers of tissue make up the heart wall: EpicardiumEpicardium MyocardiumMyocardium EndocardiumEndocardium

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

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

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

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

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

Ventricles The lower chambersThe lower chambers Receive blood from the atria and pump blood out of the heart into arteriesReceive blood from the atria and pump blood out of the heart into arteries “primary pumping chambers”“primary pumping chambers” Myocardium is thicker so more force is neededMyocardium is thicker so more force is needed

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

Atrioventricular Valves Tricuspid valve: consists of three flaps (cusps).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 tendineaeThe 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 openingBicuspid (or mitral valve): the left atrioventricular valve guards the left opening Only has two flaps.Only has two flaps. Both allow blood to flow from atria into ventricles but prevents it from flowing back.Both allow blood to flow from atria into ventricles but prevents it from flowing back.

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

BloodBlood Flow Through the Heart Blood

Heartbeat Regulation The heart beats due to a small electrical current by the cardiac conduction system. It has 5 major components: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.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.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.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.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. When cells return to normal it's called repolarization, and the process is repeated with every heartbeat.

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