CARDIOVASCULAR CARDIOVASCULAR SYSTEMSYSTEM

INTRODUCTION:INTRODUCTION: AKA: the circulatory systemAKA: the circulatory system• Consists of the heart and a closed Consists of the heart and a closed

system of vessels called system of vessels called arteries, arteries, veins, veins, and and capillariescapillaries

Two PathwaysTwo Pathways

•Pulmonary 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 VeinsDamaged Valves in Veins

Artery vs. Vein

SIZE,SHAPE & LOCATION SIZE,SHAPE & LOCATION OF HEARTOF HEART

• 4 chambered muscular organ4 chambered muscular organ• Shaped/sized roughly like a person’s closed Shaped/sized roughly like a person’s closed

fistfist• Lies in the mediastinum Lies in the mediastinum • 2/3 of heart located on left side of the 2/3 of heart located on left side of the

midline and 1/3 on the right.midline and 1/3 on the right.

Structure of the Heart Structure of the Heart CoveringCovering

• PERICARDIUMPERICARDIUM is a is a loose-fitting sac loose-fitting sac and consist of two and consist of two parts:parts:• Fibrous portionFibrous portion

tough, loose, and tough, loose, and inelastic sac around inelastic sac around the heartthe heart

• Serous portion Serous portion consist of two consist of two layerslayers

Serous portion -layersSerous portion -layers

• PARIETAL LAYER:PARIETAL LAYER: lining inside of the lining inside of the fibrous pericardiumfibrous pericardium

• VISCERAL LAYER: VISCERAL LAYER: is also known as the is also known as the EPICARDIUMEPICARDIUM - -It attaches to the large It attaches to the large blood vessels at the top of the heart blood vessels at the top of the heart

• PERICARDIAL SPACEPERICARDIAL SPACE is a space between is a space between the visceral layer (epicardium) and the the visceral layer (epicardium) and the parietal layerparietal layer

• Lubricating fluid secreted by the serous Lubricating fluid secreted by the serous membrane known as membrane known as PERICARDIAL FLUIDPERICARDIAL FLUID

Wall of the HeartWall of the Heart• Three layers of tissue make up the heart Three layers of tissue make up the heart

wall:wall:• EpicardiumEpicardium• MyocardiumMyocardium• EndocardiumEndocardium

EpicardiumEpicardium• Outer layerOuter layer• Meaning “on the Meaning “on the

heart”heart”• Is actually the Is actually the

visceral layer of visceral layer of the pericardiumthe pericardium

MyocardiumMyocardium• Makes up the bulk Makes up the bulk

of the heart wallof the heart wall• Is the thick, Is the thick,

contractile middle contractile middle layer of cardiac layer of cardiac muscle cellsmuscle cells

• Cardiac muscles Cardiac muscles do not fatiguedo not fatigue

EndocardiumEndocardium

• The lining of the The lining of the interior of the interior of the myocardial wallmyocardial wall

• Composed of a Composed of a layer of endothelial layer of endothelial tissue, which line tissue, which line the heart and blood the heart and blood vesselsvessels

Chambers of the HeartChambers of the Heart• Interior is divided into 4 Interior is divided into 4

chambers (cavities)chambers (cavities)• ATRIA (ATRIUM) ATRIA (ATRIUM) Two upper Two upper

chamberschambers• VENTRICLESVENTRICLES Two lower Two lower

chamberschambers• SEPTUMSEPTUM the left chambers the left chambers

is separated form the right is separated form the right chambers by this heart wallchambers by this heart wall

AtriaAtria• Often called the “receiving chambers”Often called the “receiving chambers”• They receive blood from vessels They receive blood from vessels

termedtermed veins veins• Myocardium is not as thick hereMyocardium is not as thick here

VentriclesVentricles• The lower chambersThe lower chambers• Receive blood from the atria and Receive blood from the atria and

pump blood out of the heart into pump blood out of the heart into arteriesarteries

• ““primary pumping chambers” primary pumping chambers” • Myocardium is thicker so more force is Myocardium is thicker so more force is

needed needed

Valves of the heartValves of the heart• Are mechanical devices that Are mechanical devices that

permit the flow of blood in one permit the flow of blood in one direction onlydirection only

• Two Atrioventricular valves (AV)Two Atrioventricular valves (AV)• Guard the opening between the Guard the opening between the

atria and the ventriclesatria and the ventricles

• Two Semilunar valves (SL)Two Semilunar valves (SL)• Located where the pulmonary Located where the pulmonary

artery (right ventricle) and the artery (right ventricle) and the aorta (left ventricle) arise aorta (left ventricle) arise

Atrioventricular ValvesAtrioventricular Valves• Tricuspid valve: Tricuspid valve: consists of three flaps consists of three flaps

(cusps).(cusps).• The free edge of each flap is anchored to The free edge of each flap is anchored to

the the papillary musclespapillary muscles by several cordlike by several cordlike structures termed structures termed chordae tendineaechordae tendineae

• Bicuspid (or mitral valve):Bicuspid (or mitral valve): the left the left atrioventricular valve guards the left atrioventricular valve guards the left opening opening • Only has two flaps.Only has two flaps.

• Both allow blood to flow from atria into Both allow blood to flow from atria into ventricles but prevents it from flowing ventricles but prevents it from flowing back.back.

Semilunar ValvesSemilunar Valves• Consist of half-moon Consist of half-moon

shaped flaps shaped flaps • Pulmonary semilunar Pulmonary semilunar

valvevalve • Aortic semilunar Aortic semilunar

valvevalve

Blood Flow Through the Flow Through the HeartHeart

Heartbeat RegulationHeartbeat Regulation

• The heart beats due to The heart beats due to a small electrical a small electrical current by the cardiac current by the cardiac conduction system. It conduction system. It has 5 major has 5 major components:components:

1. The sinoatrial node 1. The sinoatrial node (SA node):(SA node): Known as Known as the heart's the heart's "pacemaker", causes "pacemaker", causes the heart to beat.the heart to beat.

Heartbeat RegulationHeartbeat Regulation2. The atrioventricular node 2. The atrioventricular node (AV node):(AV node): the electrical "relay the electrical "relay station" between the upper and station" between the upper and lower heart chambers.lower heart chambers.

3. The bundle of His:3. The bundle of His: muscle muscle fibers that conduct the electrical fibers that conduct the electrical impulses that regulate heartbeat.impulses that regulate heartbeat.

4. Bundle branches:4. Bundle branches: Connected to the bundle of His, Connected to the bundle of His, these lead to the lower these lead to the lower ventricles.ventricles.

5. Purkinje fibers:5. Purkinje fibers: conduct conduct impulses through the heart.impulses through the heart.

Cardiac Conduction Cardiac Conduction SystemSystem

How it works!How it works!

• Special cells, produce electricity in Special cells, produce electricity in the body by rapidly changing their the body by rapidly changing their electrical charge.electrical charge.

• When the heart is relaxed the cells When the heart is relaxed the cells have a negative charge. Outside of have a negative charge. Outside of the cells are positive. the cells are positive.

• Cells depolarize as some of their Cells depolarize as some of their negative atoms move through the negative atoms move through the cell membrane, and it's this cell membrane, and it's this depolarization that causes electricity depolarization that causes electricity in the heart. in the heart.

How it works -How it works -continuedcontinued

• Once one cell Once one cell depolarizes it sparks a depolarizes it sparks a chain reaction and chain reaction and electricity flows from electricity flows from cell to cell.cell to cell.

• When cells return to When cells return to normal it's called normal it's called repolarization, and repolarization, and the process is the process is repeated with every repeated with every heartbeat.heartbeat.

Blood Pressure

• A normal blood pressure is 120/80

SystolicThe 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). 

DiastolicThe 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).