THE HEARTPresented by: Fe M. Compas, RN, MAN

HEARTA 4 chambered, hollow, muscular organLies between the lungs and within the middle mediastinumAbout the size of the fist

HEARTShaped like an inverted cone

- base - upward, backward and to the right

- apex- downward, forward and to the left- pulsation felt 2-3 fingerbreadths below the nipple

COVERING OF THE HEARTPERICARDIUM

fibro-serous covering

Parietal Pericardium

Visceral Pericardium

- EPICARDIUM- outermost wall of the heart

COVERING OF THE HEART

WALLS OF THE HEARTEPICARDIUM or VISCERAL PERICARDIUM

- outermost layer

MYOCARDIUM

- middle muscular layer- contracts rhythmically and spontaneously through the conduction system of the heart

ENDOCARDIUM

- innermost layer

MAJOR BLOOD VESSELS ATTACHED TO THE HEARTSUPERIOR VENA CAVA

- drains blood from the upper part of the body to the right side of the heartINFERIOR VENA CAVA

- drains blood from the lower part of the body to the right side of the heartPULMONARY TRUNK

- brings unoxygenated blood from the right side of the heart to the lungs for oxygenationPULMONARY VEINS

- brings oxygenated blood from the lungs to the left side of the heartAORTA

- brings oxygenated blood from the left side of the heart to the whole body

CHAMBERS OF THE HEART :ATRIARIGHT ATRIUM (RA)

- larger that the left- thinner wall- portal of entry to 3 veins- superior vena cava- inferior vena cava- coronary sinusLEFT ATRIUM (LA)

- thicker wall- portal of entry to 4 pulmonary veinsINTERATRIAL SEPTUM

- septum (wall) that separates the right and left atrium

FOSSA OVALIS

- located in the septum- represents the foramen ovale - opening between the 2 atria during fetal life

MM EspinoCHAMBERS OF THE HEART :VENTRICLESRIGHT VENTRICLE (RV)

- wall thinner than left ventricle - receives blood from the right atrium- pumps blood to the lungs through the pulmonary trunk

LEFT VENTRICLE (LV)

- very thick walled- receives blood from the left atrium- pumps blood to the whole body through the aorta

INTERVENTRICULAR SEPTUM

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VALVES OF THE HEARTPURPOSE :

- prevent backflow or reflux of blood between chambers

ATRIOVENTRICULAR (AV) VALVESSEMILUNAR VALVES (SL) VALVES

VALVES OF THE HEARTAtrioventricular (AV) ValvesTRICUSPID VALVE

- guards opening or orifice between RV and RABICUSPID or MITRAL VALVE

- guards orifice between LV and LASemilunar (SL) ValvesPULMONARY or PULMONIC VALVE

- guards opening between RV and Pulmonary Trunk

AORTIC VALVE

- guards opening between LV and Aorta

FUNCTION OF THE HEARTPump blood

Right ventricle

- pumps blood to the pulmonary circulatory systemLeft ventricle

- pumps blood to the whole body

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CONDUCTION SYSTEM OF THE HEARTSINO-ATRIAL (SA) NODEATRIO-VENTRICULAR (AV) NODEBUNDLE OF HIS or AV BUNDLEPURKINJE FIBERS

CONDUCTION SYSTEM OF THE HEARTSINO-ATRIAL (SA) NODEPosterior wall of the RA at the junction of the SVC and the RACardiac PACEMAKER

- initiates the heartbeat

ATRIO-VENTRICULAR (AV) NODERight side of the inter-atrial septum

BUNDLE OF HIS or AV BUNDLEGoes down the right side of the interventricular septumDivides into right and left branches

PURKINJE FIBERSConducting fibers of the right and left Bundle branchesExtend over the undersurface of the endocardium

CONDUCTION SYSTEM OF THE HEARTElectrical activity accompanies the spread of excitation over the heart

ELECTROCARDIOGRAM (ECG or EKG)

- instrument used to record the electrical activity of the heart using electrodes placed on the anterior chest wall

MM EspinoECGP wave

- atrial depolarization

QRS complex

- ventricular depolarization

P-R interval

- atrioventricular interval

T wave

- ventricular repolarization

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CARDIAC CYCLEAtrial depolarization

- initiates atrial contraction which forces blood into the ventricles

Atrial relaxation

- AV valves begin to close

Ventricular depolarization

- initiates ventricular contraction- closure of the AV valves - first heart sound (S1 or lubb)Increase in ventricular pressureSL valves opens

Ejection period

Ventricular relaxation

- pressure within ventricle falls- closure of the SL valves- second heart sound (S2 or dubb)

Atrial depolarization

HEART RATEObtained by placing the stethoscope between the 5th and 6th ICS MCL

- area just below the left nipple

1 heart beat=lubb and dubb

60 100 bpm

Factors Affecting Heart RateSize of the body

- the smaller the body, the higher the rate- mouse=1,000/min- elephant =30/min- man=60 80/minAge

- fetal life=120 160- newborn=120 140- young children =100 120- adults=60 - 80Body position

- 5 10 beats/min more when standing erect

Factors Affecting Heart RateIncreased heart rate with

- acute bleeding- muscular activity- emotional excitement- eating and right after a meal- warm baths or hot drinks- during ovulation

MM EspinoREGULATION OF HEART RATENervous regulation

- parasympathetic vs sympathetic stimulation- aortic reflex - stimulated when BP is high- carotid sinus reflex- stimulated when BP is highChemical regulation

- aortic and carotid sinus reflex- O2 or CO2 increases heart rate, vis-a-visMechanical regulation

- Starlings Law of the Heart- flow of blood into heart distends myocardium HR

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MM EspinoBLOOD PRESSURESYSTOLIC PRESSURE

- the pressure that develops in the large arteries during each left ventricular contractions- 120 mmHg

DIASTOLIC PRESSURE

- the pressure in the arterial system between heart beats- 80 mmHg

Normal Blood Pressure = 120/80 mmHg

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BLOOD PRESSUREBLOOD PRESSURE Equivalent to cardiac output and total peripheral resistance

CARDIAC OUTPUTVolume of blood pumped out of the ventricles in 1 minute

Stroke Volume XHeart Rate60 70 mlX60 80

BLOOD PRESSUREFactors contributing to Cardiac Output

Venous returnForce of cardiac contractionHeart rate

BLOOD SUPPLY OF THE HEARTThe heart also needs blood supply for its nourishment

RIGHT CORONARY ARTERY

- RA (SA node)- RV- inferior surface of the interventricular septum- inferior surfaces of the LVLEFT CORONARY ARTERY

- Left anterior descending artery & Left circumflex artery - superior 2/3 of the interventricular septum- superior and lateral surfaces of the LV