Heart

CIRCULATORY SYSTEMCIRCULATORY SYSTEM

CHONA ARAGA, MD.CHONA ARAGA, MD.

CARDIOVASCULAR SYSTEMCARDIOVASCULAR SYSTEM

BASIC DIVISIONS OF THE BASIC DIVISIONS OF THE CARDIOVASCULAR CARDIOVASCULAR

1. Heart1. Heart

– – a muscular pump consisting two a muscular pump consisting two receiving receiving chamber (atria)two pumping chamber (atria)two pumping chambers chambers (ventricles) (ventricles)

2. Two closed circuits of blood vessels: 2. Two closed circuits of blood vessels:

a. pulmonary circuita. pulmonary circuit

b. systemic circuitb. systemic circuit

Blood vesselsBlood vessels

1. Arteries1. Arteries

2.Capillaries 2.Capillaries

3. Veins3. Veins

HEART HEART - is a four-chambered, hollow, muscular - is a four-chambered, hollow, muscular organ lying between the lungs in the middle organ lying between the lungs in the middle mediastinum.mediastinum.

- it is about the size of a man’s fist, and in - it is about the size of a man’s fist, and in the normal male weighs approximately 250-the normal male weighs approximately 250-300gm/ 200-275gm. 300gm/ 200-275gm.

- the heart is shaped like an inverted cone, - the heart is shaped like an inverted cone, with its apex pointed downward and to the with its apex pointed downward and to the left base upwards and to the right left base upwards and to the right

- its apex anteriorly and inferiorly to the left - its apex anteriorly and inferiorly to the left at 5at 5thth ICS,MCL ICS,MCL

COVERING OF THE HEARTCOVERING OF THE HEART

PERICARDIUMPERICARDIUM- is an invaginated sac consisting of - is an invaginated sac consisting of 1. Fibrous pericardium1. Fibrous pericardium

- tough covering- tough covering- provide protection and anchors - provide protection and anchors

the the heart into mediastinumheart into mediastinum

Figure 12.3Figure 12.3


2. Serous pericardium2. Serous pericardium

1. Parietal pericardium 1. Parietal pericardium - - outer layer of the serous outer layer of the serous

membrane membrane lines the fibrous coat. lines the fibrous coat.

2. Visceral pericardium 2. Visceral pericardium – – inner layer of the serous inner layer of the serous

membrane membrane


WALLS OF THE HEARTWALLS OF THE HEART

- the wall of the heart consists of three - the wall of the heart consists of three distinct layers: distinct layers: 1. epicardium 1. epicardium

– – external layer, the visceral layer external layer, the visceral layer of of the serous pericardiumthe serous pericardium2. myocardium 2. myocardium

– – middle muscular layermiddle muscular layer3. endocardium 3. endocardium

– – inner layer of the endothelium inner layer of the endothelium

Chambers of the HeartChambers of the Heart

1.1. 2 Atria2 Atria

2.2. 2. Ventricle2. Ventricle


Valves of the HeartValves of the Heart

1. Atrioventricular valves1. Atrioventricular valves

a. Tricuspid valvea. Tricuspid valve

b. Mitral/Bicuspid valveb. Mitral/Bicuspid valve

2. Semilunar valves2. Semilunar valves

a. Aortic valvea. Aortic valve

b. Pulmonic valveb. Pulmonic valve


SeptaSepta

-- are structures separating the are structures separating the chamberschambers

1.1.Interatrial septum- separates the right Interatrial septum- separates the right and left atriumand left atrium

2.2.Interventricular septum- separates the Interventricular septum- separates the right and the left ventriclesright and the left ventricles


CHAMBERS OF THE HEARTCHAMBERS OF THE HEART

A. RIGHT ATRIUM ( A. RIGHT ATRIUM ( right border of the right border of the heart)heart)- receives the venous blood from the - receives the venous blood from the superior vena cava, inferior vena cava, superior vena cava, inferior vena cava, anterior cardiac veins, vena cordis minimae anterior cardiac veins, vena cordis minimae and the coronary sinusand the coronary sinus- larger than left atrium - larger than left atrium - with a right auricle on the external surface- with a right auricle on the external surface

musculi pectinati musculi pectinati crista terminaliscrista terminalis Fossa ovalisFossa ovalis Tricuspid openingTricuspid opening Opening of Superior vena cava and Opening of Superior vena cava and

inferior vena cavainferior vena cava

B. RIGHT VENTRICLEB. RIGHT VENTRICLE

((forming most of the anterior surface of the forming most of the anterior surface of the heart)heart)

- chamber of the heart receiving venous blood - chamber of the heart receiving venous blood from right atrium and ejecting this to the from right atrium and ejecting this to the pulmonary arteries pulmonary arteries - thinner walled than left ventricle - thinner walled than left ventricle - the infundibulum is the upper most part of - the infundibulum is the upper most part of the wall which has no musculur bundles, the wall which has no musculur bundles, leads into pulmonary arteries. leads into pulmonary arteries. - the lower portion and the rest of the wall of - the lower portion and the rest of the wall of the right ventricle are rough– trabeculae the right ventricle are rough– trabeculae carnae, papillary musclescarnae, papillary muscles

trabeculae carnae trabeculae carnae

- irregular muscular ridges probably to - irregular muscular ridges probably to hold more blood. hold more blood.

- when the ventricles contract they - when the ventricles contract they arrange themselves to form a smooth arrange themselves to form a smooth surface and effect a ventricular surface and effect a ventricular evacuation.evacuation.

ppapillary musclesapillary muscles

- conical in shape with the base - conical in shape with the base attached to the ventricular attached to the ventricular

wall and the apices wall and the apices receiving the end of chordae tendinaereceiving the end of chordae tendinae

chordae tendinae chordae tendinae

- thread-like structures connected - thread-like structures connected to to the apices of the papillary the apices of the papillary muscles muscles and to the cusps of and to the cusps of ventricular valves.ventricular valves.

Moderator band (septomarginal Moderator band (septomarginal band) band)

- a muscular band attached to - a muscular band attached to septal septal wall and to the anterior wall and to the anterior margin of margin of right ventricle right ventricle

- prevents overdistention of the - prevents overdistention of the right right ventricle ventricle

- only present in the right - only present in the right ventricle.ventricle.

C. LEFT ATRIUM ( C. LEFT ATRIUM ( base of the base of the heart)heart)

- quadrilateral in shape and its interior - quadrilateral in shape and its interior shows the openings of the four shows the openings of the four pulmonary veins from the lungs. pulmonary veins from the lungs.

- interior of the chamber is smooth - interior of the chamber is smooth except in its auricular portion where except in its auricular portion where the musculi pectinati are found. the musculi pectinati are found.

- blood leaves the left atrium and - blood leaves the left atrium and enters the left ventricle via the left enters the left ventricle via the left atrioventricular orifice or mitral orifice. atrioventricular orifice or mitral orifice.

D. LEFT VENTRICLE (D. LEFT VENTRICLE (where where apex of heart is found)apex of heart is found)

- cavity is longer and narrower than the - cavity is longer and narrower than the right and the walls are 3x thicker than right and the walls are 3x thicker than right ventricleright ventricle

- the lower anterior part forms the apex - the lower anterior part forms the apex of the heart which is at the level of the of the heart which is at the level of the 5th left intercostal space midclavicular 5th left intercostal space midclavicular line - the inner surface of the walls line - the inner surface of the walls also present muscular columns also present muscular columns

BLOOD BLOOD SUPPLY OF SUPPLY OF THE HEARTTHE HEART

- Coronary - Coronary arteries arteries


VENOUS DRAINAGE OF THE VENOUS DRAINAGE OF THE HEARTHEART

- This coronary sinus is the main - This coronary sinus is the main venous drainage of the heart.venous drainage of the heart.

Figure 12.5cFigure 12.5c

NERVE SUPPLY OF THE NERVE SUPPLY OF THE HEARTHEART

- derived from both the - derived from both the parasympathetic (vagus)nerve which parasympathetic (vagus)nerve which is inhibitory to the heart and the is inhibitory to the heart and the sympathetic which is excitatory to the sympathetic which is excitatory to the heart. heart.

IMPULSE CONDUCTING SYSTEM IMPULSE CONDUCTING SYSTEM OF THE HEARTOF THE HEART

1. Sinu-atrial node (Pacemaker of the heart) 1. Sinu-atrial node (Pacemaker of the heart) - located at the posterior wall in the groove - located at the posterior wall in the groove

between the superior vena cava and the right between the superior vena cava and the right atrium atrium 2. Atrio-ventricular node 2. Atrio-ventricular node

- located at the lower part of the interatrial septum - located at the lower part of the interatrial septum

3. Bundle of His 3. Bundle of His - a pale bundle about the size of a match stick - a pale bundle about the size of a match stick

located at the located at the interventricular septum interventricular septum - divides into a right and left bundle branch - divides into a right and left bundle branch

4. Subendocardial network of Purkinje /Purkinje 4. Subendocardial network of Purkinje /Purkinje fibers fibers

- lies beneath the endocardium distributed - lies beneath the endocardium distributed through out the through out the heart. heart.


Heart SoundsHeart Sounds

S1- first heart sound closure of the AV S1- first heart sound closure of the AV valvesvalves

S2- closure of the semilunar valvesS2- closure of the semilunar valves

S3- ventricular gallopS3- ventricular gallop

S4- atrial gallop S4- atrial gallop


P wave – represents atrial depolarization which spreads from the SA node through the contractible fibers in both atria - small upward deflection

QRS complex – represents rapid ventricular depolarization- as action potential spreads through ventricular contractile fibersT wave – represents ventricular repolarization occurs just as the ventricles are starting to relax

- dome-shaped upward deflection

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Heart