Cardiology 1

8/8/2019 Cardiology 1

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CARDIOLOGY


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The organization of the

Cardiovascular SystemBlood vessels are subdivided into a

pulmonary circuit (gas exchange) and

systemic circuit (rest of the body)

Arteries (efferent) carry blood away from the

heart and veins (afferent) return blood to the

heart, capillaries (exchange)interconnect thesmallest arteries and veins


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Anatomy of the heartFour muscular chambers: right and left

atrium and right and left ventricle

R. A L. A

R. V L. V

Pulmonary Circuit Systemic Circuit

Pulmonary CircuitSystemic Circuit


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The HeartIt is located near the anterior chest wall,posterior tothe sternum.

Base and apex.Measures: 12.5cm (fifth intercostal cartilage) and7.5 cm(to the left of the midline)

The heart is surrounded by pericardial sac

Mediastinum; between the two pleural cavities.Contains great vessels, thymus, esophagus andtrachea


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The PericardiumThe pericardial cavity is lined by the

pericardium

Can be subdivided into the visceral ( outer

surface of the heart) and parietal pericardium

( lines the inner surface of pericardial sac)

Between parietal and visceral surfaces is thepericardial cavity (15-50ml of pericardial

fluid)


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SuperficialAnatomy of the heartTwo atria have thin muscular walls and are

highly expandable portion called auricle

Coronary sulcus, a deep grove marks the

border between atria and ventricles

The anterior and posterior interventricular

sulcus mark the boundary between the leftand right ventricles


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The Heart WallEpicardium: (outer) Serus membrane, is the visceral

pericardium. It consists of an exposed

mesothelium and an underlying layer of looseareolar connective tissue

Myocardium: (middle) muscular wall, forms both

atria and ventricles, contains cardiac muscle tissue,

blood vessels, and nerves

Endocardium: (inner) simple squamous epithelium,

heart valves


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Cardiac MuscleCardiocytes contain organized myofibrils,many sarcomeras gives the cells a striated

appearance. Cells are small, has a singlecentral nucleus, the T tubules are short andterminal cisternae and its tubules contact thecell membrane as well as the T tubules

broad, there are not triads, the SR lacks, thecells are almost totally dependent on aerobicmetabolism and the reserves in form ofglycogen and lipid inclusions


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Cardiac muscleIntercalated discs: are found where cell membranes

connect, this connections helps stabilize the

relative position of adjacent cells and maintain thethree-dimensional structure,it creates a direct

electrical connections between the cells,an action

potential can travel across an intercalated disc

quicklyThey are mechanically,chemically and electrically

connected to one another


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FunctionalCharacteristics of

Cardiac tissueCardiac cells contract without neural

stimulation.Pacemaker cells (automaticity)

Cardiac muscle twitches do not exhibit wave

summation, cardiac muscle tissue cannot

produce tetanic contractions


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InternalAnatomy and organizationThe atria are separated by the interatrial

septum

The ventricles are separated by

interventricular septum. Each septum is a

muscular partition.

Atrioventriular valves, folds of fibrous tissueextend into the opening between the atria

and ventricles, and permit the flow in one

direction


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Right ventricleAV valve or tricuspid. The free edge of each

cup is attached to chordae tendinae

Papillary muscle are conical muscular

projections that arise from the inner surface

of the right ventricle. The internal surface

contain the trabecula carneaePulmonary valve


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Left atriumReceive blood from two left and two right

pulmonary veins. It has an auricle

AV valve or bicuspid call mitral, permit flow

of blood from the left atrium to the left

ventricle


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Left ventricleIt has thicker walls

Blood leaves the left ventricle by passing

through the aortic valve into ascending aorta

Differences between ventricles reflect the

functional demands placed on them. The wall

of the right is relative thin whereas the leftventricle has a massive muscular wall


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ValvesAtrioventricular valves

Semilunar valves: aortic and pulmonary


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Cardiac cycleIt is the period between the start of oneheartbeat and the beginning of the

next,includes periods of contraction andrelaxation

Systole or contraction the chambers contractand pushes blood into an adjacent chamberor into an arterial trunk. Chambers fills withblood and prepares for the next cycle

Diastole or relaxation is followed by diastole


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Pressure changesIn the curse of the cardiac cycle , the

pressure within each chamber rises during

systole and fall during diastole

Blood will flow one chamber to another only

if the pressure in the first chamber exceeds

that in the second


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Phases of cardiac cycle


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The Conducting System

The sinoatrial node: in the wall of the right atriumThe atrioventricular node: located at the junctionbetween the atria and ventricles

Conducting cells: interconnect the two nodes and

distribute the contractile stimulus throughout themyocardium

Pacemaker cells in the SA node normally establishthe rate of contraction. From the SA node, the

stimulus travel to the AV node, and ten to the AVbundle, which divides into bundle branches. Fromthere, purkinje fibers convey the impulses to theventricular myocardium


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Heart sounds

There are four heart sound:1. Know as a lubb S1 marks the start of

ventricular contraction is produced as the AVvalves close

2. dupp S2occurs at the beginning ofventricular filling, when the semilunar valvesclose

Third and fourth heart sounds are usuallyvery faint and seldom are audible in healthyadults, are associated with blood flowing intothe ventricles S3 and atrial contraction S4

rather than with valve action


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Coronary vessels

The coronary circulation meets the high O2and nutrient demands of cardiac muscle cells.

The coronary arteries originate at the base of

the ascending aorta.Interconnectionsbetween arteries, called arterial anastomoses,

ensure a constant blood supply.

Veins: great, posterior, small anterior and

middle cardiac veins carry blood from the

coronary capillaries to the coronary sinus


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Cardiology 1

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