cardiac anatomy chart

7/30/2019 cardiac anatomy chart

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Cardiovascular System

and the beat goes on


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Heart: Location & Size

The size of a persons fist

Weighs less than one pound

Located in the thorax

The apex points toward the left hip and rests on

the diaphragm at the level of the 5th

rib

The base points toward the right shoulder at

the level of the 2nd rib


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Heart Coverings and Walls

Enclosed in a double layered membrane called

the pericardium

visceral pericardium (epicardium) forms part of the wall

of the heart

parietal pericardiumloose membrane composed of denseconnective tissue

Walls of the heartthree layersEpicardiumconnective tissue

Myocardiumheart muscle

Endocardiumlayer of endothelium that lines

the chambers


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Heart chambers

Heart has four hollow chambers

2 receiving chambersthe left and right atria

2 pumping chambersthe left and right ventricles

The left and right chambers are separated by a septum

interatrial or interventricular septum

Heart works as a double pump

Right side pumps blood to the lungs

Left side pumps blood to the body


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Heart: Associated Great Vessels

Superior and Inferior venae cavaebring oxygen poor

blood from the body to the right atrium

Pulmonary Trunk and arteriescarries oxygen poorblood to the lungs

Pulmonary Veinsbring oxygen rich blood to the

left atrium

Aortacarries oxygen rich blood to the body


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Pulmonary Circulation

Carries blood to the lungs for gas exchange

Pathway - right atrium to right ventricle to

pulmonary arteries to lungs to pulmonary veins toleft atrium


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Systemic Circulation

Carries oxygen rich blood to the body and

oxygen poor blood to the heart

Pathwayleft atrium to left ventricle to aorta to

body to venae cavae to right atrium


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Heart Valves

The heart has four valves

They keep blood flowing in one direction

Atrioventricular (AV) valveslocated between the

atria and the ventricles

Left AV valve called the mitral valve (bicuspid valve)

Right AV valve called the tricuspid valve

Semilunar valveslocated between the ventricles andthe great vessels

Pulmonary semilunar valve

Aortic semilunar valve


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Cardiac Circulation

The blood pumped by the heart does not feed the

myocardium

Coronary arteriescarry oxygen rich blood to the

myocardium

Coronary veinscarry oxygen poor blood from the

myocardium

Coronary artery disease

Angina pectoris

Myocardial infarction

Coronary by-pass surgery


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Heart Physiology

Pumps about 6000 quarts of blood a day

Beats about 100,800 times a day

(70 bpm X 60 minutes X 24 hours)

Myocardial cells contract spontaneously

Contraction is regulated by the autonomic nervous

system as well as by nerves in the heart itself


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Regulation of Heart Beat

Autonomic nervous system acts to speed up and

slow down the heart rate

Intrinsic Conduction System , or Nodal System

Built into the heart tissue

Causes heart muscle depolarization to occur only from

atria to ventricle

-Produces a coordinated beat with a contraction

rate of about 75 BPM


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Intrinsic Conduction System

Sinoatrial Node

Located in the right atrium

It starts each heart beat and sets the rate

Called the pacemaker

Atrioventricular Node

Located at the junction of the atria and ventricles

- Relays the impulse to the ventricles

The AV bundle (bundle of His)

Right and left bundle branches

Purkinjie fibers


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Conduction Pathway

SA node to atria to the AV node

AV node to AV bundles to bundle branches to purkinje fibers

Atria contract before ventricles

Ventricles contract from the apex toward the atria

Produces coordinated contractions

Disorders of regulation

Heart block1st, 2nd, 3rd degree

Fibrillation

Bradycardia

Tachycardia


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Cardiac Cycle

Diastolemuscle relaxes and chamber fills

Systolemuscle contracts and blood is ejected

Cardiac cyclerefers to events of one complete heartbeat3 stages

mid-to-late diastole

Ventricular systole

Early diastole


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Mid-to-Late Diastole

Heart is in complete relaxation

Atria are filled

Ventricles empty

AV valves open

Blood flows passively from atria into the ventricles

Atria then contract and pump blood into the ventricles


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Ventricular Systole

Ventricles contract ejecting blood into the great vesselsSemilunar valves open

AV valves are closed

Atria are relaxed and the chambers are filling with blood


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Early Diastole

Ventricles relax

Atria are filled

All valves are closed for an instant

AV valves open and blood begins to flow

passively into the ventricles


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Heart Sounds

2 heart sounds are heard

lub dup pause lub dup

lub is the sound of the AV valves closing

dup is the sound of the semilunar valves closing

Abnormal sounds

Murmursindicate leaky valves or narrow valves

Split soundsheart enlargement


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Cardiac Output

Stroke Volumethe amount of blood ejected by aventricle with each contractionabout 70 ml per beat

Cardiac Outputthe total amount of blood pumped out by

the heart in one minuteabout 5250 ml per minute

Regulation of cardiac outputheart rate and stroke volume


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Regulation of Stroke Volume

Stretching of heart muscle cells

The more they stretch the greater the stroke volume

Stretch is regulated by venous return

- Venous return affected by heart rate and exercise


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Congestive Heart Failure

Heart muscle weakenscauses may be antherosclerosis,high blood pressure, or multiple myocardial infarcts

Cardiac output cannot keep up with venous return

Heart swells to increase output (increases filling)

Reaches a point where the swelling is so great that

output is further weakened

Left side failure

Right side failure

Generalized failure


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Blood Vessels

Blood travels away from the heart in arteries and arterioles

Blood travels back to the heart in venules and vein

Capillary beds are sites of gas exchange and

nutrientwaste diffusion


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Microscopic Anatomy of Blood Vessels

Blood vessels consist of three layers

tunica intima, tunica media, tunica externa

Tunica intima

Lines the lumen (the space inside a hollow organ)

Composed of thin layer of endothelium resting on connective tissue

Function is to decrease friction as blood flows through the vessel


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Tunica media

Composed of smooth muscle and elastic tissue

Contraction alter the diameter of the vessel

Tunica externa

Composed of fibrous connective tissue

Function is to support and protect the vessel


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Differences in arteries, veins, capillaries

Arteries Thicker and more elastic wallsTunica media is thicker

Allows vessel to withstand the higher pressure of

arterial blood

veins Thin wallsValves to prevent backflow

Relay on skeletal muscle to propel blood

capillaries Only consist of the tunica interna

Walls are one cell thick

Functionexchange of nutrients, wastes, &gases


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Physiology of Circulation

Vital signspulse, blood pressure,respiratory rate, body temperature

Pulsepressure wave that travels throughthe arterial system with each ventricular

contraction

Normal pulse averages 7076 beats per minute

Influenced by activity, posture, and emotions


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Pressure pointspoints where the pulse can be felt

These are the same areathat can be compressed to

stop blood flow to

the extremities


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Blood Pressure

The pressure the blood exerts on the inner

walls of the arteries

The pressure is highest in the larger arteries and

lessens as the blood enters smaller arteries

Blood pressure is usually measured using

the brachial artery in the arm


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Blood Pressure Measurements

Two measurements are usually made

- one measures the pressure when the heart contracts

- one measures the pressure when the heart has relaxed

Systolic pressuremeasures the pressurewhen the heart is in systole (contraction);

this represents the higher number in the measurement

Diastolic pressuremeasures the pressure whenthe heart is in diastole (relaxed); this represents the

Lower number in the measurement


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Factors that affect blood pressure

Cardiac outputamount of blood pumped by the heartIn one minute

Peripheral resistancethe amount of frictionEncountered by blood as it circulates

Many factors can affect blood pressureage, weight,

Exercise, body position; they either effect

cardiac output or peripheral resistance


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Factors that affect peripheral resistance

Arteriosclerosisfatty deposits in arteriesReduce elasticity

Reduce the diameter of blood vessels

Neural factorssympathetic nerves causetiny arterioles to contract (called vasoconstriction)

This raises blood pressure


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Renal factorsKidneys regulate fluid balance; this affects blood volume

and blood pressureKidneys release and enzyme renin that causes the formation

of another chemical angiotensin II.

Angiotensin II causes vasoconstriction as well as

the release of aldosterone (raises blood volume)

V i i i bl d


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Variations in blood pressure

Hypotensionsystemic pressure below 100 mm Hg

Hypertensionblood pressure higher than 140/90


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cardiac anatomy chart