location & structure of the heart

By : V.Atputhavadivel Reg. No : 09Diploma in Teaching and Supervision -2006Post Basic College of Nursing Colombo

General objective

By completion of this session the student should be able to acquire knowledge in position and structure of the heart

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Specific objectives To write down the shape, size and weight of

the heart. To identify the anatomicaiposition of the

heart. To describe the structure of the heart

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The heart is a roughly cone –shaped hollow muscular organ.

An adult human heart above 10 cm long, weighs between 200 and 350 grams and

is slightly larger than a fist. Each day, the average heart beats

100,000 times, pumping about 7,600 liters (2,000 gallons) of blood.

….Thoracic cavity, between the lungs, behind and

slightly to the left of the sternumA base above, it is extends to the

level of the 3nd rib. The apex below, it is about 9cm left

away from midline, at the 5 th intercostals space

Inferiorly – The apex rests on the central tendon of the diaphragm

Superiorly_ The great blood vessels ie; the aorta ,superior vena cava, pulmonary artery and pulmonary veins.

Posteriorly- The esophagus, trachea, left and right bronchus, descending aorta , inferior vena cava and thoracic vertibrae .

Laterally-The lungs the left lung overlaps the left side of the heart.

Anteriorly-The sternum, ribs and intercostals muscles.

Three layers of tissue form the heart wall.

The outer layer of the heart wall is the pericardium,

The middle layer is the myocardium,

The inner layer is the endocardium.

Pericardium

A double-layered membrane Surrounds the heart like a sac. The outer layer of the pericardium

surrounds the roots of the heart's major blood vessels and is attached by ligaments

The inner layer of the pericardium is attached to the heart muscle.

A coating of fluid separates the two layers of membrane,

MyocardiumSpecialized cardiac muscle found

only in the heart. It is not under voluntary control but

like skeletel muscle. Nuleus, intercalated disc, branching cell.

The myocardium is thickest at the apex and thins out towards the base.

Endocardium.

This forms the lining of the myocardium and the heart valve.

It is a thin , smooth glistening membrane.

It consist of flattened epithelial cell.

Interior of the heart

Interior of the heart….

A muscular septum divides the heart internally into a left and a right half.

Each half is subdivided into two

chambers, the atrium (reception) and the ventricle (pump chamber) .

Internally all four chambers have a smooth membranous lining, the endocardium.

The Right half of the Heart.

The right half of the heart is responsible for the circulation of deoxygenated (oxygen-poor) blood to the lungs so that it may be oxygenated. This circulation is called pulmonary circulation or lesser circulation.

The Right Atrium.

The right atrium is thin walled and is situated at the broad end of the heart.

The Right Ventricle.

The right ventricle receives the deoxygenated blood from the right atrium.

The Left half of the Heart.

The half is responsible for the circulation of oxygenated

blood to all parts of the body

The Left Atrium.

The left atrium is thin-walled like the right atrium and it situated in the broad end of the heart.

The Left Ventricle.

The left ventricle is characterized by its exceptionally thick muscular wall.

The Valves of the Heart.

We have learned from this section

Shape, dimension, weight of the heart

Location of the heart,

Organ associated with the heart,

Tissue composition and layers, Interior structure of the heart.

Assignment

Describe the heart wall composed three layers of tissue.

References :

Anne Waugh, Allison Grant, Ross and Wilson Anatomy and Physiology in Health and Illness, (2001), Churchill Livingstone, Edinburgh London.

Thank you