Transcript Today`s Objectives

Today’s Objectives
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Be able to explain
location, size and
position of the heart
Be able to explain the
definitions
Be able to label the
pictures of the heart
Heart:Location, Size, Position
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Located between the lungs and lower
portion of mediastinum
Two-thirds of its mass is on the left
Triangular shape - a closed fist
Thoracic cavity: between sternum in the
front and the thoracic vertebrae behind
Apex, lower edge, lies on the diaphragm
Anatomy of the Heart
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Hollow, not solid
Atria-upper chambers
Ventricles-lower
chambers
Myocardium-cardiac
muscle tissue that
lines the walls of the
chambers
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Interatrial septum- septum (divider) between the
atrial chambers
Interventricular septum-separates the ventricles
Endocardium-thin layer of very smooth tissue
that lines each chamber (“endo” means within or
inside)
Endocarditis-inflamed lining; rough and abrasive
to RBC’s passing over its surface- thrombusfatal blood clot
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Pericardium – covering of the heart that consists
of two layers of fibrous tissue:
1. Inner layer-epicardium (visceral
pericardium) Covers the heart like skin on an
apple (“epi” means upon or on)
2. Outer layer- parietal pericardium (loose
fitting sac that allows the heart to beat)
No friction because the two layers are moist
serous membranes
Pericardial fluid lubricates between heart and
pericardial sac
Pericarditis
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Inflammation of the pericardium
Trauma, bacterial and viral infections, tumors
Often visceral and parietal pericardium rub
together – severe chest pain
Pericardial effusion- pericardial fluid, pus, or
blood accumulate in the space between the two
layers and impairs pumping action of the heart
Cardiac tamponade-compression of the heart
Objectives
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1. Be able to describe the conduction
system of the heart
2. Be able to identify the structures of the
heart involved in electrical conduction
Conduction System of the Heart
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View the animation and take the quiz
http://highered.mcgrawhill.com/sites/0072495855/student_view0/
chapter22/animation__conducting_system
_of_the_heart.html
Conduction System of the Heart
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The intercalated disks are electrical
connectors.
Thus, both atrial walls will contract at
about the same time and both ventricular
walls will contract at about the same time.
Conduction System Sequence
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1. SA node (pacemaker)
2. All directions through atria causing
atrial fibers to contract
3. AV node
4. Bundle of His
5. Purkinje fibers