Cardiac System EHS Uni 5: Cardiac Cycle, contraction and electroconduction

1. Anatomy of the Cardiac System
ATS Unit 6

2. Goals
• Identify major structures of the heart.
• Discuss the Flow of blood through the
heart and major vessels.
• Review the microanatomy of the heart.

3. Functions of the Heart
• The heart is the pump that circulates the
blood to the entire body.
– It is muscular (made of myocardium)
– It is approximately the size of the fist covered
in the other hand.
– It sits in the mediastinum, underneath the
sternum.

4. Microanatomy of the heart
• Several tissue types help to construct the
heart, but the main part is cardiac muscle
tissue.
– Cardiac muscles cells are striated, branched,
share nuclei, and are connected by
intercalated discs.
– They are specially constructed to respond in a
coordinated and automated fashion to
electrical impulses created within the heart.

5. General Structure of the Heart
• The heart has four chambers.
– The upper chambers are the right and left
atria
– The lower chambers are the right and left
ventricles.
• The right and left side of the heart are
divided by the spetum.
• The atria and ventricles are divided by one
way valves.

6. As blood flows through the heart…
• Enters the Right Atrium via the Vena Cava
(superior and inferior)
• During atrial contraction, blood is pushed
through the Tricuspid valve into the Right
ventricle.

7. From the Right Ventricle…
• During ventricular contraction, blood is
pumped from the right ventricle through
the pulmonary semilunar valve.
• Blood then travels via the pulmonary
artery through the lungs and back to the
heart via the pulmonary veins.

8. From the Pulmonary Veins…
• Blood flow from the pulmonary veins into
the left atrium.
• From the left atrium, blood flows through
the Mitral (bicuspid valve) into the left
ventrical.
• During ventricular contraction, the blood is
pumped through the Aortic Semilunar
valve and into systemic circulation.

9. Detailed Structure of the Heart
• The interior of the heart is covered by a
thin epithelial tissue called endocardium.
• The myocardium is the middle layer, very
thick and is all muscle tissue.
• The heart is then covered in another thin
layer of tissue, this time tougher, called
epicaridium.

10. Pericardium
• The thick connective tissue sack that
protects heart is called the pericardium.
– Between the pericardium and epicaridium
there is a small amount of fluid that prevents
friction from occurring. It too much fluid is
present (or blood or infection), there heart will
no tbe able to beat.
– There is also fat on the surface of the heart
and in the mediastinal cavity to protect the
heart.

11. Interior Anatomy of the Heart…
• Other than being divided into it’s four
chambers, the heart has several other
important structure.
– Valves separate the atria and ventricles, and
prevent regurgitation into the major vessels.
– They are made of thick connective tissue with
few living cells.
– They are attached to muscular projections on
the walls of the heart by connective tissue
fibers called chordae tendineae.

12. Major Vessels of the Heart
• The heart is served by the coronary artery,
which branches off of the Aorta.
– The Coronary artery then branches into the
right, left main, and circumflex arteries.