1. The Heart

2. The Heart
The importance of the heart has been recognized for centuries
It is a muscular pump that drives the blood through the blood vessels
It is slightly bigger than your fist
It is located between the lungs and a bit left of the midline of the body

3. Structures of the Heart
Layers of the Heart Wall
Endocardium
A very thin smooth layer of cells that lines the interior of the heart. The valves of the heart are formed by reinforced folds of this material.
Myocardium
The muscle of the heart. It is the thickest layer and is responsible for the pumping of blood through the vessels.

4. Structures of the Heart
Layers of the Heart Wall
Epicardium
The thin, outermost layer of the heart wall just on top of the myocardium.
Pericardium
It surrounds the entire heart. It keeps the heart contained in the chest cavity prevents the heart from overexpanding when blood volume increases.

5. Structures of the Heart
Four Chambers
On either side of the heart there are 2 chambers, one is a receiving chamber (atrium), and the other a pumping chamber (ventricle).

6. Structures of the Heart
Right Atrium
Has the thinnest walls out of all 4 chambers
Receives blood low in oxygen returning from the body
Right Ventricle
Pumps blood received from the right atrium to the lungs
Left Atrium
Receives blood high in oxygen returning from the lungs
Left Ventricle
Has the thickest walls out of all 4 chambers
Pumps oxygenated blood to all parts of the body

7. Structures of the Heart
Four Valves
There are one-way valves located at the entrance and exit of each ventricle.
The entrance valves are called atrioventricular valves
The exit valves are called semilunar valves
Named because they look like a half-moon

8. Structures of the Heart
Right Atrioventricular (AV) Valve
Also known as the tricuspid valve, because it has 3 cusps, or flaps, that open and close
When the valve is open, blood flows freely from the right atrium into the right ventricle. But when the ventricle contracts, the valve closes and no blood can return into the atrium.

9. Structures of the Heart
Left Atrioventricular (AV) Valve
Also known as the mitral valve, and is made up of 2 cusps, or flaps. Also called the Bicuspid Valve.
The valve allows blood to flow freely from the left atrium to the left ventricle. When the left ventricle contracts, the valve closes and only allows blood to flow into the aorta.

10. Structures of the Heart
Pulmonic Valve
Is a semilunar valve, and is also called the pulmonary valve
Located between the right ventricle and pulmonary artery that leads to the lungs

11. Structures of the Heart
Aortic Valve
Is a semilunar valve, and is located between the left ventricle and the aorta

13. Functions of the Heart
Even though the right side and left side of the heart are separated, they work together
The active phase is called Systole, and is followed by a resting phase called Diastole

14. Functions of the Heart Diastole Atrial Systole Ventricular Systole
Atria fill with blood which begins to flow into ventricles as soon as their walls relax
Atrial Systole
Contraction of atria pumps blood into the ventricles
Ventricular Systole
Contraction of ventricles pumps blood into aorta and pulmonary arteries

15. Functions of the Heart

16. Functions of the Heart Cardiac Output
The volume of blood pumped by each ventricle in one minute
It is calculated by the stroke volume (volume of blood ejected from the ventricle from each beat), and the heart rate (number of times the heart beats per minute)