2. Introduction
The heart pumps 7,000 liters of blood through the body each day
The heart contracts 2.5 billion times in an average lifetime
It takes approximately 1 minute for a blood cell to circulate through the body (at rest)
The heart and all blood vessels make up the cardiovascular system
The blood vessels make up two circuits:
Pulmonary circuit
Systemic circuit

4. SIZE AND LOCATION OF HEART

5. The heart is located in the mediastinum in a cavity called the pericardial cavity.

6. The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs near their articulation with the costal cartilages

7. Base of heart
Sternum
Heart
Apex of heart
Diaphragm

8. Coverings of the heart

9. The heart is separated from other structures by a tough membrane known as the pericardium, or pericardial sac.

10.  The percardium is the serous membrane lining the cavity.

11. The pericardium is a continuous membrane but the part that attaches to the surface of the heart is the  visceral pericardium (a.k.a. epicardium) and the part that lines the outer wall of the cavity is the parietal pericardium

12.  The outer surface of the parietal pericardium is reinforced by a layer of dense, irregular connective tissue called the fibrous pericardium.

13. Walls of the heart

14. Structure of Heart Wall
The heart wall can be divided into three layers:
Epicardium (visceral pericardium) described previously
Myocardium consists of multiple interlocking layers of cardiac muscle tissue with associated connective tissue, blood vessels and nerves.
Endocardium is the inner lining of the heart. It is continuous with the endothelium that lines the blood vessels.

15. ` Epicardium (outer layer) Myocardium (middle layer) Endocardium
(inner layer) `

16. Heart Chambers and valves

17. Internal Heart Structures
Atrium (single)
Atria (plural)- collect blood from incoming veins; pass blood into ventricles
Ventricles- pump blood out of heart through outgoing arteries

18. The common wall between the atria is the interatrial septum and the common wall between the ventricles is theinterventricular septum.
a septum (plural = septa) refers to a wall or partition that divides the heart into chambers
word septum is derived from the Latin for “something that encloses;”

19. Path of blood

21. Right Atrium 
The right atrium receives deoxygenated blood from superior vena cava, inferior vena cava

22. Right Ventricle
The deoxygenated blood from right atrium enters the right ventricle through the right atrioventricular (tricuspid) valve.
This valve has three “flaps” or “cusps”
The edges of the cusps are attached to strings of connective tissue called the chordae tendineae.
The chordae tendineae are anchored to the ventricular wall by papillary muscles.
These help reinforce the valves and prevent backflow

24. Left Atrium
The left (2) and right (2) pulmonary veins drain oxygenated blood from the lungs into the left atrium.
The oxygenated blood enters the left ventricle through a valve with two flaps, the left atrioventricular (a.k.a. bicuspid, mitral) valve.

25. Left Ventricle The left ventricle, has a thicker wall than the right.
As oxygenated blood is ejected from the left ventricle is passes through the aortic semilunar valve and enters the ascending aorta.