CARDIOVASCULAR SYSTEM.

 1.CARDIOVASCULAR SYSTEM. 

      Cardiovascular system is a closed system through which blood flow throughout the body supplying nutrients and oxygen to tissue and removing waste and carbon dioxide. 

     It includes heart and blood vessels. Heart pumps blood into the blood vessels. Blood vessels circulate the blood throughout the body. 

A. HEART:

    Heart is the vital organ in the body. This muscular organ that pumps blood throughout the circulatory system. 

 a. Right side of the heart. 

        Right side of the heart has two chambers. 

        1.Right atrium

        2.Right ventricle

  Right atrium receives venous (deoxygenated)    blood via two large veins. 

   1.Superior vena cava

    2.Inferior vena cava. 

 b. Left side of the heart. 

       Left side of the heart has two chambers

        1.Left atrium

        2.Left ventricle

 Left atrium receives arterial(oxygenated) blood from the lungs through pulmonary veins. 

Section of the heart

SEPTA OF THE HEART:

  Right and left atria are separated from one   another by a fibrous septum called interatrial   septum. 

  Right and left ventricles are separated from     one another by interventricular septum.  LAYERS OF WALL OF THE HEART. 

Heart is made up of three layers of tissue:

   1.Outer pericardium

   2.Middle myocardium

   3.Inner endocardiumendocardium

1.PERICARDIUM.

     Pericardium is the outer covering of the heart. It is made up of two layers. 

 a. Outer parietal pericardium

 b. Inner visceral pericardium

Space between the two layers is called pericardium cavity or pericardial space and it contains a thin film of fluid. 

2.MYOCARDIUM.

      Myocardium is the middle layer of wall of the heart and it is formed by cardiac muscle fibers or cardiac myocytes. 

   Myocardium has three types of muscle fibers:

       a. Muscle fibers which from contractile                    unit of heart. 

       b. Muscle fibers which from pacemaker. 

       c. Muscle fibers which from conductive                   system. 

Cardiac muscle fibers. 

3.ENDOCARDIUM.

     Endocardium is the inner most layer of heart wall. It is a thin, smooth and glistening membrane. It is formed by a single layer of endothelial cells, lining the inner surface of the heart. 

VALVES OF THE HEART:

 There are four valves in human heart. 

 Two valves are in between atria and the ventricles are called atrioventricular valves. 

  Other two are the semilunar Valves, placed at the opening of blood vessels arising from ventricles, namely systemic aorta and pulmonary artery. Valves of the heart permit the flow of blood through heart in only one direction. 

Valves of the heart.

ATRIOVENTRICULAR VALVES:

 Left atrioventricular valve is otherwise known as mitral valve or bicuspid valve. It is formed by two valvular cusps or flap. 

 Right atrioventricular valve is known as tricuspid valve and it is formed by three cusps. 

SEMILUNAR VALVES:

 Semilunar valves are present at the opening of systemic aorta and pulmonary artery, and are know as aortic valve and pulmonary valve respectively. 

  Because of the halfmoon shape, these two valves are called semilunar valves. 

 Semilunar valves are made up of three flaps. 

Semilunar valves.