Circulatory System

No. Heart       
1. Heart lies in thorx cavity between lungs and above the diaphragm.
2. It pumps the blood to all the parts of the body.
3. Heart is made up of a special tissue called cardiac muscle fibres.
4. The heart is a four chambered organ.
5. It has two auricles and two ventricles.
6. The upper two chambers are called auricles.
7. The two lower chambers are called ventricles.
8. Auricles receives blood from veins.
9. The walls of auricles are thin.
7. Aorta is the largest artery in the body.
8. The left ventricle opens into the Aorta.
9. The right ventricle opens into the pulmonary artery.
10. Blood passes from left auricle to left ventricle.
11. From left ventricle blood passes to different parts of the body through Aorta.
12. Coronary arteries supply oxygenated blood to the heart for its nurishment.
13. The coronary arteries origin from the point where the Aorta leaves the heart.
14. The right auricle receives deoxygenated blood from superior vena cava and inferior vena cava.
15. The superior vena cava carries blood from upper part of the body to the heart.
16. The inferior vena cava carries the blood from lower part of the body.
17. The deoxygenated blood is oxygenated in lungs and returns to left auricle through pulmonary veins.
18. Contraction of heart muscles is called systole.
19. Relaxation of the heart muscle is called diastole.
20. Stethoschope is the instrument used to hear the sound of heart beat.
21. The heart beat on an average is 72 to 80 times per minute.
22. Heart is enclosed in a double walled membrane.
23. Pericardial fluid is present between the two membranes. It protects from external shocks.