Blood Vessels

Blood Vessels

1. CIRCULATORY SYSTEM

2. What is Circulatory System? Circulatory system is the system that circulates blood and lymph through the body. Its is a transport system that carries gases, nutrients, hormones wastes, and many other substances. This is composed of th e heart, blood vessels, blood, lymph and the lymphatic vessels.

3. Blood Vessels

4. What is Blood Vessels? The blood vessels are the part of the circulatory system that transports blood throughtout the human body. The blood is the circulating medium in the cardiovascular system. It moves in circles inside the blood vessels.

5. Three major types of blood vessels: Arteries - Carry blood away from the heart. Capillaries - Enable the actual exchange of water and chemicals between blood and tissues. Veins - Carry blood from the capillaries back toward the heart.

6. Blood Vessels The arteries receive the propelled oxygenated blood from the ventricles of the heart. The blood from the arteries goes to the smaller blood vessels called arterioles , which are connected to the capillaries in the tissues.

7. Venules , which are small veins drain the capillary beds (interweaving capillary networks), which empty into veins then into the great veins that enter the heart.

8. The walls of blood vessels except those of microscopic capillaries have coats of tunics : Tunica intima (interior of the vessels) Tunica media (bulky central tunic) Tunica adventitia (outermost coat).

9. The walls of arteries are thicker than those of veins. The walls of arteries are strong enough to withstand the pressure of blood from the heart. On the contrary, veins have low pressure. This is why veins have thinner walls .

10. Arteries often carry oxygenated blood, while veins often carry deoxygenated blood. The flow of blood in the arteries is away from the heart, while in veins the blood goes toward the heart.

11. Because the blood in veins is directed toward the heart,it is against gravity. This is the reason why veins have valves to prevent the backflow of blood.

12. Capillaries The transparent walls of the capillaries are very thin, which make the exchanges between the blood and tissue cells easy. A capillary bed has vessels that connect an arteriole and a venule .

13. Blood Pressure Blood pressure is the pressure that blood exerts against the inner walls of the blood vessels. It rises and falls as the heart contracts and relaxes. The systolic pressure is the pressure in the arteries during the contraction of the ventricles.

14. Blood Pressure On the other hand, the diastolic pressure is the pressure in the arteries during the relaxation of the ventricles. A blood pressure reading of 120 over 80 means a systolic pressure of 120 and diastolic pressure of 80.

15. Sphygmomanometer A sphygmomanometer is a device used for measuring blood pressure. An Inflatable cuff is warapped around the arm to constrict the arteries during measurement.