Cardiovascular system

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  • Publicado : 24 de marzo de 2010
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Function of the cardiovascular system:

The circulatory system is an organ system that passes nutrients (such as amino acids and electrolytes), gases, hormones, blood cells, nitrogen waste products, etc. to and from cells in the body to help fight diseases and help stabilize body temperature and pH to maintain homeostasis.

Blood circulates through a network ofvessels throughout the body to provide individual cells with oxygen and nutrients and helps dispose of metabolic wastes. The heart pumps the blood around the blood vessels. Blood is made up of about 45% solids (cells) and 55% fluids (plasma). The plasma is largely water, containing proteins, nutrients, hormones, antibodies, and dissolved waste products.

Functions of blood:
• Circulates OXYGENand removes Carbon Dioxide.
• Provides cells with NUTRIENTS.
• Removes the waste products of metabolism to the excretory organs for disposal.
• Protects the body against disease and infection.
• Clotting stops bleeding after injury .
• Transports HORMONES to target cells and organs.
• Helps regulate body temperature.
The heart

The heart is a muscular organ found inmost vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions.

The heart is divided Into four parts or chambers. The top ones are called the left atrium and right atrium and the bottom two are the left ventricle and right ventricle.
Blood first enters the heart at the right atrium, passes through the tricuspid valve into theright ventricle. The blood is then sent out through the pulmonary valve to the lungs. It picks up oxygen and comes back to the heart at the left atrium. From there it passes through the mitral valve into the left ventricle where it is pushed through the aortic valve and out to the body. The mitral valve differs from the rest of the valves because it is made up of just two flaps; the others havethree flaps. Those flaps can also be called leaflets or cusps.
The chambers each have a purpose. The atria act as reservoirs for the blood before it moves on to the larger ventricles. The ventricles are the strong pumps of the heart with the left one, the one that pushes blood out to most of the body, being the strongest. These chambers can be damaged by disease, resulting in scarring, weakeningof the muscle, thickening of the muscle or hardening of the heart wall. (Read about "Cardiomyopathy")
The main artery from the heart is the aorta. Veins carry oxygen-poor blood back to your heart. At the lungs, it is the pulmonary artery that brings oxygen-poor blood into the lungs and the pulmonary vein that carries oxygen-rich blood back to the heart.

In a four-chamberedheart, such as that in humans, there are two ventricles: the right ventricle pumps blood into the pulmonary circulation for the lungs, and the left ventricle pumps blood into the systemic circulation through the aorta for the rest of the body.

Comparing the left and right ventricles, the left ventricle has thicker walls because it needs to pump blood to the whole body.


Theright atrium receives de-oxygenated blood from the superior vena cava, inferior vena cava and coronary sinus. The left atrium receives oxygenated blood from the left and right pulmonary veins.
The atria do not have valves at their inlets. As a result, a venous pulsation is normal and can be detected in the jugular vein

the heart valves maintain the unidirectional flow of blood inthe heart by opening and closing depending on the difference in pressure on each side.

There are four valves in the heart (not counting the valve of the coronary sinus, and the valve of the inferior vena cava):
• The two atrioventricular (AV) valves between the atria and the ventricles.
• The two semilunar (SL) valves, in the arteries leaving the heart.
Atrioventricular valves...
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