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In the centre of our chest, behind one of the strongest bone of our body ( sternum) lies a fist sized very vital organ called Heart. Our muscular heart is a main organ in our cardiovascular system. Its parts works together to move blood through our body in a very coordinated way. It constantly sends oxygen to our cells and takes away waste.

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The heart is a fist sized organ that pumps blood throughout our body. Muscles and tissues make up this powerhouse organ. It is our heart that controls the rhythm and speed of our heart rate and maintains our blood pressure. Heart is just not an important organ of circulatory system but it do work with other systems like nervous systems (that sends signals to our heart to beat slower during rest and faster during stress) and endocrine system ( that sends out hormones that tell our blood vessels to constrict or relax, which affects our blood pressure).

Refer to image 3 for more clarity.

Our heart anatomy includes :-

1. Heart walls - these are muscles that contract and relax to send blood throughout our bod. A layer of muscular tissue called septum divides our heart walls into left and right sides. Our heart walls have three layers :

1. Endocardium - Inner layer

2. Myocardium - Muscular middle layer

3. Epicardium - Protective outer layer

2. Chambers - Our heart has four separate chambers out of which two chambers are on top and two on the bottom. The chambers on the top are called auricles and the bottom chambers are called ventricles. In image 3 marked number 8 and 9 are auricles and number 6 and 7 are ventricles.

Lets understand individual chambers :

1. Right auricle/ atrium - Two large veins of our body deliver hypoxic blood( means blood with low oxygen) to our right auricle. Those 2 veins are superior vena cava and inferior vena cava. As name indicates superior vena cava collects oxygen-poor blood from from our superior/ upper body and inferior vena cava collects oxygen-poor blood from lower parts of body. All the blood collected by vena cavas goes into right auricle which is then pumped to right ventricle through tricuspid valve.

2. Right Ventricle - The lower right chamber pumps the oxygen-poor blood to our lungs through pulmonary artery. The lungs reload the blood with oxygen.

3. Left Auricle - After the lungs fill your blood with oxygen, the pulmonary veins carry the blood to the left atrium. This upper chamber pumps the blood to your left ventricle.

4. Left Ventricle - The left ventricle is slightly larger than the right. It pumps oxygen-rich blood to the rest of your body.

Heart valves - Heart valves are like doors between heart chambers. They open and close to allow blood to flow through and prevent back flow. Heart valves are divided into two categories atrioventricular valve and semilunar valves.

1. Atrioventricular valves - These atrioventricular valves open between your upper and lower heart chambers. They include tricuspid valve and bicuspid valve.

a. Tricuspid valve - door between our right auricle and right ventricle.

b. Mitral valve - door between our left auricle and left ventricle.

2. Semilunar Valves - These valves open when blood flows out of your ventricles. They include aortic valve and pulmonary valve.

a. Aortic Valve - Opens when blood flows out of our left ventricle to our aorta.

b. Pulmonary valve - Opens when blood flows from our right ventricle to our pulmonary arteries.

Blood vessels - We have 3 different types of blood vessels that our heart pumps blood through.

1. Arteries - carry oxygen rich blood from our heart to our body's tissues.

2. Veins - carry oxygen poor blood back to our heart

3. Capillaries - small blood vessels where our body exchanges oxygen rich and oxygen poor blood.

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Image 3  with all parts numbered from 1 to 13 for better understanding

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Image 3  with all parts numbered from 1 to 13 for better understanding

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Lets understand all parts starting with :-

No. 1 - Superior Vena Cava

No. 2 - Pulmonary Artery

No. 3 - Pulmonary Vein

No. 4 - Mitral Valve

No. 5 - Aortic Valve

No. 6 - Left Ventricle

No. 7 - Right Ventricle

No. 8 - Left Atrium/ Auricle

No. 9 - Right Atrium

No. 10 - Aorta

No. 11 - Pulmonary Valve

No. 12 - Tricuspid Valve

NO. 13 - Inferior Vena Cava