1. The Circulatory System

2. The Circulatory System
Your circulatory system, also known as the cardiovascular system, is a complex network of different organs and vessels that ensure proper flow of nutrients, blood, hormones and oxygen to and from cells.
Your body cannot be able to maintain a healthy internal environment or fight diseases in the absence of your circulatory system.
Generally, the circulatory system organs help maintain proper pH and temperature in your body to keep healthy.

3. Major organs
Your circulatory system consists of the Heart, Blood vessels, and about 5 liters of blood that your heart transports through your blood vessels.

4. The Heart
Located slightly to the left of the middle of your chest, the heart is made of strong muscle tissue and is protected by your rib cage.
Even though it is no larger than the size of your fist, it plays a vitally important role in your body.
It consists of four hollow chambers – two ventricles and two atria. All four chambers work quite like pumps and push blood throughout your body. The blood that moves towards the heart enters it through the atria and then goes out to your body through the ventricles.

5. The Blood Vessels
The Blood Vessels
The blood vessels are one of the most important circulatory system organs.
Your blood vessels allow blood to flow quickly from one region to another and then allow it to come back to your heart.
The size of your vessels increases with an increase in the amount of blood that passes through the vessel.
Blood vessels have a hollow area that allows for easy flow of blood – it's called lumen. There will be a wall around the lumen, which can be thick as in arteries or thin as in capillaries.

6. Types of blood vessels
1. Arteries: - carry blood away from the heart to the tissues of the body - are usually positioned deeper within the body - are more muscular than veins, which helps in transporting blood that is full of are more muscular than veins, which helps in transporting blood that is full of oxygen efficiently to the tissues - would generally remain open if blood flow stopped, due to their thick muscular layer.

7. Types of blood vessels
2. Veins: - carry blood from the tissues of the body back to the heart are usually positioned closer beneath the surface of the skin - are less muscular than arteries, but contain valves to help keep blood flowing in the right direction, usually toward the heart - would collapse if blood flow stops.

8. Types of blood vessels
3. Capillaries: Capillaries are the tiniest blood vessels. They connect arteries to veins.

9. Blood
Your heart pumps blood throughout your body and travels through thousands of miles, mainly because it has to move through the network of blood vessels within your body.
Your blood is an amazing substance that carries water, nutrients, waste products and oxygen to and from your body cells. A young person will have up to a gallon of blood, whereas an adult will have about 5 quarts of blood.
It is important to note that your blood looks like an ordinary red liquid, but it's in fact made up of solids, liquids and small amounts of carbon dioxide and oxygen.