The human circulatory system
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Evolution and inheritance
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Summary
The human circulatory system
In a nutshell
The circulatory system is the body's way of bringing the oxygen that is breathed in from the air into the body. It also removes carbon dioxide and circulates nutrients to muscles and organs.
Parts and functions of the circulatory system
The heart
The heart is a muscle that pumps blood around the body. It is the size of a closed fist and beats times a minute. It has four sections called chambers which allow blood rich in oxygen and carbon dioxide to be kept apart.
Blood vessels
Blood vessels are a network of tubes that blood travels in. There are three types you should know.
| | Blood vessel | Function |
| 1. | Arteries | Transport blood away from the heart to the body. |
| 2. | Veins | Transport blood towards the heart. |
| 3. | Capillaries | Tubes with thin walls that allow gases and nutrients to pass through. |
Blood
Blood travels through blood vessels and carries cells, dissolved nutrients, and gases. There are four components of blood you should know.
Plasma | A liquid that carries cells and dissolved nutrients. |
Red Blood Cells | Cells that carry oxygen or carbon dioxide. These cells also give blood its red colour. |
White Blood Cell | Cells that fight infection. |
Platelets | Cell pieces that help the blood to get sticky (clot) if there is damage. |
Transport in the circulatory system
The human circulatory system helps to deliver nutrients, water, and oxygen to cells and tissues and carries away waste products like carbon dioxide.
1. | The heart pumps blood that is low in oxygen to the lungs through arteries. |
2/3. | Oxygenated blood (blood rich in oxygen) flows back to the heart through veins. |
4. | The heart pumps blood that is high in oxygen around the body to cells and tissues. Deoxygenated blood (blood low in oxygen) flows back to the heart through veins, carrying carbon dioxide from cells and tissues. |
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FAQs - Frequently Asked Questions
What is the function of the heart?
The heart is a muscle that pumps blood around the body.
What are blood vessels?
Blood vessels are a network of tubes that blood travels in.
What is the function of the circulatory system?
The circulatory system is the body's way of bringing the oxygen from the air you breathe into the body, removing carbon dioxide and circulating nutrients to the muscles and organs that need them.
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