COMPONENTS OF THE CIRCULATORY SYSTEM
Answers
Components of the circulatory system :
- Blood.
- The heart.
- Blood vessels.
- Arteries.
- Capillaries.
- Veins.
Blood :
Blood consists of:
- Red blood cells – to carry oxygen
- White blood cells – that make up part of the immune system
- Platelets – needed for clotting
- Plasma – blood cells, nutrients and wastes float in this liquid.
The heart :
The heart pumps blood around the body. It sits inside the chest, in front of the lungs and slightly to the left side. The heart is actually a double pump made up of four chambers, with the flow of blood going in one direction due to the presence of the heart valves. The contractions of the chambers make the sound of heartbeats.
Blood vessels :
Blood vessels have a range of different sizes and structures, depending on their role in the body.
Arteries :
Oxygenated blood is pumped from the heart along arteries, which are muscular. Arteries divide like tree branches until they are slender. The largest artery is the aorta, which connects to the heart and picks up oxygenated blood from the left ventricle. The only artery that picks up deoxygenated blood is the pulmonary artery, which runs between the heart and lungs.
Capillaries :
The arteries eventually divide down into the smallest blood vessel, the capillary. Capillaries are so small that blood cells can only move through them one at a time. Oxygen and food nutrients pass from these capillaries to the cells. Capillaries are also connected to veins, so wastes from the cells can be transferred to the blood.
Veins :
Veins have one-way valves instead of muscles, to stop blood from running back the wrong way. Generally, veins carry deoxygenated blood from the body to the heart, where it can be sent to the lungs. The exception is the network of pulmonary veins, which take oxygenated blood from the lungs to the heart.
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