Question

Q1. what are the circulatory system in humans?

Q2.Explain the heart.​

Answer 1

Question:-

• What are the circulatory system in humans?

Answer:-

$\sf\purple{Blood:-}$

Blood is a red coloured fluid that flows in the blood vessels. It transports digested food for the small intestine to other parts of the body. It also transports oxygen from the lungs to cells of the body and carbon dioxide from tissues in lungs.

Plasma:-

• It is the fluid part of the blood that is composed of water, proteins, liquid etc.

Red blood cells(RBCs):-

• They are bio-concave cells that contain a red-coloured pigment called Haemoglobin, which gives blood its red colour.
• Haemoglobin binds with oxygen to form oxyhaemoglobin and transports oxygen to all parts of the body.

White blood cells:-

• They are irregular in shape and are colorless, as they do not contain Haemoglobin.
• They are bigger than RBCs, but fewer in number.

Platelets:-

• These are cell fragments that help in the clotting of blood.
• They release various substance to stop bleeding at the site of the wound.

$\sf\purple{Blood \ vessels:-}$

Blood flows in the body through long tube-like pipes called as blood vessels. They are of following types :-

Arteries:-

• They carry oxygenated or pure blood away from the heart.
• They are deep seated and have thick elastic walls
• Valves are absent in arteries.

Veins:-

• They bring impure blood to the heart from different parts of the body.
• They can be seen lying closer to the surface of skin, as greenish - blue lines.
• They have thinner walls, as compared to arteries.

Capillaries:-

• These are very thin walled blood vessels that connect arteries to veins.
• The walls of capillaries are so thin that the diffusion of gases and chemical substance takes place very easily.

Note:-

• See the first attachment to see the diagram of "human circulatory system".
• See the second attachment for red and white blood cells.
• See the third attachment for the diagram of blood vessels.

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Question:-

• Explain the heart

Answer:-

$\sf\purple{Heart:-}$

• The heart is muscular organ located in the chest cavity and is titled slightly towards the left. It is about the size of your closed fist.
• The heart is a pumping organ of the body that works non-stop throughout the life and pumps blood to all part of the body through blood vessels.

$\sf\purple{Internal \ structure \ of \ the \ heart:-}$

• The heart is enclosed in a double layered membrane called the pericardium.
• It is divided into four chambers - the upper two chambers are called as auricles and the Lower two chambers are called ventricles.
• The left side of the heart is completely separated from the right side by a partition, called as septum, which prevents the mixing of oxygenated blood with deoxygenated blood.

Note:-

• Check the fourth attachment for the diagram of "internal structure of human heart".

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