HUMAN SYSTEMOur body is a wonderful machine. It has many soft and hard organs. These organs perform vital functions in the body. These are two main types of organs. They are external organs and internal organs. External Organs are those parts of body that can be seen. The soft organs present inside our body that cannot be seen are known as Internal Organs. These organs are protected by hard bones.

The internal organs of our body form different groups called Organ System to carry out the functions of the body . For example :- heart, veins, arteries, capillaries and blood together for the circulatory system of our body.

1) The skeleton system- bones.

2) The muscular system- muscles.

3) The nervous system- brain, spinal chord and nerves.

4) The respiratory system- nose, trachea and lungs.

5) The circulatory system- heart, blood vessels and blood.

6) The digestive system- mouth, stomach, liver, teeth, large and small intestines.

7) The excretory system- kidneys, urethra, urinary bladder and ureter.

Our body consist of the following systems.

THE SKELETAL SYSTEMThe skeletal system is a framework of bones that keeps our body in proper shape. A child has 350 bones. As a human grows, many bones join together. An adult has 206 bones. The bones have a network of blood vessels and nerves. The soft proportion inside the bone is known as Bone marrow where blood cells are made.

FUNCTIONS OF THE SKELETON:-

• It gives shape and strength to the body.• It protects the delicate internal organs. • It gives support to the body.• Blood cells are made in the bone marrow.• Bones make the movement of the body possible with the help of the muscles

How do bones work?Our bones don't work on their own. The bones join together to form joints. The end of each bone is covered by a tough, smooth shiny substance called cartilage that works like oil in a car. All of this is so your bones won't scratch and bump against each other when you move. Our bones are held together by strong stretchy bands called ligaments.

•The smallest bones in the body are found in the ear. •The longest bone in the body is the femur. •The bones are filled with something called bone marrow which makes red and white blood cells. •Over half the body's bones are in the hands and feet. •The only joint-less bone in your body is the hyoid bone in your throat. •As your bones grow, you get taller.When you were born, your skeleton had around 350 bones. •By the time you become an adult, you will only have around 206 bones. This is because, as you grow, some of the bones join together to form one bone.

Interesting Facts

THE MUSCULAR SYSTEMMuscles help in our body movements. Our body has about 650 muscles. The smallest movement of our body requires at least two muscles working in opposite directions.Muscles help you do almost everything — from pumping blood throughout your body to lifting heavy objects.You control some of your muscles, and others, like your heart, do their jobs without you thinking about them at all.

Function of Muscles

How Muscles Work?• Muscles work in a very simple way. All they do is tighten up--that is, contract--and relax.

• You have two sets of muscles attached to many of your bones

which allow them to move. • Muscles can only pull. They

never push.

THE NERVOUS SYSTEM

It controls all the other systems of our body. It consist of brain, spinal chord and nerves.The spinal cord is the main pathway for information connecting the brain and peripheral nervous system.The human spinal cord is protected by the bony spinal column.The spinal column is made up of bones called vertebrae.

THE BRAINInside our head is the brain. It controls how our bodies work and is protected by the a thick bone called the skull.The brain makes sure our hearts keep beating and our lungs keep working without us having to think about it.Part of the brain makes our muscles work.The biggest part of the brain makes us think, see, hear, feel and taste.

We each have a backbone, called a spine. Inside it there is a spinal cord. The spinal cord joins the brain at the top of our neck. Its main function is to serve as a pathway for the messages from the nerves to travel to the brain and back so we know what we are seeing, touching, hearing, and tasting, and if something hurts or feels.

THE SPINAL CHORD

All through our body there are nerves which connect to the spinal cord.This is called the nervous system. Messages from the nerves travel to the spinal cord, which sends them to the brain.The brain works out what the messages are so we know what we are seeing, touching, hearing, and tasting, and if something hurts or feels.

THE NERVE

THE RESPIRATORY SYSTEMOur body needs oxygen. It is essential for our body cells. Our respiratory system provides oxygen to our body. Oxygen helps to break down the food absorbed by our body, and releases energy to carry out the activities of the body. Respiration also helps to remove carbon dioxide which is a waste product formed in the body.

The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body.

THE CIRCULATORY SYSTEMThe circulatory system is a combined function of heart, blood vessels and blood. The Heart and the Blood vessels are important organs of the circulatory system. Blood vessels consist of Arteries, Veins and Capillaries. •Arteries carry blood from the heart to other parts of the body. •Veins carry blood from other parts of the body to the heart. •Capillaries are the link between the veins and arteries.

Heart

WHAT IS THE IMPORTANCE OF THE

CIRCULATORY SYSTEM?The circulatory system regulates the blood flow and body temperature. We can feel our heartbeat by putting our hand on the left side of our chest. Our heart beats 72 times in a minute.

THE DIGESTIVE SYSTEMThe function of the digestive system is to break down and digest the food that we eat. It breaks the food into smaller particles that can be absorbed into our blood.

The digestion process begins in the mouth, where the food is chewed by our teeth. Then it passes through the food pipe into our stomach produces juices which helps in digestion. From the stomach, it reaches the small intestine, where it reaches the small intestine, where it is further digested and is reached the large intestine. The liver and the pancreas also help in digestion. The undigested food passes out of the large intestine as a faecal matter.

THE LUNGS

THE LIVERTHE STOMACH

THE BLADDER

THE BRAIN

THE EXCRETORY SYSTEMThe excretory system helps to remove waste products from our body. The 3 excretory organs of our body are the kidneys, lungs and skin. Kidneys are the most important. The kidneys helps to remove urine from our body. The urine is carried to urinary bladder though the ureters and passes out of the body through the urethra. The lungs help to remove carbon dioxide, the skin removes sweat, while faeces are removed from the intestine through the anus.