Current Affairs 5th Class

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Human Body and Nutrition

Human Body

The organs of our body work together to perform various functions for the body. A group of organs doing some particular jobs for the body form an organ system.

Human body has the following systems performing certain functions:

• Respiratory system is responsible for carrying oxygen. Oxygen is necessary for human life.
• Digestive system breaks the food we eat into simpler forms.
• Skeletal system gives shape to human body and helps in the movement.
• Nervous system performs the functions of thinking, smelling, seeing, tasting, etc.
• Circulatory system helps in transportation of oxygen, carbondioxide, nutrients and other substances to various parts of the body.
• Muscular system helps in movement.

Skeletal System

It is the framework of bones which gives support to human body. Adult human skeleton has 206 bones. Different parts of the human skeleton are:

Skull

Skull consists of 22 bones which protects the brain. All bones of skull are immovable except the lower jaw. With the help of movable lower jaw, we can talk and eat. In lower and upper jaw, we have teeth for cutting and chewing food.

Rib Cage

Ribs make a cage of bones around the chest which is called rib cage. It protects our internal organs. Generally adults have 12 pairs of ribs. There is a long bone at the centre of the chest, which holds the ribs in place, called sternum. Ribs are attached to the backbone. Last two ribs are not attached to the sternum and are known as floating ribs. These floating ribs are attached to the backbone.

Backbone

It is made up of 33-ring shaped small bones called vertebrae. Backbone is also called as vertebral column. It is a hollow tube through which spinal cord runs.

Limbs

All human beings have two pairs of limbs: the forelimbs (arms) and hindlimbs (legs). Both forelimb and hindlimb is made up of 30 bones each. Thigh bone or femur is the longest bone in the body.

Note: The smallest bone of the body called stapes is present in the ear.

Functions of the Skeletal System

The skeletal system has the following functions:

• It gives shape and support to our body. Without the skeleton, our body would be floppy like a jelly. Forget about walking, we would not even be able to stand.
• It protects our soft internal organs.

(i) The skull protects the brain.

(ii) The rib cage protects the heart and the lungs.

(iii) The backbone protects the spinal cord.

• It allows the movement of different body parts.
• Bones contain marrow, where our blood cells are made.

Joints

A joint is the place where two bones meet. Most joints are movable. There are five kinds of free movable joints in our body.

Ball and Socket Joint

This type of joint allows movement in many directions. The shoulder joint and the hip joint are the examples of ball and socket joint.

Hinge Joint

This type of joint works like the hinges in the door. This kind of joint only allows back and forth movement. Bones in the knee, elbow, fingers, and toes have this type of joint.

Knee joint                      Elbow joint

Pivot Joint

This type of joint is found between the first two vertebrae of our backbone. It allows us to move our head up, down, and sideways.

Gliding Joint

This type of joint is found in the bones of the wrist and the ankle. It allows these bones to slide against each other in a gliding motion.

            Wrist joint                                  Ankle joint?

Saddle Joint

This type of joint is present in between the bones of thumb.

Fixed/Immovable Joint

This type of joint does not allow movement of bones. In our body fixed joint are found in skull and hip bones.

Note: Ligaments are strong elastic tissues that joints the bones together.

Tendons are strong, tough tissues that joint muscles to bones.

Nervous System

The nervous system controls the different organs of our body.   

Brain

Brain is a very important organ. It controls our body movements and helps us to store information in our memory. The human brain has three parts:

Cerebrum

It is the largest part of the human brain and is responsible for learning, memory, intelligence and logic. It also controls functions of eyes, ears, nose and tongue.

Cerebellum

It is situated below the cerebrum and is responsible for muscle coordination and for maintaining the balance of our body.

Medulla Oblongata or the Brain Stem

It controls activities such as heartbeat, breathing swallowing and sneezing.

Spinal Cord

The spinal cord is a thick cord of nerve tissue, which extends from the brain stem. It is protected by the backbone. The spinal cord is responsible for the transfer of information between the brain and the rest of the body. It even controls the actions that do not involve the brain. The automatic response of the body to an event is called a reflex action. Reflex actions are due to messages sent by the spinal cord. These actions are very fast. For example,

If you touch a hot object accidentally you withdraw your hand almost immediately.

Nerves

A network of nerves runs throughout our body. Sensory nerves pass through the spinal cord and carry messages of the body to the brain. Motor nerves carry messages back from the brain to the body.

Sense Organs

Our sense organs help us to see, hear, taste, smell and touch.

Skin

There are tiny nerve endings in our skin connected to spinal cord. These nerve endings help us to feel things. They also help us to detect heat, cold and pain. Skin is the largest external organ of human body.

Eyes

Eyes help us in seeing the various objects around us. Each eye has a lens. When we see an object the light passes through the lens and image is created and the message from this image is carried to brain. The brain recognizes the image and help us see things.

Ears

Ears help us in hearing. They also help us maintaining body balance. It consist of external, middle and internal ear.

Nose

Nose helps us to smell a variety of objects, from flowers to rotten eggs.

Tongue

Tongue helps us in tasting things. Different regions of the tongue help us in tasting different kind of substances.

Nutrition

Nutrition is defined as the process through which organisms take in and utilises materials necessary to support life. Food contains chemical substances called nutrients that are required by all living organisms. Our body requires carbohydrates, proteins, fats, minerals and vitamins. In addition to the five nutrients, our body also requires water and roughage.

Carbohydrates

Carbohydrates contain carbon, hydrogen and oxygen. Large amount of food that we eat consists of carbohydrates. The simplest form of carbohydrate is sugar such as glucose and fructose. For example, glucose is present in food items like jams, jellies, etc. and fructose is present in various fruits such as banana, apple, etc.

Complex form of carbohydrate is starch. Starch is present in food items such as wheat, rice, potato, etc. Glucose is stored in our body as glycogen.

Fats

Fats contain carbon, oxygen and hydrogen. Energy given by one gram of fat is more than the energy given by one gram of carbohydrate. Fat is present in food items such as butter, ghee, milk, etc. Our body takes long time to break down fat than to break down carbohydrate. Fats can be stored in the body. If the carbohydrates consumed are more than the required quantity, then excess amount is converted into fats and is stored in the body.

Proteins

Proteins contain nitrogen, carbon, oxygen and hydrogen. Proteins are required for the growth and repair of the body. Our hairs, nails, skin and muscles are made up of proteins. Protein is found in food items such as pulses, soya bean, nuts, egg, meat, etc. Protein cannot be stored in our bodies. If excess amount of protein is consumed then it is excreted from the body in the form of urea as urine or is stored as fats.

Vitamins

Vitamins are required for the healthy functioning of the body. However they are required in very small quantity by our bodies. If required quantities of vitamins are not present in our diet, then one can fall ill. The various vitamins required by our body are vitamin A, B-complex,

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Our body gets vitamins from outside sources such as plants. Vitamin D can be manufactured in the body in the presence of sunlight.

Minerals

Minerals are also required in small quantities by our body. Various minerals are sodium potassium, calcium, magnesium, chlorine, iron, fluorine, sulphur, phosphorus and iodine.

Water

Most of the weight of a person is due to water content in the body. Water is very essential for the existence of organisms. Water carries the digested food around the body. Water is the constituent of blood and carries chemicals and gases throughout the body. Water is responsible for regulating the body temperature.

Roughage

Roughage or fibre is required for the smooth functioning of digestive system. Roughage swells up in the intestine by absorbing water and helps in smooth movement of digested food in intestine. Fibre is present in whole grain flour, whole pulses, green peas, leafy vegetables and fruits.

Balanced Diet

A diet that contains all the nutrients required by the body in the right proportion is called a balanced diet.

Deficiency Diseases

If there is not a proper intake of food then a person suffers from malnutrition. The malnourished body does not function properly, and the person can suffer from diseases.

Children suffering from malnutrition have slow mental and physical growth and catches infection easily.