All living things have the following characteristics

They breathe in air and release air from their bodies

 

They reproduce

 

They feed

 

They grow

 

They remove waste (excrete) (Please note the spelling of "excretion" has no "a")

 

They move from place to place or parts of their body like plants do.

 

They sense (react to the changes in environment).

By being sensitive, living things, in particular the animals, are able to

  1. Find food.

  2. Find partners with whom to reproduce.

 

  3. Identify enemies or predators that may harm them.

  4. Escape from these enemies or predators.

 

  5. Identify the presence of harmful things such as poisons like gases,  fires and rotten food.

Human beings have five senses.

These are:

• Sight
• Smell
• Hearing
• Touch (feeling)
• Taste

The Eye

The eye is a sense organ for sight. The human eye is found in the socket or orbit found in front of the head.

The eye is shaped like a ball therefore called ‘eyeball’.

The eyeball is attached to the socket by muscles. The eye is used to see properly care is a must to avoid infection and to prevent any damage to the eye.

 

Strength of the eyes

The strength of the eyes is measured by how clearly one can see far or near objects. In a hospital, eye checking involves standing about two and a half metres away from a board with letters written in different sizes.

A person is then required to close one eye and read the letters as they are pointed out by the OPTICIAN.

Thereafter, one is supposed to close the second eye and read with the other eye.

 

The sense of sight helps us to tell:

• The distance from an object or thing. We can tell this when an object becomes smaller and smaller as it gets further and further away from our vision.
• The depth of something hollow if we look at it from its top.

• The size of an object by comparing two things next to each other using terms like smaller, bigger or larger.

The eye is a very important part of the body that must be well taken care of.

We can take care of the eye by

• Washing the eye with clean water to remove any foreign body in it. This ensures that the eye is constantly kept clean.
• If the foreign body is an insect or dust particle, it can be removed gently with a damp cloth or cotton-tipped stick.
• If it is a chemical, the eye should be washed with running water as first-aid but the person should be rushed to a doctor as fast as possible.

The Ear

The ear is a sense organ for hearing. The outer ear or pinna is at the side of the head.

It helps to concentrate and direct sound into the ear. There is a passage leading from the pinna into the inside of the ear. This passage directs sound into the ear.

The passage has a skin called the eardrum that connects the outer ear to the inner ear.

The passage of the ear must be protected from harmful things. This passage produces some substance called wax, which traps dirt to prevent harmful things and particles from entering the ear.

The wax must be cleaned out as often as possible as it may affect hearing if too much of it accumulates in the ear.

A person who cannot hear is said to be deaf and learns to communicate using sign language.

 Too much ear wax may lead to deafness but can be cleaned using cotton buds.

A deaf person is an able person with rights like every body else. The ear should therefore be cleaned regularly.

How to take care of our ears

1. If an insect gets into the ear, it is trapped by the wax. A person should therefore remove the wax together with the insect using cotton buds. Objects like beans or peas that may get into the ear as children play should be removed by tilting the head and using a blunt object to remove them.
2. To remove dust, bacteria and excess wax, the ear passage should be regularly cleaned using a cotton bud or match straw with a tiny ball of cotton or a clean piece of cotton cloth.
3. Avoid loud noises or sounds which can burst the ear drum and lead to deafness.
4. All ear infections should be treated immediately.

Communication using body parts

We can use our body parts to communicate with each other without necessarily using words.

This kind of communication is referred to as the use of gestures. Gestures can be classified into facial and body gestures.

The Tongue

This is the sense organ for tasting. The parts of the tongue that sense the taste are called taste buds. There are different taste buds for the different tastes.

These tastes include:

• Sweet: The sweet taste is detected by taste buds at the tip of the tongue. 
• Salty: The salty taste is also felt at the tip of the tongue. Anything salty contains salt.
• Sour: The sour taste is felt at the sides of the tongue. A sour taste is sharp and is acidic. An example is the taste of lemon or vinegar.
• Bitter:The bitter taste is detected by taste buds at the back of the tongue. Bitter taste is sharp and unpleasant, for example the taste of peels of lemon or peels of an orange.

It is important to take care of the tongue. This is done by brushing it using a soft brush to remove remains of food particles.

Cleaning the tongue ensures that the taste buds remain fresh and produce good breath.

The Nose

The nose is the sense organ that detects smell.

The inside of the nose has a sensitive, moist lining. What the nose smells is usually in gaseous form.

To be able to sense different smells, the sensitive lining of the nose should be exposed to the environment by regular cleaning of the mucus in the nose.

Rough objects should not be used to clean the nose as they may injure the delicate inner lining and this could lead to nose infections.

Colds which cause the secretion of mucus reduce the strength of the sense of smell.

The Skin

Below is a photography of human skin on a cold morning notice the pimples on it. Why do the pimples form?

The skin is the sense organ for feeling or touch.

The sense of touch helps us to identify and distinguish between varieties of texture whether rough or smooth, hard or soft.

By touching, we can also tell the shape of an object.

Some parts of the body are more sensitive to touch than others.

Fingertips are more sensitive than other parts of the body.

Other sensations the skin can help identify are:

1. Pressure

2. Temperature

3. Pain

Functions of the skin include

• Skin protect the inner tissues from mechanical damage, from bacterial invasion and from drying up
• Skin pigment protects the inner tissues from harmful ultraviolet rays and also determines the skin colour.
• Vitamin D is synthesized in the skin in the presence of sunlight.

• Control of body temperature
• Skin glands which produce oily sebum that is an antiseptic and also prevents the skin from drying or cracking. Skin has subcutaneous fat which insulates the body against heat loss.
• The skin is  a sensory organ.Skin has nerve endings which are sensitive to various stimuli such as touch, heat and pressure.

Facial gestures

These are gestures made by the face to communicate information such as emotions. For example;

1. Frowning to show inability to understand.
2. Smiling to show happiness.
3. Crying to show sadness or anger.
4. Gasping to show pain.

 

Body gestures

These are communication gestures using other parts of the body apart from the face.

Body gestures include nodding the head as a sign of agreement, shaking the head to imply denial or disagreement and shrugging to show a non-caring attitude.

Deaf people communicate through gestures example is the "I love you"sign below.

This is called sign language.

Traffic police communicate with motorists on the road through gestures, which is a special type of sign language.

Prevention of nearsightedness

Nearsightedness also called myopia may develop in a child because of spending too much time reading or looking at a computer.

Study the image below:

To prevent this it is good to ask the optician to issue the child with reading glasses so that the eyes are not damaged during reading.

Play this video:

This test has shown that

1. Some people are unable to see objects that are very near, but they can see far or distant objects easily. Such people are described as being long-sighted.
2. Other people are unable to see far or distant objects but can only see objects that are nearer. These people are said to be short-sighted.
3. Some people cannot see at all and are described as blind.

People who are either short sighted or long sighted can help correct the sight defect by wearing appropriate spectacles that enable them to see better.