UNIT 7 NATURAL SCIENCE 4º

UNIT 7  -  WE INTERACT WITH THE WORLD

■ The interaction function in human beings

• How does our body react?

The interaction function uses three types of apparatus: receptors, controllers and effectors.

Receptors, controllers and effectors

The receptors

The receptors are the sense organs. They capture what is happening outside or inside our bodies and send the information to the controllers.

The controllers

The controllers are the organs of the nervous system: ● The brain is inside the skull. It receives information from the receptors, interprets the information and produces a response. It collects information in its memory and coordinates all the organs of the body. ● The spinal cord is inside the spinal column. It controls the organs of the body and produces quick and simple order and responses. ● The nerves connect the sense organs to the brain and spinal cord.

The effectors

The effectors are the organs which carry out the orders from the controllers.

• What else can we do?

Human beings are the animal with the most complex and advanced interaction function, because our brains are very developed.

Because of brain:

-  We have memory.

-  We can learn everything

-  We can communicate.

-  We have a highly developed sensibility.

-  We can have feelings for other people and notice feelings other people have for us.

■ How our senses work

• Senses and the senses organs

Sight and the eyes

The eyes are the sense organs of sight. They work like a camera:

·         Light enters through the pupil.

·         The lens focuses the light and forms an image on the retina.

·         The retina converts the image into signals which it sends to the brain through the optic nerve.

·         The brain interprets the signals and permits us to perceive the shape, colour, etc.

Hearing and the ears

The ears are the sense organs of hearing and they detect vibrations.

·         Vibrations enter through the auditory canal.

·         The eardrum vibrates and transmits the vibration to the cochlea.

·         The cochlea transforms the vibrations into signals and they are sent to the brain through the auditory nerve.

·         The brain interprets the signals as sounds.

Taste and the taste buds on the tongue

The taste buds are the sense organs of taste.

·         For each substance, the taste buds send different signals to the taste nerve.

·         The brain interprets these signals as different tastes.

Smell and nose

The nose is the sense organ of smell.

·         For each substance, the receptors in the nose send different signals to the brain through the olfactory nerve.

·         The brain interprets the signals as different smells.

Touch and receptors in the skin

Skin is the sense organ of touch. It contains a lot of receptors thatare sensitive to temperature and pressure.

·         When the receptors feel something, they send signals to the brain through the nerves.

·         The brain interprets the signals as cold, heat, pain, etc.