Unit 2 INTERACTION SUMMARY

1

THE SENSE ORGANS

HUMANS are LIVING THINGS who carry out INTERACTION using…

PROCESS The sense organs detect the change (something different)

The sensory neurons send information to the brain.

The brain interprets the information and decides what to do.

The brain sends an order to the muscles.

The muscles move the body.

Stimulous

Sense organs

Locomotor System Nervous System

SIGHT 1. Light enters our eye through the

cornea and the pupil. 2. The iris is a muscle that makes the

pupil bigger or smaller. 3. The lens focuses the light which

allows images to be projected onto the retina at the back of our eye.

4. Nerve receptors in the retina send this information along the optic nerve to our brain.

SMELL Our sense of smell detects chemicals in

the air. When air enters our nose through our nostrils, these chemicals

come into contact with the nerve receptors. The nerve receptors send this information along the olfactory nerve

to our brain.

TASTE The receptor cells for taste are on the tongue inside

each taste bud. They detect different tastes (bitter, sour, salty and sweet).

HEARING 1. Sound waves enter our ear through the auditory canal (outer ear) and make

the eardrum vibrate. 2. This vibration also causes the three small bones in our middle ear to vibrate. 3. When these vibrations reach the cochlea in our inner ear, they are

transformed into electrical signals. 4. The auditory nerve sends these signals to our brain.

The main function of the semicircular canals in our inner ear is to keep our

balance and equilibrium.

TOUCH The middle layer of skin,

called the dermis, contains nerves and tiny

blood vessels. These nerves detect sensations,

such as temperature, pain and texture and

send this information to our brain.

Unit 2 INTERACTION SUMMARY

2

CONCEPT It is the system that we use to receive information from the sense organs, and after analyzing and interpreting this information, it responds sending messages which cause the body to react. It is made up of neurons. It is divided into two parts: the central nervous system and the peripheral nervous system.

PARTS The

nervous system is made up

of...

THE NERVOUS SYSTEM

Central Nervous S.

Peripheral Nervous S.

The brain: protected by the cranium, it controls the body and has three parts:

1. The cerebrum controls thoughts, emotions, language and behavior. Also our voluntary movements. It is divided into the left and right hemispheres. 2. The cerebellum co-ordinates movements and balance. 3. The brain-stem controls involuntary movements.

The Spinal Cord goes from the bottom of the brain to the bottom of the spine and it is protected by the spinal column. It is formed by the nerves, which carry messages to and from the central nervous system. Nerves can be: 1. The sensory nerves carry information from the sense organs to the Central Nervous System. 2. The motor nerves carry orders from the Central Nervous System to the muscles and organs.

Unit 2 INTERACTION SUMMARY

3

THE LOCOMOTOR

SYSTEM

Function

1. The muscle receives an order from the brain. 2. The muscle contracts (gets shorter) and pulls

from the bone connected to it. 3. The order stops and the muscle relaxes (it goes

back to normal), having the bone return to its original position.

MUSCLES. They contract and relax and give our body shape. Tissues called tendons connect muscles to bones. We have voluntary and involuntary muscles.

JOINTS. Our bones are connected to the joints by ligaments. There are three types (fixed joints, semi-flexible joints and flexible joints)

THE SKELETON. It supports, gives shape and protects the internal organs. It is made up of bones (hard bone tissue) and cartilage (flexible tissue). 3 types of bones (short, flat, long)