Sensitivity

Sensitivity:
Sense organs detect changes inside and outside your body. Scientists used to think humans had 5 senses but now we know we have many more including heat, cold, pain and changes in position. A stimulus are change in a environmental factor that is detected by receptors. Sense organs contain receptor cells which detect a stimulus.

Receptor cells create electrical signals which are called impulses, they usually travel to the brain. The brain processes this information and sends impulses to other organs to alter the way the body works.

Electrical impulses travel along cells called neurones. The travelling of impulses are called neurotransmission. There are many dendrons in a neurone which have many branches at the end of it called dendrites. The dendrites receive impulses from receptor cells. The impulse moves along the dendron to the axon. It then goes to the ending where it passes on to other neurones.

Neurones are all packed together to create nerves. The spinal cord is connected to the brain and contains many packed together nerves. The brain and spinal cord together form The Central Nervous System. This controls your body.


Key Words:

Sense organs
Stimulus
Receptor cells
Impulses
Neurones
Neurotransmission
Dendrons
Dendrites
Axon
Nerves
Spinal cord
Central Nervous System


Questions:

1. What is a stimulus?
2. State one way in which the brain alters the way the body works to stop it getting too cold.
3. Why is it necessary for neurones to link to each other?
4. Which organs are in the CNS?
5. When you pick up an ice cube how does your brain know it's an ice cube?


What you should've learnt:

That the Central Nervous System consists of the brain and spinal cord and is linked to sense organs by nerves.

The structure and function of dendrons and axons in the nervous system.

How stimulation of receptors in the sense organs send electrical impulses along neurones.