Biology Unit 1

Sense Organs detect Stimuli: A stimululas is a change in the enviroment which you may need to react to. For exsample when you touch a hot plate (stimuli) and you pull away really fast (that was your nerves) 

You have five different sense organs eyes, ears, nose, toungue and skin.They all contain different receptors:

1) Eyes: Light receptors

2) Ears: Sound and "balance" receptors

3) Nose: Smell receptorssensitive to chemical Stimuli

4) Toungue: Taste receptors- sensitive to bitter, salt, sweet amd sour, plus the taste of savoury things like monosodium glutamate (MSG)- chemical receptors

5) Skin: Sensitive to touch, pressure and tempreture change

The Cental Nervous System (CNS) coordanites a responce:

1) the CNS is where all the information from the senses organ is sent, and where reflexes and actions are coordinated.The central nervous system consists of the brain and spinal cord ONLY.

2) Neurons (nerve cells) transmit the information (as electrical impulses) very quickly to and fromthe CNS.

3) "Instructions" from the CNS are sent to the effectors (muscles and glands), which respond accordingly.

TYPES OF NEURONES:

Sensory Neurones: The nerve cells that carry signals as electrical impulces from the receptors in the sence organs to the CNS.

Motor Neurones: the nerve cells that carry signals to the effector muscles or glands.

Effectors: Muscles and glands are known as effectors. They respond in different ways- muscles contract in responce to a nervous impulse, whereas glands secrete hormones.