By Po-Han (George) Chen

Creatures on the world can feel the surrounding in order to adapt the environment for survival. Animals relies on Endocrine system and Nervous system to adjust itself. Nervous system controls muscle contraction and coordinate the organs within a short time in order to protect itself.

3% of overall mass, but it is the most complicated system in body

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body

Your Nervous system is mainly made up of

The nervous system is made up of Neurones.

Each neurone consists of a cell body and extending nerve fibre

Neurons can be divided into 3 types

Sensory

Motor

Interneurons

INPUT From sensory organs to the brain and spinal cord.

I.e., from Nose, eyes to brain

OUTPUT From the brain and spinal cord To the muscles and glands.

Interneurons carry information between other neurons only found in the brain and spinal cord.

The Neuron can be separated into 4 parts :

The cell bodyDendritesAxonMyelin sheath

Contains the Cell’s Nucleus•Round structure

•Contains DNA

•Dose Protein manufacturing

•Directs metabolism

•No role in neural signaling

•Information collectors

•Receive inputs from neighboring neurons

•If enough inputs the cell’s AXON may generate an output

•Output structure

•One axon per cell, 2 distinct parts

•The tube branches at the end and attaches to other cells.

http://www.youtube.com/watch?v=i-NgGKSNiNw

Neurons communicate by electrical signal called the Action Potential.

it is based on movements of ions between cells.

When an Action Potential occurs a molecular message is sent to neighboring neurons

The nervous system is divided into two sections:

Central Nervous System+

Outer Nervous System

The Central Nervous System is made up of Brain and Spinal cord

Electrical Signals are carried from the Brain to the receptors through Spinal

cord

Between the receptors and the effectors, the Central Nervous system coordinates the action potentials passing through the nervous system.

The Outer Nervous System is made of the nerves and the sense organs

Sense Organs includes

Skin - Touch Nose - Smell

Tongue - Taste

Resting neurons have Potential Difference

Outer surface-> Positively chargedInner surface -> Negatively charged

Resting potential (-65mV), therefore said Polarised

Resting potential is generated by Sodium-

potassium pump and a potassium channel

The pump moves three sodium ions out by active

transport for every two potassium ions brings in.

The facilitated diffusion allowed to let potassium

ions back out.

More positive ions move out than move in.

Sodium potassium pumps work all the time, but Channel protein can be opened or closed.

Depolarisation requires another protein channel, which is Sodium Channel.

When Stimulated, sodium channel opens and then ions diffuses in. This increases the positive

charge inside the cell. Charge is now Reversed. With a potential difference of +40mV, This is

Action Potential and membrane is depolarised.

http://www.youtube.com/watch?v=SCasruJT-DU

Q: What do sensory, relay and motor neurons do in the nervous system?

Answer:Sensory – INPUT From sensory organs to the

brain and spinal cord.

Relay – Interneurons carry information between other neurons only found in the brain and spinal cord.

Motor – OUTPUT From the brain and spinal cord To the muscles and glands.

Q: Give two factors that increases the speed of conduction of action potentials

Answer:

Bigger axon diameters

Increase in temperature

www.deafed.net/PublishedDocs/www.psych.wright.edu/Wayne/http://academic.luzerne.edu/http://en.wikipedia.org/wiki/Neuronhttp://en.wikipedia.org/wiki/Action_potential

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/nervous%20system/neurons.htm

Thank you for your attention