The Nervous SystemBy Po-Han Chen

What good does it make?

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

Nervous System

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

Parts

Your Nervous system is mainly made up of

The NervesSpinal cord

The Brain

Nerve Cells

The nervous system is made up of Neurones.

Each neurone consists of a cell body and extending nerve fibre

Neurons and Synapses

Neurons can be divided into 3 types

Sensory

Motor

Interneurons

Sensory Neurons

INPUT From sensory organs to the brain and spinal cord.

I.e., from Nose, eyes to brain

Motor NeuronsOUTPUT From the brain and spinal

cord To the muscles and glands.

Interneurons (Relay Neurons)

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

Structure of Neuron

The Neuron can be separated into 4 parts :

The cell bodyDendritesAxonMyelin sheath

The cell body

Contains the Cell’s Nucleus

•Round structure

•Contains DNA

•Dose Protein manufacturing

•Directs metabolism

•No role in neural signaling

Dendrites

•Information collectors

•Receive inputs from neighboring neurons

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

Axon

•Output structure

•One axon per cell, 2 distinct parts

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

YouTube Video

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

How neurons communicate 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 Big Boss

Brain is the organ that controls everything in your body, including

your thought and reaction.

Nervous System

The nervous system is divided into two sections:

Central Nervous System+

Outer Nervous System

Central 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

The Path

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

Outer Nervous System

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

Sense Organs includes

Skin - Touch Nose - Smell

Tongue - Taste

Nerve Impulse

Electrical signals are carried through nerve impulse which is widely spread in

the body

Action Potential

An action potential is a short-lasting event in which

the electrical membrane potential of a cell rapidly rises and falls, following a

stereotyped trajectory

Polarisation

Resting neurons have Potential Difference

Outer surface-> Positively chargedInner surface -> Negatively charged

Resting potential (-65mV), therefore said Polarised

How does it work?

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.

Depolarise when Stimulated 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.

Makes it much easier

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

Practice Questions 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.

Practice Questions

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

Answer:

Bigger axon diameters

Increase in temperature

Bibliography

Notes from Richardwww.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

THE ENDThank you for your attention