Explanation of Peripheral nervous system ?

RE: Explanation of Peripheral nervous system ?

The peripheral nerves consist of two types of nerve fibres, motorwhich control movement and sensory nerves which permit feeling. These nerves work together like a two way cable system. Messages from the brain travel via the upper motor neurones, down the spinal cord, through the lower motor neurones (such as the sciatic nerve in the leg) to the muscles. In the sensory system the messages travel the other way, from the sensory neurones to the spinal cord to the brain.

The peripheral nerves themselves are likened to an electrical cable with an inner fibre the 'Axon' wrapped in a protective insulating sheath of a substance called 'myelin'. If the myelin is damaged the nerve impulses tend to be conducted more slowly than usual. whereas if the Axon is damaged thespeed of conduction is normal but the strength of the signal is reduced.

Two of the diseases of the Nervous system is Muscular sclerosis , damage to the Axon.
Charcot Marie Tooth Neuropathy (CMT) damage to the
peripheral nerves.

RE: Explanation of Peripheral nervous system ?

Hiya

Nervous system in general is composed of two main parts
[blockquote]
1. Central Nervous System = Brain and Spinal column
and

2. Peripheral Nervous System is the part of the nervous system that lies outside the brain and spinal cord andis comprised of two parts
a. Autonomic Nervous Systemmainly involuntary reactions [which is comprised of two parts]
i. Sympathetic Nervous System [fight and flight in emergencies][/blockquote]

• stimulates heartbeat
• raises BP
• dilates the pupils
• dilates the trachea and bronchi
• stimulates the conversion of liver glycogen into glucose
• shunts blood away from the skin and viscera to the skeletal muscles, brain, and heart
• inhibits peristalsis in the gastrointestinal (GI) tract
• inhibits contraction of the bladder and rectum

ii. Parasympathetic Nervous System [rest and digest in non-emergencies] reacts in this way:

• slowing down of the heartbeat
• lowering of blood pressure
• constriction of the pupils
• increased blood flow to the skin and viscera
• peristalsis of the GI tract

iii. Enteric Nervous System [gastro-intestinal tract, pancreas and gall bladder]

b. Somatic Nervous System [sensory and largely voluntary reactions]

If you want a clear and simple explanation have a look at the bbc website link:

[link= http://www.bbc.co.uk/science/humanbody/body/factfiles/peripheralnervoussystem/peripheral_nervous_system.shtml ]http://www.bbc.co.uk/science/humanbody/body/factfiles/peripheralnervoussystem/peripheral_nervous_system.shtml[/link]

it gives a nice description. For a diagram of the Nervous system including Central, Peripheral, Somaticand Autonomic have a look at:
[link= http://www.sci.port.ac.uk/rad/anatomy/03/001.htm ]http://www.sci.port.ac.uk/rad/anatomy/03/001.htm[/link]
and there are "small arrows" forward and back at top of page to browse through several pages of text and diagrams.

Types of neurons:
In the peripheral nervous system, neurons can be functionally divided in three ways:
[blockquote]
1. Sensory (afferent) - carry information INTO the central nervous system from sense organs
2. Motor (efferent) - carry information away from the central nervous system (for muscle control).
3. Cranial - connects the brain with the periphery or spinal - connects the spinal cord with the periphery.
4. Somatic - connects the skin or muscle with the central nervous system or
5. Visceral - connects the internal organs with the central nervous system.[/blockquote]
for more info on Interneurones see:

[link= http://www.blackwellpublishing.com/press/pressitem.asp?ref=1196 ]http://www.blackwellpublishing.com/press/pressitem.asp?ref=1196[/link]

hope this helps
Am sending some pics as private mail which I hope will help too.
Little red
xxx

RE: Explanation of Peripheral nervous system ?

Hi Littlered

I have PM'd you just a second ago but wondered if you knew any of the below:-

Q . The Autonomic System has an effect on different parts of the body give examples of :-
Bladder - Sympathetic
Bladder - Parasympathetic

Digestive - Sympathetic
Digestive - Parasympathetic

Liver -Sympathetic
Liver -Parasympathetic

Salivery Glands- Sympathetic
Salivery Glands- Parasympathetic

I had 25 to do for my homework & have 4 left which i'm finding difficult !!!!

Can you help me at all please ?

Many thanks

Suex

RE: Explanation of Peripheral nervous system ?

Hi caringsoul

Thanks sooooo much for your reply, its helped know end, really thankful to you.

Many thanks again

Suex

RE: Explanation of Peripheral nervous system ?

Actually, having to describe how the sympathetic and parasympathetic nervous systems affect the liver, salivary glands, bladder and digestive system is a really good way of building an understanding of the "flight and fight" - emergency response as opposed to the "rest and digest" relaxed response when all is safe! I think the pics I've sent you privately back this up really simply and well.

Best wishes
Little red
xxx