Nervous System 2 Flashcards
What is pain ?
Sensation involved with emotion
What is the pain receptor called and what does respond to ?
Nociceptor a.k.a free nerve endings - responds to NOXIOUS stimulus e.g. harmful situations
What activates axon and example of one?
Receptors switched on by chemical activation
E.g. HISTAMINE released by mast cells which caused vasodilation (dilated blood vessels so increases blood flow to the area)
What are prostaglandins ?
Get released by damaged cell in area and stimulate pain receptors
What is aspirin ?
Pain relief drug, reduces production of prostaglandins therefore reduce pain sensation.
Where is the densest area of pain receptors, least dense and none?
Cornea= lots
Earlobes - few
Brain and Aveoli = none
What are the two types of axon ( that can carry pain messages ) and what type on pain and what info given to brain?
Sensory axons ;
1. A-Delta sensory fibres (very quick, thick axons, myelinated) - immediate sharp pain
2. C-fibres = thin and unmyelinated and slow - delayed throbbing pain
> fibres give Brain info about temperature and crude touch - tells CNS that something touched the body
What is the third type of fibre ( not directly involved to pain ) ?
A- beta sensory fibre - very large, myelinated, FASTEST
- provide info about quality of touch sensation e.g. fine tough e.g. smooth/rough/jaggy
- and also proprioception - body perception, knowing location of joints
What are local anaesthetics ?
Class of drug for pain relief which block conduction of axons a.k.a sensory fibres
What are the types of ascending pathways ? Spinal cord- brain
Spinothalamic pathway - crude touch / pain / temp - crosses over in spinal cord immediately
Posterior column pathway - fine touch and proprioception - travels on same side then crosses in medulla oblongata
What are the types of transactions called ?
Complete transection - spinal cord sliced across the way — would loose all sensation below that level of motor control - cut all communication
Hemilateral transection - only one side of spinal cord is chopped so will only affect a certain level e.g. legs will feel other sensations but not fine touch or proprioception on left leg and opposite on right leg - BROWN SEQUARD SYNDROME
What is the mechanism called where the spinal cord can modify messages ? Types of cells involved with what fibre and what purpose ?
Gate-control system;
- A- beta input - REDUCES pain by activating SUBSTANTIA GELATINOSA CELLS (pain relief cells) - e.g. when you hold an area in that hurts, activates A Beta Input and reduces pain
- A Delta and C Fibre input = PAIN MESSAGES to brain by activating TRANSMISSION CELLS
What is the neurotransmitters that inhibits the transmission cells ?
ENKEPHALIN neurotransmitters = body’s own morphine
