Pain + analgesics Flashcards
(38 cards)
Where do pain signals travel to + how can they be used to reduce pain?
From damaged tissues into spinal cord and up towards the brain.
Pain can be reduced by:
Interfering with nerve signals carrying pain.
Reducing inflammatory response therefore reducing intensity of pain signals.
What are the 3 types of pain?
Visceral (stretch receptors)
Neurogenic pain/Neuropathic
Somatic pain (A-delta= milenated, acute pain. C-fibres= non-milenated, acute pain.)
What are the characteristics of visceral pain?
Comes from internal body organs (tumours, fluid collection, heart problems)
It is throbbing pain that is hard to pinpoint the source of.
What are the characteristics of somatic pain?
Pain from bones, tendons and tissues.
It is sharp, cutting pain with an easily identifiable source.
What is nociceptive pain?
A type of physical pain, caused by potentially harmful stimuli being detected by nociceptors around the body.
What is neurogenic/neuropathic pain?
Pain that develops when the nervous system is damaged or not working properly.
Can be caused by disease or illness.
It does not develop in response to any specific circumstance or stimulus.
How does the brain process pain?
Fore-brain, hypothalamus
Brain makes judgements as to whether pain is important, contextualises it.
Fore-brain controls emotional response to pain.
Hypothalamus controls autonomic/physical responses to pain (HR, sweating, dilated pupils)
What are the sensory (afferent) pathways in pain?
1st order neurone (primary afferent) is first in chain, carries pain from injury to spinal cord.
Pain arrived in dorsal horn and synapses with 2nd order neurone - crosses from one side of dorsal horn to other + up spinal cord.
Pain travels up spinal cord along 2nd order neurone up into brain and synapses in thalamus with 3rd order neurone.
What does the vecticular formation + the limbic system do in response to pain?
Recticular formation - increases alertness and triggers increase in HR + BP.
Limbic system - emotional response
What does the cortex + the hypothalamus do in response to pain?
Cortex - determines location, intensity and discriminates pain and determines the meaning of incoming pain signals.
Hypothalamus - autonomic and endocrine response to pain.
What is descending inhibition?
Certain areas of the brain (periaqueductal grey matter) can activate descending pathways, sending signals back down the spinal cord to block transmission of the incoming psi signal between 1st + 2nd order neurone.
This has the capacity to block incoming pain signals.
What is the process of descending inhibition?
- Pain signals travel along 1st order nerves to spinal cord.
- In spinal cord the 1st order neurone synapses with 2nd order neurone.
- Signals travel up brain and are transmitted and processed.
- Regions of brain (PAG) respond by sending inhibitory signals down to 1st + 2nd order neurone synapse, inhibiting it and blocking pain signals.
What are the 4 phases of nociception?
Transduction
Transmission
Modulation
Perception
What is transduction?
The process of stimuli activating nerve endings.
What is transmission?
Transmission is the functions by which pain is carried to the brain.
What is modulation?
Modulation acts to reduce activity in the transmission system.
What is perception?
Perception is the awareness produced by sensory signals.
What are our natural analgesics?
Endorphins - morphine, fentanyl etc mimic these.
What is a receptor?
How are they used in pain relief?
A binding agent on a cell that allows the cell to respond to externals in its environment.
The brain releases endorphins which bind to receptors.
What is morphine and what are it’s effects?
Morphine is an opioid analgesic.
It affects respiration, causes miosis (pinpoint pupils), it sedates, is euphoric and is a dependent/addictive drug.
How does morphine work in the body?
Descending inhibition releases endorphins and morphine mimics these endorphins and shuts down the synapse in the pain pathway, blocking pain signals.
What are the side effects of morphine?
It can cause respiratory + GI tract problems by acting on the neuroreceptors in the smooth muscle of the airways and the GI tract.
Can cause nausea and vomiting.
Acts on CNS + CVS.
What is morphine used to treat + who should it be avoided in?
Pain, coughing and diarrhoea.
Not always suitable for people with decreased liver function as the liver is responsible for metabolising opioids.
What are other opioids besides morphine?
Codeine, diamorphine, fentanyl.
