7 sensory systems Flashcards
why do we need sensory systems
- maintain homeostasis
- detect and react to changes in environments
- protect the body from damaging stimuli
what are the touch receptors
- mechanoceptors (pressure)
- thermoceptors (temp)
- nociceptors (noxious stimuli - pain)
what are the types of nociceptors
- thermoreceptors (extreme temps)
- mechanoreceptor (intense pressure)
- polymodal (high intense mechanical, chemical and thermal stimuli)
is the pain always felt at the site of injury
no
eg heart attack pains been felt in arm
is there a specific pain region in the brain
no
can pain become less sore, if so how
yes, there are modulators which can make 2nd instance of pain less sore due to previous experience
steps of pain transmission pathway
- transduction
- transmission
- relay
- interpretation
- modulation
what nerve fibres are the first pain related with
A epsilon fibres
are A epsilon fibres myelinated
yes
what nerve fibres are the second pain related to
C fibres
what type of pain is first vs second
first - sharp pain
second - delayed long lasting pain
what does the myelin allow
the action potential to maintain
where is the dorsal route found
outside the cns
what is the excitatory neurotransmitter in nociceptive pathways
glutamate
how do nociceptive pathways project to the brain
via the spinothalmic tract - descending inhibition and perception
where do nociceptive pathways synapse
in the dorsal horn of the spinal cord
what does peripheral sensitisation cause
increase sensitivity to the skin
eg suburn making skin more sensitive
what does central sensitisation cause
structural and chemical changes at the synapse
eg chronic pain
what can modulate perception of pain
previous experiences, mood, genetics etc
what causes acute/physioloical pain
activation of A epsilon fibres and C fibres
what is acute pain related to
actual or potential tissue injury, initiates protective reflexes
what is the gate theory of pain
pain signals can be interrupted in the spinal cord which acts as a gate
can people with heart issues have cox inhibitors
NO
why is paracetamol thought to be so good
affects many pathways
how do local anaesthetics work
by intracellular blocking of Na channels
steps of local anaesthetics mode of action
- unionised LA enters cell
- LA becomes ionised intracellularly
- LA blocks Na channels
- Pain signalling inhibited
what primarily mediates analgesia
activation of U receptors
what does inflammation do in regards to na channels
increase
what does nerve damage or cns damage do in regards to na channels
increase some channels and decrease others
