Week 4- pharmacology Flashcards
Where do spinal interneurons receive input from?
Primary sensory axons
Descending axons from the brain
Collateral branches of LMNs
Other interneurons
NOTE- Input into spinal interneurons can be excitatory or inhibitory. But they themselves can also be excitatory or inhibitory.
:)
For a muscle movement to occur you need…
What is this called?
One group of muscles to contract
The opposing group of muscles to contract.
Termed- reciprocal inhibition
Describe the process of reciprocal inhibition
The myototic reflex causes the extensor muscle to contract, but for the leg to extend the flexor muscle must also relax.
The 1a afferent from the muscle spindle interacts with a spinal interneuron. It has an excitatory effect on the alpha motor neurone supplying the quad muscles and an inhibitory effect on the alpha motor neurone supplying the hamstrings.
This is called a polysynaptic reflex.
Voluntary movement arises from the motor cortex. Describe its innervation.
It travels from the cell body within the motor cortex to two sets of targets. Alpha motor neurones of the extensor and inhibitory neurones of the flexor.
What is the flexor reflex?
Noxious stimulus causes limb to flex by-
Contraction of flexor muscles via excitatory interneurones
Relaxation of extensor muscles via excitatory and inhibitory interneurons
What is the extensor reflex?
Noxious stimulus causes limb to extend by
Contraction of extensor muscles via excitatory interneurons
Relaxation of flexor muscles via excitatory and inhibitory interneurons.
For an activity like walking to occur, you need rhythmic, alternating activity that moves the limb. What do you need for this to occur?
A pacemaking interneuron that rhythmically discharges APs
Describe the set up of pacemaking interneurons and how they extend and flex muscles?
The pacemaker interneuron synapses an excitatory and inhibitory interneuron. These then synapse with the excitatory to an inhibitory and an inhibitory to an excitatory interneuron.
There are two rhythmic interneurons and they can’t be active at the same time.
Which areas of the brain have input into the actions of muscle movement?
Neocortex and basal ganglia- strategy- what is the aim of the movement
Motor cortex and cerebellum- which muscles need to move to carry out this strategy
Brainstem and spinal cord- execution of the activity.
What is pain?
An unpleasant sensory and emotional experience related to actual tissue damage or described in terms of such damage.
How can pain be classified?
Three forms
- Nociceptive- acute pain e.g. pin prick
- Inflammatory-prolonged pain e.g. sunburn, wound infection
- Pathological- neurogenic pain e.g. IBS, fibromyalgia, diabetes, cancer
If there is a problem with the skin, how will the pain feel?
Well localised to a specific area.
Pricking, stabbing or burning.
If there is a problem with the viscera, how will the pain feel?
Poorly localised
Dullness, vagueness, fullness and nausea.
If there is a problem with the muscles, how will the pain feel?
Poorly localised
Aching, soreness/tenderness, cramping stabbing burning.
