W3 - Signalling (Sensory/motor) Flashcards
What afferent endings are responsible for converting energy of stimulus into an electrical signal?
Somatosensory afferents
Once the cation channels open, what can the generator potential become if the threshold is reached?
Action potential (during depolarisation)
What is particular about a-alpha or a-beta mechnaoreceptor endings?
They are encapsulated
What are a-gamma and C nerve fibre endings called?
Free nerve endings
Which afferents detect skin motion/grip and which detect edges/changes in texture?
1 - Meissner’s afferents, 2 - Merkel cell afferents
What afferents detect skin stretch and which tetect vibrations?
1 - Ruffini afferents, 2 - Pacinian afferents
What does two-point discrimination threshold measure?
Minimum interstimulus distance required to perceive two simultaneous stimuli individually
What nerves are visceral afferents sent through?
Sympathetic nerves
What is proprioception?
The understanding of where our body is in space and in relation to other parts of the body
Where are proprioceptor mechanoreceptors found?
Muscles, tendons and joints
Basal ganglia and cerebellum control complex movements/proprioception, is this true or false?
True
What are 3 things proprioceptors detect?
Force of movement, muscle tension and muscle stretch
What muscles do somatic innervation involve?
Skeletal muscles
What do muscles do visceral innervation involve?
Smooth, cardiac (+ glands)
What do large alpha motor neurons innervated and what do they facilitate?
Extrafusal skeletal muscle fibres, posture and movement
What do small gamma motor neurons innervated and what do they facilitate?
Intrafusal muscle fibres ?????????????
What does a motor unit consist of?
A motor neuron (usually alpha) and the muscle fibre(s) it innervates
Why can one action potential cause all muscle fibres in one motor unit to contract?
Multiple muscle fibres are innervated by a single ventral horn alpha motor neuron
What does the size of a motor unit depend on?
The number of muscle fibres innervated (smaller motor neurons innervate fewer)
What is particular about the threshold for activation for smaller vs larger motor units?
Smaller motor units have a lower threshold, needing fewer ions to influx for an AP
What are the 3 types of motor units?
Slow, fast fatigue resistant and fast fatigable
What are slow motor units used for and when are they recruited?
Used for sustained contraction (standing) and recruited earlier
When are FR motor units recruited?
After slow, before FF
What activity would a FF motor unit be needed to be recruited for? An FF motor unit is recruited last
Short, fast bursts of movement such as for a sprint
