HES 202 EXAM QUESTIONS AND ANSWERS LATEST
UPDATE
Force is controlled by:
1. Altering the # of active MUs (de/recruitment)
2. Changing Frequency of activation (rate coding - MU discharge rate)
know how to draw this
Saltatory conduction
propagation of action potential down the axon
Myelination
insulates the axon and prevents movement of ions (Na+ and K+) across the membrane
benefits to saltatory conduction and myelination
1. Increases conduction velocity without a change in axon diameter
2. Reduces metabolic cost as only small segments of the axon require the Na+-K+
pump to restore the resting membrane potential
Curare (d-Tubocurarine)
prevents binding Ach to
Ach receptor
- used as medical paralyzing agent
Botox (Botulinum Toxin)
prevents
release of Ach
3 types of motor units
Type I: Slow
Type IIa: Fast fatigue-resistance
Type IIx: Fast fatigable
Twitch:
physiological response of a MU to stimulation (force response)
Force modulation by:
- # of recruited MUs (Size principle)
- Rate coding (discharge rate of action potentials
Rheobase
direct measure of the current that has to be put into a neuron to get it to fire
The Size Principle
Motor units recruited from smallest to largest
Recruitment threshold
amount of force needed to 'turn on' motor unit
recruitment
Increase the number of motor units
rate coding
Increase rate of firing of individual motor units
electromyography (EMG)
Recording of the electrical activity from muscle
Divergence in neurons
, single neuron -->multiple neurons
convergence in neurons
multiple neurons --> single neuron
afferent
towards cns
efferent
away cns
Conduction velocity depends on diameter
Larger diameter = faster conduction
Group Ia afferents
- muscle spindles
- length and velocity
Group II afferents
- muscle spindles
- static length
Two types of receptors:
1. Bag (based on shape)
-Bag 1: Dynamic
-Bag 2: Static
2. Chain: Static
Two types of afferents
1. Type Ia (primary) - length & velocity
-Innervate bag 1, bag 2, & chain
2. Type II (secondary) - length
-Innervate bag 2 & chain
how do we record muscle spindles
Microneurography: single unit action potentials
alpha motor neuron
sends info to muscle fibers or skeletal fibers
gamma motor neuron
sends info to muscle spindles
Dynamic gamma
sends info to bag 1
static gamma
sends info to bag 2 and chain
Turning on the gamma system prevents the
spindle from becoming unloaded during shortening contractions, and keeps it sensitive
to stretch
Gamma dynamic makes the spindle more
velocity sensitive
Gamma static makes the spindle more
length sensitive
Whats the role of the muscle spindle receptors?
- Sense muscle length
- Sense muscle velocity
Whats the function of the GTO receptors?
UPDATE
Force is controlled by:
1. Altering the # of active MUs (de/recruitment)
2. Changing Frequency of activation (rate coding - MU discharge rate)
know how to draw this
Saltatory conduction
propagation of action potential down the axon
Myelination
insulates the axon and prevents movement of ions (Na+ and K+) across the membrane
benefits to saltatory conduction and myelination
1. Increases conduction velocity without a change in axon diameter
2. Reduces metabolic cost as only small segments of the axon require the Na+-K+
pump to restore the resting membrane potential
Curare (d-Tubocurarine)
prevents binding Ach to
Ach receptor
- used as medical paralyzing agent
Botox (Botulinum Toxin)
prevents
release of Ach
3 types of motor units
Type I: Slow
Type IIa: Fast fatigue-resistance
Type IIx: Fast fatigable
Twitch:
physiological response of a MU to stimulation (force response)
Force modulation by:
- # of recruited MUs (Size principle)
- Rate coding (discharge rate of action potentials
Rheobase
direct measure of the current that has to be put into a neuron to get it to fire
The Size Principle
Motor units recruited from smallest to largest
Recruitment threshold
amount of force needed to 'turn on' motor unit
recruitment
Increase the number of motor units
rate coding
Increase rate of firing of individual motor units
electromyography (EMG)
Recording of the electrical activity from muscle
Divergence in neurons
, single neuron -->multiple neurons
convergence in neurons
multiple neurons --> single neuron
afferent
towards cns
efferent
away cns
Conduction velocity depends on diameter
Larger diameter = faster conduction
Group Ia afferents
- muscle spindles
- length and velocity
Group II afferents
- muscle spindles
- static length
Two types of receptors:
1. Bag (based on shape)
-Bag 1: Dynamic
-Bag 2: Static
2. Chain: Static
Two types of afferents
1. Type Ia (primary) - length & velocity
-Innervate bag 1, bag 2, & chain
2. Type II (secondary) - length
-Innervate bag 2 & chain
how do we record muscle spindles
Microneurography: single unit action potentials
alpha motor neuron
sends info to muscle fibers or skeletal fibers
gamma motor neuron
sends info to muscle spindles
Dynamic gamma
sends info to bag 1
static gamma
sends info to bag 2 and chain
Turning on the gamma system prevents the
spindle from becoming unloaded during shortening contractions, and keeps it sensitive
to stretch
Gamma dynamic makes the spindle more
velocity sensitive
Gamma static makes the spindle more
length sensitive
Whats the role of the muscle spindle receptors?
- Sense muscle length
- Sense muscle velocity
Whats the function of the GTO receptors?
