7- Muscles and PNS Flashcards
Cite the (5) fundamental components of muscles
Receptor (muscle spindle), afferent nerve pathway, connection in spinal cord, efferent nerve pathway and effector (muscle for example).
What’s a reflex arc ?
A reflex that strats and ends in the same organ.
Cite the fifts movement type, their CNS component and the functionnal circuit.
1-Muscle tone/tension/ spinal chord (single segment)/simple reflex arc
2-Involuntary, single purpose movement via groups of muscles, primitive rhythmic mvt / multiple segments of SC/polysynaptic reflex arc
3-Balance, gait/ Cerebellum/Vestibular sys
4-Modulation on spinal reflexes/ Brainstem, striatum/extrapyr sys
5-Voluntary mouvements/Cerebral cortex/pyr sys
What’s the role of motor units?
Incremental control of function and mvt
On what the size of motor unit depends?
On the function: example of the rectus oculus lateralis, many motor units with 13 muscle fibers each. This is for a tght control of the muscle. As a comparison, biceps has 774 Motor units with 750 muscle fiber each, it allow more streng but not a fine control.
Why is there mytochondrias in neuromuscular end plate ?
It gives energy (ATP)
Why the junction of the axon to the muscle is folded ?
To increase the contact areas (more receptors and ion channels)
What are the two tubular systems in muscle fibers ?
The T-system (from muscle to its depth ) and the sarcoplasmatic reticulum that brings the AP to contraction of the muscle.
What leads to muscle contraction (AP, chimical reaction in the muscle fibers)
AP is in T-sys - transfered to Sarcoplasmatic reticulu that release CA2+, calcium goes in muscle fibers and the potential goes drom +30 to -80mV.
Describe the phenomenon of muscle contraction at the level of electro mechanical coupling
Myosin needs to bind to the aktin to move its hat and produce sliding. Calcium binds to troponin, it gives he myosin access to the actin. Magnesium support phosphorilation of ATP into Pi + ADP and myosin binds atin, Pi leaves and the myosin hat bind from 90 to 50°, then ADP leaves and it binds to 45° after that another ATP binds the myosin and it detaches from the aktin.
What is the different between basic EMG and compound EMG ?
basic emg = electrical activity of a single MU. Muscle AP = 10s, diagnostic application (qualitativ & quant analysis of singe muscle fibers and Mus)
compound EMG = Comprises many MUs, amplitude depends on number and size of MUs, different MU active at diff time, not synchroneous, longer duration and diag application (innervation of MUs and muscle groups)
How to measure electical activity in nerves ?
Electromyography - generation of AP with electrical stimulation - measurement of AP using differential amplification
What is the diagnostic applications for electrical activity in nerves ?
Threshold measurement, nerve conduction speed and reflexes.
Why can we check nerve conduction velocity ?
To check for trauma on injury of nerves, for disease of nerve?
Which distinction there is between nerve conduction velocity ?
Sensory nerve or motor nerve conduction velocity.
