1. Structural elements and mechanisms involved in the transformation of neural activity to muscle contraction and secretion
Shokoya Mariam Majida

2. MOTOR NEURON:
Cell body located in the spinal cord
Axon is efferent, it carries information from the spinal cord to the effectors in the PNS (muscles and glands)
Two main categories : Somatic / Visceral motor neurons
Somatic motor neurons:
Originate from CNS direct axons to skeletal muscles  control locomotion
Types of efferent motor neurons: Alpha / Beta / Gamma motor neurons
Types of muscle fibers they innervate: Intrafusal / Extrafusal muscle fibers

3. Extrafusal muscle fibers:
generate tension  allow skeletal movement
mostly striated fibers attached to the bone by tendons
innervated by ALPHA motor neurons :
cell body in ventral horn of the spinal cord
contribute to maintain muscle tone  resist further stretches
Intrafusal muscle fibers:
serve as sensory organs  detect the amount of change in the muscle
innervated by both sensory afferent and motor efferent neurons
Motor neurons are BETA and GAMMA
beta: axon collateral to extrafusal muscle
gamma: regulate sensitivity of the fiber to stretching

4. Visceral motor neurons:
indirectly innervate cardiac muscle, smooth muscle and glands
disynaptic command: visceral motor neuron (CNS) 
 ganglionic neuron (PNS)  visceral muscles (PNS)
sypmpathetic (noradrenalin release) or parasympathetic (acetylcholin release) nerve fibers
Basicly all motor neurons release acetylcholin.
Neuromuscular junction:
action potencial
Calcium ion inflow in axon terminal
fusion of synaptic vesicles  release Acetylcholin
postsynaptic membrane: binding to nicotinic acetylcholin receptors
depolarization of muscle fiber  contraction

5. Thank you for your attention!
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