Which of the following has the slowest conduction velocity?
The region between atrium and atrioventricular node has the slowest conduction velocity (. 05 M./see.) and lowest safety factor. Conduction through the A-V node is at about .
Which nerve fiber has the fastest conduction velocity?
myelinated axons
The fastest signals in our bodies are sent by larger, myelinated axons found in neurons that transmit the sense of touch or proprioception – 80-120 m/s (179-268 miles per hour).
What does the alpha motor neuron do?
Alpha motor neurons (also called lower motor neurons) innervate skeletal muscle and cause the muscle contractions that generate movement. Motor neurons release the neurotransmitter acetylcholine at a synapse called the neuromuscular junction.
How do you calculate conduction velocity?
The conduction velocity of the action potential is determined by measuring the distance traveled (length of the nerve in m) and dividing by the time (sec) taken to complete the reflex arc, also called the latency. Conduction velocity = distance (m)/time (sec).
What factors affect conduction velocity?
Conduction velocity is influenced by myelin sheath thickness and internode distance (i.e. the distance along the axon between the nodes of Ranvier) (Hursh, 1939), and both parameters are linearly related to axon diameter.
Where is alpha motor neuron found?
spinal cord
alpha motor neurons are lower motor neurons whose cell bodies are found in the anterior horn of the spinal cordand whose axons travel down to the body to innervate skeletal muscle to cause muscle contraction.
What increases conduction velocity?
Conduction velocity increases with both axon diameter, and with myelination and, in the central nervous system, the great majority axons that are > 0.3 microns in diameter are myelinated. The myelin sheath, produced by specialized glial cells, is a compacted spiral of membrane.
What two factors affect conduction velocity?
When does the nerve conduction velocity become normal?
However, the nerve conduction velocity may remain normal until late in a disease process as long as a few normal neurons survive. In addition, the nerve conduction velocity reflects conduction of the fastest nerve fibres, usually motor neurons.
How are alpha motor neurons influenced by sensory input?
The alpha motor neurons are influenced not only by upper motor neurons in the motor cortex and motor control neurons in the brainstem but also by sensory inputs from the periphery.
How many muscle fibers does an alpha neuron innervate?
J. Cuevas, in Reference Module in Biomedical Sciences, 2015. Each α motor neuron innervates a population of muscle fibers termed a motor unit. The number of muscle fibers innervated by a single motoneuron varies depending on the size and function of the muscle, but averages about 150 muscle fibers per motor unit.
Is the conduction of nerves in LEMS normal?
Nerve conduction studies performed on the Ulnar motor and sensory, Median motor and sensory, Tibial motor, and Peroneal motor nerves in patients with LEMS have shown that the conduction velocity across these nerves is actually normal.
