Nerves

multipolar neuron

The effector cell responds to a nerve impulse and can be either a muscle cell or a gland cell.

Two one behind each eye.

Sometimes it happens when a limb has had a shortage of circulation for a while, and then the circulation is restored. You might be in a position where you are resting on a limb in such a way that circulation is interrupted. As a child, I remember one night when I reached under the pillow and felt a strange hand under the pillow! I almost tossed my cookies. It only took a moment to realize that one hand had gone completely numb under the pillow, so my brain didn't get the message that the hand under the pillow was mine.

Short branched extensions that carry impulses towards the nerve cell body are called dendrites.

divergence

The left side of the body. And vice versa.

Norephinephrine

Second order neuron cell bodies reside in the dorsal horn of the spinal cord.

ventral root

l2l3l4

Saltatory conduction is made possible by gaps in the myelin sheath (called nodes of Ranvier) along the axon, which allow for the action potential to "jump" from one node to the other, increasing conduction velocity.

third order neuron

The synaptic knob contains vesicles filled with neurotransmitters. Therefore, Acetylcholine is the neurotransmitter that stimulates skeletal muscle to contract. It is released into the synaptic clefts between motor neuron axons and motor end plates.

Electrophysiology is the study of the electrical properties of biological cells and tissues.Explain how you can actually use your experience of carrying out "researh" work in this experiment to get IV characteristic of a NEURON

refractory period

An UMN lesion may in fact present with atrophy, but it does so over time.

With a LMN lesion, the muscle loses its innervation directly and thus will not be receiving any neurological stimulus at all. However, damage to an UMN leaves the corresponding LMN to that particular muscle intact, thus leaving it to fire somewhat irregularly, but firing nonetheless. Macroscopically the muscle is no longer under central control and thus can't perform proper function, but microscopically the muscle fibers are still receiving some neurological input, or signal from the LMN innervating it, thus the muscle integrity appear unaffected at first. Over time, the muscle will atrophy because of a lack of use, but this happens more gradually than with a direct LMN lesion.

-Onyx (Medical Student)

Burns can expose the most nerve endings. Pain from burns is pretty substantial.

they stop the signals travelling down the nerves by blokcing the synapses

progressive regeneration or reinnervation of the more proximal motor units during recovery ..seen in case of axonotomesis

It is the inflammation of the blood vessels in your head.

Sensory

There are 12 pairs of cranial nerves. Of those, the ones with the most anterior origin are called olfactory I. Olfactory I nerves are responsible for the sense of smell.

Yes and No. White communicating rami contain mylinated preganglionic sympathetic nerve fibers, but are only present at the levels of spinal cord segments T1-L2 (where the cell bodies for these nerve fibers exist in the lateral horn of the spinal cord). Although the sympathetic fibers only arise in the T1-L2 spinal cord segments, they are dispersed to all spinal nerves by traveling through the sympathetic chain. The preganglionic sympathetic fibers will enter the sympathetic chain thru whit rami communicans and then do one of 4 things: 1. synapse with a postganglionic cell body in the sympathetic chain at the level it enters 2. ascend within the chain to synapse 3. descend within the chain to synapse 4. splanchnic nerves leave the chain without synapsing and synapse closer to the organ they innervate.
There are, however, GRAY rami communicans for all spinal nerves.

I hope that helps