5

Question 1

Organization of neurons in the neuronal pools.

sensory pathways.

Answer 1

Convergence
. -Many input fibers converge to one neuron:

Question 2

Organization of neurons in the neuronal pools.
Motor

Answer 2

Divergence:-The input fiber divides into many branches which synapse with the many neurons in the neuronal pool.

Question 3

Lateral (reciprocal inhibition): - The nerve fiber give collateral fibers to excite inhibitory neurons to inhibit surrounding neurons. Significance?

Answer 3

Significance:
1- Increase sharpness of sensation by decrease
lateral spread of stimulus.
2- Has a major role in reciprocal inhibition:
contraction of a certain group of muscle &
relaxation of the antagonistic group.

Question 4

After discharge: has 3 mechanisms:

Answer 4

has 3 mechanisms:
1-Synaptic after discharge
2-Parallel circuits
3-Reverberating circuits.

Question 5

input fiber is connected to the output
neuron by several pathways.

Answer 5

Parallel circuit after discharge

Question 6

stimulus of the input fiber produces EPSP
which lasts for 15 m.sec .
If it reaches firing level during this time, the output fiber will discharge in spite of end of
stimulation

Answer 6

Synaptic after discharge:

Question 7

Reverberating circuit after discharge:

Answer 7

The input fiber is excites the output an interneuron
which in turn excites the output neuron.

Question 8

Examples of reverberating circuits

Answer 8

Wakefulness:
It is due to reverberating circuit started in the reticular formation & stimulate cerebral cortex all the day.