NERVOUS TISSUE

*origin- ectoderm.
*cells of nervous tissue have least power of regeneration.
*neuron is the longest animal cell.
*length of neuron in human being- 2-3m
*total number of neuron in human being=100billion
*cell of nervous tissue also contain very less quantity of matrix.
*important cell of nervous tissue-

Neuron
Neuroglia
Schwann cell
Neurocrine cell
Amacrine cell

*Neurons

1.  DENDRON-it is thin thread like structure originated from cyton.

2.  CYTON- it is small spherical structure and considered as as main part of the neuron. it contains following structure-

• nucleus-small spherical structure present in centre.
• neuroplasm-cytoplasmic content of neuron
• neurofibrils-it is thin thread like structure present in neuroplasm, gives mechanical support and acts as endo-skeletal.
• nissl's granules-it is nucleo protein, present in cyton and dendron only.
• axon-it is long tubular structure present behind the cyton.
• myelin sheath-it is thick covering of lypoprotein formed by schwann cells. it prevents loss of energy even transmission of impulse.

3.  NODE OF RANVIER-small gap present on axon (both neurilemma and myelin sheath are completely absent. it increase the speed of impulse by jumping action.

 speed of nerve impulse in human-150-200 m/s.