Nervous System 1

Histology:2nd stage
2015-2016 Dr. Raja Ali
--------------------------------------------------------------------------------------------
Nerve Tissue & the Nervous system:

Chapter Outline:
Neurons (Cell Body (Perikaryon) , Dendrites , Axons ) .
Synaptic Communication.
Glial cells & Neural Activity :( Oligodendrocytes , Astrocytes , Ependymal cells ,Microglia ,Schwann cells(Neurolemmocytes), Satellite cells of Ganglia).
Myelin.
Central Nervous System (Brain &Spinal Cord , Meninges ).
Periperal NervousSystem : ( Nerves , Ganglia ) .
Neural Plasticity& Regeneration.

Learning Objective:

? Name and describe the divisions of nervous system.
? State the function of nerve cells.
? Name , locate &describe the structures of synapses.
? State the function of glial cells.
? Name , locate &describe the structures of the brain and spinal cord.
? Describe the peripheral nervous system.

Terminology:
• Input: sensory = sensory input.
– Receptors monitor changes.
– Changes called “stimuli” (sing., stimulus)
– Information sent by “afferent” nerves.
• Integration:
– Info processed.
– Decision made about what should be done.
• Output: motor = motor output.
– Effector organs (muscles or glands) activated.
– Effected by “efferent” nerves.
Remember the difference between the English words “affect” and “effect”.
• Neuron = nerve cell.
• Neuroglia = supporting cell.
• Nerve fiber = long axon.
• Nerve = collection of nerve fibers (axons) in PNS.
• Tract = collections of nerve fibers (axons) in CNS.
• Nucleus = cluster of cell bodies in CNS.
• Ganglia = cluster of cell bodies in PNS.
• Unilateral: on one side.
• Ipsilateral: on the same side.
• Contralateral: on the opposite side.
Remember also:
• CNS vs PNS.
• Input: sensory: afferent: to brain.
• Output: motor : efferent: from brain.
• Dense network of fibers from processes of both neurons and glial cells fills the interneuronal space of the CNS and is called the neuropil .
Introduction:
The nervous tissue is composed of interconnecting network of specialized cells called neurons (nerve cells) supported by neuroglial cells. There are about 10 million neurons in human beings. The function of neurons is to receive stimuli and conduct them to a central site, the central nervous system (CNS), where they are analysed and integrated to produce a desired response in the effector organs.