Your SlideShare is downloading. ×
corelating neurohistology with functions By Dr. Arshad
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

corelating neurohistology with functions By Dr. Arshad

968
views

Published on

Published in: Technology

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
968
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
26
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Neurohistology – correlating structure to function
  • 2.  
  • 3.  
  • 4. Facts that matter
    • Neurons are cells specialized for rapid communication.
    • Most of the cytoplasm of a neuron is in long processes, the neurites (dendrites and axon, which conduct signals toward and away from the cell body, respectively).
  • 5.
    • In the central nervous system (CNS), neuronal cell bodies and dendrites occur in gray matter .
    • White matter consists largely of axons, most of which have myelin sheaths that serve to increase the velocity of conduction.
  • 6.
    • A neuronal surface membrane has a resting potential of -70 mV, maintained by the sodium pump.
    • This is reversed to +40 mV in an axon during the passage of an action potential.
  • 7.
    • The fastest signals, known as impulses or action potentials, are carried in the surface membrane of the axon.
    • The surface membrane of the perikaryon and dendrites does not conduct impulses.
  • 8.
    • Neurons communicate with one another at synapses
    • Chemical transmitters released by axonal terminals evoke changes in the membrane of the postsynaptic cell, which may be either stimulated or inhibited.
  • 9.
    • The effect depends on the transmitter and the type of receptor molecule in the postsynaptic membrane.
  • 10.
    • Much of the cytoplasm of a neuron is removed when the axon is transected.
    • The segment that has been isolated from the cell body degenerates together with its myelin sheath, and the fragments are eventually phagocytosed.
  • 11.
    • In the absence of axonal regeneration, the cell body may later shrink or die.
    • Axons severed in the peripheral nervous system can regrow and reinnervate their targets.
  • 12.
    • Axons transected within the CNS fail to regenerate effectively.
    • Synaptic rearrangements, however, can occur in partly denervated regions of gray matter, and some recovery of function occurs as a result of recruitment of alternative neuronal circuitry.
  • 13.
    • Two classes of cells are present in the central nervous system (CNS)
    • Neurons, or nerve cells, are specialized for nerve impulse conduction and for exchanging signals with other neurons.
    • Responsible for most of the functional characteristics of nervous tissue
  • 14.
    • Neuroglial cells , collectively known as the neuroglia or simply as glia , have important ancillary functions.
    • The neuroglial cells of the normal CNS are astrocytes, oligodendrocytes, ependymal cells (derived from neural tube ectoderm), and microglia (derived from mesoderm)
  • 15.
    • Astrocytes occur throughout the brain and spinal cord
    • Oligodendrocytes produce myelin and are also found next to the cell bodies of some neurons.
  • 16.
    • Microglial cells become phagocytes when local injury or inflammation is present.
    • The neuroglial cells of the peripheral nervous system are Schwann cells in nerves and satellite cells in ganglia.
  • 17. Neurons
    • 20 billion
    • Functionally classified into sensory, motor and interneurons
  • 18. Sensory neurons
    • Convey impulses from receptors to CNS
    • Their processes are included in somatic and visceral afferents
    • Somatic afferents convey pain, temperature, touch, pressure, proprioception
  • 19.
    • Visceral afferents convey pain and other sensations from mucous membrane, glands and blood vessels
  • 20. Motor neurons
    • Convey impulses from CNS/ganglia to effector cells
    • Their processes are included in efferent nerve fibres
    • Somatic efferents -> skeletal muscles
    • Visceral efferents -> smooth muscle, heart, glands
  • 21. Interneurons
    • ≥ 99% of all neurons
    • Form a communicating and integrating network between sensory and motor neurons
  • 22. Anatomical classification
    • Depends on number of processes
    • Multipolar
    • Bipolar
    • Unipolar
  • 23.  
  • 24.  
  • 25.
    • Motor neurons and interneurons are multipolar
    • Bipolar neurons are located in retina and CN VIII ganglia
  • 26.  
  • 27. Unipolar neurons
    • Develop as bipolar neurons
    • Body expands asymmetrically
    • Become unipolar as processes migrate around cell body and fuse into a single process
    • Located in dorsal root and cranial nerve ganglia
  • 28. Synapse
  • 29. Synapse
  • 30. Types of synapses
  • 31.  
  • 32. Neurons, neuropil, and the common glial cells of the CNS
  • 33. Neurons, neuropil, and the common glial cells of the CNS
  • 34. Supporting cells
    • Glia/neuroglia in CNS
    • Schwann cells and supporting cells in PNS
    • Schwann cells surround neurites, isolating them from adjacent cells and extracellular matrix
  • 35.
    • In PNS ganglia, supporting cells are Satellite cells- surround nerve cell bodies [nucleus containing part]- analogous to Schwann cellsS
  • 36. Functions
    • Physical support for neurites
    • Electrical insulation for nerve cell bodies and processes
    • Metabolic exchange pathway between vascular system and neuronsS
  • 37.  
  • 38.  
  • 39.  
  • 40.  
  • 41.  
  • 42.  
  • 43.  
  • 44.  
  • 45. White versus gray matter,
  • 46.  
  • 47. Nerve injury/regeneration
    • Nerve cells, unlike neuroglial cells, cannot proliferate but can regenerate their axons, located in the PNS
  • 48.