Structure of neuron

Vijaylaxmi Pattanshetti
Nissl bodies

 .
Cell Body Seen in histology
Like other cells, each neuron has a cell
body that contains
*big nucleus,
*smooth and rough endoplasmic reticulum
, ..*Golgi apparatus,
* mitochondria,
*Ribosomes(Nissl substance) and other .
.*cellular components.

1.CELL BODY

2. What are Dendrites?
Dendrites are the branched short cytoplasmic
extensions arising from the cell body and enable
neurons to receive nerve impulses
simultaneously from different receptors
located all over the body. Motor neurons and
interneurons usually possess highly branched
dendrites.
Certain neurons have numerous extensions
arising from their dendrites called dendritic
spines, and that increases the surface area
available to receive nerve impulses. Dendrites
do not contain neurofibrils, but Nissl’s granules
are presents

4. Myelin Sheath
Some axons are covered with
myelin, a fatty material that wraps
the axon to form the myelin sheath.
Myelin’s presence on the axon increases
the
speed of conduction of the electrical
signal, because the fat prevents electricity
from leaking out.
Periodic gaps in the myelin sheath are
called nodes of Ranvier
At these nodes, the signal is
as it travels along the axon.
.

5. Glial Cells:
Myelin is produced by glial cells which are non-
neuronal cells that provide support for the nervous system.
Glia function to
i) holds neurons in place
,ii) supply them with nutrients,
iii) provide insulation,
iv) remove pathogens and
v) dead neurons.
In the central nervous system, the glial cells that form the
myelin sheath are called oligodendrocytes;
In the peripheral nervous system myelin sheath formed by
Schwann cells.

1.Axons vs Dendrites
The axon is the long
extension of the neuron
that passes nerve
impulses away from the
cell body.
The dendrites are the
short extensions that
pass nerve impulses
towards the cell body.
2. Structure
Axons are a long thin
process of uniform
thickness and
smoothness.
Dendrites are short
processes, thickness
diminishes, and the
branches are studded
with spiny projections.
3.Number per Cell Body
One neuron has one
axon.
One neuron has multiple
projections of dendrites.
Q; What is the Difference Between Axons and
Dendrites?
4.Neurofibrils
Neurofibrils are present in
axons.
Neurofibrils are absent in
dendrites.
5.Presence of Nissl’s Granules
Nissl’s granules are absent in
axons.
Nissl’s granules are
present in axons.
6.Ribosomes
Ribosomes are absent in
axons.
Ribosomes are present in
axons.
7.Myelin Insulation
Myelin sheath may be or may
not be present in axons.
Myelin sheath is absent in
dendrites.
8.Branching Points
Branching points of axons
branch away from the cell
body.
Branching points of
dendrites branch closer to
the cell body.

1.Classification of neurons according to functions

2.DIAGRAMS OF Classificationof neurons according functions

2.Classification of neurons accordingto NUMBEROF CYTOPLASMIC PROCESSES
Q: Classify Neurons according to
number of cytoplasmic processes.

Histology of nervous TISSUE
1).neurons have large central nucleus ---------
WITH PROMINENT NUCLEOLUS
2). SEVERAL RADIATING CELL PROCESSES THE -------
-- DENDRITES PRESENT, WITH SINGLE AXON
3). CONE SHAPED CLEAR AREA OF NEURON IS ……
AXON HILLOCK
4). CYTOPLASM OF NEURON HAVE NISSL BODIES ARE
DARKLY STAINED, EXTEND IN TO DENDRITES,
BUT NOT IN TO AXON HILLOCK
5). SURROUNDING DARK STAINED NUCLEUS …….
ARE OF NEUROGLIAL CELLS
6). SURROUNDING NEURONS AND NEUROGLIA ARE ..
.. NUMEROUS BLOOD VESSELS OF DIFFERENT SIZE.
VJAYLAXMI PATTANSHETTIVijaylaxmi Pattanshetti

Structure of neuron

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