for D.Pharm students

1. NERVOUS TISSUE
• Each neurone consists of a cell body and its
processes, one axon and many dendrites.
• Neurones are commonly referred to simply
as nerve cells.
• Bundles of axons bound together are called
nerves.
• Neurones cannot divide and for survival
they need a continuous supply of oxygen
and glucose. Unlike many other cells,
neurones can synthesise chemical energy
(ATP) only from glucose.

3. No

4. Properties of neurones
• Neurones have the characteristics of
irritability and conductivity.
• Irritability is the ability to initiate nerve
impulses in response to stimuli from:
• outside the body, e.g. touch, light waves
• inside the body, e.g. a change in the
concentration of carbon dioxide in the
blood alters respiration; a thought may
result in voluntary movement.

5. • In the body this stimulation may be
described as partly electrical and partly
chemical — electrical in that motor
neurones and sensory nerve endings initiate
nerve impulses, and chemical in the
transmission of impulses between one
neurone and the next or between a neurone
and an effector organ.
• Conductivity means the ability to transmit
an impulse.

6. Parts of Neuron
1. Cell body 2.Dendrites 3.Axon
Cell Body: Vary in size & shape; contains
nucleus surrounded by cytoplasm,
contains lysosomes, mitochondria, Golgi
complex & clusters of ER-Nissl bodies
Dendrites: receiving portions of neuron;
usually short, tapering & highly branched.
Contains Nissl bodies, mitochondria.

7. Axons
• Each nerve cell has only one axon, carrying
nerve impulses away from the cell body.
They are usually longer than the dendrites,
sometimes as long as 100 cm.
• Structure of an axon
• axolemma -The membrane of the axon, it
encloses the cytoplasmic extension of the
cell body.

8. •Large axons and those of peripheral
nerves are surrounded by a myelin
sheath. This consists of a series of
Schwann cells arranged along the length
of the axon. Each one is wrapped around
the axon so that it is covered by a
number of concentric layers of Schwann
cell plasma membrane. Between the
layers of plasma membrane there is a
small amount of fatty substance called
myelin.

9. Cytoplasm
Myelinated Non-myelinated

10. • Postganglionic fibres and some small fibres
in the central nervous system are non-
myelinated.
• In this type a number of axons are
embedded in Schwann cell plasma
membranes .The adjacent Schwann cells are
in close association and there is no exposed
axolemma. The speed of transmission of
nerve impulses is significantly slower in
non-myelinated fibres.

11. Axon Terminal- Each axon finely divides in
many branches
Synaptic end-bulb- Each terminal swell into
it. Contains many tiny sacs-Synaptic
vesicles
Neurotransmitter- Chemical in synaptic
vesicles e.g. acetylcholine, dopamine
One axon may have 1-3 neurotransmitters