1. KILIMANJARO CHRISTIAN MMEDICAL UNIVERSITY
COLLEGE
Faculty of Nursing and Rehabilitation Medicine
Department of Anatomy and Neuroscience
Anatomy Lecture for BSc.Nursing and BSc.Physiotherapy
LECTURE 8,9
TOPIC: NERVOUS TISSUE
Date: Nov. 21st 2022, from 10:30 am -12:30pm, GYM – Physiotherapy School
Lecturer: J. S. Kauki, BSc, MSc, on PhD, Email: jskauki@gmail.com.
Office ext. 70 Block C, 3RD Floor, Anatomy dept.
2. Objectives of NS Histology:
At the end of the session, students should be able to:
• Learn about the cellular components and the structural
components of nervous tissue
• Describe the structure and components of neurons
• Classify neurons structurally and functionally
• Describe the structure and function of Glia cells.
• Explain about healing and repair of Neurons
3. CELLS OF THE NERVOUS TISSUE
2 categories
1. Nerve cells/neurons- concerned with
information processing and signalling
2. Glial cells- supporting role. There are 100
billion neurons and may be more glial
cells
Neurons convey information by combined
electrical and chemical
signaling mechanisms
Electrical signals- rapid transmission of
information from one part of
neuron to another
Chemical messengers carry information
between neurons
4. Components of a Neuron
•Cell body= soma/perikaryon [karyon=nucleus]
Fn: Supports metabolic and synthetic needs of the rest of the neuron
•Dendrites : Series of branching tapering processes which receive information from
other neurons via synaptic contacts/synapses
•Axon: One long cylindrical process which conducts information away from cell body.
Gives rise to a series of terminal branches, forming synapses on other neurons
5. • Neuron synthesizes
1. Neuronal enzymes,
2. Structural proteins,
3. Membrane components,
4. Organelles and
5. Some of its chemical
messengers [neurotrnsmitters]
6. Structural classifications of Neurons
Functional classification
• Motor (efferent) neuron
•Sensory (afferent) Neuron
•Relay (inter) neuron
7. The cell body of a neurone
contain the Nucleus.
The Nucleus is large, pale
staining with dispersed
chromatin
Also at the cell body, there
are:
-Abundant RER, free
ribosomes, stacks of Golgi
apparatus and many
mitochondria.
8. • Nissl bodies/Nissl substance- ribosomes, stained intensely
with basic dyes, appear as clumps- prominent in large neurons
• Many mitochondria
• Cytoskeleton composed of microtubules, neurofilaments
[aggregates of these are called neurofibrils] and
microfilaments
9. Dendrites
• Tapered extensions of neuronal body
• Collectively provide a great increase
in surface area available for synaptic
inputs
• In spinal cord, dendritic surface area
may be 30 or more times that of cell
body
• Dendrites of many neurons are
studded with small protuberances
called dendritic spines
• These are preferred sites of some
synaptic contacts
10. Axons
• Is a cylindrical process which arises
abruptly from an axon hillock on one side
of neuronal cell body
• Initial segment has bundles of
microtubules, neurofilaments and
mitochondria- no Nissl substance
• It is electrically most excitable part of a
neuron
• Beyond initial segment, many axons are
encased in spiral wrapping of a membrane
called myelin sheath- greatly increases
speed of propagation of electrical impulses
• Myelinated axon conducts faster (Saltatory)
than unmyelinated axons (Continous
conduction).
11. • Transport of macromolecules and
organelles synthesized by cell body
occurs away from soma[anterograde]
and towards it [retrograde]
• It can be slow or fast
• Microtubules act as ‘railroad tracks’ for
fast transport
• Many peripheral nerves are myelinated
• Myelin sheath between 2 nodes is called
internode- formed by s single Schwann
cell
• Most of smaller axons in peripheral
nerves are unmyelinated- slow
conductors of electrical signals
Axon cont……
