1. The Nervous Tissue - Nervous SystemThe Nervous Tissue - Nervous System
 Human nervous system is the most complex
system in the body formed by a network of many
billion of nerve cell called neuron and all assisted
by many more supporting glial cell
 Neurons (nerve cell )
 long processes respond to environmental change
(stimuli)
 Glial cell (Neuroglia ) “glue cell”
 short processes and support protect neurons
 participate in
 neural activity
 neural nutrition
 defence of cell in Central nervous system

2. Development of nerve tissueDevelopment of nerve tissue
Nerve system develop from the outer embryonic layer
(ectoderm) 3rd
week of human embryonic life

3. 1. Central nervous system (CNS)
 Component: Brain (cerebrum and cerebellum) and
Spinal cord
 Function : Overall “command center” processing
and integrating information
 Location: CNS nerve cell bodies are present only in
the gray matter
1. Peripheral nervous system (PNS)
 Component: nerve (Cranial and spinal) and ganglia
 Function: receives and projects information to and
from the CNS
 Location: found in ganglia and in some sensory
region like olfactory mucosa
Two Anatomical Divisions of the nervous
system

5. Neuron structure

7. 1. Cell body (perikaryon)
 Trophic center for the entire
nerve cell and is receptive to
stimuli
2. Dendrites
 Many elongated process
specialized to receive stimuli
from the environment
3. Axon
 Single process specialized in
generating and conducting
nerve impulse to other
cell(nerve,muscles gland cell)
Synapse:
interact with other neurons or
nonnerve cells
Responsible for the
transmission of nerve
impulse
Contact between neurons and
other effector cell by
releasing neurotransmitters

8. Structural classes of neurons :
• Anaxonic neurons
 no anatomical clues to determine
axons from dendrites
 functions unknown
• Multipolar neuron
 multiple dendrites & single axon
 most common type
• Bipolar neuron
 two processes coming off cell body
– one dendrite & one axon
 only found in eye, ear & nose
• Pseudounipolar (Unipolar) neuron
 single process coming off cell body,
giving rise to dendrites (at one end) &
axon (making up rest of process)

9. 3 Main Types of Neuron
1. Sensory (afferent)
involved in the reception of sensory stimuli from the environment
and from within the body through presence of receptors
transmit sensory information from receptors of PNS towards the
CNS
 most sensory neurons are unipolar, a few are bipolar
2. Association (interneurons)
interpretation of sensory information (information processing);
complex (higher order) functions
are all multipolar
3.Motor (efferent)
 control muscle contraction and glandular secretion
(muscles/glands/adipose tissue)
all are multipolar

10. Neuroglia (glial cells)
CNS neuroglia:
• Astrocytes
create supportive framework for
neurons
create “blood-brain barrier”
monitor & regulate interstitial fluid
surrounding neurons
Metabolic exchanges
Origin : neural tube
•Oligodendrocytes
create myelin sheath around axons of
neurons in the CNS,
Myelinated axons transmit impulses
faster than unmyelinated axons
Origin: neural tube

11. •Microglia
“brain macrophages”
phagocytize cellular wastes &
pathogens
Immune-related activity
Origin: bone marrow
•Ependymal cells
 produce, monitor & help
circulate CSF (cerebrospinal
fluid)
Lining of CNS
Origin:Neural tube

13. PNS neuroglia:
•Schwann cells (Neurolemmocytes)
 surround all axons of neurons in the PNS creating a
neurilemma around them. Neurilemma allows for potential
regeneration of damaged axons
 creates myelin sheath around most axons of PNS
Orgin : neural tube
Satellite cells
 support groups of cell bodies of neurons within ganglia
of the PNS

14. Things to know:Things to know:
 The axons of neurons are
bundled together to form nerves
in the PNS & tracts/pathways in
the CNS. Most axons are
myelinated so these structures
will be part of “white matter
 The cell bodies of neurons are
clustered together into ganglia in
the PNS & nuclei/centers in the
CNS. These are unmyelinated
structures and will be part of
“gray matter”
Ganglia

15. •Most axons of the nervous system are surrounded by a
myelin sheath (myelinated axons)
•The presence of myelin speeds up the transmission of
action potentials along the axon
•Myelin will get laid down in segments (internodes) along
the axon, leaving unmyelinated gaps known as “nodes of
Ranvier”
•Regions of the nervous system containing groupings of
myelinated axons make up the “white matter”
•“gray matter” is mainly comprised of groups of neuron cell
bodies, dendrites & synapses (connections between
neurons)

16. Blood brain barrier
Fuction :
shields the brain from toxic substances in the blood,
 supplies brain tissues with nutrients,
 filters harmful compounds from the brain back to the
bloodstream.
Compotents :
Capillary endothelium
Meninges
The skull and the vertebral column protect the CNS
Between the bone and nervous tissue are membranes of
connective tissue
Three layer:
1.Dura mater : outer layer lining of skull
2.Arachnoid mater : contain blood vessel
subarachoid space : filled with CSF
3.Pia mater : cover the brain
Choroid plexus
Fuction :
remove water from blood and release it as CSF

17. Microscopic specimenMicroscopic specimen

18. Cross section of a nerveCross section of a nerve

19. Peripheral nerve connective tissuePeripheral nerve connective tissue

20. Cross section of the spinal cordCross section of the spinal cord

21. Neuron and neurogliaNeuron and neuroglia

22. AstrocytesAstrocytes

23. MicrogliaMicroglia

24. ependymal cellsependymal cells

25. GangliaGanglia

26. Cerebral cortexCerebral cortex

27. cerebellumcerebellum

28. Choroid plexusChoroid plexus

29. the end