Nervous tissue Flashcards
Central nervous system
- brain and spinal cord
Peripheral nervous system
– cranial and spinal nerve
Nervous tissue Consists of:
Neuron
Supporting cells (neuroglia)
Neuroglia found in CNS
Ependymal cells
Astrocytes
Oligodendrocytes
Microglia
Neuroglia in PNS
Satellite cells
Schwann cells
transmit electrical impulses from one site in the body to another, and receive and process
information
Neurons
are non-conducting cells that are in
intimate physical contact with neurons
- Neuroglia
Functional unit of nervous
system
neurons
neurons consist of
cell body
processes (neurites)
types of neurites
axon
dendrites
long, cylindrical process
up to 1m
Axon
nissl substance absent
Axon
impulse – away from cell
body
Axon
commonly refer to as nerve fibers
Axon
Numerous, Highly branched
Dendrites
Terminate near the cell body
Dendrites
Nissl granules – present
Dendrites
Impulse – towards the cell body
Dendrites
– cell body of neuron; Unmyelinated
Gray matter
myelinated fibers
White matter
Aggregation of cell body
Within CNS – k/a –
nuclei
Aggregation of cell body
Outside CNS – k/a –
ganglia
Types of neurons are according to
a. According to the shape of cell body
b. According to variation in axon
shape of the cell body dependent on the number
of processes arising from it.
a. According to the shape of cell body
many processes arises from the cell body
eg: motor neurons
Multipolar neuron
single dendrites and axon
eg: olfactory neuron, retina
Bipolar neurone
single dendrite and the axon arise from common
stem of the cell body
eg: dorsal root ganglian
Unipolar neuron
b. According to variation in axon
2 Types
Golgi type I
Golgi type II: (microneurons)
Long axon and connect remote regions
Golgi type I
Short axon and end near the cell body
Inhibitory in function
Golgi type II: (microneurons)
- Small diameter axon
- Simple envelop by the cytoplasm
Non myelinated
- Large diameter fiber
- Concentric layers
Myelinated fibers
Afferent and efferent
nerve fiber
Peripheral nerve
1 or more bundle
(fascicles) of nerve
fibers
within fascicle, each
nerve fibers with its
investing Schwann cells
endoneurium
each fascicle is surrounded – tough Collagenous tissue
with epithelial Cell
perineurium
if > 1 fascicle, further layer of loose collagenous tissue
epineurium
Supporting cell also called
(neuroglia)
Non neural cell
* Highly branches cell that occupy the space between
neurons
* Mechanical and metabolic support.
Supporting cell (neuroglia)
Most numerous glial cell
Long branched processes
Astrocytes
Small cell
* Mesenchymal in origin
* Elongated nuclei
* Little cytoplasm which forms, highly branch
process
Microglia
Becomes active after damage (Microglia)
phagocytes
Epithelial lining of ventricles and spinal canal
* Cuboidal to low columnar, and tightly bounded at
luminal surface
Ependyma
Responsible for myelination of axon
* Wraps itself as spirally around a short segment of
axon
* Myelinate single axon
Schwann cell
(lemnocytes, peripheral glial)
Schwann cell
(capsular gliocytes)
Satellite cell
- Flat cell that surround the cell bodies of neuron of
PNS ganglia - Regulate exchange of material between neuron cell
bodies and interstitial fluid
Satellite cell
Collection of cell body in PNS
Ganglion
2 types Ganglion
- Sensory
- Autonomic
(Ganglion) unipolar, Fibers passes centrally
* Ganglion cell located
peripherally
Sensory
(Ganglion) multipolar, Neuron are scattered
throughout the ganglion
* Nerve fiber are non
myelinated and thinner
so, less conspicuous than
sensory
Autonomic ganglion
