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Skeletal Cardiac SmoothSite: skeleton heart visceraSize: Largest Medium Smallest Shape cylindrical Cylindrical Fusiform Sarcomere Regular ↓ regular Absent Sarcolemma thick very thin Thin Striation Distinct less distinct Non
Satellite cells Present Absent Absent
Skeletal Cardiac SmoothNuclei: Peripheral,
multiple, ovalcentral, single,
oval
central, single, oval
Cell Junction absent Intercalary discs
Gap Junction
Regeneration Satellite cells no regeneration
pericytes & U.M.C. mitosis
Tubular sys Triad Diad Absent
Origin: Myoblast Myoblast U.M.C.
Nerve suppl Somatic Autonomic Autonomic
Dr. Samar Asker
Structural and functional unit
consists of:
Cell body
Nucleus cytoplasm.Processes: dendrites and axon.
Dr. Samar Asker
THE CELL BODYTHE CELL BODY
The nucleusThe nucleus:: Large, rounded, Large, rounded,
usually central usually central and vesicular and vesicular with a with a prominent prominent nucleolus. nucleolus.
The cytoplasmThe cytoplasm: : OrganellesOrganelles::
Nissl granulesNissl granules Neurofibrils Neurofibrils Golgi Golgi
apparatus apparatus Mitochondria Mitochondria
Centrioles is Centrioles is
absent absent
b- Inclusionsb- Inclusions: : * Melanin * Melanin
pigments:pigments: in in some nerve some nerve cells cells
eg. cells of eg. cells of substania substania nigra. nigra.
* Lipofuscin * Lipofuscin pigmentspigments: : yellow yellow pigments pigments increase in old increase in old age. age.
* Glycogen * Glycogen granules. granules.
* Fat droplets. * Fat droplets.
The axon The dendrites
Number: Single. Numerous
Thick& Length:
Thin & long.
Thick & short.
Diameter:
It has a constant diameter along its length.
decrease gradually towards their ends i.e. tapering.
The axon The dendrites
Contour: Smooth. Irregular.
Branching: at its terminal end only i.e.but it may give collateral branches which arise at right angles. No spines
give extensive branching like a tree .The branches arise at acute angles and may show spines.
Content: Contains mitochondria
and neurofibrils
only (no Nissl granules).
Contain neurofibrils and Nissl granules.
Dr. Samar Asker
Classification of the neuronsClassification of the neuronsAccording to the number of processes (Polarity): Unipolar nerve cells: Nerve cells are rounded with only one process. Site: spinal ganglia mesencephalic nucleus of the trigeminal nerve.
Dr. Samar Asker
Bipolar nerve cells:Bipolar nerve cells:
with 2 processes, a with 2 processes, a dendrite and an dendrite and an axon.axon.
Retina of the eye. Retina of the eye. Cochlear and Cochlear and
vestibular ganglia vestibular ganglia in the ear.in the ear.
Olfactory Olfactory epithelium of the epithelium of the nose. nose.
Multipolar nerve cells: Multipolar nerve cells: Have many dendrites Have many dendrites
and one axon. and one axon. stellate :stellate :- Anterior horn cells of the - Anterior horn cells of the
spinal cord. spinal cord. Pyramidal: Pyramidal: cerebral cortex. cerebral cortex. Pyriform:Pyriform: Purkinje cells Purkinje cells
of the cerebellumof the cerebellum
NERVE GANGLIACollection of nerve cells and fibers, outside the C. N. S. They are sensory (spinal) & autonomic (sympathetic ganglia)
Spinal Sympathetic1. Thick CT capsule .
2. Unipolar cells.3. Variable Size4. poor blood vessels 5. Large cells 6. Arranged in groups or
rows.7. Glomerulus: Present8. large number of satellite
cells
9. Myelinated nerve fibers .10. No synapse () cells
Thin.
Stellate Multipolar
uniform size.
Rich.
Smaller
Scattered
Absent
Few satellite cells
non myelinated
Synapse present