K1-Nerve Tissue & Nervous System (Histologi)
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Transcript of K1-Nerve Tissue & Nervous System (Histologi)
Alya Amila Fitrie , Radita N.A. Ginting, ZulhamAlya Amila Fitrie , Radita N.A. Ginting, ZulhamDepartment of HistologyDepartment of Histology
Medical FacultyMedical FacultyUniversity of Sumatera UtaraUniversity of Sumatera Utara
Nerve Tissue & Nervous System
Topics
1. Histology of Nerve Tissue2. Histology of Central nervous System3. Histology of Peripheral Nervous System4. Nerve Regeneration
HISTOLOGY OF NERVE TISSUE
Cells of Nervous System
Neurons
Cell body
Ultrastructure of a neuronal cell body. (From Lentz TL: Cell Fine Structure: An Atlas of Drawings of Whole-Cell Structure. Philadelphia, WB Saunders, 1971.)
Main types of neurons
1. Multipolar : most neuron of body
2. Bipolar : cochlear & vestibular ganglia, retina & olfactory mucosa
3. Pseudounipolar : spinal ganglia
Special types of neuron
NeurogliaGlial cells : 10 times abundant than
neurons
Glial cells surround both cell bodies and their processes that occupy the interneuronal space
Oligodendrocytes & Schwann cell•Oligodendrocyte : Produces the myelin sheath that provides the electrical insulation of neurons in CNS
•Schwann Cell : Produce a myelin sheath that located around axons in PNS
Astrocytes
Ependymal cells &Microglia
• Ependymal cells : cuboidal or low columnar epithelial cells, lining the ventricles of the brain and central canal of the spinal cord.
• Microglia : small elongated cells with short irregular processes.
HISTOLOGY OF CENTRAL NERVOUS SYSTEM
Central Nervous System
Cerebrum
Cerebellum
Spinal cord
Cerebrum
Neuron types in the cerebral cortex:1. Pyramidal cells2. Stellate (granul cells)3. Cells of Martinotti4. Fusiform cells5. Horizontal cells of Cajal
Cerebrum (cont..)
Layers
1.Gray Matter / cerebral cortex:
a. Plexiform (molecular) layer
b. Outer granular layer
c. Pyramidal cell layer
d. Inner granular layer
e. Ganglionic layer
f. Multiform cell layer
2.White matter
Cerebellum
Function : coordinates muscular activity and maintain posture & equilibrium.
Consist of :
1. Gray matter :
• Molecular layer
• Purkinje cell layer
• Granular layer
2. White matter
Cerebellum (cont..)
Spinal Cord
Consist of :
1. White matter, in the outer
2. Grey matter, has the shape of butterfly
Meninges
Consists of 3 layer :
1. Dura mater : composed of dense connective tissue, continuous with the periosteum of the skull.
2. Arachnoid : has 2 component :
• A layer in contact to dura mater
• A system of trabeculae
3. Pia mater : loose connective tissue containing many blood vessels
Blood-Brain Barrier
• BBB, a functional barrier, prevents the passage of some substances, from the blood to the nerve tissue.
• Supported by :1. Occluding junction between
endothelial cells of blood capillaries of nerve tissue.
2. The expansion of neuroglial cells processes that envelop the capillaries.
Blood
braIn
Choroid Plexus & Cerebrospinal Fluid
• CP, composed of loose connective tissue of the piamater, covered by simple cuboidal or low columnar epithelium.
• Function of CP is to elaborate CSF, that fills ventricles, central canal of spinal cord, subarachnoid space & perivascular space.
• CSF is clear,low density, & very low in protein content.
Spinal cordSubarachnoid space
Perivascular space
HISTOLOGY OF PERIPHERAL NERVOUS SYSTEM
Peripheral Nervous System
Nerve fibers
Ganglia
Nerve endings
Nerve fibers
Consist of axons enveloped by a special sheath derived from cells of ectodermal origin.
The sheath cell of – PNS Schwann cell – CNS oligodendrocyte
Axon of small diameter unmyelinated nerve fibers
Thicker axons myelinated nerve fibers
Nerve fibers
• E : epineurim• P : perineurium• F : fasiculus• V : blood vessels
Nerve fibers
Nerve fiber
Nerve fibers
Electron microscope of a peripheral nerve containing both myelinated (M) and unmyelinated (U) nerve fibers.
Ultrastructural features of myelinated & unmyelinated nerve
fiber1. Nucleus & cytoplasm of a Schwann
cell
2. Axon
3. Microtubule
4. Neurofilament
5. Myelin sheath
6. Mesaxon
7. Node of Ranvier
8. Interdigitating processes of Schwann cells at the node of Ranvier
9. Side view of an unmyelinated axon
10.Basal lamina
Ganglia
• Ganglia are ovoid structures containing neuronal cell bodies and glial cells supported by connective tissue.
• They serve as relay stations to transmit nerve impulses.
• There are Sensory ganglia & Autonomic ganglia.
Sensory Ganglia Receive afferent impulses that go
to CNS. Two types :
Cranial ganglia : associated with cranial nerves.
Spinal ganglia : associated with the dorsal root of the spinal nerves.
Large neuronal cell bodies with prominent fine Nissl bodies surrounded by abundant small glial cells called satellite cells.
Autonomic Ganglia
• Appear as bulbous dilatation in autonomic nerves.
• Usually have multipolar neurons.• Have neuronal perikaryons with
fine Nissl bodies.• Enveloped by satellite cells.
Autonomic Nervous System
ANS related to the control of smooth muscle, the secretion of some glands & modulation of cardiac rhythm.
ANS are organized & regulated in the CNS. Anatomically, ANS composed of :
collection of nerve cell located in CNS fibers that leave the CNS through cranial or spinal nerves. nerve ganglia situated in the paths of these fibers.
Consist of : Sympathetic & Parasympathetic System
The Nuclei of ANS
• Sympathetic System : collection of nerve cell bodies (nuclei) located in the thoracic & lumbar segments of the spinal cord thoracolumbar division of ANS
• Parasympathetic System : nuclei in the medulla and midbrain & sacral position of the spinal cord craniosacral division of ANS
Nerve Regeneration
Nerve Regeneration
Nerve cell (neuron) : no regeneration if soma or dendrites injured. But, nerve fiber injured : regeneration (+)
Neuroglia of CNS, Schwann cell & ganglionic satellite cells of PNS : able to divide by mitosis regeneration.
Degeneration & regeneration of peripheral nerve