1. Kharkov National Medical University
LECTURE for dentistry students
Department of
Histology, cytology and embryology

2. Nervous Tissue consists of
2 types of cells
Neurons-
Neuroglia-
Embryogenesis
Neural tube
Neural crest – cranial, spinal, autonomic ganglia,
neuroendocrine cells (APUD),
Shwann cells of neuroglia
Monoblast – microglia

3. Neurons. Structure Neurons = nerve cells
Specialized to perception, excitement and transmition messages
Cell body
Processes – that extend from the cell body (dendrites and axons)
Nerve endings (synapses and others)
Slide 4

4. Neuron
Cell body
Slide 5

5. Neurofibrils:
A network of neurofibrils is in the perikaryon and in the dendrites and axon. Is unique to neurons. Support, drainage.

6. Nissl body clumps of basophilic material is unique to neurons.
an aggegation of
the rough endoplasmic
reticulum and free
ribosomes.

7. Neuron processes Extensions outside the cell body
dendrite
Extensions outside the cell body
Dendrites – conduct impulses toward the cell
Axons – conduct impulses away from the cell (only 1!)
axon
Slide 8

8. Classifications of neurons
According to amount of processes – structural classification:
Unipolar neurons
Pseudounipolar neurons
Bipolar neurons
Mutipolar neurons
Slide 11

9. (2) Functional Classification
1. Sensory (afferent) neurons
Carry impulses from the sensory receptors
2. Motor (efferent)
Carry impulses from the central nervous system
3. Interneurons (association) ,9% In the central nervous system
Connect sensory and motor neurons

10. (2). Neuron Classification

11. Support Cells (Neuroglia)
Support Cells (Neuroglia) Macroglia Microglia Ependymal cells Astrocytes Schwann cells

12. processes, covered by sheaths
Nerve fibers –
processes, covered by sheaths
1. Unmyelinated Myelinated

13. Unmyelinated nerve fiber
Processes are invaginated in Schwann cell cytoplasm
cytoplasm
N.c. process
nucleus
N.c. process

14. Myelinated nerve fibers
2 sheaths: myelin and Schwann (neurilemma)
process
nucleus
process
cytoplasm
cytoplasm
nucleus
process
myelin

15. The Nervous Tissue

16. Nerve endings
I. Synapses
Peripheral:
II. Sensory
III. Motor

17. NERVOUS System

18. Nervous system consists of: Central nervous system (CNS)
--Brain
--Spinal cord
Peripheral (PNS):
- ganglia
- nerves

19. Nervous system consists of: Somatic – innervates skeletal muscles
Autonomic – innervates viscera:
- sympathetic
- parasympathetic

20. PNS Ganglia are aggregations of nerve cells
Sensory ganglia lie on the dorsal root of the spinal cord, contain sensory neurons
Autonomic ganglia lie near or inside organs, contain motor neurons

21. PNS Nerves Nerve = bundle of myelinated and un- myelinated fibers
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

22. Structure of a Nerve Figure 7.20
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

23. Connective tissue in the nerve:
individual nerve fibres are covered by loose connective tissue - endoneurium.
Bundles of Nerve fibres, fascicles, are surrounded by perineurium.
The entire nerve is surrounded by a thick layer of dense connective tissue, the epineurium.

24. PNS
ganglia are surrounded by a c.t. capsule,
Neurons
N.fibers

25. consists of Gray and white matters.
CNS
consists of Gray and white matters.
Gray matter – neurons and
unmyelinated fibers
white matter – fibers
– Clusters of neurons form Nuclei

26. Spinal Cord- participates in formation of reflex arcs and connects body with the brain cortex
Nerves begin from:
Dorsal root
Ventral root

27. Spinal Cord grey matter
white mater – conduction tracts
Dorsal horn
Ventral horn

28. Anterior horn: two motor nuclei: medial and lateral
The axons of motor neurons form anterior root

29. Posterior horn
two integrative (intercalated) nuclei of somatic nervous system:
proper nucleus and Klark’s nucleus.

30. Lateral horn medial and lateral nuclei
intercalated neurons of ANS (mostly SNS)

31. Somatic reflex arc 1-st neuron – sensory ganglion
2-d neuron – dorsal horn
3-d neuron – ventral horn
Target – skeletal muscle
Testing Patellar Reflex

32. Somatic reflex arc

33. Sympathetic reflex arc
1-st: sensory neuron - in the spinal ganglion)
2-d: intercalated (preganglionic) neuron – in the lateral horn of the thoracic and upper lumbar segment of spinal cord.
Its axon is called preganglionic fiber.
3-d, motor (efferent) neuron is located in the sympathetic ganglion. The axon of the ganglion cell is called the postganglionic fiber,
carries impulse to the effector

34. Parasympathetic reflex arc
1-st: sensory neuron (in the spinal ganglion)
2-d neuron: is in the sacral spinal cord segments and in the brain stem.
3-d neuron is in the parasympathetic ganglia, which lie close to the viscera or into wall of viscera.

35. Cerebellum Two hemispheres form ’’arbor vitae’’
Provides involuntary coordination of body movements

36. Cerebellum

37. Cerebellar cortex 1)Molecular layer 2)Purkinje cells layer – main,
Receive all infor-
mation
3)Granular layer

38. Trough spinal cord receives all the information,
Cerebral cortex
Trough spinal cord receives all the information,
analyzes it,
forms respond

39. Cerebral cortex = grey matter

40. Cerebral cortex 1)molecular layer 2)external granular layer
3 )pyramidal layer
4)internal granular layer
5)ganglionic layer
6)multiform layer

41. Main =Pyramidal cells the biggest Betz cells

42. Structural unit – module = vertical column = processes of neurons around neuroglial cell