This document provides an overview of the nervous system, including its central and peripheral components. It describes the main cell types - neurons and glial cells. It discusses the key parts of neurons - dendrites, axons, axon hillock. It outlines the main types of neurons and glial cells in both the central and peripheral nervous systems. It provides details on how neurons communicate at synapses and how glial cells support neuronal function.

1. Nervous system
 Central nervous system
 Brain
 Spinal cord
 Peripheral nervous system
 Nerves
 Ganglia
 Nerve endings

2. Nervous tissue
nerve cells
NEURONS
supporting cells
GLIAL CELLS

5. Dendrites
 Multiple processes
 Receptor processes
 Usually short
 Branch profusely forming
a dendritic tree
 Become thinner as they subdivide
into branches

6. Axons
 Single processes
 Effector processes
 Usually long
 Don’t branch profusely
 Ends in terminal arborization –
telodendron
 Have constant diameter

7. Types of neurons
 Sensory (afferent)
 Motor (efferent)
 Interneurons

8. Types of neurons
 Bipolar neurons
 Retina
 Olfactory mucosa
 Cochlear and
vestibular ganglia
 Pseudounipolar
neurons
 Sensory neurons
 Multipolar neurons
 Motor neurons
 Interneurons

9. Nuclei of glial cells
dendrite
Axon hillock

10. Nissl bodies
rough endoplasmic reticulum
cisternaes and free ribosomes

11. Types of synapses
Axosomatic
Axodendritic
Axoaxonic

13. Types of synapses
 Excitatory
 Inhibitory

14. Types of glial cells
Central nervous system
 Oligodendrocytes
 Astrocytes
 Ependymal cells
 Microglia
Peripheral nervous system
 Schwann cells
 Satellite cells

15. Astrocytes
 Glial cells of central nervous system
 2 types
 Protoplasmic
 Fibrous






support neurons
surround neurons, blood vessels, synapses
form a layer on outer surface of the brain and spinal cord
control ionic and chemical environment of neurons
regulate neuronal activity and metabolism
joined to one another by gap junctions forming
a continous network

18. Astrocytes
Blood vessel

19. Microglial cells – Microglia
 glial cells of central nervous
system
 phagocytic cells – belong to
mononuclear phagocytic
system
 macrophages of CNS
 derive from precursor cells in
bone marrow
 involved in inflammation
processes in CNS
 phagocyte dead neurons and
an excess of neurons during
embryogenesis

20. Ependymal cells
 glial cells of CNS
 cuboidal cells
 line the ventricles of the brain
and the central canal of the spinal cord

21. Oligodendrocytes
 glial cells of CNS
 have only a few small processes
 myelin – forming cells in CNS

23. Cells forming the myelin sheath
PNS
Schwann cells
CNS
Oligodendrocytes

24. Schwann cell
Internode
Node of Ranvier

27. Peripheral nervous system
Myelinated fibers
Unmyelinated fibers
One Shwann cell→ one axon
One Schwann cell→ several axons
Axon
Shwann cell
Shwann cell

28. Oligodendrocyte
Axons

29. Central nervous system
Myelinated fibers
Unmyelinated fibers
Oligodendrocytes
Bare nerve fibers
– not imbedded in glial cells

30. Peripheral nervous system
 nerves
 sensory nerves
 motor nerves
 mixed nerves
 ganglia
 nerve endings

31. Epineurium
Perineurium
Endoneurium

32. Nerve
 Endoneurium – loose connective tissue
 Perineurium – a few layers of flattened
epithelium – like cells
 Epineurium – dense irregular connective
tissue containing blood vessels

41. Nucleolus
Satelite cells
Nucleus of nerve cell

42. Sensory ganglia
 lie in dorsal roots of spinal cord, outside of CNS
 contain cell bodies of sensory neurons –
pseudounipolar
 2 regions
 central region – nerve fibers
 peripheral region – cell bodies
 cell bodies are covered by satellite cells
 satellite cells – a kind of glial cells of PNS

43. Nervous system
 Somatic nervous system – voluntary
functions – control skeletal muscles
 Autonomic nervous system –
involuntary functions – control smooth
muscle, secretion of some glands, modulation of
cardiac rhythm

45. Autonomic nervous system
 Sympathetic system – presynaptic
neurons are located in thoracic and lumbar
segments of spinal cord
 Parasympathetic system – presynaptic
neurons have their nuclei in medulla, midbrain,
sacral portion of spinal cord

46. Nerve endings
 afferent – sensory receptors
 efferent

47. Sensory receptors
 exteroceptors
 proprioceptors
 interoceptors

48. Sensory receptors
 Nonencapsulated
 Free nerve endings
 Merkel endings
 Encapsulated
 Meissner corpuscle
 Pacinian corpuscle
 Ruffini corpuscle

49. Free nerve endings
 Found in skin and
corneal epithelium
 Terminate in
epidermis
 Devoid of Schwann
cells and myelin
 Respond to touch,
heat, cold, pain

50. Merkel ending
 Nerve endings are
attached to Merkel
cells
 Merkel cells –
modified epidermal
cells located in skin
 Mechanoreceptors –
sensitive to touch

51. Pacinian corpuscles
 Encapsulated receptors
 Ovoid structure resembling
a hemisected onion
 Nerve ending is
surrounded
by concentric lamellae of
flattened cells
 Found in hypodermis and
deed fascia tissues
 Respond to vibrations and
deep pressure

53. Meissner’s corpuscles
Encapsulated receptors
Contain Schwann cells that
form irregular, tortuous
lamellae
 Nerve fibers pass between
lamellae
 Found in the papillary layer
of hairless skin (lips,
fingers, hands, foots)
 Respond to touch



56. Proprioceptors
 Muscle spindles
 Golgi tendon organs

63. Degeneration and regeneration of
peripheral nerve - steps
1.
2.


3.
4.
5.
6.
7.
8.
Schwann cells proliferate and bridge the scar.
The axon degenerate
Anterograde degeneration – (refers to distal segment) – comprise the
whole distal segment including axon and myelin sheath
Retrograde degeneration – (refers to proximal segment) –extends for a
short distance
Debris is phagocyted by macrophages.
The cell body undergoes chromatolysis.
The muscle fiber shows a denervation atrophy.
Shwann cell prolipherate within a connective tissue sleeve.
The axon grows and penetrate the Schwann cell columns.
Schwann cells produce myelin sheath on the regenerated axon.