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
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
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
27. Peripheral nervous system
Myelinated fibers
Unmyelinated fibers
One Shwann cell→ one axon
One Schwann cell→ several axons
Axon
Shwann cell
Shwann 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
44.
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
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
52.
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
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.