Bez tytulu slajdu

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Nervous system

• Central nervous system
• Brain
• Spinal cord
• Peripheral nervous system
• Nerves
• Ganglia
• Nerve endings

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Nervous tissue
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Dendrites

• Multiple processes
• Receptor processes
• Usually short
• Branch profusely forming a dendritic tree
• Become thinner as they subdivide into branches

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Axons

• Single processes
• Effector processes
• Usually long
• Dont branch profusely
• Ends in terminal arborization telodendron
• Have constant diameter

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Types of neurons

• Sensory (afferent)
• Motor (efferent)
• Interneurons

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Types of neurons

• Bipolar neurons
• Retina
• Olfactory mucosa
• Cochlear and vestibular ganglia
• Pseudounipolar neurons
• Sensory neurons
• Multipolar neurons
• Motor neurons
• Interneurons

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Nuclei of glial cells
dendrite
Axon hillock
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Nissl bodies
rough endoplasmic reticulum cisternaes and free
ribosomes
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Types of synapses

• Axosomatic
• Axodendritic
• Axoaxonic

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Types of synapses

• Excitatory
• Inhibitory

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Types of glial cells

• Central nervous system
• Oligodendrocytes
• Astrocytes
• Ependymal cells
• Microglia

• Peripheral nervous system
• Schwann cells
• Satellite cells

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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

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Astrocytes
Blood vessel
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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

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Ependymal cells

• glial cells of CNS
• cuboidal cells
• line the ventricles of the brain and the central
  canal of the spinal cord

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• glial cells of CNS
• have only a few small processes
• myelin forming cells in CNS

Oligodendrocytes
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Cells forming the myelin sheath
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Schwann cell
Internode
Node of Ranvier
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Peripheral nervous system
Axon
Shwann cell
Shwann cell
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Oligodendrocyte
Axons
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Central nervous system
Unmyelinated fibers Bare nerve fibers not
imbedded in glial cells
Myelinated fibers Oligodendrocytes
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Peripheral nervous system

• nerves
• sensory nerves
• motor nerves
• mixed nerves
• ganglia
• nerve endings

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Epineurium
Perineurium
Endoneurium
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Nerve

• Endoneurim loose connective tissue
• Perineurium a few layers of flattened
  epithelium like cells
• Epineurium dense irregular connective tissue
  containing blood vessels

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Nucleolus
Satelite cells
Nucleus of nerve cell
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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

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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

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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

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Nerve endings

• afferent sensory receptors
• efferent

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Sensory receptors

• exteroceptors
• proprioceptors
• interoceptors

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Sensory receptors

• Nonencapsulated
• Free nerve endings
• Merkel endings
• Encapsulated
• Meissner corpuscle
• Pacinian corpuscle
• Ruffini corpuscle

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Free nerve endings

• Found in skin and corneal epithelium
• Terminate in epidermis
• Devoid of Schwann cells and myelin
• Respond to touch, heat, cold, pain

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Merkel ending

• Nerve endings are attached to Merkel cells
• Merkel cells modified epidermal cells located
  in skin
• Mechanoreceptors sensitive to touch

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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

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Meissners 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

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Proprioceptors

• Muscle spindles
• Golgi tendon organs

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Degeneration and regeneration of peripheral nerve
- steps

• Schwann cells proliferate and bridge the scar.
• The axon degenerate
• Anterograde degeneration (reffers to distal
  segment) comprise the whole distal segment
  including axon and myelin sheath
• Retrograde degeneration (reffers 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.