CELLS OF THE NERVOUS SYSTEMS

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CELLS OF THE NERVOUS SYSTEMS
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TYPES NERVOUS TISSUE

• NEURONS
• NEUROGLIA

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NEURONS

• SPECIALIZED FOR TRANSMITTING ACTION POTENTIALS
• FUNCTIONAL COMPONENT OF NERVOUS SYSTEM
• RESPONDS TO STIMULI
• INTIATES AND CONDUCTS ELECTRICAL SIGNALS

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STRUCTURE OF A NEURON

• CELL BODY, SOMA OR PERIKARYON

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CYTOPLASMIC COMPONENTS

• NUCLEUS WITH LARGE NUCLEOLUS
• MITOCHONDRIA
• GOLGI APPARATUS
• NISSLE BODIES OR CHROMATOPHILIC SUBSTANCE
• NEUROFIBIRLS

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IMPORTANCE OF LOCATION

• MOST CELL BODIES ARE IN CENTRAL NERVOUS SYSTEM
• CALLED NUCLEI IN CENTRAL NERVOUS SYSTEM
• CALLED GANGLIA IN PERIPHERAL NERVOUS SYSTEM

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PROCESS OF NEURONS
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DENDRITES

• DENDRITIC ZONE
• RECEPTIVE PORTION
• MAY INCLUDE CELL BODY ALSO
• CARRIES IMPULSE TO CELL BODY
• NUMBER, LENGTH AND BRANCHING VARY

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AXONS

• CONDUCTS IMPULSES AWAY FROM CELL BODY
• ARISES FROM CELL HILLOCK
• LENGTH VARIES CONSIDERABLY
• GENERALLY HAVE COLLATERALS
• TERMINATE IN TELIODENRIA AND SYNAPTIC BULBS

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AXON
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MYELINATED VS UNMYELINATED NEURONS
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NERVES

• BUNDLES OF AXONS IN PERIPHERAL NERVOUS SYSTEM

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NEURILEMMA OR SHEATH OF SCHWANN
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MYELINATED AXONS IN THE PERIPHERAL NERVOUS SYSTEM

• SCHWANN CELL WRAPS AROUND AXONS SEVERAL TIMES
• ALTERNATING LAYERS OF PROTEINS AND LIPIDS
• OUTERMOST PORTION IS THE NEURILEMMA

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NEURILEMMA
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NODES OF RANVIER
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UNMYELINATED AXONS IN THE PERIPHERAL NERVOUS
SYSTEM
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MYELINATED TRACTS IN THE CENTRAL NERVOUS SYSTEM

• OLIGODENDRITES
• SENDS OUT PROCESSES THAT ENVELOPE AXONS
• FORMS MYELIN SHCEATH
• NO NEURILEMMA

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TYPES OF NEURONS

• STRUCTURE VS FUNCTION

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CLASSIFICATION BY STRUCTURE

• BIPOLAR
• UNIPOLAR
• MULITPOLAR

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BIPOLAR NEURONS
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UNIPOLAR NEURONS
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MULTIPOLAR NEURONS

• MANY PROCESSES EXTENDING FROM CELL
• DENDRITE
• ONLY ONE AXON
• BRANCHES ARE COLLATERAL

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CLASSIFICATION BY FUNCTION

• MOTOR OR EFFERENT
• SENSORY OR AFFERENT
• INTERNEURONS OR ASSOCIATION

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MOTOR NEURONS
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SENSORY NEURONS
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INTERNEURONS

• MULTIPOLAR NEURONS
• ONLY IN CENTRAL NERVOUS SYSTEM
• CONNECT NEURONS TO ONE ANOTHER

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ANATOMY OF A NERVE
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ANATOMY OF A NEURON

• PROCESSES OF MANY NEURONS HELD TOGETHER BY
  CONNECTIVE TISSUE SHEATHS
• ENDONEURIUM
• PERINEURIUM
• EPINEURIUM
• FASCICULUS

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SENSORY, MOTOR AND MIXED NERVES
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TYPES OF RECEPTORS

• LOCATION OF STIMULUS VS TYPE OF STIMULUS

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CLASSIFICATION BY LOCATION OF STIMULUS

• EXTEROCEPTORS
• INTEROCEPTORS OR VISCEROCEPTORS
• PROPRIOCEPTORS

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CLASSIFICATION BY TYPE OF STIMULUS

• MECHANORECEPTORS
• THERMORECEPTORS
• CHEMORECEPTORS

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NEUROGLIA

• ASTROCYTES
• OLIGODENDROCYTES
• MICROGLIA
• EPENDYMAL CELLS
• SATELLITE CELLS
• SCHWANN CELLS

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ASTROCYTES

• LARGE CELLS
• STAR SHAPED BODIES
• ATTACH TO NEURONS AND CAPILLARIE BY END FEET
• MOST ABUNDANT OF NEUROGLIA
• BLOOD BRAIN BARRIER

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OLIGODENDROCYTES

• WRAP AROUND AXONS TO FORM MYELIN SHEATHS

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OLILGODENDROCYTE
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MICROGLIA

• PHAGOCYTIC
• PART OF MACROPHAGE SYSTEM

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MICROGLIA
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EPENDYMAL CELLS

• LINE VENTRICLES AND CENTRAL CANAL

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EPENDYMAL CELLS IN CHOROID PLEXUS
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CHOROID PLEXUS
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SATELLITE CELLS
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SCHWANN CELLS
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EFECTS OF AGING ON NERVOUS TISSUES

• MOST NEURONS STOP IN GO PHASE
• THIS MEANS WHEN THEY DIE THEY ARE NOT REPLACED
• AGING SEEM STO CAUSE SOME LOSS OF MYELIN
• CONDUCTION RATES DECREASE
• REDUCTION OF NEUROTRANSMITTERS AND RECEPTORS
• REDUCTION IN GOLGI APPARATUS AMD CHROMATOPHILIC
  SUBSTANCE