CELLS OF THE NERVOUS SYSTEMS

1
CELLS OF THE NERVOUS SYSTEMS
2
TYPES NERVOUS TISSUE

• NEURONS
• NEUROGLIA

3
NEURONS

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

4
STRUCTURE OF A NEURON
5
CYTOPLASMIC COMPONENTS

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

6
NISSL BODIES
7
IMPORTANCE OF LOCATION

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

8
PROCESS OF NEURONS
9
AXONS

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

10
DENDRITES

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

11
AXON
12
TYPES OF SYNAPSES BETWEEN NEURONS

• AXODENDRITIC
• AXOSOMATIC
• AXOAXONIC

13
MYELINATED VS UNMYELINATED NEURONS
14
NERVES

• BUNDLES OF AXONS IN PERIPHERAL NERVOUS SYSTEM

15
NEURILEMMA OR SHEATH OF SCHWANN
16
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

17
NEURILEMMA
18
NODES OF RANVIER
19
UNMYELINATED AXONS IN THE PERIPHERAL NERVOUS
SYSTEM

• AXON OF SEVERAL NEURONS BECOME EMBEDDED IN
  CYTOPLASM OF A SINGLE SCHWANN CELL
• NO MYELIN SHEATH
• COVERED BY NEURILEMMA

20
MYELINATED TRACTS IN THE CENTRAL NERVOUS SYSTEM

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

21
TYPES OF NEURONS

• STRUCTURE VS FUNCTION

22
CLASSIFICATION BY STRUCTURE

• BIPOLAR
• UNIPOLAR
• MULITPOLAR

23
BIPOLAR NEURONS
24
UNIPOLAR NEURONS
25
MULTIPOLAR NEURONS
26
CLASSIFICATION BY FUNCTION

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

27
MOTOR NEURONS
28
SENSORY NEURONS
29
INTERNEURONS
30
ANATOMY OF A NERVE
31
ANATOMY OF A NERVE

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

32
SENSORY, MOTOR AND MIXED NERVES
33
PERIPHERAL NERVE ENDING MODIFICATIONS
34
ENDINGS OF MOTOR NEURONS

• NEUROMUSCULAR JUNCTIONS

35
NEUROMUSCULAR JUNCTIONS

• SOMATIC MOTOR NEURONS
• EFFERENT NEURONS
• MYONEURAL JUNCTION

36
ENDINGS OF SENSORY NEURONS

• FREE NERVE ENDINGS
• MERKEL DISC
• ENCAPSULATED SENSORY ENDINGS MEISSNERS
  CORPUSCLES PACINIAN CORPUSCLES END-BULBS OF
  KRAUSE RUFFINIS CORPUSCLES MUSCLE
  SPINDLES NEUROTENDINOUS ORGANS (GOLGI TENDON
  ORGANS)

37
FREE NERVE ENDINGS
38
FREE NERVE ENDINGS
39
MERKEL DISC
40
ENCAPSULATED SENSORY ENDINGS

• MEISSNERS CORPUSCLES
• PACINIAN CORPUSCLE
• END-BULB OF KRAUSE
• RUFFINIS CORPUSCLE
• MUSCLE SPINDLES
• NEUROTENDINOUS ORGANS

41
MEISSNERS CORPUSCLES
42
MEISSNERS CORPUSCLE
43
MEISSNERS CORPUSCLE
44
PACINIAN CORPUSCLE
45
PACINIAN CORPUSCLE
46
PACINIAN CORPUSCLES
47
END-BULBS OF KRAUSE
48
RUFFINIS CORPUSCLE
49
MUSCLE SPINDLES
50
MUSCLE SPINDLES
51
MUSCLE SPINDLE
52
NEUROTENDINOUS ORGANS
53
TYPES OF RECEPTORS

• LOCATION OF STIMULUS VS TYPE OF STIMULUS

54
CLASSIFICATION BY LOCATION OF STIMULUS

• EXTEROCEPTORS
• INTEROCEPTORS OR VISCEROCEPTORS
• PROPRIOCEPTORS

55
CLASSIFICATION BY TYPE OF STIMULUS

• MECHANORECEPTORS
• THERMORECEPTORS
• CHEMORECEPTORS

56
RECEPTORS

• CONVERT INFORMATION ABOUT CONDITIONS ABOUT BODY
  OR ENVIRONMENT
• TRANSDUCERS
• ADEQUATE STIMULI

57
GENERATOR POTENTIALS

• SPECIALIZED NEURONAL ENDING
• GRADED POTENTIAL
• LAST LONGER THAN ACTION POTENTIAL
• NO REFRACTORY PERIOD
• SUMMATION CAN OCCUR
• CAUSE ACTION POTENTIALS

58
RECEPTOR POTENTIALS

• SEPARATE CELL THAT IS CONNECTED TO NEURON BY
  SYNAPSE
• GRADED POTENTIAL SIMILAR TO GENERATOR POTENTIAL
• CHEMICAL NEUROTRANSMITTER FROM RECEPTOR CELL
• IT AFFECTS ASSOCIATED NEURON
• CAUSES RELEASE OF NEUROTRANSMITTERS

59
DIFFERENCES IN STIMULUS INTENSITY

• MAGNITUDE OF ACTION POTENTIAL DOES NOT VARY WITH
  THE INTENSITY OF THE STIMULUS
• INSTEAD BRAIN INTERPRETS
• NUMBER OF NEURONS ACTIVATED
• FREQUENCY OF ACTION POTENTIALS GENERATED

60
NUMBER OF NEURONS ACTIVATED

• THE MORE EXTENSIVE THE TISSUE DAMAGE THE MORE
  NEURONS WILL BE PRODUCING ACTION POTENTIALS

61
FREQUENCY OF ACTION POTENTIALS GENERATED

• THE MORE EXTENSIVE THE TISSUE DAMAGE THE MORE
  ACTION POTENTIALS PRODUCED BY NEURONS

62
ADAPTATION

• STIMULUS IS CONTINUOUSLY APPLIED
• NUMBER OF ACTION POTENTIALS MAY DIMINISH
• SOME SENSATIONS DO NOT ADAPT
• PAIN THIRST

63
EFFECTORS

• MUSCLES
• GLANDS

64
SYNAPSES

• ELECTRICAL VS CHEMICAL

65
ELECTRICAL SYNAPSE
66
CHEMICAL SYNAPSE
67
NEUROTRANSMITTER REMOVAL

• ACETYLCHOLINE
• RAPIDLY DESTROYED BY ACETYLCHOLINESTERASE
• CHOLINE IS TAKEN BACK UP INTO PRESYNAPTIC
  TERMINAL AND USED TO REGENERATE ACETYLCHOLINE
• ACETIC ACID DIFFUSE OUT OF CLEFT AND CAN BE
  ABSORBED AND USED BY A VARIETY OF CELLS

68
NEUROTRANSMITTER REMOVAL

• CATECHOLAMINES
• MOST OF NEUROTRANSMITTER IS ACTIVELY TRANSPORTED
  BACK INTO PRESYNAPTIC TERMINAL FOR REUSE
• MONAMINE OXIDASE (MAO) INACTIVATES SOME
• SOME DIFFUSES AWAY FROM SYNAPSE
• NOREPINEPHRINE IN CIRCULATIN IS TAKEN UP BY LIVER
  AND KIDNEY CELLS WHERE MONAMINE OXIDASE AND
  CATECHO-METHYLTRANSFERASE (COMT) CONVERT IT INTO
  INACTIVE METABOLITES

69
SPECIFICITY OF RECEPTORS

• HIGHLY SPECIFIC RECEPTOR SITES
• ONLY NEUROTRANSMITTER MOLECULES OR CLOSELY
  RELATED SUBSTASNCES NORMALL BIND TO RECEPTORS
• NEUROTRANSMITTERS ONLY AFFECT CELLS WITH
  RECEPTORS FOR THEM

70
SOME NEUROTRANSMITTERS INHIBIT CELLS OTHERS
STIMULATE CELLS

• MORE THAN ONE TYPE OF RECEPTOR EXISTS FOR SOME
  NEUROTRANSMITTERS
• ACITIVITY OF NEUROTRANSMITTER DEPENDS ON TYPE OF
  RECEPTOR FOUND ON CELL

71
SOME RECEPTORS ARE FOUND ON PRESYNAPTIC MEMBRANES

• MOST ARE FOUND ON POSTSYNAPTIC MEMBRANES
• NEUROTRANSMITTERS CAN MODIFY THEIR OWN RELEASE BY
  BINDING TO THESE PRESYNAPTIC RECEPTORS

72
SOME NEURONS CAN SECRETE MORE THAN ONE TYPE OF
NEUROTRANSMITTER
73
EFFECTS OF NEUROTRANSMITTERS ON NEURONS

• DIRECT EFFECTS
• INDIRECT EFFECTS VIA G PROTEINS
• INDIRECT EFFECTS VIA INTRACELLULAR ENZYMES

74
NEUROTRANSMITTER FUNCTIONSDIRECT EFFECTS
Figure 12.21a
75
NEUROTRANSMITTER FUNCTIONSINDIRECT EFFECTS VIA G
PROTEINS
Figure 12.21b
76
NEUROTRANSMITTER FUNCTIONSINDIRECT EFFECTS VIA
INTRACELLULAR ENZYMES
Figure 12.21c
77
EXAMPLES OF NEUROTRANSMITTERS
78
ACETYLCHOLINE

• NUCLEI
• TRACTS
• NEUROMUSCULAR JUNCTION
• AUTONOMIC NERVOUS SYSTEM SYNAPSES
• EXCITATORY OR INHIBITORY

79
ACETYLCHOLINE STRUCTURE
80
BIOGENIC AMINES

• CATECHOLAMINES EPINEPHRINE NOREPINEPHRINE DOPAM
  INE
• INDOLAMINES SEROTONIN HISTAMINE

81
CATECHOLAMINES

• DERIVED FROM TYROSINE
• L-DOPA
• DOPAMINE
• NOREPINEPHRINE
• EPINEPHRINE

82
DOPAMINE

• NUCLEI
• TRACTS
• VERY RESTRICTED DISTRIBUTION
• SOME AUTONOMIC NERVOUS SYSTEM SYNAPSES
• GENERALLY EXCITATORY

83
DOPAMINE STRUCTURE
84
NOREPINEPHRINE

• NUCLEI
• TRACTS
• AUTONOMIC NERVOUS SYSTEM SYNAPSES
• EXCITATORY OR INHIBITORY

85
NOREPINEPHRINE STRUCTURE
86
EPINEPHRINE

• CLOSELY RELATED TO NOREPINEPHRINE
• NERVES IN BRAIN STEM
• BEHAVIOR
• MOOD
• SOME EMOTIONS

87
INDOLAMINES

• SEROTONIN
• HISTAMINE

88
SEROTONIN

• NUCLEI
• TRACTS
• GENERALLY INHIBITORY
• PRODUCED FROM TRYPTOPHAN
• TAKEN BACK UP BY AXON TERMINAL

89
HISTAMINE

• HYPOTHALAMUS
• TRACTS
• GENERALLY INHIBITORY

90
AMINO ACIDS
91
GAMMA-AMMINOBUTYRIC ACID (GABA)

• EXERT MOSTLY LOCAL CONTROL IN THEIR PORTION OF
  CNS
• MOST NEURONS IN CNS HAVE GABA RECEPTORS
• POSTSYNAPTIC INIBITION IN BRAIN
• PRESYNAPTIC INHIBITION IN SPINAL CORD
• INHIBITORY

92
GLYCINE

• SPINAL CORD
• BRAIN
• LOCALIZED EFFECTS
• POST SYNAPTIC INHIBITION IN SPINAL CORD

93
GLUTAMATE AND ASPARTATE

• BRAIN
• SPINAL CORD
• ASCENDING AND DESCENDING TRACTS
• EXCITATORY

94
NITRIC OXIDE

• BRAIN
• SPINAL CORD
• ADRENAL GLAND
• PLEXUSES OF DIGESTIVE TRACT
• NERVES TO PENIS
• EXCITATORY

95
CARBON MONOXIDE

• CO
• STIMULATES SYNTHEISS OF CYCLIC GMP

96
NEUROPEPTIDES

• CHAINS OF AMINO ACIDS
• ALSO HAVE NON NEURAL EFFECTS
• SUBSTANCE P
• ENKEPHALINS LEU-ENKEPHALIN MET-ENKEPHALIN
• NEUROTENSIN
• CHOLECYSTOKININ
• VASOACTIVE INTESTINAL POLYPEPTIDE
• BRADYKININ

97
ENDORPHINS AND ENKEPHALANS

• CENTRAL NERVOUS SYSTEM
• PERPIPHERAL NERVOUS SYSTEM
• GENERALLY INHIBITORY
• WIDELY DISTRIBUTED IN BRAIN
• ACTS ON OPIATE RECEPTORS

98
ENDORPHINS

• REGULATE FEELINGS OF PAIN AND HUNGER
• CONNECTED TO SECRETION OF SEX HORMONES
• ACTS ON OPIATE RECEPTORS
• WIDELY DISTRIBUTED IN CNS

99
SUBSTANCE P

• BRAIN
• SPINAL CORD
• PAIN SENSORY NEURONS
• GENERALLY EXCITATORY

100
SOMATOSTATIN

• INHIBITS RELEASE OF GROWTH HORMONE
• BRAIN-GUT HORMONE
• GENERALLY INHIBTIORY
• INDIRECT ACTION BY SECOND MESSENGERS
• RELEASE IN CNS, OTHER PARTS OF BRAIN, RETINA AND
  PANCREAS

101
CHOLECYSTOKININ

• CCK
• POSSIBLE NEUROTRANSMITTER
• SECRETED BY CEREBRAL CORTEX AND SMALL INTESTINE
• GUT-BRAIN PEPTIDE
• MAY BE INVOLVED IN FEEDING BEHAVIORS

102
ATP

• MAJOR NEUROTRANSMITTER IN CNS AND PNS
• PRODUCES A DIRECT FAST EXCITATORY RESPONSE OR
  SLOWER SECOND MESSENGER RESPONSE

103
FUNCTION OF NEURON

• RELAY INFORMATION BY ACTION POTENTIALS
• INTERGRATE INCOMING SIGNALS BY INFORMATION
  DECODING
• EXPRESS INFORMATION BY INFORMATION ENCODING
• FREQUENCY OF ACTION POTENTIAL GENERATION

104
INFORMATION DECODING

• MOST NEURONS RECEIVE INPUT FROM MULTIPLE
  TERMINALS
• SOME EXCITATORY-SOME INHIBITORY
• SUM OF ACTIVITY DETERMINES WHETHER NEURONS
  GENERATE ACTION POTENTIALS AND THEIR FREQUENCY

105
SUMMATION

• POSTSYNAPTIC POTENTIALS CAN ADD TOGETHER TO
  INFLUENCE THE ACTIVITY OF A NEURON
• BOTH INHIBITORY AND EXCITATORY POST SYNAPTIC
  POTENTIALS UNDERGO SUMMATION

106
TEMPORAL SUMMATION

• MANY NERVE IMPULSES ARRIVE AT A SINGLE SYNAPSE
  WITHIN A SHORT PERIOD OF TIME

107
SPATIAL SUMMATION

• NERVE IMPULSES ARRIVE VERY CLOSE, IN TIME, TO ONE
  ANOTHER AT A NUMBER OF DIFFERENT
  SYNAPSES

108
NEURONAL CIRCUITS

• DIVERGENCE
• CONVERGENCE
• FEEDBACK CIRCUIT
• PARRALLEL CIRCUIT
• TWO NEURON CIRCUIT
• THREE NEURON CIRCUIT

109
INPUT NEURONS

• CONVEYS INFORMATION FORM ONE GROUP OF NEURONS TO
  ANOTHER
• NUCLEUS OR NEURON POOL
• GROUP OF CELL BODIES AND THEIR DENDRITES AND
  AXONS
• CHARACTERIZED BY THEIR PHYSIOLOGICA ACTIVITY
• WHEN STIMULATED ACT TOGETHER TO CAUSE SOME KIND
  OF RESPONSE

110
INTRINSIC NEURON

• LOCAL CIRCUIT NEURON
• INTERNEURON
• LOCATED IN NUCLEUS/NEURON POOL

111
RELAY NEURON

• INTERNEURON
• PROJECTS FROM ONE NUCLEUS/NEURON POOL TO ANOHTER

112
EXAMPLES OF NEURON CIRCUITS

• DIVERGENCE
• CONVERGENCE
• FEEDBACK CIRCUIT
• PARALLEL CIRCUIT
• TWO NEURON CIRCUIT
• THREE NEURON CIRCUIT

113
DIVERGENCE

• ONE SINGLE PRESYNAPTIC NEURON CAN AFFECT MANY
  POSTSYNAPTIC NEURONS

114
CONVERGENCE

• MANY DIFFERENT PRESYNAPTIC NEURONS SYNAPSE WITH A
  SINGLE POSTSYNAPTIC NEURON

115
REVERBERATING CIRCUITS
116
PARALLEL AFTER DISCHAGE CIRUCITS
117
TWO NEURON CIRCUIT

• SIMPLEST NEURON CIRCUIT
• AFFERENT NEURON
• SYNAPSE
• EFFERENT NEURON
• EXAMPLE
• PATELLAR EXTENSION REFLEX

118
THREE NEURON CIRCUIT
119
FACILITATION

• EXCITATORY POSTSYNAPTIC POTENTIALS MOVE MEMBRANE
  TOWARDS THRESHOLD
• MAKES ACTION POTENTIALS EASIER TO GENERATE

120
WHAT HAPPENS AT THE POSTSYNAPTIC NEURON

• EPSPs VS IPSPs
• ECITATORY VS INHIBITORY POSTSYNAPTIC POTENTIALS
• TYPE OF INTEGRATIVE PROCESS

121
PRESYNAPTIC INHIBITION

• RELEASE OF EXCITATORY NEUROTRANSMITTERS BY ONE
  NEURON IS INHIBITED BY ACTIVITY OF ANOTHER NEURON

122
PRESYNAPTIC FACILITATION
123
RECEPTORS

• CONVERT INFORMATION ABOUT CONDITIONS ABOUT BODY
  OR ENVIRONMENT
• GENERAL SENSES OR SPECIAL SENSES
• LIGHT, TOUCH, WARM, COLD, SOUND, AND ETC.
• TRANSDUCERS
• CONVERT ENERGY IN STIMULUS TO GRADED POTENTIAL
• ADEQUATE STIMULI
• THE SPECIFIC STIMULI THAT WILL STIMULATE A
  RECEPTOR

124
GENERATOR POTENTIALS

• SPECIALIZED NEURONAL ENDING
• GRADED POTENTIAL
• LAST LONGER THAN ACTION POTENTIAL
• NO REFRACTORY PERIOD
• SUMMATION CAN OCCUR

125
RECEPTOR POTENTIALS

• SEPARATE CELL THAT IS CONNECTED TO NEURON BY
  SYNAPSE
• GRADED PROTENTIAL SIMILAR TO GENERATOR POTENTIAL
• CHEMICAL NEUROTRANSMITTER FROM RECEPTOR CELL
• IT AFFECTS ASSOCIATED NEURON

126
RECEPTOR AND GENERATOR POTENTIALS ARE GRADED
POTENTIALS

• MAGNITITUDE VARIES WITH STRENGTH OF STIMULUS
• ACTION POTENTIALS ARE ALL OR NONE

127
NEUROGLIA

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

128
ASTROCYTES

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

129
OLIGODENDROCYTES

• WRAP AROUND AXONS TO FORM MYELIN SHEATHS

130
OLIGODENDROCYTE
131
MICROGLIA
132
EPENDYMAL CELLS

• LINE VENTRICLES AND CENTRAL CANAL

133
CHOROID PLEXUS
134
EPENDYMAL CELLS IN CHOROID PLEXUS
135
SATELLITE CELLS
136
SCHWANN CELLS
137
EFECTS OF AGING ON NERVOUS TISSUES

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