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Histology > Nervous Tissue > Flashcards

Nervous Tissue Flashcards

1
Q

T/F neuron has 1 cell body with 1 dendrite and multiple axons

A

F, 1 axon with multiple dendrites

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2
Q

Neuron cell body

A

. Call soma or perikaryon
. Metabolic center of neuron w/ tons mitochondria
. Nucleus w/ euchromatin and prominent nucleolus (active DNA and rRNA synthesis)
. Nissl substance

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3
Q

Nissl bodies

A

Extensive stacked layers of ER that look like basophilic patches

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4
Q

Pathological Chromatolysis

A

Absence of basophilic staining in the soma in response to injury (nissl bodies disappear)

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5
Q

Neurofibril function

A

. Structural support/cytoskeleton elements
. Have microtubules that transport neurotransmitter-filled vesicles that course from neuronal cell body to axonal terminal endings

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6
Q

Neurofibril EM appearance

A

Groups of intermediate filaments and microtubules

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7
Q

Neurofibril cytoskeletal elements

A

. Actin filaments (3-4 nm)
. Neurofilaments (10nm)
. Microtubules (24-28 nm) that extend to axon and continue down entire thing

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8
Q

Axon hillock

A

. Cone-shaped region where axon arises

. No nissl substance

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9
Q

Initial segment.

A

. Part of axon adjacent to hillock

. Anatomical location for initiating action potentials

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10
Q

Neuron classifications and where they can be found

A

. Unipolar (rods/cones)
. Bipolar cell (olfactory receptors)
. Psuedounipolar cell (peripheral ganglia)
. Multipolar cell (majority)

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11
Q

Distinguishing feature between axon and dendrites

A

dendrites have ribosomes and axons do not

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12
Q

Axoplasm

A

. Cytoplasm of axon

. Dense bundle of microtubules and neurofilaments and organelles that are being transported down axon

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13
Q

Difference between nerve fiber and axon

A

Nerve fiber is axon with sheath made by glial cells

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14
Q

Terminal arbors

A

. Fine branches at end of axon

. Each terminal capped w/ terminal boutons corresponding to synapses between neurons

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15
Q

Axonal transport

A

. Moves organelles and macromolecules between cell body and axon and it’s terminals
. Transport occurs in both directions

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16
Q

Anterograde axonal transport

A

. Transport from cell body towards terminals
. Moves macromolecules-containing vesicles and mitochondria along microtubules for passage of info from neuron to neuron

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17
Q

Retrograde axonal transport

A

. Transports from terminals toward cell body
. Allows neurons to respond to molecules (nerve growth factor/NGF)
. Aids in recycling components of axon terminals

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18
Q

How does rabies virus infect CNS?

A

. Transported in retrograde direction to cell bodies of neurons innervating muscle

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19
Q

Is tetanus toxin transported retrograde or anterograde?

A

Retrograde

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20
Q

Types of synapses

A

Chemical and electrical

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21
Q

Components of typical synapses

A

. Presynaptic element
. Post synaptic element
. Synaptic cleft

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22
Q

Presynaptic element in synapse

A

. Axonal Bouton w/ mitochondria supplying energy

. Collections of vesicles w/ neurotransmitters

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23
Q

Postsynaptic element in synapse

A

. Thick, dark in EM

. Mitochondria but no vesicles

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24
Q

Functional properties of synapses

A

. Unidirectional (only presynaptic had neurotransmitter and postsynaptic has receptor proteins)
. Strength of effect dependent on amt neurotransmitter released

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25
Q

What dictates excitatory or inhibitory response to neurotransmitters in synapses?

A

. Nature of specific receptors on postsynaptic membrane

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26
Q

Types of dopamine receptors and whether excitatory/inhibitory

A

. D1: excitation

. D2: inhibition

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27
Q

Classifications of synapses

A

. Axosomatic: axon ending on cell soma
. Axodendritic: axon ending on dendrite
. Axoaxonic: axon ending on axon
. Motor end-plate/neuromuscular plate: axon ending on muscle cell

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28
Q

How do dendrites receive signals

A

Via synapses or environment via special receptors

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29
Q

How does info travel in dendrites?

A

Distal to proximal (tip to base) to converge at cell body

30
Q

Dendrite characteristics

A

. Branching inc. surface area for receiving signals
. Dendritic spines (bud-like extensions) on distal branches on dendritic tree
. Some rER, polyribosomes, and mitochondria found in prox. Portion in primary branches
. Only cytoskeletal elements seen in distal portions to maintain structure

31
Q

What is preferential site for synapses?

A

. Dendritic spines

. Protrusions from dendrite provide contact point w/ neighboring neurons

32
Q

How can neurons be classified as functionally?

A

. Sensory (afferent)

. Motor (efferent)

33
Q

Primary sensory neurons and examples

A

Receive info from environment

, photoreceptors, chemoreceptors, mechanoreceptor, thermoreceptors, nociceptors

34
Q

Transduction

A

. Converting sensory input into form interpretable by nervous system
. Sensory receptors tranduce environmental chemical or physical stimulus into electrical or chemical changes transmitted as signals in nervous system

35
Q

Photoreceptors

A

. Rods and cones

. Tranduce light into photons

36
Q

Primary types of chemoreception

A

Taste epithelial receptors and olfactory neuroreceptors

37
Q

Mechanoreceptors

A

. Tranduce qualities of physical force into electrical signals transmitted by sensory neurons
. Found in vestibular, auditory, and somatosensory systems

38
Q

Thermoreceptors

A

. Sense temp. Changes in skin and viscera while nociceptors tranduce noxious stimuli

39
Q

Neurotransmitter specificity

A

. Can be used to describe neurons and their axons
. Dopamine releasing = dopaminergic
. Glutamate releasing = glutamatergic

40
Q

Neuroglia

A

. Non-neuronal cell types that support and nourish neurons

. 40% total CNS volume

41
Q

How much can glial cells outnumber neurons?

A

5-50 times

42
Q

Types of glial cells found in CNS

A

. Astrocytes
. Micoglia
. Oligodendrocyte
. Ependymal cell

43
Q

Astrocyte

A

. Largest most numerous
. Branched w/ processes from capillaries to neurons
. Forms BBB
. Stores and transfers metabolites from capillaries to neurons
. Stores glycogen
. Multiplies and activates in response to CNS injury inc. protein and intermediate filaments to create astrocytic scar
. Regulate K in ECM
. Removes glutamate from synaptic clefts preventing accumulation of excitatory neurotransmitter

44
Q

Astrocytic scars

A

. Neuroprotective to wall off and contain injury site
. Have molecules that are inhibitory to neurite (axon or dendritic) outgrowth inhibiting regeneration or repair of neuron

45
Q

Microglia

A

. Small mesodermal cells related to macrophages
. Small cigar shaped w/ ratified processes
. Aid in remodeling neuronal circuits
. Aid in developmental pruning of synapses
. Regulates neuronal activity at synaptic level
. When around disease: defense, phagocytize and remove debris

46
Q

Oligodendrocyte

A

. Small w/ few short processes
. Myelin forming
. 1 cell can myelinated portions of numerous (5-50) axons
. Express neuronal growth inhibitory molecules that inhibit aberrant outgrowth of axons

47
Q

Ependymal cells

A

. Ciliated low columnar/cuboidal epithelium that lines ventricular cavities of brain and central canal of spinal cord
. Cilia promote movement of CSF
. Adjacent cells jointed by desmosomes
. Basal lamina btw ependymal cells and glia discontinuous for easy fluid exchange btw CSF and brain parenchyma

48
Q

Choroid plexus epithelium

A

. Ependymal cells that produce and secrete CSF

49
Q

Types of glia in PNS

A

. Satellite cell

. Schwann cell

50
Q

Satellite cell

A

. Small cells that surround/nourish dorsal root ganglion neurons and autonomic ganglion neurons

51
Q

Schwann cells

A

. Myeline forming in PNS
. 1 cell only myelinate portion of single axon (intermodal segment)
. Important in regeneration/re-myelination of severed axons in PNS

52
Q

Myelination

A

. Formation of concentric wrapped myelin sheath around axons to electrically insulate them

53
Q

Nodes of Ranvier

A

. Gaps in myelin sheath where adjacent oligodendrocytes/Schwann cells meet so axon isn’t wrapped
. Electrical activity jumps from node to node completing Saltatory conduction

54
Q

What is myelin composed of?

A

Plasmalemma of oligodendrocyte/Schwann cells made of lipid and protein

55
Q

Peripheral nerves

A

. Establish communication btw. Peripheral targets/sources of sensory inputs and CNS
. Comprised of numerous fibers myelinated and unmyelinated enclosed by CT

56
Q

CT Components of nerve

A

. Endoneurium: surrounding individual fiber
. Perineurium: surround fascicles (group of fibers)
. Epineurium: surrounding entire peripheral nerve

57
Q

Where is nerve blood supply found?

A

Epineurium and perineurium

58
Q

T/F There are nerves in CNS

A

F, in CNS fibers organized in bundles forming tracts

59
Q

T/F All spinal nerves are mixed nerves

A

T, only cranial nerves are pure sensory or motor

60
Q

Ganglia

A

. Peripheral clusters of neurons/glial cells (satellite and Schwann) surrounding connective capsule
. Sensory ganglia hosts cell bodies of pseudounipolar neurons

61
Q

Which ganglion house bipolar neurons instead of pseudo-unipolar ones?

A

. Ganglion of Scarpa (vestibular system)

. Ganglion of Corti (auditory system)

62
Q

What do autonomic (parasympathetic and sympathetic) ganglia house?

A

. Second order neuron in bi-neuronal chain connecting effector multipolar neurons providing involuntary moor control of viscera

63
Q

Main organizational difference between motor control of skeletal muscle and visceral muscles?

A

. 1 neuron conveys impulses from CNS to skeletal muscle
. Chain of 2 neurons (presynaptic in spinal cord, postsynaptic in autonomic ganglion) conveys impulses from CNS to viscera

64
Q

Enteric nervous system

A

. Nerve cells in GI tract controlling gut motility
. May have more nerves than spinal cord
. Myenteric (auerbach’s) and submucosal (meissner’s) ganglia plexuses

65
Q

Myenteric plexus

A

. Located btw inner and outer muscle layers of muscularis externa

66
Q

Submuscosal plexuses

A

. Located in submucosa

67
Q

Physiological chromatolysis

A

Area between axon hillock and initial segment where there is no coloration due to no rER

68
Q

Fibrous astrocyte

A

Found within white matter, skinnier

69
Q

Protoplasmic astrocyte

A

Within gray matter, fatter

70
Q

Sympathetic ganglia neural organization

A

1 short preganglionic neuron to sympathetic trunk then one longer postganglionic neuron from trunk to viscera using noradrenaline

71
Q

Parasympathetic ganglion neuron organization and neurotransmitter

A

. 1 long preganglionic neuron from spinal cord to parasympathetic ganglion
. 1 short postganglionic neuron from ganglion to viscera
. Uses Ach

Histology (22 decks)

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