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(J) Histology Test 2 > Lecture 15 - Nervous Tissue > Flashcards

Lecture 15 - Nervous Tissue Flashcards

1
Q

What do irritability and conductability mean with respect to nerve tissue?

A

Irritability:
-specialized to receive stimuli

Conductibility:
-specialized to transmit impulses

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2
Q

What are the cellular components of nerve tissue and what are their functions?

A

Neurons:

  • conduct impulses
  • functional unit of nervous system

Neuroglial cells:

  • nonconductive
  • support and protect the neurons
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3
Q

What are the features associated with the cell body? (8)

Slide 18

A
  • contains nuclei
  • Nissl bodies; RER and ribosomes
  • extensive RER
  • elaborate Golgi
  • abundant mitochondria
  • abundant microtubules (neurotubules) and intermediate filaments (neurofilaments)
  • lipofuscin granules (increase with age)
  • ligand gated channels; local potentials
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4
Q

What are the features associated with the dendrites? (6)

Slide 19

A
  • conduct local potential towards body
  • contains Nissl substance
  • does not contain Golgi
  • may have dendritic spines
  • taper distally and may branch
  • ligand gated channels
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5
Q

What is the axon hillock?

A
  • site of origin of the axon
  • does not contain Nissl substance
  • generates action potenial
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6
Q

What are the features associated with the axon? (7)

Slide 20

A
  • voltage gated channels; action potentials
  • contains mitochondria and microtubules
  • lacks other organelles
  • constant diameter
  • terminate in branching telodendrites
  • synaptic vesicles in telodendrites
  • may have a myelin sheath
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7
Q

What are the classifications of neurons according to function and what differentiates them?

(Slide 24)

A

Sensory (afferent):
-transmit sensory impulses towards CNS

Motor (efferent):
-transmits impulses from CNS to muscle (somatic) or glands (autonomic)

Interneurons:
-transmits impulses within CNS between sensory and motor neurons

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8
Q

What are the classifications of neurons according to the number of processes?

(Slide 25)

A

Multipolar:

  • most common
  • single axon, multiple dendrites

Bipolar:

  • two processes, one at each end of neuron
  • associated with special senses

Pseudounipolar:

  • single process from cell body that bifurcates
  • found in dorsal root ganglia
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9
Q

What are the classifications of neurons according to the length of the axon?

(Slide 26)

A

Golgi I:
-long axons which leave grey mater they are a part of

Golgi II:
-short axons which ramify through gray matter

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10
Q

What is the terminology used to describe neuron structures in the CNS and PNS?

(Slide 32)

A

Nerve:
-bundle of axons in the PNS

Tract:
-bundle of axons in the CNS

Ganglion:
-aggregation of cell bodies and dendrites in PNS

Nucleus:
-aggregation of cell bodies and dendrites in the CNS

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11
Q

What are the different outer layers of a nerve and what are the features of each?

(Slide 33-34)

A

Epineurium:

  • thick fibrous coat around entire nerve
  • supplied by blood and lymphatic vessels
  • contains fibroblasts and type I collagen

Perineurium:

  • dense connective tissue covering bundles of axons (fascicles) within he nerve
  • inner layer of fibroblasts joined by tight junctions
  • blood nerve barrier

Endometrium:

  • thin layer of reticular connective tissue surrounding individual fibers and Schwann cells
  • type III collagen
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12
Q

What are the different membrane specialization of nerves?

Slide 34

A

Receptors

Ion channels:

  • ligand-gated channels on dendrites and cell bodies
  • potassium channels on axon
  • voltage gated sodium channels on axon
  • voltage gated calcium channels on axon
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13
Q

What features differentiate presynaptic membranes and postsynaptic membranes?

(Slide 38)

A

Presynaptic:

  • synaptic vesicles
  • vesicular docking proteins and synapsin filaments
  • dense bodies
  • mitochondria
  • voltage-gated calcium channels

Postsynaptic:

  • receptors
  • ligand-gated ion channels
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14
Q

Differentiate anterograde transport and retrograde transport along the axon.

(Slide 42)

A 
Anterograde:
-from cell body to distal axon
-uses kinesin
-slow (1-6 mm/day)
—SCa (preassembled mitrotubules and neurofilaments)
—SCb (enzymes, actin, and clathrin)
-intermediate (50-100 mm/day)
—mitochondria and other organelles
-fast (400 mm/day)
—synaptic vesicles and neurotransmitters

Retrograde:

  • from axon to cell body
  • uses dynein
  • carries endocytosis material and recycled proteins
  • 100-300 mm/day
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15
Q

What are glial cells and what are the different types?

Slide 46

A
  • non-neuronal cells
  • support neurons in the PNS and CNS
  • capable of cell division

Types:

  • astrocytes
  • oligodendrites
  • Schwann cells
  • microglial cells
  • ependyal cells?
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16
Q

What are the characteristics of astrocytes?

Slide 46

A
  • derived from neural crest
  • only in CNS
  • many processes that terminate on capillaries or the pia mater

Fibrous astrocytes:

  • predominately in white matter
  • long processes with few branches

Protoplasmic astrocytes:

  • predominately in gray matter
  • shorter processes with many short branches
18
Q

Describe the functions of astrocytes.

Slide 47

A
  • provides structural support
  • establishes blood-brain barrier
  • development of cerebral cortex
  • potassium sink
  • secretes neuron trophic factors
  • uptake/metabolism of neurotransmitters
  • helps form noncollagenous scar tissue following CNS injury
19
Q

What are the characteristics and functions of oligodendrocytes?

(Slide 50)

A
  • derived from neural crest
  • only in CNS

Functions:

  • function as satellite cells; closely associated with cell bodies
  • surround axons of unmyelinated fibers
  • myelinates axons in CNS (several axons)
20
Q

What are the characteristics and functions of Schwann cells?

Slide 51

A

-derived from neural crest

Functions:
-Mylinates axons in PNS (portions of single axons)

21
Q

What are the characteristics and functions of microglial cells?

A

-derived from macrophage precursors (bone marrow)

Functions:

  • phagocytic in PNS
  • recruits leukocytes across blood-brain barrier
  • modulates initiation and progression of immune responses
22
Q

What are the characteristics and functions of ependymal cells?

(Slide 54)

A
  • ciliated cuboidal
  • derived from neuroepithelium and line ventricular system

Functions:

  • transport
  • secretes CSF (choroid plexus)
23
Q

What are the characteristics and functions of satellite cells?

(Slide 54)

A
  • derived from neural crest
  • forms crescents around cell bodies in ganglia

Functions:
-insulation

24
Q

What are internal and external mesaxons?

Slide 57

A

Internal mesaxon:
-internal termination of the myelin sheath

External mesaxon:
-external termination of the myelin sheath

25
Q

Differentiate the major dense lines, intraperiod line, and Schmidt-Lanterman clefts.

(Slide 58-59)

A

Major dense line:

  • electron dense line created by cytoplasmic space between innerleaflets
  • contains myelin basic protein

Intraperiod line:

  • electron dense line created by extracellular space between outer leaflets
  • contains major protein zero (PNS) or proteolipid protein (CNS)

Schmidt-Lanterman clefts:
-area of cytoplasm within the major dense lines

26
Q

Mutation of which proteins are responsible for Charcot-Marie-Tooth diseases and Pelizaeus-Merzbacher disease?

(Slide 58)

A

Charcot-Marie-Tooth:
-major protein zero

Pelizaeus-Merzbacher:
-proteolipid protein

27
Q

What structures are found on the presynaptic membrane and what role do they play?

(Slide 66)

A

Voltage-gated calcium channels

SNAPs:

  • bind synaptic vesicle to presynaptic membrane
  • soluble NSF

Vesicle docking proteins:
-SNAP receptors

Synapsins:
-filaments of he presynaptic membrane

28
Q

What are the types of synapses?

Slide 68

A

Axosomatic:
-axon terminal synapses with neuron cell body

Axoanxonic:
-axon terminal synapses with another axon terminal

Axodendritic:
-axon terminal synapses with dendrite

Axospinous:
-axon terminal synapses with dendritic spine

Excitatory:
-more positive end-plate potential (closer to threshold)

Inhibitory:
-more negative end-plate potential (farther from threshold)

29
Q

What are the components of the meninges from superficial to deep?

(Slide 71)

A

-epidural space
-dura mater
-subdural space
-leptomenix
—arachnoid membrane
—arachnoid villi
—pia mater

30
Q

What are the characteristics of the dura mater?

Slide 72

A
  • thick sheet of tough, fibrous connective tissue
  • lines cranial vault and acts as periosteum (cranial cavity)
  • connective tube separated from bone by epidural space (vertebral column)
  • venous sinuses that receive blood from cerebral drainage and CSF
31
Q

What are the characteristics of the arachnoid mater?

Slide 73

A
  • composed of delicate connective tissue
  • separated from dura mater by single layer of arachnoid barrier cells
  • connected to pia mater by delicate strands forming subarachnoid space
  • arachnoid villi extend into venous sinuses allowing CSF to drain
32
Q

What are the characteristics of the pia mater?

Slide 74

A
  • thin, delicate connective tissue associated intimately with brain and spinal cord
  • continuous with blood brain barrier
33
Q

What are the characteristics of the choroid plexus?

Slide 77

A
  • highly infolded layer of simple cuboidal epithelium found in the ventricles
  • connected by tight junctions
  • apical microvilli and abundant mitochondria
  • contains leaky capillaries
  • apical membrane transport proteins responsible for CSF producitionn
34
Q

What are the characteristics of ependyma?

Slide 79

A
  • simple cuboidal epithelium lining ventricles
  • linked by zonula adherens
  • apical microvilli and cilia
  • basal domain in contact with astrocytic processes forming part of blood-brain barrier
35
Q

Compare sensory and autonomic ganglia.

Slide 82

A

Sensory (dorsal root):

  • capsule of epineurium
  • pseudounipolar neurons
  • postganglionic axons are myelinated
  • satellite cells; similar to Schwann cells and form a single layer around each neuron

Autonomic:

  • capsule of epineurium
  • multipolar neurons
  • postganglionic axons are not myelinated
  • similar to sensory

(J) Histology Test 2 (8 decks)

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