COT - Exam 1 > 7.3 - Lecture - Nerve > Flashcards

7.3 - Lecture - Nerve Flashcards

(86 cards)

Study These Flashcards
1
Q

What are the three neuron classifications

A
  • unipolar (pseudounipolar)
  • bipolar
  • multipolar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What defines each of the three classification types

A
  • they are based on the relationship of the cell body (soma) to the peripheral processes, i.e. axons and dendrites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Nissl Bodies

A
  • in the LM sometimes help to recognize cell bodies of neurons
  • representing large amount of basophilic ER
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Axodendritic Synapses

A
  • axon synapsing on a dendrite
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Presynaptic element

A
  • part of synapse that contains a region specialized for the vesicular release of NT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Postsynaptic element

A
  • part of synapse that contains membrane receptors that convert the chemical signal from the NTs into a membrane potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Axosomatic synapse

A

axon synapsing on the soma of a neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

axoaxonic synapse

A
  • axon synapsing on the exposed portion of an axon - nearer to the soma on the axon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two locations/names for presynaptic elements

A

1) Bouton en passant - if the presynaptic element occurs along the length of the axon
2) terminal bouton if the presynaptic element occurs at the end of the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a Dendritic spine in relation to a synapse

A
  • postsynaptic element normally occurs here
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Axon hillock

A
  • typically the area of a cell at which an AP (spike) is generated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe an AP in Myelinated axons

A
  • spikes propagate via saltatory conduction

- spikes are regenerated at nodes of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe an AP in unmyelinated axons

A
  • spikes travel more slowly due to the lack of a myelin sheath
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Oligodendrocyte

A

= the support cell of the CNS responsible for making myelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Schwann Cell

A

= the support cell of the PNS responsible for making myelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two appearances of myelin sheaths in EM

A

alternating:
1) major dense lines
and
2) Intraperiod lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Major Dense Lines

A

= two apposed cytoplasmic faces of the unit membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Intraperiod lines

A

= two apposed extracellular faces of the unit membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Inner mesaxon

A

= ending of cell membranes contributing to the myelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Outer mesaxon

A

= ending of cells membrane contributing to the myelin that connects to the cell body of the support cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Glial cells

A

= non-neuronal cells
- fxns: scaffolding, metabolic support of neurons, contributing to the blood-brain barrier
include:
- astocytes, fibrous astrocytes, protoplasmic astrocytes, microglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Astocytes (astroglia)

A
  • in the CNS
  • contain unique intermediate filament - glial fibrillary acidic protein (GFAP) - useful for recognition by antibody staining
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Glial Fibrillary acidic protein (GFAP)

A
  • a unique intermediate filament

- found in astrocytes in the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Ganglia

A
  • collections of cell bodies outside the CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Satellite cells
- support the neuronal cell bodies in the ganglia
26
Nucleus (not organelle)
- a discrete group of cell bodies inside the CNS (in the brainstem mostly) e. g. brainstem nuclei, paraventricular nucleus, lateral geniculate nucleus
27
Grey matter
- CNS organization largely containing neuronal cell bodies, neuropil, and glial cells
28
Neuropil
mesh of axons and dendrites
29
white matter
- CNS organization largely containing axons + oligodendrocytes
30
The three covering of the brain
are meninges - three layers of fibrous tissue 1) pia mater - thin/wispy 2) Arachnoid mater 3) Dura mater - extremely tough
31
Subarachnoid space
- common site of brain hemorrhage
32
Two classifications of neurons in the periphery
1) Sensory | 2) Motor
33
Motor neurons in the PNS
- motor neurons of the spinal cord - directly control skeletal muscle - axons of motor neurons from specialized NMJs with the muscle fibers and post-synaptic region of the muscle cell plasmalemma= motor end plate - leave the spinal cord and pass through ventral roots
34
Sensory Neurons in PNS
- pass through the dorsal root ganglion | - cell bodies are located in the DRG
35
Motor end plate
= the post-synaptic region of the muscle cell plasmalemma
36
ANS
- innervates organs and glands - has 2 divisions 1) parasympathetic 2) Sympathetic 3) Enteric NS - in the gut
37
Sympathetic ganglia
located between the spinal cord and organ of innervation
38
Parasympathetic ganglia
located immediately adjacent to the innervated organ
39
Perineurium
- CT encircles large nerve fibers
40
Epineurium
= CT that is adventitial between the nerve fiber and surrounding structures
41
Endoneurium
= fine CT immediately surrounding axons
42
Endoneurial tubes (Schwann tubes)
= tubes in which axons travel made by schwann cells | - important structures in axon regeneration
43
Describe the characteristic nuclear morphology of a neuron
- large spherical euchromatic nucleus | - contains very prominent nucleolus (tells you the nucleus is active)
44
What are Nissl Bodies and the Nissl Stain
- correspond to stacks of ER that fill the neurons because they are very actively producing proteins - shown by the Nissl Stain - accumulating in cytoplasmic globules of dye = nissl bodies - charcateristic of neurons
45
Golgi Stain
- stains only 1-5% of the neurons --> allows visualization of a neuron and its processes - myelin disturbs Golgi stain
46
Describe the typical characteristics/morphology of a local process or dendrite
- multiple dendrites emerge from soma at different sites and branch extensively at less than 90 degree angles - dendrites tape with increasing distance from cell body - appears studded with Golgi stain
47
Describe the typical characteristic/morphology of a distal process or axon
- one axon - emerges from cell body at a specialized region = axon hillock - maintains fix diametere throughout its long course - branches emerge at 90 degree angles - appears smooth in Golgi stain
48
Describe the fine structures of dendrites
- microtubules - mitochondria - large dendrites - contain ER, ribosomes, neurofilaments - dendritic spines
49
What are dendritic spines
= specialized evaginations of dendritic plasmalemma that receive signals - each spine can move (increase or decrease in size) - they are highly dynamic - each receives a synapse
50
Describe the fine structures of an axon
- neurofilaments - microtubules - stray mitochondria - no rER or free ribosomes
51
Describe the morphology of axons in Nissl stains
- axons don't stain with nissl (because do not contain ER)
52
Describe the morphology of axons in H and E stains
- eosinophilic core = axon - white space = myelin - can see perpindicular line = indicating node of Ranvier of myelinated axons (in longitudinal sections)
53
Describe the morphology of axons in osmium and what osmium stains for
- Osmium is a heavy metal stain for lipids | - therefore it will show myelin staining around myelinated axons
54
Compare myelination of axons in the CNS and PNS
- in PNS 1 schwann cell contributes 1 internode of myelin to a single axon - in CNS 1 oligodendrocyte contributes internodes to multiple axons
55
Describe the morphology of unmyelinated axons in H and E stains and their relation to the myelin-producing cells
- they appear as froth in H and E stains - many unmyelinated axons are enveloped by a single supporting cell - which offers partial support (not to the level of myelination though) - i.e. Schwann cells that are not involved in myelinating an axon encapsulate a group of unmyelinated axons
56
Describe the different axonal terminations
- axo-dendritic (on a dendrite) - axo-spinous (on the dendrite spine) the above ones are the most common - axo-somatic (on the soma) - axo-axonic (on the inital segment of an axon) - in rare cases dendrites can have vesicles and be presynaptic to other vesicles
57
What are the two types of synapses and are they differentiable in EM?
- The two types are excitatory and inhibitory and they are differentiable in EM
58
Describe the characteristics of Excitatory Synapses
use the acronym WEAR - Wide synaptic cleft - Excitatory - Asymmetric synapse - Round Vesicle
59
Describe the characteristics of Inhibitory Synapses
use acronym PINS - Pleomorphic vesicles - Inhibitory - Narrow Synaptic Cleft - Symmetrical Synapse
60
Describe the multipolar classification of neurons
- Multiple processes into and out of the cell body- Multiple dendrites + multiple axons ex. Chandelier cells with "candles" axons - effective rapid inhibitory neuron - shuts down cells very effectively ex. Purkinje Neurons
61
Describe the Bipolar classification of neurons
- morphologically simlified neurons - 1 input process - 1 output process - only found in retina and olfactory bulb
62
Describe the Unipolar classification of neurons
- only found in sensory ganglia of the PNS --> DRG - AP initiation and summation happens at sensory end - AP signal doesnt have to go though the cell body (unlike multipolar or bipolar neurons) - almost always myelinated - have satellite cells (subclass of Schwann cell)
63
2 Differences of CNS and PNS
- supporting cells/elements | - response to injury
64
Describe the relative size of a supporting cell
- essentially equivalent to nucleolus of neuron --> (might only apply to unipolar neurons???)
65
What are the non-neuronal cells of the CNS
- generally known as glia (glue) - support neuronal function and provide structure 1) Macroglia 1A) Astrocytes 1B) Oligodendrocytes 2) Microglia
66
Describe astrocytes
- star shaped marcoglial cells of CNS - provide structure to brain and fill space between neuronal processes (CNS doesnt have CT) - Contains intermediate filaments - GFAP in cytoplasm to provide structural support - maintain stable ionic medium around nucleus by taking up excess NT and regulating ionic composition - provide metabolic support to neurons - forms glial scar - by proliferating and forming scar in regions of CNS damage
67
What are the types and localizations of the two types of astrocytes
1) Protoplasmic Astrocytes - in grey matter | 2) Fibrous Astrocytes - in white matter
68
Describe Oligodendrocytes
- macroglial cells of CNS | - each cell gives rise to several processes that each forms myelin internode on a different axon
69
Describe Microglia
= phagocytic cells that patrol the brain + spinal cord - are part of the Mononuclear phagocytic system (MPS) - derived from bone marrow - from monocytes (like macrophages, alpha-synoviocytes, osteoclasts) - incredibly dynamic cells - highly motile within nervous tissue - responsible for immune surveillance
70
What are the nonneuronal cells of the PNS
``` - nerves in periphery are ensheathed, organized, supported by CT + the microenvironment bathing the neuronal elements in PNS is strictly controlled by: Epineurium Perineurium Endoneurium External Lamina Schwann Cells Satellite Cells ```
71
Function of epineurium in PNS - in relation to support cells it provides
- dense CT sheath around perineurium | - separating perineurium from rest of tissues
72
Function of perineurium in PNS - in relation to support cells it provides
- collagen fibers with squamous cells | - surround and support nerves
73
Function of endoneurium in PNS - in relation to support cells it provides
- type III collage fibers (reticular fibers) - between myelin sheaths
74
Function of external lamina in PNS - in relation to support cells it provides
- basal lamina surrounding schwann cells
75
Function of Schwann cells in PNS - in relation to support cells it provides
- surround myelinated and unmyelinated axons in peripheral nerves
76
Function of Satellite cells in PNS - in relation to support cells it provides
- a subclass of Schwann Cell - encapsulate neuronal cell bodies in peripheral ganglia (DRG) - protect cell - joined together by gap JXNs - to separate it from ECF
77
Which support cell is responsible for the glial function of physical support in CNS and PNS
CNS - Astrocyte | PNS - CT
78
Which support cell is responsible for the glial function of Control of Microenvironment in CNS and PNS
CNS - Astrocyte | PNS - Schwann Cell/satellite cell
79
Which support cell is responsible for the glial function of Myelin synthesis in CNS and PNS
CNS - Oligodendrocyte (multiple internode per cell) | PNS - Schwann Cell (1 internode per cell)
80
Which support cell is responsible for the glial function of Defense/Immune in CNS and PNS
CNS - Microglia | PNS - Immune System
81
What happens during peripheral nerve injury with respect to retrograde RXN?
Retrograde RXN - produce cell that completely cahnges morphology - Nissl substance dissolves - undergoes chromatolysis
82
What happens during peripheral nerve injury with respect to Local Changes?
- Axon terminals are completely dependent on the soma organelles - so the axon and its associated wrapped myelin cytoplasm are phagocytosed (but the schwann cell remains intact)
83
What happens during peripheral nerve injury with respect to Anterograde RXN?
- Distal Axon and myelin are phagocytosed - Schwann cells proliferate and form tubes = Schwann tubes = Band of Bungner - cell body begins heightened production and proximal axon sprouts and growth into the Schwann tubes - Schwann cells wil re-myelinated and guide the axon to its target
84
What happens if their is failure of regeneration
- traumatic neuroma occurs - results is sprouting axon cannot reach Schwann cell tubes and therefore cannot reach its target
85
Describe Central Nerve (CNS) Regeneration
- Regeneration in CNS is extremely rare - ECM (External lamina) does not exist in CNS and cannot guide axon sprouts - Schwann cells secrete chemical factors that attract and encourage growth of axon sprouts in PNS, but oligodendrocytes do not - Central myelin = a potent inhibitor of axonal growth in CNS - After CNS injury - astrocytes fill in the spaces and form a physical barrier (gliotic scar) to regeneration
86
Why does regeneration work in the PNS but not CNS following nerve damge
- largely due to the CT organization in the PNS - external lamina - ECM - schwann cells - which secrete chemical factors to aid targeting and encourage growth as well as form Schwann tubes/Bands of Bungner ==> all of these factors aid/guide the axonal growth and are not present in CNS
COT - Exam 1
flashcards
Decks in class (26)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions