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Flashcards in Neural Cell Types Deck (13):

Neurons: Location, Structure, Origin

-Found in both central nervous system (from Neural Stem Cells) and peripheral nervous system (from Neural Crest Cells)

1) Dendrites: receptors for input
2) Soma: cell body, hold most organelles
3) Axon: output of information via electrical signals
- the terminal can output electrical signals or vesicles
- "axon hillock" where the soma and axon are joined, the initial trigger zone


Glia/Neuroglia Cells: Types, Location

-Vary depending on location
-CNS: astrocytes, microglia, oligodendrocytes, ependymal cells
-PNS: Schwann Cells
-Less common: satellite cells, olfactory cells, sheathing cells


Growth of Neurons in the Central Nervous System

-Originate from neural stem cells
- can become almost any time of neuron
-Mature into Neuroblasts, which may only become one type
- neuroblasts migrate to where the soma should be
- axons grow towards targets based on signals, tipped with a Growth Cone


Structural Neuron Types "Polarity"

1) Unipolar: have only an axon
2) Bipolar: one main dendrite and one main axon process
3) Multipolar: many dendrite processes and one main axon process
4) Pseudounipolar: one axon process that splits in two, with one side acting much like a dendrite


Astrocytes: Location, Structure, Functions

-Located in CNS, comprised of a soma and multiple processes with "end feet"
1) Scaffolding
2) Glial Scarring
3) Homeostasis
4) Blood-Brain Barrier
5) Clearing out synapses between neurons


Astrocytes: Scaffolding

-Occupy a huge amount of space in the central nervous system
-Comprise most of the structure


Astrocytes: Glial Scarring

-aka Astrocytosis
-Injury to the CNS results in proliferation of astrocytes
-Migrate to the location surrounding the damage
-"Process Hypertrophy": processes grow larger and more numerous to wall off site of damage


Astrocytes: Homeostasis

-Maintain interstitial fluid concentrations via
1) rapid ion exchange between interstitial fluid and blood
2) absorption and recycling of neurotransmitters


Astrocytes: Blood-Brain Barrier

-Prevents large molecules from entering/leaving the junction of the circulatory and nervous systems
-Composed of parts of the vessel walls and the end feet of astrocytes


Microglia: Structure, Functions

1) Resting microglia have small soma and long, highly branched processes for monitoring interstitial fluid
2) Active microglia are large and blob-shaped
- find foreign cells or dead/damaged CNS cells to release cytotoxic chemicals
- phagocytosis of these cells/bacteria
- "Antigen Presentation" of bits of these cells for detection by lymphocytes


Ependymal Cells: Location, Function

-Glial cells of CNS, from neural stem cells
-Gaps of cerebrospinal and interstitial fluid are connected via a line of ependymal cells

1) form barrier between cerebrospinal and interstitial fluid
2) secrete cerebrospinal fluid


Oligodendrocytes: Location, Function

-Glial cells of the central nervous system, arising from neural stem cells

Function: to myelinate neurons in the central nervous system
- comparable to Schwann cells in the peripheral nervous system


Schwann Cells: Location, Types, Functions

-Glial cells in the peripheral nervous system, from neural crest cells

1) Non-myelinating Schwann cells: shapeless, and have troughs on their surface that thin axons pass through

2) Myelinating Schwann cells: Schwann cells myelinate only one segment of a single axon
- shaped like a roll of tape, with the soma contained within a "bump" on said tape