Neural Cell Types Flashcards
(13 cards)
Neurons: Location, Structure, Origin
-Found in both central nervous system (from Neural Stem Cells) and peripheral nervous system (from Neural Crest Cells)
Structure:
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
Function:
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
