Topic 19: Nervous System - Cell Types - Neurons Flashcards
What are the two cell types?
-Neurons
- Neuroglia
What is the function of neurons (2)
- make up CNS and PNS
- conduct impulses
Why are neurons mostly irreplaceable? (2)
- mostly amitotic (do not undergo mitosis)
- exceptions are taste, olfactory, memory
What are the structures of a neuron? (4)
- cell body
- RER
- Nuclei
- ganglia
What is the cell body of a neuron?
typical organelles
What is the RER of a neuron called?
Nissl bodies
note that when stained. it causes cell body to look gray
What is the nuclei of a neuron?
- groups/clusters in CNS
What is the ganglia of a neuron?
groups/clusters in PNS
What are the two processes from the cell body of a neuron?
- dendrites
- axon
What do dendrites receive?
- receive incoming messages and relay to cell body
What do axons do?
- carry impulses away from cell body
- note that there’s only one axon, but can have multiple dendrites
What is the axon hilock?
- where axon meets cell body
What is the axon terminal?
- typically branched with synaptix end bulbs (enlarged tips)
What is a myelinated axon? (3)
- wrapped in many layers of cell membrane from either:
- schwann cells (PNS)
- Oligodendrocytes (CNS)
What does myelin provide?
electrical insulation
What are nodes of ranvier?
gaps in myelin sheath
Where do myelinated axons bunndle in? (2)
CNS - tracts (white matter)
PNS - nerves
What are unmyelinated axons?
- no myelin
slower signals
