6.2 Flashcards
(23 cards)
What are the cells in the nervous system?
Neurons and glial cells
What are features of neurons?
Main functional cell
10% of all NS cells
Don’t divide
What are features of glial cells?
Support, nourish, protect
90% of all NS cells
Divide and proliferate
Astorcytes
Microglia/satellite cells
Oligodendroctyes/schwann cells
What are is the structure of a neuron?
Cell body
Dendrites
Axon
Myelin sheath
Terminal branches
How does info flow through the neuron?
Dendrites —> cell body —> axon
What is the function of dendrites?
Sensors
Receive info
What is the function of the cell body (soma)
House the nucleus and organelles
Metabolic brain of the neuron
What is the function of the axon?
Pathway for electrical signalling
One axon per neuron
Bi-directional flow
What is the function of the axon terminal
Communication point
Site of synapse
What is the function of the myelin sheath?
Insulating coat
What are the nodes of ranvier?
Gaps in the myelin
What are the three universal properties of neurons?
Excitable (responds to environmental changes)
Conductive (sends electrical signals)
Secretory (secrete neurotransmitters)
What are the three structural classifications of neurons?
Unipolar: single process extending from the cell body
Bipolar: two processes extending from the cell body, axon and dendrite
Multipolar: multiple processes extending from cell body Bipolar
What are the three functional classifications of neurons?
Sensory: receives input/ detect changes in the environment, transmit signals from PNS to CNS
Interneurons: 90% of all neurons, store and process info, reside within the CNS
Motor neurons: transmit signal from CNS to PNS to effector organs
What is a nerve?
A bundle of axons + associated connective tissue
What makes up a nerve?
Connective tissue
- endoneurium: delicate CT surrounding myelin, fascicle (bundle/cluster)
- perinerurium: CT surrounding fascicles
- epineurium: outer most CY surrounding the entire nerve
What are microglia in the CNS?
Defence cells
Phagocytes
“Macrophages” of the CNS
Moving scavengers- multiple extending processes
Involved in inflammation
What are astrocytes in the CNS?
Astro(star) shaped
Provide structural support
Comprise the blood-brain barrier
Regulate concentrations of ions, nutrients, dissolved gasses
Absorb and recycle neurotransmitters
Form glial scares after CNS injury
What are the satellite cells of the PNS?
Astrocyte-like
Cover nerve cell bodies
Support and protect nerves
Control extracellular environment
What are ependymal cells in the CNS?
Epithelial-like cells
Form ependyma
Line the ventricles of the CNS
Produce CSF
Involved in CSF circulation
What are oligodendrocytes in the CNS?
Produce myelin (insulator)
Wrap processes around axons of neurons (each process myelinated one atonal segment, a single oligodendrocyte can contain up to 15 processes)
Do not possess regenerative capacity
What are Schwann cells in the PNS?
Myelin production
Atonal insulation
Conduction of signals
Regeneration and repair nerves
What is the role of the myelin?
Insulator (lipid rich protein complex)
Produced by oligodendrocytes (CNS) and Schwann cells (PNS)
Covers axons
Essential for signal conjunction
Increases in amount from birth to maturity
Allows for fast signaling conductions along axons
