Nerves Flashcards
(35 cards)
What types of glial cells does the central nervous system contain?
- Ependymal cells
- Astrocytes
- Microglia
- Oligodendrocytes
What are ependymal cells?
Cells which create barriers between compartments and are a source of neural stem cells
What are astrocytes?
- Source of neural stem cells
- Take up K+, water and neurotransmitters
- secrets neurotrophic factors
- Help form blood brain barrier
- Provide substrate for ATP synthesis
What are microglia?
Act as scavengers
What are oligodendrocytes?
Form myelin sheaths
What type of glial cells does the peripheral nervous system contain?
- Schwann cells
- Satellite cells
What are schwann cells?
- Form myelin sheaths
- Secrete neutrophic factors
What are satellite cells?
Support nerve cell bodies
What is the structure of the neuron?
Cell body, branched dendrites that receive signals and a long axon that transmits signals
In which direction does information flow in neurons?
From the dendrite to the synapse
What ion is present in the intracellular fluid?
K+
What ion is present in the extracellular fluid?
Na+
What is electrical disequilibrium?
When the inner surface of the membrane have a negative charge relative to outer surface
What is electrochemical gradient?
The net effect of electrical and chemical forces across the membrane
How are voltage gated channels opened and closed?
Change in charge of membrane
How are ligand gated channels opened and closed?
A ligand bond to the channel to open it and then when it is removed it closes it
How are stress activated channels opened and closed?
Mechanical stimulus such as the membrane being pulled
What is depolarisation?
When there is more positive potential
What is hyperpolarisation?
When there is more negative potential
What is repolarisation?
The return to resting potential
What must occur for an action potential to be generated?
The graded potential must be above threshold in the trigger zone
What is summation?
When two or more sub-threshold graded potential can combine to generate action potential
What is temporal summation?
Graded potential at the same location close in timing
What is spatial summation?
Graded potential at close location at the same time
