Neuronal Signaling Flashcards
An increase in axon diameter results in what?
Decrease in resistance within the axon membrane - ions more more rapidly
Increases conduction velocity
Absolute Refractory period
NO action potentials can be generated
K channels open - hyperpolarization
Na channels inactive
Directly behind propagating action potential
Voltage gated channels
Responds to changes in voltage
Propagation of an action potential from the soma to the axon terminal is unidirectional because…
of the inactivation of the Na channels
[Ca] mM
ECM 2.5
ICM .0001
Schwann Cells
Make myelin in PNS
Voltage
Electrical potential difference between two regions of charge
A change in membrane potential from -40 mV to -70 mV…
would occu in response to opening K channels
Membrane potential
Ionic concentration difference between ECT and Intracellular fluid across membrane results in electrical potential/voltage
Neurons differ in size - they can range from ____ to _____
um to meters
Name the 4 glial cells
Astrocytes
Oligodendrocytes
Schwann Cells
Microglia
Microglia
Macrophage-like - activated by injury
Phagocytize and digest waste products
unipolar neuron
one process
Tetrodotoxin
Toxin isolated from Japanese Puffer fish
Blocks Na channels/nerve conduction
Guillain-Barre Disease
Autoimmune disorder that attacks myelin in the PNS
Acute - days to weeks
Na voltage gated channels
High number in axon for depolarization
Closed at resting potential
Opens in response to nerve pulse = Na enters cell
Inactivated for a period after activation - refractory period - will not respond to a new signal
Pseudounipolar neurons
One process fromsoma splitting to form 2 axons
Relative Refractory period
Action potentials can be generated but at a higher threshold
Na channels closed
K channels open - hyperpolarization
Behind absolute refractory period
What kind of proteins are in the neuronal membrane?
Ion pumps
Ion channels
Receptors for neurotransmitters
Which glial cell is most common?
astrocytes
[K] mM
ECM 4
ICM 130
Equilibrium potential/voltage
balance between chemical force (concentration gradient) and electrical force (charge gradient)
Ca voltage gated channels
high number in axon terminal for the release of neurotransmitters and docking of vesicles
Ion channel
Ions move through pores via diffusion via chemical gradients
Etiology of multiple sclerosis
Viral infection triggers
A change in a cell membrane potential that makes it more negative…
hyperpolarization
What two factors affect the conduction velocity in axons?
Axon diameter
Myelination
State dependent blockade
More effecting at blocking channels/nerve conduction during the open or inactivated state
Symptoms of multiple sclerosis
Loss of sensation/motor function in multiple sites
tx of guillain barre disease
Immunoglobulins and plasmapheresis (remove plasma, which may be source of immune factors)
A change in a cell membrane potential that makes it more positive is….
depolarization