Neuro 5 Flashcards
What is the purpose of the refractory period?
ensures an AP travels in one direction and limits rate at which signals can be transmitted
Two physical parameters that determine the velocity of APs
diameter of axon and resistance of axon to ion leakage
conduction velocity is more rapid in…..
myelinated axons because decreased ion leak with high resistance membranes
saltatory conduction
conduction occurs from node to node
__________ axons are larger diameter axons that ____________ axons.
myelinated, unmyelinated
what can alter electrical activity?
chemical factors (local anesthetics) and changes in extracellular conc of cellular ions
the conc. gradient for K+ is crucial in setting…
the resting membrane potential
normokalemia
above threshold; AP
hyperkalemia
stimulus that would normally be sub threshold can trigger an AP
hypokalemia
neuron less likely to fire an AP that would normally be above threshold
cells communicate at…
synapses
synapses found on…
dendrites, soma and even on axon and axon terminals
electrical synapses
ions flow from cell directly to the next
chemical synapses
majority in nervous system
neurocrine
a chemical substance released from neurons used for communication
types of neurocrines
neurotransmitters, neuromodulators, and neurohormones
neurotransmitters
chemical released that acts on postsynaptic cell in close vicinity and causes a rapid response
neuromodulator
chemical released that acts on postsynaptic cell in close vicinity and causes a slow response
neurohormones
secreted into the bloodstream and act on targets throughout the body
two categories of neurocrine receptors
ionotropic receptors and metabotropic receptors
inotropic receptors
mediate fast postsynaptic responses (neurotransmitters) through ligand gated ion channels
metabotropic receptors
linked to a three part membrane transducer (g-protein) and mediates slower responses (neuromodulators)
metabotropic receptors interact with…
ion channels or with a membrane bound enzyme
