Lesson 1-4 Physio Ex Flashcards
What is the resting membrane potential of a neuron caused by?
the electrochemical gradient of ions Na+ and K+
T/F: Alterations to the ion concentration inside or outside of the neuron will alter the resting membrane potential.
True
Increasing extracellular [K+] causes the membrane potential to do what?
go from -70mV to -40mV
increasing extracellular [Na+] causes the membrane potential to do what?
drop from -70mV to -72mV
What is indicated by the greater change of the resting potential when [K+] is changed than when the [Na+] is changed?
there are more passive K+ channels than passive Na+ channels
What maintains the difference in concentration of K+ and Na+ inside/outside the cell?
the Na+/K+ pump, without it the leak channels would eventually bring the potential to 0
decreasing the extracellular [Na+] will cause what?
the membrane potential to become more negative since less Na+ will enter the cell via Na+ channels
increasing the extracellular [K+] will cause what?
the membrane potential to become less negative since less K+ will leave the cell via passive K+ channels
If the correct stimulus is applied to a sensory receptor will cause it to…
open or close membrane ion channels aka sensory transduction
opening or closing ino channels with produce a _____ _____ that may be either depolarizing or hyperpolarizing
graded (local) potential
What do Pacinian corpuscles respond to?
ranges of pressure
What do Pacinian corpuscles NOT respond to?
chemicals, heat, or light stimuli
Olfactory receptors respond to?
ranges of chemical stimulus
What are olfactory receptors NOT responsive to?
pressure, heat, and light
T/F: free nerve ending can respond to multiple modalities of stimuli
true
What can free nerve endings respond to?
ranges of heat and pressure
What is one reason free nerve endings can respond to multiple types of stimuli?
They are involved in detecting different types of excessive stimuli that will be perceived as pain
a stimulus voltage of _____ and above elicited an action potential in the nerve
20mV
Did increasing the voltage affect the speed or strength of the action potential?
no
Why was there no decrease in the magnitude of the action potential between R1 and R2?
the action potential is regenerated at each segment of axon
What triggers the depolarization of adjacent axon segments during action potential propagation?
an influx of Na+ into the axon triggers this
why do action potentials only propagate in one direction?
because the regions of the membrane behind the action potential are in their absolute refractory period
what are tetrodotoxin (TTX) and lidocain?
two nerve agents that disrupt nerve signaling by blocking Na+ channels
TTX
a sodium channel antagonist; will permanently block Na+ channels preventing them from depolarizing
Lidocaine
will not permanently block Na+ channels
