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Nurs 8022 case study 1

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NURS 8022 Case Study #1
1. Lidocaine and local anesthetics agents block action potentials in nerve fibers
by binding to specific ion channels. At low concentration, these drugs
decrease the rate of the rise of the upstroke of the AP. At higher
concentrations, they prevent occurrence of the AP altogether. Based on this
information and your knowledge of the ionic basis of the action potential,
which ion channel would you conclude is blocked by Lidocaine? Explain how
these ion channels are important.
Lidocaine as well as anesthesia causes a block in the Na + channels - When
Lidocaine and anesthesia are administered at low concentrations sodium
poses a slower upstroke thus leading to a slower action potential. Hence,
when Lidocaine and anesthesia are administered at a higher rate there is a
total blockade of the upstroke capabilities causing no action potential.
Investigations during the last few decades presented evidence implicating the
sodium (Na
+
) channel protein as a target for specific, clinically important, local
anesthetic effects on mammalian neurons. At clinically relevant concentrations
local anesthetics can also affect potassium (K
+
) and calcium (Ca
2+
) channels, which
might help explain some of their side‐effects (2002).
https://academic.oup.com/bja/article/89/1/52/256293
When Lidocaine/anesthesia (stimulus) is administered in high dosages the
threshold of the Na+ is met and in higher dosages there causes an upstroke
during depolarization until the action potential is met at the equilibrium. At
the peak of the action potential when the equilibrium is met, the Na+
channels open and enters the cells. Respectively, positive charges repel each
other. At the peak, the voltage gated potassium reaches a peak where the
potassium gates open up and potassium leaves the cell which is known as
repolarization. Potassium leaves the cell during repolarization towards it’s
resting membrane potential.
2. Based on your knowledge of how nerve action potentials are propagated,
how would you expect lidocaine to alter the conduction of the AP along a
nerve fiber?
Action potentials are propagated by starting at the local regions to the
depolarization regions. This upstroke at the depolarized regions triggers the
opening gates and inward flow of the Na+ of the upstroke action potential.
The stimulus of lidocaine thus blocks the voltage gate of the Na+. When the
voltage gate of Na+ is blocked, the inward current of the Na+ does not
happen thus this is the propagation of the action potential that transpires
from depolarization of the inward current in prevented. Small positive
shifts of the membrane potential, beyond a threshold causes
Na
+
channels to move open. Channel opening results in a rapid

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NURS 8022 Case Study #1 1. Lidocaine and local anesthetics agents block action potentials in nerve fibers by binding to specific ion channels. At low concentration, these drugs decrease the rate of the rise of the upstroke of the AP. At higher concentrations, they prevent occurrence of the AP altogether. Based on this information and your knowledge of the ionic basis of the action potential, which ion channel would you conclude is blocked by Lidocaine? Explain how these ion channels are important. Lidocaine as well as anesthesia causes a block in the Na + channels - When Lidocaine and anesthes ...
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