last for the day pl answer fast - aimhigh

[ArchivalUser]

32. An 18-year-old man is admitted to the hospital after an
automobile accident. He has not lost a large amount of
blood but has a severe crush injury to his right leg. He is
conscious and exhibits flaccid paralysis. ECG results show
a shortened QT interval and an increase in the PR interval.
Laboratory results indicate his serum potassium is 7.5
mEq/L. His acute hyperkalemia would be predicted to
cause which of the following?
(A) Decreased driving force for potassium from cells
(B) Decreased excitability of motor nerves
© Decreased excitability of skeletal muscle fibers
(D) Decreased intracellular potassium concentration
(E) Decreased Nernst potential for potassium (more
negative)
(F) Decreased resting membrane potential (more negative)

[ArchivalUser]

B....

[ArchivalUser]

is that A?

[ArchivalUser]

D?

[ArchivalUser]

my ans is ddd lets see

[ArchivalUser]

The correct answer is A. The driving force for K+ from
the cells is a function of the concentration gradient
(concentration force) across the cell membrane as well
as the membrane potential (electrical force). The negative
membrane potential (inside is negative relative to
outside) of a cell will tend to pull potassium into the
cell. The relatively low K+ concentration outside the cell
compared with inside the cell has the opposite effect,
i.e., the chemical gradient tends to cause K+ loss from
the cell. The equilibrium potential (i.e., Nernst potential)
is the theoretical intracellular electrical potential
that would be equal in magnitude but opposed in direction
to the force created by the concentration difference
across the membrane. The Nernst potential (millivolts)
for K+ = “60 log (intracellular K+ conc./extracellular K+
conc.). In the present problem, the K+ concentration
outside the cell (extracellular K+ conc.) is increased.
According to the Nernst equation, this increase in
extracellular K+ concentration will make the Nernst
potential less negative (choice E), and thus decrease the
driving force for K+ from the cells. Also, the resting
membrane potential will be less negative when the K+
Nernst potential is less negative because the cell membrane
is highly permeable to K+ compared with other
ions. Thus, in the present problem, the membrane
potential will be less negative (compare with choice F).
When the membrane potential is less negative, it is closer
to the threshold potential for an action potential,
which increases the excitability of motor nerves (choice
B), skeletal muscle fibers (choice C), and other excitable
tissues.
Because the driving force for K+ from the cells is
decreased, it should be clear that the intracellular K+
concentration will not decrease (choice D).

[ArchivalUser]

good night

[ArchivalUser]

thanks a lot Aimhigh for your help....wish you all the best...