Resting Membrane Potentials
Resting membrane potentials
Definition:
Large nerve fibers when not transmitting nerve signals is about 90 millivolt. That is, the potential inside the fiber is 90 millivolts more negative than the potential in the extracellular fluid on the outside of the fiber.
The Na+-k+ pump also causes large concentration gradients for sodium and potassium across the resting nerve membrane.
These gradients are the following:
Sodium ( outside): 142 mEq/L
Sodium ( inside): 14 mEq/L
Potassium ( outside): 4 mEq/L
Potassium ( inside): 140 mEq/L
The ratios of these two respective ions from the inside to the outside are:
Na+ (inside)/ Na+ ( outside) =0.1
K+ (inside)/ K+( outside) = 35.0
Hypokalemia periodic paralysis
Definition: Is an autosomal dominant disorder, which means that one abnormal copy of the gene is all that is needed to have symptoms. Typically, this means that one parent has the disease, but it is possible to have the gene as a result of a new mutation not present in the parents, or it is possible that a parent has the gene but is not expressing symptoms enough to be clinically evident. Typically, someone will first show clear signs of hypokalemic periodic paralysis sometime in the teens, but careful observation and knowledge of the paralysis triggers, the disease can be recognized earlier and in higher percentages of those carrying the gene abnormality.
Cause: Hypokalemic periodic paralysis is congenital. This means it is present at birth. In most cases, it is passed down through families (inherited) as an autosomal dominant disorder. In other words only one parent needs to pass the gene related to this condition on to you in order for you to be affected.
Occasionally, the condition may be the result of a genetic problem that is not inherited.
Unlike other forms of periodic paralysis, persons with congenital hypokalemic periodic paralysis have normal thyroid function. But they have a very low blood level of potassium during episodes of weakness. This
Definition:
Large nerve fibers when not transmitting nerve signals is about 90 millivolt. That is, the potential inside the fiber is 90 millivolts more negative than the potential in the extracellular fluid on the outside of the fiber.
The Na+-k+ pump also causes large concentration gradients for sodium and potassium across the resting nerve membrane.
These gradients are the following:
Sodium ( outside): 142 mEq/L
Sodium ( inside): 14 mEq/L
Potassium ( outside): 4 mEq/L
Potassium ( inside): 140 mEq/L
The ratios of these two respective ions from the inside to the outside are:
Na+ (inside)/ Na+ ( outside) =0.1
K+ (inside)/ K+( outside) = 35.0
Hypokalemia periodic paralysis
Definition: Is an autosomal dominant disorder, which means that one abnormal copy of the gene is all that is needed to have symptoms. Typically, this means that one parent has the disease, but it is possible to have the gene as a result of a new mutation not present in the parents, or it is possible that a parent has the gene but is not expressing symptoms enough to be clinically evident. Typically, someone will first show clear signs of hypokalemic periodic paralysis sometime in the teens, but careful observation and knowledge of the paralysis triggers, the disease can be recognized earlier and in higher percentages of those carrying the gene abnormality.
Cause: Hypokalemic periodic paralysis is congenital. This means it is present at birth. In most cases, it is passed down through families (inherited) as an autosomal dominant disorder. In other words only one parent needs to pass the gene related to this condition on to you in order for you to be affected.
Occasionally, the condition may be the result of a genetic problem that is not inherited.
Unlike other forms of periodic paralysis, persons with congenital hypokalemic periodic paralysis have normal thyroid function. But they have a very low blood level of potassium during episodes of weakness. This