BIO 137 Case Study Kaly Barren is a 16-year-old sprinter on the high school trac
ID: 244252 • Letter: B
Question
BIO 137 Case Study Kaly Barren is a 16-year-old sprinter on the high school track team. Recently, after completing her events, she felt extremely weak and her legs became "like rubber". After the most recent event, she was unable to walk and had to be carried from the track on a stretcher. Her parents were very alarmed and made an appointment for Kaly to be evaluated by her pediatrician. As a part of the workup, the pediatrician measured Kaly's serum K concentration, which was normal (4.5 mEq/L). However, because the pediatrician suspected a connection with K', the measurement was repeated immediately after a strenuous exercise treadmill test. After the treadmill test, Kaly's serum K was alarming low (2.2 mEq/L). Kaly was diagnosed as having an inherited disorder called primary hypokalemic periodic paralysis and subsequently treated with K' supplements. QUESTIONS 1. In what body fluid is most of our K located? 2. What is the role of K in the resting membrane potential of neurons? 3. How does exercise lower Kt in body fluids? If less K is available to cells, will this cause the development of action potentials to occur faster or slower? 4. 5. What other excitable tissues does a decrease in K' affect? 6. How does taking K supplements improve Kaly's condition? 7. What other cation plays a role in maintaining the electrochemical gradient? 8. In what body fluid is most of this cation found? 9. In what phase of an action potential does this other cation participate? 10. Will taking supplements of this cation cause the development of action potentials to occur faster, slower or no change?Explanation / Answer
1. Potassium is the major ICF cation, with 98% of the body potassium being intracellular
For example, potassium concentration within muscle cells is approximately 140 mEq/L; potassium concentration in the ECF is 3.5 to 5.omEq/L.
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2.Resting membrane potential
It is the voltage (charge) difference across the cell membrane when the cell is at rest
Under resting membrane potential sodium ion/potassium ion pump creates a concentration gradiant by moving 3 Na ion out of the cell 2 k ion into the cell.
The pump continues to move sodium ion out of the cell even more number of sodium ion present in the extra-cellular space, at the same time potassium is pumped inside the cell against the concentration gradient.
Cell membranes are more premeable to potassium ion than sodium ion because it contains more potassium leak channels.
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