BIO 137 Case Study Kaly Barren is a 16-year-old sprinter on the high school trac
ID: 3517371 • 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. Most of the potassium ions are located in intracellular fluids, potassium serves as the predominant cation in thses fluids.
2. When the concentration of K+ increases surrounding a myocyte, then the potassium gradient across the cell membrane decreases. Hence, the resting membrane potential becomes more positive. Similarly, if the concentration of extracellular potassium decreases, then the resting membrane potential becomes more negative.
3. During exercise, large amounts of heat is produced owing to the demand for energy. To maintain the body temperature, the excess heat should be dissipated from the body. This takes place through sweat which involves fluid and water loss from the body. The fluid loss is also distributed among plasma; concentration of sodium and potassium falls rapidly.
4. If less K+ is available to the cells, it intensifies the concentration gradient. As a result, the potassium ions starts to move out of the cell. The inside of the cell becomes more negative and the resting membrane potential becomes hyperpolarized. As a result, greater then normal stimulus is required to generate an action potential. So, the actionpotental develops quite slowly.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.