Nerve and muscle firing is a difficult concept for students, involving as it does the rather abstract
Question:
Nerve and muscle firing is a difficult concept for students, involving as it does the rather abstract concepts of ion channels and electric potentials. Once they have memorized the basics, however, a horde of fascinating clinical applications open up. Perhaps the most important of these is potassium's control of resting potential and the consequences for cell firing. The case goes further to introduce a second ion that affects excitable tissues Ca2+ , which the doctor uses as emergency treatment for the patient's hyperkalemia. While K+ affected resting potential, Ca2+ affects Na+ channels and therefore threshold potential. Between them, they provide a review of some of the sticky concepts in nerve firing.
Mr. M is a Type 2 diabetic with diagnoses of (poorly controlled) hypertension and chronic renal failure. He has come in for a routine checkup and claims to be feeling fine, just a little tired. He presents as an overweight 58-year-old man with a sunburn on his cheeks and ears and a BAND-AID® on one cheek (where he says he nicked himself shaving that morning), a heart rate of 66 bpm, blood pressure of 124/80 mm Hg, normal breath and heart sounds, and slightly puffy ankles, face, and hands. His weight has increased by 1.5 lbs since he was last seen eight months ago.
Do you see anything to concern you in Mr. M's description?
There are several worrying signs in Mr. M's presentation. Can you pick them out?