USMLE Step 1 QUESTION of the DAY!

An old man is found in the basement of his house. He was on the floor with rigor mortis setting in. What is the mechanism responsible for rigor mortis?

A) He overdosed on Baclofen
B) Increase in ATP production before he died
C) Myocyte death
D) Depletion of ATP
E) Myosin cross-bridge detachment

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Answer: D) depletion of ATP. ATP is required for Myocyte contraction. However, ATP is also required for the myosin cross-bridge to detach. During the moments of dying the muscles contract using the remaining ATP in the body. After some time there is no ATP in the body to detach the myosin cross-bridge.



USMLE Step 1 D.O.C. of the DAY!

Drug of choice for

Proteus causing urinary tract infection

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Quinolones



FACT of the DAY!

Touch receptors:
Pacinian corpuscle- vibration, most rapid adapting, travel in dorsal column
Meissner’s corpuscle- touch, fast adapting, travel in dorsal column
Merkel’s discs- pressure, slow adapting, travel in dorsal column
Pain and temperature- fibers travel in spinothalamic tract and are mostly free nerve endings