Repeated USMLE Questions Step 1- 357



Q- Which of the following is the most common cancer of the lower third of esophagus in non-alcoholic, non-smoker patients?

A- Adenocarcinoma

B- Melanoma

C- Sarcoma

D- Squamous cell carcinoma

A- Adenocarcinoma- It is strongly associated with Barrett esophagus. Squamous cell carcinoma is the most common in the first and middle parts of esophagus worldwide
.



Q- Which of the following muscles are responsible for primary abduction of the arm at the shoulder joint?

A- Coracobrachialis and deltoid

B- Deltoid and infraspinatus

C- Deltoid and supraspinatus

D- Supraspinatus and infraspinatus

C- Deltoid and supraspinatus- These are the primary adductors of shoulder joint. 



Q- Which of the following is the cellular mechanism of epinephrine?

A- Activation of adenylyl cyclase

B- Activation of acetylcholinesterase

C- Activation of phospholipase

D- Inhibition of adenylyl cyclase

A- Activation of adenylyl cyclase- Epinephrine activates α1-adrenoceptors to cause a release of intracellular stored Ca 2+ and β1- and β2-adrenoceptors to activate adenylyl cyclase. 



2 thoughts on “Repeated USMLE Questions Step 1- 357”

  1. Epinephrine exerts effects on a1, b1, and b2. Alpha 1 receptors are Gq mediated and b1 and b2 are Gs mediated. Therefore, the correct answer choice would be a combination of adenylyl cyclase and phospholipase, no?

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