Repeated USMLE Questions Step 1- Review- 360

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Q- The tracheal tube is originated from which of the following structures?

A- Ductus arteriosus

B- Foregut

C- Fourth pharyngeal arch

D- Third pharyngeal arch

B- Foregut- Trachea and lungs are originated from invagination in the foregut 



Q- Which of the following endocrine disorders is characterized by high blood pressure, sodium and water retention, low potassium level and decreased renin activity?

A- Addison’s disease

B- Pheochromocytoma

C- Primary hyperaldosteronism

D- Secondary hyperaldosteronism

C- Primary hyperaldosteronism- Secondary hyperaldosteronism is almost the same as primary but renin activity increases. 



Q- Which of the following is the mechanism of action of digoxin to increase cardiac contractility?

A- Inhibition of K/Ca ATPase

B- Inhibition of Na/Ca ATPase

C- Inhibition of Na/K ATPase

D- Inhibition of phosphodiesterase

C- Inhibition of Na/K ATPase- Digoxin increases cardiac contractility by inhibiting the Na⁺/K⁺ ATPase, which raises intracellular sodium levels. This reduces the activity of the Na⁺/Ca²⁺ exchanger, causing calcium to accumulate in cardiac cells and increasing contractility.

 

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