Which structure allows blood to flow from the right to left atrium in utero and normally closes after birth?

A patient who is hospitalized with pneumonia has a low SaO2. What is the primary pathophysiological explanation for this?

Select the correct functions of the kidney. (Select all that apply.)

Pulmonary edema may be caused by which of the following?

Psoas and obturator signs can be helpful in the diagnosis of: 

A patient comes into the emergency department complaining of abdominal pain and hematemesis.  The patient describes the vomit as looking like coffee grounds.  What is the most likely cause in this patient?

Psoas and obturator signs can be helpful in the diagnosis of: 

A previously independent 98-year-old woman presents with acute onset of confusion and fatigue. Her daughter found her in bed early this afternoon and would like to have her admitted. The nurse suspects which of the following conditions? 

The small intestine contains microvilli, villi and circular folds. Select their main function:

What is the pathophysiology underlying the pain (renal colic) related to kidney stones?