, Physiologist. 1  In four chambered avian and mammalian hearts, the two upper chambers are known as the atria. The atria are believed to act as primer pumps which boost the end diastolic volume (the volume at the end of ventricular filling) just before contraction of the ventricles.
Disunion follows the Civil War as it unfolded. New Orleans was the jewel of the Confederacy. In addition to being the Southâs largest city, it boasted considerable industry that produced ironclads, munitions and uniforms, among other items. More important, it controlled access to the Mississippi River from the Gulf of Mexico.
It was the final battle of the War of 1812, and it occurred after the two countries had signed a treaty ending the war days earlier. New Orleans is the birthplace of jazz, widely considered Americaâs greatest contribution to art. The city is also the home of the oldest opera house in America and known as Americaâs First City of Opera. The city hosted the first opera in North America on May 22, 1796. The New Orleans based Louisiana Philharmonic Orchestra is the countryâs only musician-owned symphony. The Port of New Orleans is one of the busiest ports in America. The city is the home of major shipbuilding facilities, a naval base, the nationâs Marine reserve headquarters and the worldâs first World Trade Center.