There are typically three types of atrial septal defects: ostium secundum, sinus venosus, and ostium primum. Of the three, ostium secundum, which occurs around the region of the foramen ovale, is the most common.

Smooth muscle relaxants that are direct-acting vasodilators include nitroprusside and nitroglycerin. These medications, which are used in the treatment of heart failure, work to reduce cardiac filling pressures and dilate coronary arteries. Furosemide is a loop diuretic.

The sinoatrial (SA) node contains two specialized cell types: border zone cells and specialized pacemaker cells. Cardiomyocytes are heart muscle cells, and chondrocytes are cartilage producing cells.

Arterial blood gas (ABG) analysis includes five measurements: pH, arterial partial pressure of carbon dioxide (PaCO₂), bicarbonate ion (HCO₃^-), arterial partial pressure of oxygen (PaO₂), and base excess (BE). Fraction of inspired oxygen (FiO₂) is not apart of an ABG analysis.

The four phases of ventilation are as follows: Phase I is the movement of ambient air in and out of the respiratory tract; Phase II is the diffusion of oxygen and carbon dioxide in the alveoli; Phase III entails the delivery of oxygen to erythrocytes, and the removal of carbon dioxide from the erythrocytes and the bloodstream; Phase IV is the regulation of ventilation.

Sepsis is defined as a systemic response to an infection that includes the presence of two or more of the following conditions: a temperature greater that 38°C or a temperature less than 36°C; a heart rate greater than 90 beats per minute; a respiratory rate greater than 20 breaths per minute; a WBC greater than 12,000 cells/mm³; or a PaCO₂ less than 32 mmHG. If sepsis occurs along with hypoperfusion and organ dysfunction, it becomes classified as severe sepsis. If sepsis occurs with hypotension and insufficient tissue perfusion that does not respond to fluid resuscitation, it becomes classified as septic shock.

Hypernatremia is an electrolyte imbalance characterized via elevated sodium levels in the blood. This condition results in water retention and the development of excess extracellular fluid volume. In patient's with normal renal function, the condition is typically caused by a lack of ADH secretion via the posterior pituitary. In patients with renal dysfunction, the condition is typically the result of an inability of the renal tubules to respond to ADH secretion. The renin-angiotensin-aldosterone system functions to increase sodium reabsorption via the renal tubules, and thus insufficient secretion of either renin or aldosterone would work to produce the opposite effect of hypernatremia.

Tularemia is an infectious disease caused by the bacterium Francisella tularensis. The bacteria is generally found in rodents and rabbits, and the most common vectors are ticks and deer flies. A patient who has been exposed to tularemia is likely to be treated with antibiotics (streptomycin, gentamycin, tetracyclines, or fluoroquinolones).

The major organs that make up the GI tract are: the mouth, the esophagus, the stomach, the small intestine, the large intestine, the rectum, and the anus. The accessory organs of digestion include the liver, the gallbladder, and the pancreas. The spleen plays a major role in filtering blood, working to remove old red blood cells.

Pancreatitis is an inflammatory disease in which pancreatic enzymes, which normally function to digest food in the small intestines, become activated in the pancreas and initiate autodigestion. The most common causes of acute pancreatitis are alcoholism and biliary disease (gallstones). Other less common causes of acute pancreatitis include: codeine reaction, cystic fibrosis, and use of steroid medications.