While Sputum Smear Microscopy is often the first step due to its speed, Sputum Culture remains the gold standard because it can detect low numbers of mycobacteria and allows for drug sensitivity testing, though it takes several weeks for results.

Lactase is produced in the small intestine. It breaks down the disaccharide lactose into the simple sugars glucose and galactose for absorption.

Lipase is secreted primarily by the pancreas and works in the small intestine to digest fats after they have been emulsified by bile.

Probiotics are live beneficial bacteria found in fermented foods like yogurt and kefir. They help balance the intestinal flora, which is crucial for digestion and immune health.

FODMAPs are fermentable carbohydrates that are poorly absorbed in the small intestine. A low-FODMAP diet helps identify and eliminate triggers for gas, bloating, and abdominal pain in IBS patients.

Vitamin D acts more like a hormone than a vitamin; it increases the synthesis of calcium-binding proteins in the intestinal wall, allowing for the efficient uptake of dietary calcium.

Celiac disease is an autoimmune disorder where the ingestion of gluten (found in wheat, barley, and rye) leads to damage in the small intestine. Currently, the only treatment is total avoidance of gluten.

Vitamin B12 (cobalamin) must bind to intrinsic factor produced by parietal cells in the stomach. The B12-intrinsic factor complex is then absorbed in the terminal ileum of the small intestine.

Villi, and the smaller microvilli on their surface, dramatically increase the absorptive area of the small intestine, allowing nutrients to quickly pass into the bloodstream or lacteals.

Testosterone is an androgen responsible for the development of male primary and secondary sex characteristics and is essential for the production of sperm.