Human Digestive System

After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food. Many microbes (bacteria like Bacteroides, Lactobacillus acidophilus, Escherichia coli, and Klebsiella) in the large intestine help in the digestion process.

The stomach has a priority to destroy the bacteria and viruses using its highly acidic environment but also has a duty to protect its own lining from its acid. The way that the stomach achieves this is by secreting mucin and bicarbonate via its mucous cells, and also by having a rapid cell turn-over.

The pancreas is also the main source of enzymes for digesting fats (lipids) and proteins. The enzymes that digest polysaccharides, by contrast, are primarily produced by the walls of the intestines.

Amylases are used in breadmaking and to break down complex sugars, such as starch (found in flour), into simple sugars. Yeast then feeds on these simple sugars and converts it into the waste products of alcohol and CO2. This imparts flavour and causes the bread to rise.

This is a significant brush border enzyme.This enzyme decreases with age, and as such lactose intolerance is often a common abdominal complaint in the older population, manifesting with bloating, abdominal pain, and osmotic diarrhea.

Peyer's patches are covered by specialized epithelium (follicle-associated epithelium). Some of these epithelial cells have surfaces, which seem folded under the scanning electron microscope. These microfold, or M, cells sample and actively transport particulate antigens from the lumen into the dome area, where priming of both T and B lymphocytes occurs.

Fructose is absorbed by facilitated diffusion in the small intesstine.

Von Ebner glands are glands found in a trough circling the circumvallate papillae on the dorsal surface of the tongue near the sulcus terminalis. They secrete a purely serous fluid that begins lipid hydrolysis.

Segmentation occurs only in the small intestine as short segments of intestine contract. Segmentation helps to increase the absorption of nutrients by mixing food and increasing its contact with the walls of the intestine.

The pancreas is also the main source of enzymes for digesting fats (lipids) and proteins. The enzymes that digest polysaccharides, by contrast are primarily produced by the walls of the intestines.

After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food. Many microbes (bacteria like Bacteroides, Lactobacillus acidophilus, Escherichia coli, and Klebsiella) in the large intestine help in the digestion process.

Dehydration is the excessive loss of water from body tissues when fluid intake cannot replace fluid loss due to bleeding, diarrhea, vomiting, or excessive sweating. Rehydration is the process of restoring fluids, while retardation and deformation are unrelated to fluid loss.

The digestive system performs three main activities: Ingestion (taking in food), Digestion (breaking down food), and Elimination (removing waste). All these functions are essential, making 'All of the above' the correct answer.

The sphincter of Oddi is a muscular valve that controls the opening of the common hepatopancreatic duct (also called the common bile duct) into the duodenum. It regulates the flow of bile from the liver and digestive enzymes from the pancreas. It is not associated with the pyloric stomach, esophagus, or colon.

During swallowing, the soft palate (velum) elevates and the uvula swings backward to close off the nasopharynx. This prevents food/liquid from refluxing into the nasal cavity. The hard palate is anterior bone and doesn't move. Uvula alone cannot seal the opening.