As chyme enters the small intestine, the pancreas will release bicarbonate ions. This not only helps lower the acidity of the chyme that has just left the stomach, but also allows enzymes in the small intestine to be at their ideal pH when functioning.

Proteases, such as chymotrypsin, break down proteins and hydrochloric acid from parietal cells in the stomach contributes to the acidity of the stomach contents.

In the pancreas, islets of Langerhans are collections of alpha, beta, and gamma endocrine cells (these are most numerous in the tail of the pancreas). Beta cells are more centrally located and are responsible for insulin secretion. Alpha cells are peripherally located and release glucagon, while delta cells are interspersed and release somatostatin. Chromaffin cells are located in the adrenal medulla and produce catecholamines.

The liver detoxifies everything we consume and thus must have the ability to regenerate the damage from such intense metabolism. The liver converts fat soluble toxins to water soluble ones so that they can be secreted in urine. It also manages by products of regular digestion such as converting the ammonia formed from protein digestion into urea.

This patient most likely has vitamin B12 deficiency. B12 is found in meats and thus a vegan individual would be deficiency in this vitamin. It takes several years to develop B12 deficiency because the liver can store B12 for a few years before signs and symptoms present of the deficiency. B12 deficiency is associated with neurological symptoms (peripheral neuropath) and macrocytic/megaloblastic anemia. B9 also presents with megaloblastic/macrocytic anemia but it does not have neurological signs or symptoms. Additionally, B9 is found in green vegetables and there is nothing in the patient's history to suggest B9 deficiency. B6 presents as sideroblastic anemia. 

Pancreatic function is crucial for the absorption of fat-soluble vitamins (ADEK). Toxins, such as alcohol, have the potential to harm the pancreas, leaving it non-functional. Best treatment in this person would be to stop alcohol consumption, and to administer the deficient vitamins and pancreatic enzymes to replace those that are not working. 

As macromolecules are absorbed in the small intestine, polar molecules are able to float freely into the bloodstream due to their hydrophilic nature. Nonpolar molecules, such as fats and lipids, require a carrier protein in order to move throughout the body. Fats are carried through the lymphatic system by chylomicrons and are then dumped into the bloodstream through the thoracic duct.

Proteins, nucleic acids, and carbohydrates all contain polar regions that allow them to travel easily within aqueous environments.

The small intestine is composed of three sections: the duodenum, the jejunum, and the ileum. The duodenum is the first section, and experiences the majority of chemical digestion in the small intestine. The pancreatic duct empties into the section, carrying enzymes to facilitate digestion of carbohydrates, lipids, and fats as well as bicarbonate to neutralize stomach acid. These enzymes break down macromolecules in the duodenum. The jejunum and ileum are largely responsible for absorbing the nutrients digested in the duodenum. The cecum is a region of the large intestine, which is primarily responsible for water absorption. The pylorus is a region of the stomach, and connects the stomach to the small intestine.

Lactose is composed of a galactose monomer and a glucose monomer. The glycosidic bond is a  1-4 linkage.

Sucrose is composed of a glucose monomer and a fructose monomer. The glycosidic bond is an  1-2 linkage.

Maltose is composed of two glucose monomers joined by an  1-6 linkage.

Substances from the small intestine enter the large intestine via the ileocecal valve; thus the first place chyme enters the large intestine is the cecum, which is on the lower right side of the abdominal cavity. The large intestine "outlines" the abdominal cavity; thus next is the ascending colon up towards the liver (on the right side of the abdominal cavity) where it turns toward the midline via the hepatic flexure. The transverse colon moves substances from right to left across the abdominal cavity until it reaches the area near the spleen (on the left side of the body), where it turns down via the splenic flexure into the descending colon. Then comes the sigmoid colon towards the rectum. The anus is not part of the large intestine. 

Bile is necessary to emulsify fats. Proteases break down proteins, not fat. Fiber is broken down by bacteria in the large intestine. The stomach does not release bile. Note that the liver synthesizes bile, but it is stored in and released from the gallbladder.