Human Digestive System

Amylase is an enzyme that helps digest carbohydrates. It is produced mainly in the pancreas and the glands that make saliva. When the pancreas is diseased or inflamed, amylase releases into the blood.

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces. It is not a part of small intestine.

Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes.

Mass movement of feces into the rectum stimulates a defecation reflex that opens the internal anal sphincter. Unless the external and sphincter is voluntarily closed, feces are evacuated through the anus. Defaecation is the main function of large intestine.

Parietal (oxyntic) cells are scattered along the neck and lower walls of the ducts. They secrete hydrochloric acid (HCl) and intrinsic factor. Intrinsic factor is necessary for the absorption of Vitamin B12 in the small intestine.

The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. It is not an accessoary part of digestive system.

Chymosin or rennin is an enzyme found in rennet. It is produced by cows in the lining of the abomasum (the fourth and final, chamber of the stomach). Chymosin is produced by gastric chief cells in infants to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption.

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, such as bones cellulose or lignin.It is not a part of small intestine.

An ulcer is fundamentally a break or sore in the epithelial lining. This can occur on the skin (like bed sores or diabetic foot ulcers) or in the mucous lining of internal organs (like peptic ulcers in the stomach/duodenum). Both manifestations involve tissue breakdown and impaired healing, whether external (skin) or internal (organ lining).

Gastric specifically refers to the stomach. Therefore, a gastric ulcer is a sore that develops in the stomach lining. Peptic ulcers is the broader category that includes both gastric ulcers (stomach) and duodenal ulcers (upper part of small intestine). The term helps distinguish the location of the ulcerative damage.

Mucus in the respiratory tract is a physical barrier of innate immunity.

Saliva contains the enzyme salivary amylase (also called ptyalin), which begins the breakdown of starch into simpler sugars like maltose. This is the first step of carbohydrate digestion. Saliva does not contain enzymes that digest proteins (requires pepsin/trypsin) or fats (requires lipase). Fiber is indigestible by human enzymes.

Streptokinase (Tissue Plasminogen Activator or TPA) is an enzyme obtained from the cultures of some haemolytic bacterium Streptococcus and modified genetically to function as clot buster. It has fibrinolytic effect. Therefore, it helps in clearing blood clots inside the blood vessels through dissolution of intravascular fibrin.

Cysteine strengthens the protective lining of the stomach and intestines, which may help prevent damage caused by aspirin and similar drugs.

Digestive enzymes (like amylase, protease, lipase) break down food molecules into smaller absorbable units during digestion. They catalyze specific reactions - carbohydrates to sugars, proteins to amino acids, fats to fatty acids. While enzymes play roles in many body processes, the digestive system is their primary domain.