Digestion: Physiology and Nutritional Disorders

Crohn's disease, also known as regional enteritis, is an inflammatory disease of the intestines.

Coeliac disease is an auto-immune disorder of the small intestine.

Pancreas are a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that pass to the small intestine.

As the name suggests, these enzymes catalyze hydrolysis reactions (and their reverse reactions). The hydrolysis of an ester would be an example of such a reaction.

These enzymes catalyse geometric or structural changes within one molecule. According to the type of isomerism, they may be called racemases, epimerases, cis-trans-isomerases, isomerases, tautomerases, mutases or cycloisomerases.

A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Older publications may use terms such as polynucleotidase or nucleodepolymerase. Nucleases are usually further divided into endonucleases and exonucleases, although some of the enzymes may fall in both categories.

The kidneys play key roles in body function, not only by filtering the blood and getting rid of waste products, but also by balancing levels of electrolyte levels in the body, controlling blood pressure, and stimulating the production of red blood cells.They do not secrete any digestive enzymes.

It is present in the duodenum and increases the migrating myoelectric complex component of gastrointestinal motility and stimulates the production of pepsin.

Hind III is a type II site-specific deoxyribonuclease restriction enzyme isolated from Haemophilus influenzae that cleaves the palindromic DNA sequence AAGCTT in the presence of the cofactor Mg2+ via hydrolysis. The cleavage of this sequence between the AA's results in 5' overhangs on the DNA called sticky ends.

Metalloproteinases constitute a family of enzymes from the group of proteases, classified by the nature of the most prominent functional group in their active site. These are proteolytic enzymes whose catalytic mechanism involves a metal. Most metalloproteases are zinc-dependent, some use cobalt.

Tropical sprue is a malabsorption disease commonly found in the tropical regions, marked with abnormal flattening of the villi and inflammation of the lining of the small intestine.

Stomach is a small 'J'-shaped pouch with walls made of thick, elastic muscles, which stores and helps break down food. Food which has been reduced to very small particles is more likely to be fully digested in the small intestine, and stomach churning has the effect of assisting the physical disassembly begun in the mouth.

Mucosa is the extensively folded innermost layer. It can be divided into the epithelium, lamina propria, and the muscularis mucosae, though some consider the outermost muscularis mucosae to be a distinct layer, as it develops from the mesoderm rather than the endoderm (thus making a total of five layers).

Mastication is the process by which food is crushed and grinded 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. During the mastication process, the food is positioned between the teeth for grinding by the cheek and tongue.

Lipoprotein lipase encodes lipoprotein lipase, which is expressed in heart, muscle, and adipose tissue. Lipoprotein lipase functions as a homodimer, and has the dual functions of triglyceride hydrolase and ligand/bridging factor for receptor-mediated lipoprotein uptake.

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.

Colon, representing the greater part of the large intestine, consists of four sections: the ascending, transverse, descending, and sigmoid colons. At regular distances along the colon, the smooth muscle of the muscularis layer causes the intestinal wall to gather, producing a series of pouches called haustra.

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.

Goblet cells, located throughout the epithelial layer, secrete mucus that helps protect the epithelial layer from digestion.

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.