Ascariasis is an infection caused by a parasitic worm, ascarsis lumbricoides. This parasite is a pale, cylindrical, tapered roundworm that grows to between fifteen and forty centimetres in length. It lives in the small intestine of its host. The infection is common worldwide, especially in the tropics. It affects 80% to 90% of the population in poorer countries where standards of public hygiene and sanitation are low. One or several worms may be present in the infection, but symptoms generally only appear when there is multiple infestation. The eggs of the worm are carried by the wind in drier climates. In most cases, however, they are transmitted through water, food, and hands. The eggs are swallowed via the mouth of the new host and then hatch into larvae in the small intestine. The larvae travel through the wall of the intestine and are carried by the lymphatic vessels and the bloodstream to the lungs, up the trachea, and are swallowed back to the small intestine where they mature in the jejunum.
The worms reach maturity about two months after ingestion. The adult worms release eggs which are passed out through faeces to be acquired by a new host and start the cycle over. The lifespan of the worm is under 18 months, however, female worms produce up to 200,000 eggs per day. The eggs can remain viable for months or years. The condition is diagnosed by the presence of the eggs in an infected person's faeces during microscopic examination. Light infestation generally causes no symptoms or may cause slight nausea. Early symptoms of the passage through the respiratory system include coughing, wheezing, and a slight fever. Heavy infestation of the parasites compete with the host for food, leading to malnutrition and anaemia. In children, migration of the worms to the liver, gall bladder, or peritoneal cavity may cause death. Research Ascariasis
The cecum is the large, primary section of the large intestine, which accepts fluid food-by-products from the ileum of the small intestine through the ileocecal orifice. About eight centimeters long, the cecum transmits this by-product to the ascending section of the colon. Research Cecum
The digestive system is responsible for processing food, breaking it down into usable proteins, carbohydrates, minerals, fats, and other substances, and introducing these into the bloodstream so that they can be used by the body. The digestive, or alimentary, tract begins at the mouth, where the teeth and tongue begin the breakdown of food, aided by saliva secreted by the salivary glands. The chewed food, combined with saliva, is swallowed, carrying it in peristaltic waves down the esophagus to the stomach. In the stomach, the food combines with hydrochloric acid which further assists in breaking it down. When the food is thoroughly digested, the fluid remaining, called chyme, is passed through the pylorus sphincter to the small intestine and large intestines. Within the long, convoluted intestinal canals, the nutrients are absorbed from the chyme into the bloodstream, leaving the unusable residue. This residue passes through the colon (where most of the water is absorbed into the bloodstream) and into the rectum where it is stored
prior to excretion. This solid waste, called faeces, is compacted together and, upon excretion, passes through the analcanal and the anus. Along the way through the digestive tract, the pancreas, spleen, liver, and gall bladder secrete enzymes which aid in the digestive process. Research Digestive System
Epithelium is an anatomical term for a basic type of bodily tissue. It comprises the external surface of the skin, the internal surfaces of the digestive, respiratory and urogenital systems, the closed serous cavities, the inner coats of the vessels, the acini and ducts of the secreting and excreting glands, the ventricles of the brain and the central canal of the spinal cord. The constituent cells of an epithelium are always closely packed together and the intercellular substance is reduced to a minimum. The cells comprising an epithelium are arranged in one (simple epithelium) or more (stratified epithelium and transitional epithelium) layers, usually supported on a basementmembrane and united together by a cement-like substance which is chemically similar to the matrix or ground-substance of the connective tissues.
The epithelium serves various purposes. The epithelium of the skin (known as the epidermis) serves primarily to protect the underlying tissue (the true skin, nerves and vessels which it contains). Th epithelium of the salivary glands, the pancreas, the gastric glands and the glands of the small intestine are comprised of cells which prepare the digestive juices. The cells comprising the epithelium of the intestinal villi are concerned with the absorption of the products of digestion. The cells of the epitheliums of the serous cavities provide a smooth, moist surface. Rather unusually in the body, the epithelium is devoid of a blood supply Research Epithelium
Gastro-enterostomy is an operation in which the duodenum is short-circuited by a loop of small intestine being joined directly to the lower border of the stomach. It is performed for three distinct reasons: (a) pyloric obstruction or duodenal stenosis due to some congenital deformity. (b) pyloric obstruction due to scarring following duodenal or gastric ulceration. (Partial gastrectomy is usually preferable but not always necessary). (c) pyloric obstruction due to carcinoma as a purely palliative measure when the primary tumour cannot be removed. Research Gastro-Enterostomy
The hepatic ducts transport bile out of the liver. The main hepatic duct is formed by two smaller ducts and this leads to the cystic duct. Joining with the cystic duct (which connects with the gall bladder), the hepatic duct then forms the ductus communis choledochus, or common bile duct, which leads to the duodenum of the small intestine. Research Hepatic Ducts
The intestines are the convoluted membranous tube which extends from the stomach to the anus and which receives the ingested food from the stomach, mixes it with bile, pancreatic juice and intestinal secretions, gives origin to the chyle and delivers the indigestible products from the system. The intestines are divided into the small and large intestine (colon). The small intestine is further divided into three parts: the duodenum, the jejunum and the ileum. The large intestine is divided into the ascending colon, the tansverse colon, the descending colon and the rectum that terminates at the anus. Research Intestines
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Abdomen
