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
Bile is a yellow, bitter, liquor, secreted from the liver stored in the gall bladder. After secretion, bile is collected by the biliary ducts, which unite to form the hepatic duct, whence it passes into the duodenum, or by the cystic duct into the gall-bladder to be retained there until required for use. Research Bile
The celiac ganglia are large clusters of nerve fibres which are related to the sympathetic nervous system. They are located on either side of the aorta, near where the celiac artery begins. Nerves extend from the sympathetic trunk to the celiac ganglia and from there to the stomach, gall bladder, bile ducts, adrenal glands, and further to the inferior and superior mesenteric ganglia, which innervate the intestines. Research Celiac Ganglia
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
The gall bladder serves the function of concentrating and storing bile, produced in dilute form by the liver, and secreting the bile through the cystic ducts into the duodenum where it can help in digestion. The gall bladder itself is a blue-green organ, about eight centimeters long, located on the underside of the liver. Bile is composed of cholesterol, bilesalts, and bile pigment. The
gall bladder is not critical to the survival of the human, and may be removed without severely adverse effects. The crystallization of the bilesalts in the gall bladder gives rise to gallstones, which often requires surgical correction. Research Gall Bladder
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 small intestine is descriptively divided into three sections: the duodenum, the ileum, and the jejunum. The duodenum accepts the digested food paste, called chyme, from the stomach, through the pylorus sphincter. The duodenum is about ten inches long and forms a curve around the head of the pancreas. The duodenum secretes digestive enzymes invertase and erepsin, necessary for digestion. The gall bladder, liver, and pancreas also deposit enzymes and bile into the duodenum. The jejunum is the intermediate section of the small intestine, measuring a little over two meters long. The jejunum carries digested food through the small intestine rapidly by peristaltic waves and, as a result, seldom has much food matter in it. It is connected to the abdominal wall by the mesentery. The ileum is the last, and longest, segment of the small intestine, measuring up to four meters or longer. Most of the absorption of useful food nutrients takes place in the ileum before it empties out into the cecum of the large intestine. Research Small Intestine
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Abdomen
