Divisions The intestine is divided into small intestine and large intestine. The former extends from the stomach onwards for 6·5 metres (22 feet) or thereabouts. The large intestine is the second part of the tube, and though shorter (about 1·8 metres [6 feet] long) is much wider than the small intestine. The latter is divided rather arbitrarily into three parts: the duodenum, consisting of the ?rst 25–30 cm (10–12 inches), into which the ducts of the liver and pancreas open; the jejunum, comprising the next 2·4–2·7 metres (8–9 feet); and ?nally the ileum, which at its lower end opens into the large intestine.
The large intestine begins in the lower part of the abdomen on the right side. The ?rst part is known as the caecum, and into this opens the appendix vermiformis. The appendix is a small tube, closed at one end and about the thickness of a pencil, anything from 2 to 20 cm (average 9 cm) in length, which has much the same structure as the rest of the intestine. (See APPENDICITIS.) The caecum continues into the colon. This is subdivided into: the ascending colon which ascends through the right ?ank to beneath the liver; the transverse colon which crosses the upper part of the abdomen to the left side; and the descending colon which bends downwards through the left ?ank into the pelvis where it becomes the sigmoid colon. The last part of the large intestine is known as the rectum, which passes straight down through the back part of the pelvis, to open to the exterior through the anus.
Structure The intestine, both small and large, consists of four coats, which vary slightly in structure and arrangement at di?erent points but are broadly the same throughout the entire length of the bowel. On the inner surface there is a mucous membrane; outside this is a loose submucous coat, in which blood vessels run; next comes a muscular coat in two layers; and ?nally a tough, thin peritoneal membrane. MUCOUS COAT The interior of the bowel is completely lined by a single layer of pillar-like cells placed side by side. The surface is increased by countless ridges with deep furrows thickly studded with short hair-like processes called villi. As blood and lymph vessels run up to the end of these villi, the digested food passing slowly down the intestine is brought into close relation with the blood circulation. Between the bases of the villi are little openings, each of which leads into a simple, tubular gland which produces a digestive ?uid. In the small and large intestines, many cells are devoted to the production of mucus for lubricating the passage of the food. A large number of minute masses, called lymph follicles, similar in structure to the tonsils are scattered over the inner surface of the intestine. The large intestine is bare both of ridges and of villi. SUBMUCOUS COAT Loose connective tissue which allows the mucous membrane to play freely over the muscular coat. The blood vessels and lymphatic vessels which absorb the food in the villi pour their contents into a network of large vessels lying in this coat. MUSCULAR COAT The muscle in the small intestine is arranged in two layers, in the outer of which all the ?bres run lengthwise with the bowel, whilst in the inner they pass circularly round it. PERITONEAL COAT This forms the outer covering for almost the whole intestine except parts of the duodenum and of the large intestine. It is a tough, ?brous membrane, covered upon its outer surface with a smooth layer of cells.... intestine
Bladder cancer is more common in smokers and workers in the dye and rubber industries. Haematuria (blood in the urine) is the main symptom of bladder cancer. A tumour may obstruct the entry of a ureter into the bladder, causing back pressure and pain in the kidney region, or may obstruct the urethral exit, causing difficulty in passing, or retention of, urine.
Bladder tumours are diagnosed using cystoscopy and biopsy of the abnormal area. If small, they can be treated by heat or surgically during cystoscopy. They tend to recur at the same or other sites within the bladder, so that regular follow-up cystoscopy is needed. Bladder tumours that have spread through the bladder wall may be treated by radiotherapy or by surgical removal of part or all of the bladder.... bladder tumours
Both the small and large intestine may develop carcinoid tumours (leading to carcinoid syndrome) and lymphomas.
Cancer of the small intestine is rare, but cancer of the large intestine is one of the most common of all cancers (see colon, cancer of; rectum, cancer of).... intestine, cancer of
Noncancerous tumours occur less frequently than cancers.
The most common form of noncancerous tumour is a bronchial adenoma, which arises in the lining of a bronchus.
Adenomas often cause bronchial obstruction; affected people may also cough up blood.
Treatment involves surgical removal of the tumour.
Other rare noncancerous tumours include fibromas (which consist of fibrous tissue) and lipomas (which consist of fatty tissue).
No treatment is necessary unless the tumours are causing problems.... lung tumours
Keratoses and squamous papillomas are common types of noncancerous tumour; other types include sebaceous cysts, cutaneous horns, keratoacanthomas, and haemangiomas.... skin tumours
Several diseases and conditions are treated under separate headings. (See APPENDICITIS; CHOLERA; COLITIS; CONSTIPATION; CROHN’S DISEASE; DIARRHOEA; DYSENTERY; ENTERIC FEVER; HAEMORRHOIDS; HERNIA; INFLAMMATORY BOWEL DISEASE (IBD); ILEITIS; INTUSSUSCEPTION; IRRITABLE BOWEL SYNDROME (IBS); PERITONITIS; RECTUM, DISEASES OF; ULCERATIVE COLITIS.)
In?ammation of the outer surface is called peritonitis, a serious disease. That of the inner surface is known generally as enteritis, in?ammation of special parts receiving the names of colitis, appendicitis, irritable bowel syndrome (IBS) and in?ammatory bowel disease (IBD). Enteritis may form the chief symptom of certain infective diseases: for example in typhoid fever (see ENTERIC FEVER), cholera and dysentery. It may be acute, although not connected with any de?nite organism, when, if severe, it is a very serious condition, particularly in young children. Or it may be chronic, especially as the result of dysentery, and then constitutes a less serious if very troublesome complaint.
Perforation of the bowel may take place as the result either of injury or of disease. Stabs and other wounds which penetrate the abdomen may damage the bowel, and severe blows or crushes may tear it without any external wound. Ulceration, as in typhoid fever, or, more rarely, in TUBERCULOSIS, may cause an opening in the bowel-wall also. Again, when the bowel is greatly distended above an obstruction, faecal material may accumulate and produce ulcers, which rupture with the ordinary movements of the bowels. Whatever the cause, the symptoms are much the same.
Symptoms The contents of the bowel pass out through the perforation into the peritoneal cavity, and set up a general peritonitis. In consequence, the abdomen is painful, and after a few hours becomes extremely tender to the touch. The abdomen swells, particularly in its upper part, owing to gas having passed also into the cavity. Fever and vomiting develop and the person passes into a state of circulatory collapse or SHOCK. Such a condition may be fatal if not properly treated.
Treatment All food should be withheld and the patient given intravenous ?uids to resuscitate them and then to maintain their hydration and electrolyte balance. An operation is urgently necessary, the abdomen being opened in the middle line, the perforated portion of bowel found, the perforation stitched up, and appropriate antibiotics given.
Obstruction means a stoppage to the passage down the intestine of partially digested food. Obstruction may be acute, when it comes on suddenly with intense symptoms; or it may be chronic, when the obstructing cause gradually increases and the bowel becomes slowly more narrow until it closes altogether; or subacute, when obstruction comes and goes until it ends in an acute attack. In chronic cases the symptoms are milder in degree and more prolonged.
Causes Obstruction may be due to causes outside the bowel altogether, for example, the pressure of tumours in neighbouring organs, the twisting around the bowel of bands produced by former peritonitis, or even the twisting of a coil of intestine around itself so as to cause a kink in its wall. Chronic causes of the obstruction may exist in the wall of the bowel itself: for example, a tumour, or the contracting scar of an old ulcer. The condition of INTUSSUSCEPTION, where part of the bowel passes inside of the part beneath it, in the same way as one turns the ?nger of a glove outside in, causes obstruction and other symptoms. Bowel within a hernia may become obstructed when the hernia strangulates. Finally some body, such as a concretion, or the stone of some large fruit, or even a mass of hardened faeces, may become jammed within the bowel and stop up its passage.
Symptoms There are four chief symptoms: pain, vomiting, constipation and swelling of the abdomen.
Treatment As a rule the surgeon opens the abdomen, ?nds the obstruction and relieves it or if possible removes it altogether. It may be necessary to form a COLOSTOMY or ILEOSTOMY as a temporary or permanent measure in severe cases.
Tumours are rare in the small intestine and usually benign. They are relatively common in the large intestine and are usually cancerous. The most common site is the rectum. Cancer of the intestine is a disease of older people; it is the second most common cancer (after breast cancer) in women in the United Kingdom, and the third most common (after lung and prostate) in men. Around 25,000 cases of cancer of the large intestine occur in the UK annually, about 65 per cent of which are in the colon. A history of altered bowel habit, in the form of increasing constipation or diarrhoea, or an alternation of these, or of bleeding from the anus, in a middle-aged person is an indication for taking medical advice. If the condition is cancer, then the sooner it is investigated and treated, the better the result.... intestine, diseases of
Retinoblastoma is a cancerous tumour of the retina that occurs in one or both eyes and most often affects children. It may be treated by radiotherapy, laser treatment, or cryosurgery, but the eye may have to be removed to prevent spread of the tumour.
Malignant melanoma is a cancer of the choroid. It usually affects older people. There are no symptoms in the early stages, but it eventually causes retinal detachment and distortion of vision. Small tumours can be treated by laser, but the eye may need to be removed to avoid spread of the tumour.
Secondary eye tumours occur when cancer elsewhere in the body spreads to the eye. Symptoms depend on the tumour’s location and growth rate. It may be controlled by radiotherapy.
Basal cell carcinoma is the most common type of tumour affecting the eyelid. It usually has a crusty central crater and a rolled edge. In the early stages, treatment may be possible by surgery, radiotherapy, or cryosurgery.... eye tumours
Structural abnormalities may be present from birth (congenital) or may develop later. They cause blockage of the intestine (see intestine, blockage of) and include atresia, stenosis, and volvulus. In newborns, meconium (fetal intestinal contents) may block the intestine.
Generalized inflammation of the intestine may result from viral or bacterial infections or from noninfectious causes, as in ulcerative colitis and Crohn’s disease. Gastroenteritis is the term commonly applied to inflammation of the stomach and intestines. Infection encompasses food poisoning, traveller’s diarrhoea, typhoid fever, cholera, amoebiasis, and giardiasis. Intestinal worm infestations include roundworms and tapeworms. Sometimes inflammation is localized, such as in appendicitis and diverticular disease.
Tumours of the small intestine are rare, but noncancerous growths, lymphomas, and carcinoid tumours (causing carcinoid syndrome) occur. Tumours of the large intestine are common (see colon, cancer of; rectum, cancer of). Some forms of familial polyposis may progress to cancer. Impaired blood supply (ischaemia) to the intestine may occur as a result of partial or complete obstruction of the arteries in the abdominal wall (from diseases such as atherosclerosis) or from the blood vessels being compressed or trapped, as in intussusception or hernias. Loss of blood supply may cause gangrene.
Other disorders that affect the intestine include peptic ulcers, diverticulosis, malabsorption, coeliac disease, and irritable bowel syndrome.... intestine, disorders of
A blockage in the small intestine usually causes intermittent cramp-like pain in the centre of the abdomen with increasingly frequent bouts of vomiting and failure to pass wind or faeces. An obstruction in the large intestine causes pain, distension of the abdomen, and failure to pass wind or faeces.
Treatments involve emptying the stomach via a nasogastric tube and replacing lost fluids through an intravenous drip In some cases, this will be sufficient to correct the problem. However, in many cases, surgery to deal with the cause of the blockage is necessary.... intestine, obstruction of
The causes of pituitary tumours are unknown. They may lead to inadequate hormone production, causing problems such as cessation of menstrual periods or reduced sperm production. They may also cause the gland to produce excess hormone. Overproduction of growth hormone causes gigantism or acromegaly; too much thyroid-stimulating hormone (TSH) can lead to hyperthyroidism. Investigations include blood tests, X-rays, MRI of the pituitary, and usually also vision tests. Treatment may be by surgical removal of the tumour, radiotherapy, hormone replacement, or a combination of these techniques. The drug bromocriptine may be used; it can reduce production of certain hormones and shrink some tumours.... pituitary tumours
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