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Diarrhea is an increased frequency and decreased consistency of fecal discharge as compared with an individual's normal bowel pattern. Frequency and consistency are variable within and between individuals. For example, some individuals defecate as many as three times a day, while others defecate only two or three times per week. Most cases of acute diarrhea are caused by infections with viruses, bacteria, or protozoa and are generally self-limited (Pharmacotherapy Handbook, Joseph T. DiPiro et al.,2009)
Poorly absorbed substances retain intestinal fluid , resulting in osmotic diarrhea. This process occurs with malabsorption syndromes,lactose intolerance, administration of divalent ions(e.g. magnesium containing antacids), or consumption of poorly soluble carbohydrates(e.g. lactulose)
Altered intestinal motility produces diarrhea by three mechanisms; reduction of contact time in small intestine, premature emptying of colon, and bacterial over growth. chyme must be exposed to intestinal epithelium for a sufficient time period to enable normal absorption and secretion process to occur. If this contact time decreases, diarrhea results.
Constipation does not have a single definition, generally agreed upon definition. Normally people pass at least three stools per week. Some of the definitions of constipation include: lesser than three stools per week for women and five for men despite a high-residue diet or a period of greater than 3 days without a bowel movement; straining at stool greater than 25% of the time and/or two or fewer stools per week; or straining at defecation and less than one stool daily with minimal effort. (Pharmacotherapy Handbook, Joseph T. DiPiro et al., 2009)
(diabetes), or endocrine disorders (hypothyroidism) may be involved. Constipation commonly due to a diet low in fiber or from use of constipating drugs such as opiates. Finally, it is believed that constipation may sometimes be psychogenic in origin. Constipation is a frequently reported problem in the elderly, probably the result of improper diets (low in fiber and liquids), diminished abdominal wall muscular strength, and possibly diminished physical activity. However, as previously stated, the frequency of bowel movements is not decreased with normal aging. In addition, diseases that may cause constipation, such as colon cancer and diverticulitis, are more common with increasing age. (Pharmacotherapy A Pathophysiologic approach, Joseph T. DiPiro)
The three consecutive phases of emesis include nausea, retching, and vomiting. Nausea, the imminent need to vomit, is associated with gastric stasis and may be considered a separate and singular symptoms. Retching is the labored movement of abdominal and thoracic muscles before vomiting. The final phase of emesis is vomiting.
Vomiting is triggered by afferent impulses to the vomiting center, a nucleus of cells in the medulla. Impulses are received from sensory centers, such as the chemoreceptor trigger zone(CTZ),cerebral cortex, and visceral afferents from the pharynx and GI tract. When excited, afferent impulses are integrated by the vomiting center , resulting in efferent impulses to the salivation center ,respiratory center, and the pharyngeal, GI, and abdominal muscles, leading to vomiting.
The CTZ, located in the area postreme of the fourth ventricle of the brain, is a major chemosensory organ for emesis and is usually associated with chemically induced vomiting. Because of its location, blood-borne and cerebrospinal fluid toxins have easy to access to the CTZ. Therefore cytotoxic agents stimulates primarily this area rather than the cerebral cortex and visceral afferents. Similarly, pregnancy associated vomiting probrbly occurs through stimulation of the CTZ. Numerous neurotransmitter receptors are located in the vomiting center, CTZ and GI tract. Example of such receptors include cholinergic and histaminic, dopaminergic, opiate, serotonergic, neurokinin, and benzodiazepine receptors. Chemotherapeutic agents, their metabolites, or other emetic compounds theoretically trigger the process of emesis through stimulation of one or more of these receptors. Effective antiemetics are able to antagonize or block the emetogenic receptors. (Pharmacotherapy A Pathophysiologic approach, Joseph T. DiPiro)
Wheezing is a clinical symptoms present n asthma and other illness including bronchiolitis and other viral infection, foreign body inhalation, tuberculosis, pneumonia, cystic fibrosis, immune deficiency, bronchomalacia, hypersensitivity pneumonia and condition compressing airways. Wheezing during infancy could be due to viral infection. Absence of faml history and personal history of atopy with gradual decrease in frequency of episodes is seen in many transient wheezers who grow out of ther wheezing episodes. Wheezing n asthma is recurrent , gets worse n night and after exercise, seasonal and may be associated with other allergic illness like atopic dermatitis. Allergic rhinitis etc. clinical features suggestive of other cause of wheezing are; neonatal on set, associated with difficulty in feeding, choking or vomiting, localized findings in chest or abnormality in cardiovascular system. (SATANDARD TREATMENT GUIDELINES A manual for medical therapeutics, Sangeetha Sharma)