Pathophysiology and Pharmacology Science - Diarrhea - Essay Example

Pathophysiology and Pharmacology Science Name of the Student Name of the University Pathophysiology and Pharmacology Science Diarrhea Diarrhea is the condition causing the frequent elimination or passing of stools that are abnormally watery in nature. This condition is very common and can exist alone or as a symptom of any disease. Diarrhea could be caused due to viral or bacterial infections, the presence of parasites, intestinal disorders or diseases, intolerance to certain foods and reaction to certain medicines. The epithelial tissue present along the walls of the stomach, the lumen, intestines and the colon are generally affected by diarrhea. The epithelial tissue covers the entire surface of the body. The epithelial tissue is constructed of cells closely packed together and has one or more layers. The cells are packed together tightly, such that there almost no intercellular space between them. There is also a very limited presence of intercellular substance. This tissue forms the covering or lining of all internal and external body surfaces. Epithelial tissue that is found in the interior of the body is generally called the endothelium. Epithelial tissue is usually separated from the core tissue by means of a thin sheet of connective tissue referred to as the basement membrane. This basement membrane not only provides structural support for the epithelium, it also helps bind it to its neighboring structures. Tissues involved Epithelial tissue can be divided into two basic categories, depending on the number of layers it is composed of. Epithelial tissue that is one cell thick is known as simple epithelium and epithelial tissues that are two or more cells thick is known as stratified epithelium. Simple epithelium is further subdivided based on the shape and function of its cells. The type of simple epithelial tissue affected by diarrhea is the columnar epithelium. The cells in this epithelium occur in layers and are elongated and column-shaped. The nuclei in these cells are elongated and are situated at the base of each cell. Columnar epithelium forms the lining in the stomach and intestines. Some of these cells are specialized for sensory reception. Goblet cells which are unicellular glands can be found between the columnar epithelium cells in the duodenum and they secrete mucus or slime, a lubricating substance which keeps the surface smooth. The main function of the epithelial tissue in the intestines is to absorb nutrients from the digestion of food. The pathogenesis of the disease Non-inflammatory diarrhea causes the excretion of watery, non-bloody stools. This diarrhea is caused by the presence of a toxin-producing bacterium, or other agents such as viruses in the small intestine. These bacterium and viruses disrupt the normal absorption and secretion processes occurring in the small intestine. Fecal leukocytes are not present in this case as tissue invasion does not occur (McPhee, Tierney & Papadakis, 2007). Inflammatory and infectious diarrhea causes fever and the excretion of bloody stools. This diarrhea causes damage to the colonic tissue due to invasion. This form of diarrhea also invades the epithelial tissue in the digestive tube and intestine. The epithelium in the digestive tube is protected from invasion and insult through many mechanisms comprising the gastrointestinal barrier, but it is considerably vulnerable to breach. Due to the presence of microbial and viral pathogens in the intestine causes a disruption of the epithelium. This distraction of the epithelium brings about the exudation of serum and blood into the lumen and is often the cause for the widespread destruction of absorptive epithelial tissue. Also in this case the absorption of water occurs very inefficiently and thus causes diarrhea. Fecal leukocytes and lactoferrin are usually present in this case. Sometimes, this form of diarrhea results in an outbreak of acute and severe hemorrhagic colitis. The body automatically responds to inflammatory conditions in the bowels and this often is a cause for diarrhea. The release of white blood cells pushes the bowels to secrete inflammatory mediators and cytokins which stimulate secretion, thereby imposing a secretory component in addition to causing inflammatory diarrhea. The absorption of water in the intestines depends heavily on the absorption of solutes. When excessive amounts of solutes are retained in the lumen, water will not be absorbed and thus osmotic diarrhea. Osmotic diarrhea results in the ingestion of a poorly absorbed substrate and the offending molecule here is usually a carbohydrate or divalent ion. Osmotic diarrhea also results in malabsorption, wherein there is an inability to absorb certain carbohydrates. Secretory diarrhea occurs when the secretion of water into the intestinal lumen exceeds absorption. Secretoy diarrhea is sometimes accompanied by cholera and can cause death. In this case, “Vibrio cholerae produces cholera toxin, which strongly activates adenylyl cyclase, causing a prolonged increase in intracellular concentration of cyclic AMP within crypt enterocytes” (Bowen, 2006). This change causes the prolonged opening of the chloride channels which are responsible for secreting water thereby resulting in uncontrolled secretion of water. Furthermore cholera toxins affect the enteric nervous system causing independent stimulus of secretion. Signs and symptoms In non-inflammatory diarrhea, the signs and symptoms include periumbilical cramps, bloating, nausea, or vomiting. These symptoms are caused due to small bowel source as a result of the presence of toxin-producing bacterium or other viruses in the small intestine disrupting normal absorption and secretion processes. Prominent vomiting is a result of viral enteritis or S aureus food poisoning. Diarrhea that originates in the small intestine can sometimes result in dehydration with hypokalemia and metabolic acidosis. Inflammatory diarrhea causes fever and bloody secretions, due to the invasion of the colonic tissue or due to the presence of a toxin. This invasion can cause lower quadrant cramps, urgency and tenesmus. Sometimes this type of diarrhea can also result in severe hemorrhagic colitis. In HIV patients, the signs include intestinal ulceration with watery or bloody diarrhea, due to cytomegalovirus commonly referred to as CMV. Infectious dysentery can also result in fever, abdominal pain and bloody diarrhea, due to the invasion of the tissues in the colon. Gastrointestinal (GI) infections in the upper GI tract systems cause symptoms such as nausea, vomiting and crampy epigastric pain. A wide array of viruses, bacteria, fungi, and protozoa can infect the GI tract. GI in the small intestine can cause profuse watery secretions. GI in the large intestine results in symptoms such as tenesmus, fecal urgency and bloody diarrhea (McPhee & Ganong, 2006). Other extreme symptoms of diarrhea, that require immediate medical attention include, high fevers, hypotension, immunocompromise, and extended duration of diarrhea, namely chronic diarrhea. Contributing causes and/or risk factors Viruses, bacteria, parasites, intestinal disorders, intolerance to certain foods, reactions to some medications etc., are some of the most common causes and/or risk factors that lead to diarrhea (eMedicine Health, 2009). Viral infections cause a majority of the cases of diarrhea and these viral infections are characteristically connected with mild to moderate symptoms such as frequent watery bowel movements, abdominal pain, and low-grade fever. The diarrhea caused by viral infections typically last anywhere between 3 to 7 days. Some of the most common viruses that cause diarrhea include, rotavirus which is often the cause for diarrhea among infants, norovirus is the cause for epidemics of diarrhea among both adults as well as school children. These viruses spread from cruise ships, schools, nursing homes, restaurants etc. Adenovirus infections cause diarrhea among all age groups. Bacterial infections lead to more serious types of diarrhea. These infections cause severe symptoms such as vomiting, high fever, severe abdominal pains and cramps and are often accompanied by frequent bowel movements that may be watery. In very serious cases, the stools may contain mucus, pus or blood and these infections are primarily related to the outbreaks of diseases. Bacterial infections typically spread from consuming from contaminated food or drinks. Family members or other eating the same food may contract similar illness. Foreign travel is a very common way to contract traveler’s diarrhea. Campylobacter, salmonellae, and shigella organisms are most common bacteria that lead to diarrhea. Escherichia coli, commonly called E coli, Yersinia, listeria, and other species of bacteria are less common, although they also lead to diarrhea. The use of antibiotics can lead to the overgrowth of certain bacteria such as Clostridium difficile (C diff) in the intestines thereby causing diarrhea. Parasites infect the digestive system through the use of contaminated water. Some common parasites that cause diarrhea include Giardia lamblia, Entamoeba histolytica, and Cryptosporidium. Reaction to certain types of medication such as antibiotics, blood pressure pills, cancer drugs and antacids especially those containing a significant amount of magnesium. Intolerance to certain foods such as artificial sweeteners and lactose can also trigger diarrhea. Lastly, intestinal disorders and diseases such as inflammatory bowel disease, irritable bowel syndrome, diverticulitis, and celiac disease can also lead to diarrhea. The treatment The treatment for diarrhea covers four important dimensions, namely diet, rehydration, antidiarrheal agents and antibiotic therapy. Most mild to moderate diarrhea is first treated by administering a diet that will prevent dehydration. Replacing fluids and electrolytes is the most basic treatment given for diarrhea. The patient must take ample oral fluids containing carbohydrates and electrolytes. This is essential as it is crucial to replace the water that is lost in stools thereby preventing dehydration. Minerals that are lost through diarrhea must also be replenished as sodium, magnesium and potassium are bound to water and the body requires these minerals to prevent dehydration (Kirschmann & Nutrition Search Inc., 2006). It is advisable to avoid high fibre foods and eat easily digestible foods to give rest to the bowels. Rehydration is a very essential form of treatment in serious cases of diarrhea as dehydration can occur quickly. Oral rehydration fluids comprising of glucose, bicarbonate or citrate is administered to ensure rehydration. Oral electrolyte solutions and fluids are also administered. Fluids should be given at the rate of 50 to 200ml depending upon the dehydration levels. Intravenous fluids are given to patients with extreme dehydration. Antidiarrheal agents are given to patients with mild to moderate diarrhea to improve patient comfort. For instance Opioid agents help in decreasing the stool number and liquidity and also in controlling urgency. They also help in reducing the vomiting which is generally associated with viral enteritis. These agents should not be used in patients with bloody diarrhea, high fever and extreme symptoms. Antibiotic therapy is of two types, namely empiric treatment and specific antimicrobial treatment. Empirical treatment is given to patients with moderate to sever fever, tenesmus, bloody stools etc. Specific antimicrobial treatment is administered to patients with shigellosis, cholera, extraintestinal salmonellosis, traveler’s diarrhea, C difficile infection, giardiasis and amebiasis (McPhee, Tierney & Papadakis, 2007). Infertility Infertility refers to the inability of a person to conceive or contribute to conception. “Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term. There are many biological causes of infertility, some which may be bypassed with medical intervention” (Makar & Toth, 2002). The main tissue affected during infertility if the endometrial tissue in the uterus and fallopian tube. The endometrium is a mucosal layer of tissue lining the walls of the uterus. The endometrium comprises of a simple columnar epithelium containing ciliated and secretory cells, and a basic thick connective tissue stroma. The mucosa is invaginated and forms multiple simple, tubular glands called the uterine glands. These uterine glands extend throughout the thickness of the stroma. The stromal cells in the endometrium are entrenched in a network of reticular fibres. The endometrium is exposed to cyclical changes that result in menstruation. Only the mucosa in the body of the uterus takes part in the menstrual cycle. The endometrium can be divided into two zones based on their level of participation in the changes occurring during the menstrual cycle. It is divided into the basalis and functionalis. The basilis functions as a regenerative zone even after its rejection during the menstrual cycle. The functionalis is the luminal part of the endometrium. It is discarded during every menstruation and it is where cyclical changes in the endometrium occur. Thse cyclic changes are again divided into many phase, namely, proliferative or follicular, secretory or luteal and menstrual. The endometrium functions as a lining for the uterus preventing the opposite walls of the myometrium from sticking together. The myometrium is also a part of the walls of the uterus. By preventing them from sticking together the endometrium maintains the patency of the uterine cavity. The primary function of the endometrium is to take an active part in the implantation of the fertilized ovum and the subsequent formation of the placenta. During the menstrual cycle, the endometrium grows to a thick, blood-vessel rich glandular tissue layer which provides the optimum environment for the implantation of the ovum (Sud, 2009). During pregnancy this glandular tissue expands in size and number and vascular spaces fuse and form the placenta which supplies oxygen and nutrition to the foetus. The causative factors/ agents There are several causes to infertility and in each cause different things occur at the structural or cellular level. Infertility in males occurs as a result of problems with their sperm. The sperm count known as viability may be low; the sperm may be abnormally shaped and the term for the shape of the sperm is morphology or the sperm may move too slowly and the rate of movement of the sperm is called motility (Gliksman & DiGeronimo, 2004). The reasons for the above three dysfunctions are many. Varicocele or the varicose veins in the testicles bring about dilation of the veins which leads to an increased volume of blood in the testicles. When the blood is retained around the testes, it leads to an increase in temperature which can damage sperms thereby contributing to the low sperm count. This can also cause misshaped sperms and interfere with testosterone levels. Infections in the reproductive organs can contribute towards reduced sperm production. Some infections due to venereal diseases like gonorrhea can scar the delicate tubes through which the sperm is transported. Tuberculosis and mumps can cause physical damage to the reproductive system and viral diseases such as mononucleosis and hepatitis which cause relentless high fever can also drastically reduce sperm production. Anatomical problems, prevent the testicles from producing sperms or block the sperm from being ejaculated. Hormonal factors and other factors such as treatment for certain cancers, pituitary disorders etc., can also cause imbalance and result in infertility. Contributing causes and/or risk factors Female infertility could occur as a result of Polycystic Ovary Syndrome (PCOS), Disorders in the fallopian tube or uterus, endometriosis or weight problems (Fertility & Women’s Health Center of Louisiana, 2009). PCOS is the most common endocrine disorder affecting women and causing infertility. It is a condition that occurs as a result of an imbalance in the sex hormone production (Elsheikh & Murphy, 2008). It is a heterogeneous disorder and it results in androgen excess, ovulatory dysfunction and polycystic ovaries (Azziz, 2007). Disorders in the fallopian tube or uterus are caused by blockage in the tube or damage to the tube. Blockage of sperm can occur as a result of scar tissue caused due to endometriosis or abdominal or gynecological surgery. Infections such as Chlamydia can damage the cilia that aid in transporting the egg. Without normal cilia, the egg may not meet the sperm or it may be unable to travel to the uterus. Scar tissue can form inside the pelvis, in and around the ends of the fallopian tube can block the egg from meeting the sperm. In endometriosis, the endometrial tissue grows outside the uterus, and attaches itself to other organs in the abdominal cavity. As a result during the menstrual cycle, the blood is deposited in the abdominal cavity and having no place to go, causes inflammation. Obesity can cause irregular menstrual cycle thereby reducing the fertility. Symptoms and signs The primary symptom and sign of male infertility is failure to impregnate a fertile woman. Apart from this clinical symptoms include, atrophied testes, empty scrotum, varicocele or anteversion of the epididymis and inflamed seminal vesicles etc., which result in reduced sperm count and the sluggish movement of the sperm. Other symptoms include prostatic enlargement, nodules, swelling or tenderness. These above symptoms also result in the irregular shape of the sperm (Williams & Wilkins, 2008). In female infertility the symptoms of PCOS include, excess hair on the body, acne and other skin problems, scalp hair loss, irregular menstrual cycle, heavy periods, insulin resistance, weigh issues etc (Eden, 2005). The symptoms if endometriosis include abdominal and pelvic pain before, after and during menstruation, menstrual irregularities with variable amount of bleeding and spotting, other pains, aches and soreness such as back ache, pain in the coccyx, headache, pain in the rectum etc., sexual and reproductive symptoms such as pain during and after intercourse, miscarriage, ectopic pregnancy etc., hormonal symptoms such as hot flashed, tender breasts and PMS, digestive problems such as gas pains, diarrhea, nausea etc., urinary issues such as blood in the urine, kidney tenderness etc., cardiovascular symptoms and mind, mood and emotional states. Causes and risk factors The main causes and risk factors contributing to male infertility include, genetic defects, infection in the reproductive system, testicular trauma, hormonal imbalance, exposure to radiation and certain medications contribute towards sperm production disorders. Improper anatomy and structure of the man’s reproductive organs can contribute towards infertility. Sperm DNA damage can interfere with conception and cause miscarriage. Immune system disorders in men can also cause infertility. There are many causes and risk factors to female infertility. While there are no proven causes that can be attributed to Polycystic ovary syndrome in female infertility, many researchers believe that it may be caused due to genetic influence, with PCOS running in the family. Many researchers are of the opinion that those genes that control insulin and sex hormone production and genes that control a person’s weight may cause PCOS. Lifestyle factors and stress are also considered to be contributing factors. Disorders in the fallopian tube or uterus occur as a result of scar tissue ensuing from endometriosis or any gynecological surgery such as bowel surgery, cesarean, ruptured appendix etc and thereby cause infertility. Infection such as Chlamydia can also cause disorders in the fallopian tube and uterus. An unusually shaped uterus can also cause infertility among women. Endometriosis is a condition where the tissue that lines the inside of the uterus grows outside the uterus and attaches itself to other organs in the abdominal cavity such as the fallopian tube and the ovaries. During the menstrual cycle the blood that is shed into the abdominal cavity has no place to go, thereby causing pools of blood resulting in inflammation and scar tissue. This in turn results in infertility. While the exact reasons for endometriosis are unknown, there are two theories that suggest probable causes. The first theory suggests that during menstruation, some menstrual tissue backs up through the fallopian tube into the abdomen where it implants and grows. The second theory suggests that it is a genetic birth abnormality in which the endometrial cells develop outside the uterus during the development of the fetus. Obesity is a very prominent risk factor that increases the likelihood of infertility. Obesity causes irregular menstrual cycles, increases the risk of miscarriage and decreases the success of fertility treatments. Many procedures are employed in order to treat male infertility. Sperm Aspiration is a technique that is used for men in whom transportation or motility of the sperm is not possible due to problems in the ductal system or when it cannot be surgically constructed. This procedure involves a microsurgery to collect the sperm from the sperm reservoirs within the genital tract. Another therapy called the antioxidant therapy is utilized to educe the levels of reactive oxygen species present in the reproductive tract. Treatment is done using scavengers of these oxygen species as they will protect the sperm from oxidative damage. Assisted reproductive technologies are also utilized in the treatment of male infertility. Intrauterine insemination is a technique wherein a washed pellet of ejaculated sperm is paced within the female uterus beyond the cervical barrier. This technique is used when the sperm count and quality is low (Tanagho & McAninch, 2004). In Vitro Fertilization is a technique that is used to ensure that the sperm reaches the egg without any obstacles in the female reproductive tract. It involves the controlled ovarian stimulation and ultrasound-guided transvaginal egg retrieval from the ovaries before normal ovulation. The eggs retrieved are then fertilized in Petri dishes with 500,000 to 5 million motile sperm. This technique is used in cases where there are severe forms of male infertility. Treatment The treatment for PCOS in women includes the prescription of insulin reducing medication called Glucophage, dietary changes wherein a low glycemic diet is prescribed to the patient and surgery option known as ovarian drilling. Ovarian drilling is done during laparoscopy and is a procedure where a laser fibre or electrosurgical needle punctures the ovary about four to ten times. This puncturing of the ovary results in the dramatic lowering of the male hormones within days thereby increasing the chances of fertilization. The treatment of endometriosis includes hormonal therapy which aims to temper oestrogen levels. Laparoscopic surgery also reduces endometriosis to a great extent. Nutritional therapy is also given to ensure balance of diet and provide the ability for women to handle the difficulties that come alongside endometriosis. References Azziz, R (2007). The Polycystic Ovary Syndrome: Current Concepts on Pathogenesis and Clinical Care. Springer, 2007. Fertility and Women’s Health Center of Louisiana (2009). What is Infertility. Fertility Answers Website. Retrieved October 5, 2009. http://www.fwhcla.com/What_Is_Infertility.htm Williams, L & Wilkins (2008). Professional Guide to Diseases. Lippincott Williams & Wilkins, 2008. Eden, J (2005). Polycystic ovary syndrome: a woman's guide to identifying and managing PCOS. Allen & Unwin, 2005. Elsheikh, M & Murphy, C (2008). Polycystic Ovary Syndrome. Oxford University Press, 2008. Gliksman, M I & DiGeronimo, T F (2004). The complete idiot's guide to pregnancy and childbirth. Alpha Books, 2004. Tanagho, E A & McAninch, J W (2004). Smith's general urology. McGraw-Hill Professional, 2004. McPhee, S J, Tierney, L M & Papadakis, M A (2007). Current medical diagnosis and treatment. McGraw-Hill Professional, 2007. Kirschmann, J D & Nutrition Search, Inc (2006). Nutrition Almanac. McGraw-Hill Professional, 2006. McPhee, S J & Ganong, W F (2006). Pathophysiology of disease: an introduction to clinical medicine. McGraw-Hill Professional, 2006. EMedicine Health (2009). Diarrhea Causes. EMedicine Health Website. Retrieved October 5, 2009. http://www.emedicinehealth.com/diarrhea/page2_em.htm#Diarrhea%20Causes Bowen, R (2006). Pathophysiology of Diarrhea. Colorado State University. Retrieved October 5, 2009. http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/smallgut/diarrhea.html Sud, S (2009). Endometriosis. McGill University Student Projects. Retrieved October 5, 2009. http://www.obgyn.net/medical.asp?page=/english/pubs/features/mcgill-student-projects/endometriosis Makar, R S & Toth, T L (2002). The Evaluation of Infertility. American journal of clinical pathology 117. p 95 -103 Read More