Gastrointestinal - Diarrhea and Constipation Midterm Notes PDF

5 1 GASTROINTESTINAL – Diarrhea and Cons-pa-on Diarrhea Diarrhea is defined as an increase in the frequency, volume, or fluid content of stools. It can be classified as osmo+c or secretory diarrhea, with diffe...

5 1 GASTROINTESTINAL – Diarrhea and Cons-pa-on Diarrhea Diarrhea is defined as an increase in the frequency, volume, or fluid content of stools. It can be classified as osmo+c or secretory diarrhea, with different underlying mechanisms and causes. 1. Most Likely Cause Osmo+c Diarrhea: o Inges@on of poorly absorbed ions or sugars (e.g., lactose intolerance, sorbitol, mannitol). o Celiac disease: Gluten-induced damage to intes@nal villi results in reduced absorp@on. o Bacterial overgrowth: Can result from an@bio@cs that disturb normal gut flora. Secretory Diarrhea: o Bacterial toxins: Infec@ons with enterotoxins from Escherichia coli, Cholera, and Staphylococcus. o Reduced absorp+ve surface due to disease or resec@on of bowel. o Hormone-producing tumors (like VIPoma) that increase intes@nal secre@on. o Drugs and poisons: Certain drugs, like laxa@ves, increase secre@on of water and electrolytes into the intes@nes. 2. Pathophysiology Osmo+c Diarrhea: o Poorly absorbed substances in the lumen create an osmo+c gradient that draws water into the intes@nes. o The volume of stool is usually < 1 L/day and diarrhea improves with fas@ng. Secretory Diarrhea: o Caused by disrup@on of electrolyte transport in epithelial cells, leading to excess water and electrolyte loss. o Associated with large stool volume (>1 L/day) and persists even with fas@ng. o Vibrio cholerae: The cholera toxin increases cyclic AMP (cAMP), which ac@vates ion channels in intes@nal epithelial cells, causing secre@on of Cl⁻ and water into the lumen. 3. Disease Transmission Direct Transmission: o Diarrhea caused by infec+ous agents (like Cholera, Rotavirus, or E. coli) can be transmiNed through contaminated food or water. o Person-to-person transmission can occur in cases of viral gastroenteri@s (like Norovirus). o Diarrhea caused by medica@ons, dietary factors, or chronic diseases (like Celiac disease) is not transmissible. 4. Risk Factors Infec+ous Diarrhea:  2 o Poor sanita+on and hygiene (risk for cholera and rotavirus). o Contaminated food and water: Primary risk for E. coli and cholera. o Children under 5 years are at higher risk for severe diarrhea from Rotavirus. Osmo+c Diarrhea: o Lactose intolerance: Common in people of certain ethnic groups (e.g., African, Asian). o Consump+on of sugar subs+tutes (sorbitol, mannitol) in sugar-free gum or candies. o An+bio+c use: Alters gut flora, leading to osmo@c diarrhea. Secretory Diarrhea: o Infec+on with enterotoxin-producing bacteria (Cholera, E. coli). o Use of laxa+ves and exposure to certain medica@ons or toxins. Cons+pa+on Cons@pa@on is characterized by difficult or infrequent bowel movements, hard stools, and the need for straining during defeca@on. 1. Most Likely Cause Primary (Func+onal) Cons+pa+on: o Func+onal cons+pa+on: Normal stool passage rate, but difficulty with evacua@on. o Slow Transit Cons+pa+on (STC): Reduced colonic mo@lity, causing stool to move slowly through the colon. o Irritable Bowel Syndrome-Cons+pa+on type (IBS-C): Involves chronic cons@pa@on and abdominal pain. Secondary Cons+pa+on: o Dietary: Low-fiber diets and dehydra@on reduce stool bulk. o Medica+ons: Opioids (like morphine), an@cholinergics, and iron supplements slow gut mo@lity. o Neurological Disorders: Condi@ons like mul+ple sclerosis, Parkinson's disease, and spinal cord injuries impair colonic mo@lity. o Structural Abnormali+es: Rectal fissures, hemorrhoids, or rectal strictures obstruct stool passage. 2. Pathophysiology Func+onal Cons+pa+on: o Normal rate of stool movement, but pelvic floor dysfunc+on makes it difficult to evacuate the stool. Slow Transit Cons+pa+on (STC): o Reduced colonic mo+lity delays stool movement through the large intes@ne o This results in prolonged stool contact with colonic mucosa, leading to excessive water absorp+on and hard, dry stools. Opioid-Induced Cons+pa+on: o Opioids ac@vate mu-opioid receptors in the gut, reducing peristalsis and increasing water reabsorp@on, leading to dry, hard stools.  3 Neurological Disorders: o Condi@ons like Parkinson’s disease impair coordina@on of bowel movement, causing slow transit of feces. o Spinal cord injuries interrupt signals that coordinate defeca@on reflexes. 3. Disease Transmission Transmission: o Cons@pa@on is not an infec+ous disease, so it is not transmissible. o However, exposure to opioids or certain medica@ons may induce cons@pa@on. 4. Risk Factors Dietary and Lifestyle Factors: o Low-fiber diet: Reduces stool bulk, slowing bowel transit. o Dehydra+on: Causes stool to harden, making defeca@on difficult. o Lack of exercise: Sedentary lifestyles slow gastrointes@nal mo@lity. Medica+ons: o Use of opioids, iron supplements, and an+cholinergics reduces bowel mo@lity. o Chronic laxa+ve use can cause dependence, reducing the bowel’s natural mo@lity. Neurological Disorders: o Condi@ons like Parkinson’s disease, mul+ple sclerosis, and spinal cord injuries disrupt bowel mo@lity. Structural Issues: o Rectal fissures, rectal prolapse, and strictures cause mechanical obstruc@on. o Pelvic floor dysfunc+on can lead to difficulty in stool expulsion. Summary Table Criteria Diarrhea Cons+pa+on Infec@on (Cholera, Rotavirus), osmo@c Low fiber, dehydra@on, medica@ons, Cause load, bacterial toxins neurological issues Osmo+c: Water drawn into lumen. Slow mo@lity, increased water Pathophysiology Secretory: Cl⁻ secre@on, water follows. reabsorp@on, opioid-induced effects Infec@ous agents like Cholera and Not transmissible, but may be Transmission Rotavirus are transmissible. caused by medica@ons. Poor sanita@on, contaminated Low-fiber diet, dehydra@on, Risk Factors food/water, an@bio@c use. medica@on, neurological disorders. This summary addresses the causa+ve factors, pathophysiology, disease transmission, and risk factors for Diarrhea and Cons+pa+on as outlined in the notes. If you'd like any clarifica@on or more detail on these aspects, let me know!