Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
22 Cards in this Set
- Front
- Back
|
Gross Anatomy
of the Small Intestine Histology of LI |
-diam of colon is greater than SI
-fibers of external muscular layer are collected into longitudinal bands = teniae coli -bands shorter than the rest of the colon forms outpouchings (haustra) bw the teniae -no villi on mucosa -cecum (right side), ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon, & rectum -no villi & microvilli -simple columnar cells -crypt of liberkuhn: lots of goblet cells secrete mucus -mucosa, submucosa, muscularis externa, serosa |
|
|
Fxns of LI
|
-propulsion & storage of unabsorbed material
-place of residence for flora (bacteria) -absorption of small amts of H2O & electrolytes -defecation |
|
|
Intestinal Flora
|
-LI is home to complex family of bacteria (~500 species)
-play various roles in maintenance of health & prevention of disease -large masses of bacteria are passed in stool -birth: colon is sterile, but intestinal bacteria flora become est in early in life -some est roles of flora include: >ferm. of undigest dietary fiber to generate FA >major nutritional source for the colon & have trophic effects to promote normal mucosal growth & development >high mitotic turnover w/ feces >organic acids responsible for slightly acidic stool pH 5-7, optimal for bacteria |
|
|
Fxn of Intestinal Flora
|
1. create environment that inhospitable to pathogenic microorganisms thereby prevent their colonization
-mxn not understood -simple crowding factor & pH (pathogens favor more alkaline environment) 2. metabolism of various compounds: include bile salts & certain drugs/medications 3. Create VitK, VitB12, Folic acid: -K: essential to blood clotting factors -B12 & folic acid: esp imp for final maturation of erythrocytes |
|
|
Physiology of Diarrhea
|
-infectious, drug-induced, food-related, post-surgical, inflamm, transit-related, & psychologic causes
-all can cause diarrhea by 4 mxns: 1. increased somotic load 2. increased secretion 3. inflammation 4. decreased absorption time |
|
|
Osmotic Diarrhea
|
-unabsorb. water-soluble solutes remain in bowel where they retain water
-occurs w/ sugar intolerance (lactose) -w/ use of poorly absorbed salts (Mg sulfate, Na phosphate -> attract H2O & softens stool -sugar substitutes (hexitols: sorbitol, mannitol) cause osmotic diarrhea as a result of their slow absorp & stim of rapid small-bowel motility (dietetic food, or chewing gum) -fruits can also cause |
|
|
Secretory Diarrhea
|
-occurs when small & large bowel secrete more electrolytes & water than they absor
-secretagogues include bacterial toxins (cholera), enteropathogenic viruses, bile acids & unabsorbed dietary fat -ex: pseudomembranous colitis > hospital pt. taking large dose of antibiotic >Clostridium difficile: small amt reside in colon but C. difficile will take over if lose other good bacteria |
|
|
Exudative Diarrhea
|
-occurs w/ several mucosal disease (regional enteritis, ulcerative colitis, lymphoma, cancer) that cause mucosal inflam, ulceration, or tumefaction
-outpour of plasma, serum proteins, blood & mucus incrases fecel bulk & fluid content -involvement of rectal mucosa may cause urgency & increased stool freq bc inflamed rectum is more sensitive to distention |
|
|
Decreased Absorption Time
|
-occurs when chyme is not in contact w/ an adequate absorptive surface of the GI tract for a long enough time so that too much H2O remains in the feces
-factors that decrease contact time include small- or large-bowel resection, gastric resection, vagotomy, surgical bypass of intestinal segments, & drugs that speed transit by stim intestinal smooth muscle (side effect) |
|
|
Constipation
|
-infrequent passage of stools
-difficulty w/ definition arises from the many indiv. variation of fxns that are normal -normal bowel mvmts vary person to person -sharp rise in constipation after 65 yrs of age -can occur as primary problem or as problem assoc w/ another disease condition |
|
|
Common Causes of Constipation:
|
1. fail to respond to urge to deficate
2. inadequate fiber in diet 3. inadequate fluid intake 4. weak of abdominal muscles 5. inactivity & bed rest 6. pregnancy 7. hemorrhoids |
|
|
Disorders Assoc. w/ Chronic Constipation:
|
neurological diseases:
1. spinal cord injury 2. parkinson's disease 3. multiple sclerosis endocrine disorders 4. hypothyroidism 5. diabetic neuropathy 6. obstructive lesions in GI tract 7. opiates, anticholinergic agents, Ca channel blockers, diuretics, iron supplements & Al antacids |
|
|
Irritable Bowel Syndrome
|
-describe a fxnal GI disorder char by variable combo of chronic & recurrent intestinal symptoms not explained by structural or biochemical abnormalities
-10-20% of western countries have the disorder, most don't seek medical attention |
|
|
Symptoms of IBS
|
-ab pain
-altered bowel fxn -varying complaints of flatuence -bloatedness -nausea & anorexia -constipation or diarrhea -anxiety or depression -hallmark= ab pain relieved by defecation & assoc w/ change in consistency or freq of stools -ab pain intermittent, cramping & in lower ab -doesn't usually occur at night or interfere w/ sleep -could result from dysregulation of intestinal motor & sensory fxn modulated by the CNS -experience increased motility & abnorm intest contraction in response to psychological & physiologic stress |
|
|
Stress related to IBS
|
-role in disease is uncertain
-changes in intestinal activity are normal responses to stress, -women more affect than men -menarche often assoc w/ onset of disorder -women= exacerbation of symptoms during premenstrual cycel (suggest hormonal component) -IBS lacks anatomic or physiologic markers, diagnosis based on signs & symptoms of ab pain or discomfort, bloat, constipation, diarrhea, or an alteration bw both |
|
|
IBS designate 2 related inflammatory intestinal disorders:
|
1. Crohn disease
2. Ulcerative Colitis both show: -inflam of the bowel: activation of inflam cells w/ elaborat inflam mediators cause tissue damage -remission & exacerbation of diahrrhe, fecal urgency & weight loss -acute: intetinal obstruction develop during periods of fulminant disease -lack confirm. evidence of cause agent -both can be accompanied by systemic manifest. |
|
|
Diverticulosis
|
-mucosal layer of colon herniates thru muscularis layer
-char. by presence of diverticula in the colon (usually sigmoid) generally asymp -result from high intraluminal pressure on areas of weakness in bowel wall -diverticula inflammed -pain in LLQ, nausea & vomiting, tenderness in LLQ, slight fever, & elevated WBC count -complications include perforation w/ peritonitis, hermorrhage, & bowel obstruction |
|
|
Appendicitis
|
-inflam of veriform appendix due to obstruct w/ stool or twist of organ or its blood supply
-see pain on LRQ, fever, rebound tenderness -peritonitis occur if swollen appendix bursts before surgery -tx w/ antibiotics become necessary |
|
|
Defecation Reflex
|
-distension of the rectum w/ feces initiates reflex contractions of its musculature & the desire to deficate
-spinal cord mediated parasymp reflex that cause walls of sigmoid colon & rectum to contract & internal anal sphincter (smooth muscle) to relax -as feces forced into anal canal, elect signals reach brain allow us to decide whether external anal sphincter (skeletal muscle) should relax & remain open or be constricted to stop pass of feces temporarily -during defect. muscles of the rectum contract to expel feces -aid process voluntarily by closing glottis & contract diaphragm & ab muscles (valsalva maneuver) -pass out by defect: hear rate declines, BP falls, no O2 to brain |
|
|
Gastrointestinal Immunology
|
-intestinal epith defends non-spefically against invasion of having tight jxn bw cells
-MALT (muscosa-assoc-lymph-tissue) & peyers patches located w/in GI tract wall at certain locations -greater omentum, lesser omentum & mesentery contan large collect. of lymph nodes should pathogens breach the intestinal epith & MALT |
|
|
GI Tract Bleeding
|
-evidence of blood appear in vomit or feces
-result from disease or trauma to GI structures (peptic ulcers), blood vessel abnorm. (esophageal varices, hemorrhoids) or disorders in blood clotting -blood in stomach usually irritating & cause vomitting -hematemesis refers to blood in vomit -may be bright red or have "coffee-ground" appearance bc of action of digestive enzymes (from pancreas) |
|
|
Bright Red Blood
Tarry Stool Occult |
-indicate bleed from lower bowel
-when coats stool it is often result of bleed hemorrhoids -melena "black", pasage of black & tarry stools -char. odor that is not easily forgotten -indication source of bleed is above level of ileocecal valve -hidden, blood only detect by chem means (gastritis, peptic ulcer, or lesions of intestine) |
