Test 3 Flashcards
in the GI system, what is the breakdown of food and fluids facilitated by?
general
enzyme
majority of molecular absorption into cells occurs where?
general
small intestine
what are the 5 roles of the GI system?
- mechanical processing and movement
- secretion
- digestion
- absorption of nutrients
- elimination
what are the accessory organs of the GI system?
- salivary glands
- liver
- gallbladder
- pancreas
the pancreas produces and secretes what two things?
general
enzymes
bicarbonate - neutralize stomach contents
identify and describe the layers of the GI system from innermost to outermost
- innermost - mucosa - epithelial cells in direct contact with the lumen
- submucosa - connective tissue containing blood vessels, lymph vessels and nerves
- muscularis - smooth muscle responsible for movement and motility
- outermost - serosa - connective tissue that provides anchorage of GI structures
what layer of the GI system contains the lamina propria?
mucosa
what layer of the GI system contains the peritoneum?
serosa
what are the 5 main GI hormones?
- gastrin
- cck - cholecystokinin
- secretin
- gip - gastric inhibitory peptide
- ghrelin
describe gastrin:
* secreted by
* secretion trigger
* what it causes
- secreted by mucosal cells in stomach
- secreted in response to stomach distrention or partially digested substances
- causes increased gastric motility and relaxation of pyloric and ileocecal sphincters (promote stomach emptying)
describe CCK:
* secreted by
* secretion trigger
* what it causes
- secreted by jejunum
- secreted in response to fat
- causes contraction of gallbladder and pancreatic secretions
describe secretin:
* what it causes
- neutralizes gastric secretions
describe GIP:
* secreted by
* secretion trigger
- secreted by upper portion of small intestine
- secreted in response to fat in chyme and carbohydrates
describe ghrelin:
* secreted by
* secretion trigger
* what it is counteracted by
- secreted by stomach
- increases appetite, stimulates GH secretion, produces weight gain
- counteracted by leptin
what are the 3 physiological characteristics of movement through the GI system?
- peristalsis - progressive movement that propels material forwards
- segmental contractions - to keep contents constantly moving and facilitate mechanical breakdown
- sphincters - rings that separate sections to promote one way movement
identify and describe the defense mechanisms of the GI system
- mucous - move pathogens and prevent direct contact with epithelial layers
- muscular layer and peristalsis - move items down and prevent pathogens from stopping and invading
- stomach acidity - antimicrobial effects to prevent tract colonization
- GI bile - create a hostile environment
- microbiome - add a protective layer, compete for nutrient resources, produce helpful components (i.e. vit K - coagulation)
- GALT - adaptive response
define dysphagia
difficulty swallowing
define gastritis
inflammation of the stomach lining
define gastroenteritis
inflammation along the GI tract
define enteritis
inflammation of the colon and small intestine
define enterocolitis
inflammation of the colon and small intestine
define colitis
inflammation fo the colon
define hemmorhagic colitis
bloody diarrhea
describe constipation by:
* definition
* causes
* complications
* preventative things
- definition: small, infrequent, or difficult bowel movments, less than 3 times a week
- causes: low fiber, lack of exercise, aging (slowed peristalsis), motility impacting conditions (diverticulitis, obstruction)
- complication: fecal impaction
- preventative thing: cellulose
identify the 4 types of diarrhea
- osmotic
- secretory
- inflammatory/exudative
- motility related
describe osmotic diarrhea
diarrhea when nutrients are inadequately or poorly absorbed
describe secretory diarrhea
diarrhea caused by toxins that stimulate intestinal fluid secretion and impair absorptions
* can lose 1L or more a day
* i.e. cholera
describe inflammatory or exudative diarrhea
diarrhea caused by inflammation of the mucosal lining
* pus like formation can cause white flakes/patches
describe motility related diarrhea
rapid movement of food through tract - decreased transit time of chyme with absorptive surfaces
define dysentery
presence of blood in loose or liquid stools
what are some means of diagnosis, treatment, and prevention of GI pathologies?
- diagnosis: S&S assesment, imaging, fecal samples
- treatment: alleviate symptoms, oral rehydration therapy
- prevention: eliminate aggravators, proper health and hygiene, sanitation and food handling
what function do antacids have in treating GI pathologies?
reduce excessie acidity
what function do antiemetics have in treating GI pathologies?
relieve vomiting from drugs, motion sickness, or other therapy
what function do laxatives/enemas have in treating GI pathologies?
facilitate bowel movement to treat acute constipation
what function do antidiarrheals have in treating GI pathologies?
reduce peristaltic activity (motility) and relieve cramps
what function do coating agents have in treating GI pathologies?
enhance gastric mucosal barrier against irritants such as NSAIDs
what function do anticholinergic drugs have in treating GI pathologies?
reduce pns activity, reduced secretions and motility
what function do histamine blockers have in treating GI pathologies?
useful in gastric reflux
what function do proton pump inhibitors have in treating GI pathologies?
reduce gastric secretion
describe gastric ulcers by:
* definition
* common sites
* potential causes
* variabiltiy (traits that can be variable)
- definition: lesions in the mucosa
- common sites: stomach, duodenum, esophagus
- causes: stress, foods, meds, H. pylori
- variable traits: number, size, location, severity, causes
severity of a peptic/gastric ulcer can vary based on what?
size and depth
a true ulcer is a lesion into what layer of the GI lining?
submucosa
a pentrating ulcer goes into what layer of the GI lining? what can possibly occur with this type of ulcer?
- into the serosa
- can cause pain and bleeding - indicative when blood in stool
describe H. pylori including:
* gram state: + or -
* motility
* spore forming?
* transmission
* other implications
- gram negative
- motile via multiple polar flagella
- non spore forming
- transmitted via fecal-oral or oral-oral
- also implicated in stomach cancer and gastritis
what are some things that being H pylori positive increases risk of?
- gastric cancer
- MALT lymphoma
- gastric ulcers
- duodenal ulcers
- functional dyspepsia (indigestion)
describe the pathogenesis of H. pylori
- enabled by urease : neutralizes stomach pH
- adheres to gastric epithelial cells
- LPS and antigens stimulate immune response and inflammation
- slowed ulcer healing
- high recurrence rate
what are the 4 major virulence factors of peptic/gastric ulcers?
- LPS
- TFSS/T4SS
- Vac A
- Cag A
describe TFSS/T4SS
GI system
- secretion system
- allows pathogen to secrete virulence factors into host
- decreases host function and may induce apoptosis (contribute to erosion)
describe Vac A
GI system
- pore forming cytotoxin
- targets mitochondria
- reduces membrane potential and compromises ATP synthesis
- cytochrome c leakage - caspase activation - proapoptotic
describe Cag A
GI system
- activate of MMP that can facilitate erosion
- alter cell-cell and cell-basement leakage
- e-cadherin or beta-catenine disruption
what are some clinical manifestations of peptic and gastric ulcers?
- localized abdominal pain and burning
- nausea - vomiting and loss of apetite
- sometimes bleeding
what are some potential complications of peptic/gastric ulcers?
- hemorrhages: via erosion of blood vessels
- perforation: complete erosion that allows chyme to enter peritoneal cavity
- obstructon: via scar tissue formation (more likely in duodenum and esophagus)
what is GERD (gastroesophageal reflux disease)?
periodic reflux of gastric contents into the distal esophagus
what does the severity of GERD depend on? what can GERD cause?
- severity depends on LES competense, frequency, and amount of acid
- may cause erosion and inflammation
what are the clinical manifestations of GERD and some aggravating factors?
- manifestations - heartburn, chest pain, dysphagia
- aggravating factors - caffiene, spicy food, fatty food, alcohol, smoking, some meds
since some clinical manifestations of GERD include heartburn and chest pain it is often confused for what?
angina
what is GERD often seen in conjunction with?
hiatal hernia
what is a hiatal hernia?
when the uppermost portion of the stomach protrudes into the thoracic cavity through the hiatus (opening in the diaphragm)
what are some potential causes of a hiatal hernia?
- incompetent sphincter
- diaphragm tone
- abdominal pressure - full stomach, obesity, pregnancy
what are some risks/complications associated with hiatal hernias?
perforation/rupture into thoracic cavity due to:
* contents (bacteria and food) within the sac causing aggravation
* feedforward mechanism of inflammation causing pressure on the sac
what are some things that impact the tone of the LES?
- delayed gastric emptying
- increased transient LES relaxations
- loss of secondary peristalsis
- increased acidity
what are some complication risks with esophageal reflux disease (6)?
- stricture - stiffness caused by scar tissue formation
- pain
- obstruction - food and inflammation preventing passage of food from the esophagus to stomach
- perforation
- hemorrhage - dependent on depth may be internal or external
- pneumonia - contents rise high enough that they go down the trachea into the lungs
what is barrett’s esophagus?
change in esophageal cell morphology from squamous to columnar epithelieum
how can barrett’s esophagus be diagnosed? can it be reversed?
- diagnosis - via endoscope
- reversible - yes with removal of irritant
what type of cancer does barrett’s esophagus increase the risk of?
adenocarcinoma (glandular epithelial cells)
what are the 2 diseases within IBD?
- ulcerative colitis (UC)
- crohn’s disease
define IBD by:
* typical diagnosis time
* disease course (general)
* cause
- diagnosis time - childhood
- disease course - variable periods of exacerbation and remission
- cause - idiopathic (unknown because multifactoral)
compare/contrast IBD and food-borne infectious GI issues in terms of diagnosis and treatment
IBD:
* fecal culture - negative
* treatment - cant use antibiotics
infectious:
* fecal culture - positive
* treatment - can use antibiotics
ulcerative colitis is a chronic inflammatory disease of the mucosa of the ____ and ____.
- rectum
- colon
( distal GI tract )
in UC inflammation begins at the base of ____ causing damage and invasion with ____. this results in formation of an ____ within crypts and formation of large ____ in the mucosal layer
in UC inflammation begins at the base of intestinal crypts causing damage and invasion with leukocytes. this results in formation of an abcess within crypts and formation of large ulcers in the mucosal layer
in ulcerative colitis coalescence of abscesses results in large ulcerations through the ____.
- epithelia barrier
what are the clinical manifestations of ulcerative colitis?
- severe lower abdominal cramping
- diarrhea
- rectal bleeding
- hallmark - bloody diarrhea
what causes the diarrhea experienced in ulcerative colitis?
- mucosal destruction in colon ->
- decreased ability to absorb water and sodium ->
- excess fluid volume in intestinal contents ->
- excessive fluid loss
ulcerative colitis can be related to ____ which can cause developmental delays in youth
low weight
is ulcerative colitis associated with an increase or decrease in lumenal diameter?
decrease
what are some other names for crohns?
- regional enteritis
- granulomatous colitis
in what areas of the GI tract does crohns normally occur (2)?
- terminal ileum of SI
- ascending colon
what is crohns and what does it involve (4)?
- chronic inflammation of all layers of the intestinal wall
- includes ulcerations, strictures, fibrosis, fistulas
what can crohn’s result in?
blockage and inflammation of lymphatic vessels
what are skip lesions seen in crohn’s
- distribution of affected segments alternating with normal segements of bowel
what are fistulas seen in crohn’s?
- abnormal opening between two structures
- crohns - between the small and large intestine
what are some clinical manifestations of crohns?
- intermittent fever,
- soft or semi-formed stool (may or may not have blood - not as severe as UC when not bloody)
what comorbidities may be seen in people with crohns?
- anorexia
- weight loss
- anemia
- fatigue (malabsorption and malnutrition)
- delayed growth and sexual maturation in kids
what are the main components of crohns disease (3)?
very broad
- genomic
- immune
- microbiome
what are some potential triggering factors in crohns?
- exercise
- smoking
- infection
- envrionment
- hygiene
- diet
- drugs
- stress
what are some treatments for ulcerative colitis and crohn’s (6)?
- anti-inflammatory meds
- anti-motility agents (symptomatic relief)
- immunotherapeutic agents
- antimicrobials
- nutritional supplements
- surgical resection (extreme)
compare and contrast crohns and ulcerative colitis by:
* region affected
* distribution of lesions
* stool
* granuloma?
* fistula, fissure, abscess?
* stricture, obstruction?
* malabsorption, malnutrition?
what is the etiology of irritable bowel syndrome?
unclear or variable
what are some clinical manifestations of IBS
- lower abdominal pain
- diarrhea/constipation - abnormal bowel movements
- gas, bloating, nausea
- fecal urgency or incomplete evacuation
IBS pathogensis is associated with different types. describe abnormal gastrointestinal motility and secretion
- diarrhea type: rapid transit time of feces throguh bowel
- constipation/bloating type: delayed transit time of feces through bowel
IBS pathogensis is associated with different types. describe visceral hypersensitivity
immune system, involvement of activated mast cells and T lymphocytes
IBS pathogensis is associated with different types. describe post-infectious
low-grade inflammation associated with bacterial enteritis
IBS pathogensis is associated with different types. describe overgrowth of flora
- causes constipation and bloating due to methane gas production
- imbalance in microbial growth - i.e. with long term use of antibiotics
IBS pathogensis is associated with different types. describe food allergy or intolerance
certain food antigens may activate a hypersensitive immune response in the mucosa
IBS pathogensis is associated with different types. describe pyschosocial factors
emotional stress, affecting the nervous system and neuroendocrine pathway
what are some treatment techniques for IBS
- laxatives
- fiber supplements
- antidiarrheal medication
- antidepressants
- analgesics for pain
- antipasmodic medication
- serotonin balancing medications
define diverticulum
outpouching of the mucosa through the musculature
define diverticulosis
symptomatic diverticular disease
define diverticulitis
inflammation usually due to diverticulitis stasis
what does diverticular disease result from?
- low dietary fiber intake
what does diverticular disease result in?
high intraluminal pressure
what is diverticular disease associated with symptomatically?
- cramping
- tenderness
- nausea
- vomiting
- slight fever
- elevated white blood cell count