5 - Upper GI Problems Flashcards
Define nutrition
process by which food and nutrients affect cellular function, growth and development, + health and disease.
Define elimination
elimination: excretion of waste products primarily through the urinary + GI system
Identify the 4 histological layers of the GI tract (from inside –> outside)
- mucosa
- submucosa
- muscularis externa
- serosa
Describe the mucosa of the GI tract in terms of its composition and function
epithelial layer
produces mucus + some digestive enzymes + absorbs nutrients
Describe the submucosa of the GI tract in terms of its composition + what it contains
CT layer
contains nerves, blood, + lymph vessels
Describe the muscularis externa of the GI tract in terms of its structure and function
sm muscle layer involved in the mixing + turning of ingested material
Describe the serosa of the GI tract in terms of its structure + function
outer CT layer; forms the visceral peritoneum
wraps around the bowel wall + forms a flap called the mesentary which allows the bowel to be attached to the abdomnal cavity where it attaches to its blood + nerve supply
Compare nausea + vomiting
nausea is a sensation: a feeling of discomfort w a conscious desire to vomit.
vomiting is a reflex: the forceful ejection of emesis from the upper GI tract
Which part of our body controls n + v?
The emetic center of the medulla
Identify the 4 parts of our body in which the emetic center receives input from
CTZ
Vestibular System
Vagal + Enteric Nervous System
CNS
What is the function of the CTZ (chemoreceptor trigger zone)? Where is it located? What does it have receptors for?
- lies outside the blood brain barrier
- senses toxins in the blood and will trigger reflex sensory receptors
- has receptors for dopamine, serotonin, opiates, acetylcholine, substance P
What is the function of the vestibular system?
- sends info to the brain via cranial nerve VIII (8)
- motion sickness
- rich in muscarinic receptors [which is blocked by motion sickness drugs]
What is the function of the vagal + enteric nervous system? What will trigger this pathway? How can we help N + V in this pathway?
- inputs information regarding the state of the GI system via cranial nerve 10
- something that irritates the gut will trigger the pathway; irritation of the GI mucosa by chemotherapy, radiation, distention, or acute infectious gastroenteritis activates the serotonin receptors
- help N + V by blocking serotonin receptors
What is the function of the CNS in inputting N + V receptors to the medulla?
- mediates vomiting that arises from psychiatric disorders and stress from higher brain cells; “psychological vomiting”
- unpleasant, sights, smells
Which nerve / pathway is stimulated to result in vomiting in the digestive tract?
vagus nerve / serotonin-based pathway is stimulated
What are the causes of vomiting that stem from the digestive tract?
- gastritis (inflammation of the gastric wall)
- gastroenteritis + food poisoning
- GERD
- pyloric stenosis, bowel obstruction, peritonitis, ileus
- overeating
- food allergies
- cholecystitis
- pancreatitis
- appendicitis
- hepatitis
What are the causes of vomiting that stem from the sensory system and brain?
- motion sickness
- concussions
- cerebral hemorrhage
- migraine
- brain tumors + ICP
Which 4 drug classes produce N + V as a side effect?
- chemotherapy
- alcohol
- opioids
- SSRIs
Why is aspiration a potential complication of vomiting?
Vomiting can lead to the passage of gastric contents into airways
Why are mallory-weiss tears (tears in esophageal lining) a potential complication of vomiting?
Throwing up or dry heaving is a large muscular effort
What is alkaline tide?
loss of Hcl, K+, and increased production of HCO3- by gastric mucosa
Why can prolonged vomiting result in metabolic acidosis?
There are 2 reasons for this:
- physical losses of HCO3- in the vomit
- chemical consumption of HCO3- due to lactic acid production and ketoacidosis
What is the MOA of anticholinergic drugs (Ach blockers) as antinausea drugs?
ex - scopolamine (buscopan)
- bind to and block Ach receptors in the inner ear which therefore blocks the transmission of nauseating stimuli to the CTZ + emetic center
- also used for motion sickness via transdermal patch
Provide an example of an anticholinergic drug.
Scopolamine (buscopan)
Describe the MOA of antihistamines (H1 receptor blockers) as antiemetic + antinausea drugs
inhibit Ach by binding to M receptors in the inner ear
prevent cholinergic stimulation therefore preventing N + V
also used for motion sickness, non-prod coughs, allergy symptoms, + sedation
Provide 2 examples of antihistamine drugs
dimenhydrinate (Dramamine, Gravol)
diphenhydramine (Benadryl)
Describe the MOA of serotonin blockers as antinausea and antiemetic drugs
block serotonin receptors in the GI tract, CTZ, and emetic center of the medulla
used for n + v in pts receiving chemo and postoperative n + v
Provide 2 examples of serotonin blockers
dolasetron (Anzemet)
ondansetron (Zofran)
What is the MOA of glucocorticoids as antinausea + antiemetic drugs?
used to treat N + V associated w some chemo drugs
increases antiemetic effect of serotonin blockers like ondansetron
can be combined w
What is the MOA of tetracannabinoids?
- used for n + v associated w chemo + anorexia associated w weight loss in aids pts
- increase appetite
provide an example of a tetracannabinoid
ex - cannabidoil (Sativex)
how can ginger (a herbal product) help treat n + v? what are some potential adverse effects? drug interactions?
help w n + v caused by chemo, morning sickness, motion sickness
s/e’s: anorexia, n + v, skin rxns
drug interactions: increase abs of orla meds, increased bleeding risk w anticoagulants
What is diarrhea?
Having 3+ loose or liquid stools per day; having more stools than normal
What does diarrhea result from?
- excess secretions (ex - enterotoxins)
- malabsorption (leading to bacterial growth)
- inflammation
- exudate (increased bulk of liquid in the GI tract)
- invasion (results in bleeding, dysentery)
- increased osmotic pressure (caused by deficiency in some tpe of digestive enzyme)
Why does diarrhea lead to metabolic acidosis and hyperkalemia?
b/c GI secretions are rich in HCO3- and K+
What are the causes of diarrhea?
- infections –> gastroenteritis
- malabsorption due to:
- -> enzyme deficiencies (celiac, lactose intolerance)
- -> loss of pancreatitis secretions r/t cystic fibrosis or pancreatitis
- -> loss of bile acids (can’t emulsify + digest fat)
- -> structural defects or short bowel syndrome
- inflammatory bowel diseases
- IBS (idiopathic)
- chronic ethanol ingestion
- ischemic bowel disease
- radiation enteropathy following treatment for pelvic + abdominal cancers
What are the 2 potential risks associated w diarrhea?
rapid dehydration + hypovolemic shock
describe the MOA of adsorbent drugs and provide an example
adsorbent drugs are a class of antidiarrheal drugs
coat the walls of the GI tract to calm it, bind to the causative bacteria or toxin + eliminates it thru the stool
ex - bismuth subsalicylate (Pepto Bismol)
ex - activated charcoal
ex - aluminum hydroxide
Describe the side effects of Bismuth subsalicylate (Pepto-Bismol)
- increased bleeding time (so not good for bleeding stomach ulcers)
- constipation
- dark stools
- confusion, twitching
- hearing loss, tennitus
- metallic taste
- blue gums
- toxic to kidneys in high doses