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)