GI system: week 2 (prep material) Flashcards
what’s the difference between an voluntary and involuntary process when referring to the GI system
A voluntary GI process is something that you can decide on (ex. Chewing and swallowing food is an example of voluntary, digestion is involuntary)
what are the 4 layers of the digestive tract from inside to outside
Mucosa
submucosa
muscularis
serosa
what does the mucosal layer of the digestive tract do
it is an epithelial layer that produces mucous, digestive enzymes, and absorbs nutrients
which layer of the digestive tract would cause a change in food absorption if damaged?
mucosa
what is the submucosa and what does it contain?
it is connective tissue containing nerves, blood and lymph vessels
what does the muscular of the digestive tract do?
it is a smooth muscle layer that preforms paristalsis which moves food through Gi tract
what does the serosa do?
it is the outer connective tissue layer that forms the visceral peritoneum
why would it be bad if there was an issue with the serosa?
because the peritoneum is large so issues with it will be wide spread
what are the four gastric glands and what do they produce
Mucous neck cell: basically forms the mucosal layer of the stomach, protects the stomach from its own digestive enzymes
chief cell: pepsinogen
parietal cell: HCL
Endocrine cell: histamine
why are mucous cells so important?
they protect the stomach from its own digestive enzymes so that it doesn’t cause a gastric ulcer
what does the villi mucousa do?
it increases the surface area of the small intestine to maximise absorption
what do the crypts do in the large intestine?
they aide in reabsorption of fluid and electrolytes, if there is an issue with these it will cause F&E imbalances
where is most alchohol absorbed
in the small intestine (jejunum)
which neurons control swallowing
skeletal motor neurons
what are the three major symptoms associated with GI disorders
anorexia
nausea
vomiting
why is it important to know what is triggering vomiting
it helps us know what antiemetic to use because they trigger different things
define nausea
subjective feeling of discomfort in the epigastrium
which receptors does the vestibular system use (nausea and vomiting brain mechanisms)
Muscarinic receptors
which receptors does the enteric and vagus nervous system use to cause nausea and vomiting
serotonin receptors
which part of the brain will cause commixing from stress or strong emotions
the CNS
which receptors does the CTZ use?
dopamine, serotonin, opiate, acetylcholine
what are 3 complications that can occur with constant vomiting
- aspiration: stomach contents enter respiratory tract
- Mallory weiss tear: tear in mucosal lining of esophagus
- fluid and electrolyte imbalance: metabolic alkalosis
why would prolonged vomiting cause metabolic acidosis
- physical loss of bicarb (basic)
- forceful vomiting produces lactic acid from the effort, which consumes bicarb
- ketoacidosis from body trying to find energy from fat because you can’t consume glucose if you’re vomiting
what is the main structure that causes GERD
the lower oesophageal sphincter (it tightens during normal digestion, GERD is abnormal relaxation, and the stomach contents of back up into esophagus)
what is pyrosis
heartburn
when would pyrosis occur
it would typically occur 30-60 minutes after a meal, worse when bending at the waist
define regurgitation
effortless return of gastric contents, often described as hot butter r sour liquor
what is esophageal stricture?
narrowing of esophagus caused by scar tissue formation which can lead to dysphagia (as a response to ongoing inflammation)
what is Barrett’s esophagus and why is it a significant compliation of GERD
long term inflammation can cause change in cell structure of esophagus to resemble stomach/intesting (stratified squamous turns into simple columnar epithelium)
only 10% of patients will develop cancer
what is a hiatal hernia
portion of stomach pushing into the esophagus through an opening in the diaphragm
what would symptoms look like in a patient with hatial hernia
symptoms will be similar to GERD and often occur when supine, after a large meal, and with smoking/alcohol
what are 2 contributing factors that could lead to a hiatal hernia
- weakening of muscles around the diaphragm around esophogastric opening
- increase in intra abdominal pressure (ex. obesity, pregnancy, heavy lifting)
how would symptoms of oesophageal cancer progress
- starts off asymptomatic
- you would notice dysphagia with meat, then soft food, then liquids
- then neck pain
- sore throat
- weight loss
what is a complication of esophageal cancer
bleeding as tumour erodes the mucosal lining of esophagus
why can GERD cause respiratory symptoms
if you aspirate stomach contents (which is very possible) that is BAD
Why would oesophageal cancer cause dysphagia
because tumour restricts esophagus which makes food harder to get down
what is PUD
Peptic Ulcer Disease occurs when lesions are caused by exposure of the stomach mucose to HCL acid-pepsin secretions (which are used to break down food)
what are the two most common causes for PUD
H. pylori infection and NSAID use
what are some preventative risk factors for PUD
diet (lack of high fibre foods and vitamin A)
smoking
alcohol
stress
what do prostaglandins do
they promote secretion of bicarb and protective mucous, suppress secretion of gastric acid so it doesn’t go all crazy, and it maintains a submucosal blood flow via vasodilation
why would NSAIDS cause PUD
because they suppress prostaglandins which causes a decrease in mucous production, increased gastric acid and vasoconstriction
how deep is a chronic ulcer
it would go al the way down to the serosa (deepest layer from stomach to abdomen)
what’s the difference in symptoms of a gastric ulcer vs. a duodenal ulcer
gastric will have gaseous pain in the epigastric area which occurs 1-2 hours after eating
duodenal will have cramp like pain in midepigastric 2-4 hours after eating
where would pain be located in a gastric ulcer
in the epigastric area
where would pain be located in a duodenal ulcer
midepigastric of back pain
what is hematemesis
blood in vomit
what is occult blood
small amount of blood in stool, only detected when stool is sent for testing
how could PUD cause peritonitis
If the ulcer perforates and gastric contends enter peritoneal cavity (life threatening because its a sterile area, may cause sepsis)
how would PUD cause emesis
if there is a gastric outlet obstruction (ongoing inflammation can obstruct a gastric outlet which means things won’t go down as easy)
what are the 3 major complications of PUD
haemorrhage, perforation, gastric outlet obstruction
what are 3 common causes of diarrhea
- decreased fluid absorption
- increased fluid secretion
- mobility disturbances
how would mucosal damage cause diarreha
it can decrease fluid absorption which in turn will cause water to stay in digestive tract so stool is not properly formed
why would someone experiencing diarrhoea also experience kussmauls respirations (heavy breathing)
prolonged diarrhoea will result in loss of bicarbonate which will cause metabolic acidosis
your body will try and compensate by breathing faster and deeper to get rid of acidic CO2
why would someone with diarrhoea experience cardiac arrhythmias
because they are likely hypokalemic from losing potassium in stool
what’s the difference between melena and frank rectal bleeding
melena is black stool and indicates and issue with the upper GI
frank rectal bleeding will be bright red and indicate an issue in the lower GI tract
what are some risk factors for constipation (just broad categories)
- diet
- medications
- metabolic and muscular disorders
- structural and functional abnormalities
- physiologic reasons
what happens to the appendix to cause it to become inflamed
obstruction (by fecalith/hard piece of feces) or twisted bowel
what causes pain in appendicitis
obstruction causes pressure within appendix which leads to schema and necrosis which will cause pain `
why is an inflamed appendix so dangerous
because it can rupture into the peritoneum which is life threatening
what is the mcburney point
area where the appendix is located in the right lower quadrant
what are some indicators of appendicitis
anorexia, N/V, rebound tenderness, persistent and continuous pain
What is peritonitis
inflammation of peritoneal membranes from chemical irritation or bacterial infection
what is gastroenteritis
inflamation of the mucosa of the stomach and small intestine due to an infection (the stomach flu)
what are the 2 types of IBD
Crohn’s disease and Ulcerative colitis (both chronic and autoimmune)
what’s the difference between crohns and ulcerative colitis
crohns: affects ileum and any other part of the GI tract (can skip around) , deep
ulcerative colitis: more superficial to mucosa and submucosa, affects rectum and up
how can a patient with an intestinal obstruction become hypotensive
swelling will increase pressure on fluid wall, fluid will exit the CV system and enter the intestine which will cause low circulating fluid = hypotenstion
which IBD is more likely to cause wight loss
Crohns
what are the two types of intestinal obstuction
mechanical (something physical is blocking)
nontechnical: occupes from a numerological impairment or peristalsis aint working (often called paralytic ileus)
what’s the difference in symptoms between an obstruction in the small bowel vs. large bowel
small bowel will have rapid onset of symptoms, it will be crampy and usually involves vomiting since its so high up in the tract
large bowel will include low grade cramping with significant abdominal distention and no BM (minimal N/V because food has to accumulate farther
where is the most common place for colorectal cancer to occur
in the colon within reach of sigmoidoscope
