General GI Flashcards
`steatorrhoea
passage of pale bulky stools that contain fat + indicates fat malabsorption as a result of small bowel, pancreatic disease or cholestatic liver/biliary disease
a feacal marker of intestinal inflammation + tissue damage
feacal cal protein
what does OGD stand for
oesophagogastroduodenoscopy, ‘gastroscopy’
how to investigate the small bowel? given that its so long
balloon-assisted enteroscopy
video (wireless) capsule endoscopy
what are oral white patches associated with
smoking, candida infection, lichen plants, trauma + syphilis
what may cause a smooth sore tongue with loss of filiform papillae?
vit b12 deficiency
what may cause mouth dryness?
anxiety, drugs such as tricyclic anti-Ds, Sjogren’s syndrome + dehydration
whats dysphagia?
difficulty swallowing
achalasia
a motility disorder
muscles of the lower part of the oesophagus fail to relax, preventing food from passing into the stomach
Odynophagia
pain during swallowing particularly with alcohol and hot liquids
suggests oesophagitis due to GORD, infections of the oesophagus to drugs such as slow release potassium or bisphosphonates
Muscle type distribution in the oesophagus
pros 3rd = skeletal –> mixed –> smooth
What phase of swallowing is it when the soft palate closes of the nasopharynx and elevation of the hyoid bone shortens and widens the pharynx?
Phase 2: involuntary
whats the voluntary phase of swallowing?
the 1st phase.
the tongue compresses food against the roof of the mouth + pushes it towards the oropharynx
in swallowing, what phase is it when the constrictor muscles sequentially contact, and what’s it followed by?
phase 3: involuntary
the 2nd part of this phase is the return/depression of the hyoid bone and pharynx
whats the gag reflex?
elevation of the pharynx
caused by irritation of the oesophagus
reflex arc between IX (sensory) and X (motor)
4 functions of saliva
- contains mucus
- amylase
- dissolves
- antibacteria
what type of acini have a small central duct and what do they secrete?
serous acini
water and alpha-amylase
what connects acini to larger striated ducts?
intercalated interlobular ducts
which gland does the facial nerve pass through?
the parotid
which nervous system stimulates salivary secretion?
parasympathetic nervous system
BMR
metabolic rate when a person is at mental + physical rest but not sleeping. at a comfortable temp
fasted at least 12 hrs
functions of the stomach
storage mixing dissolving continuing digestion regulate emptying kill microbes secrete + lubrication
PC HIP pneumonic for stomach cell secretions
Parietal cells secrete HCl and IF
Chief cells secrete pepsinogen
where are chief cells located? (stomach)
F + B + P
which cell type is located just in the fundus and body of the stomach
parietal cells
which stomach cells secrete gastrin?
enteroendocrine cells (G cells) located in the antrum
which cells secrete histamine
ECL cells
what do D cells secrete?
somatostain
mediators of acid secretion
ACh - increases
Gastrin - increases
Histamine - increases
Soamtostain - decreases
what does the vagus nerve secrete (stomach)
ACh
cephalic phase
sight, smell taste and chewing lead to ACh release
ACh (enteric) acts directly on parietal cells
also triggers gastrin + histamine release
what happens in the gastric phase
- gastric distension, presence of peptides and AAs increases HCl secretion (gastrin + histamine release, and somatostatin inhibiton)
- low luminal pH inhibits gastrin directly. also stimulates somatostatin release, indirectly inhibiting parietal cells
intestinal phase
duodenal distension, low luminal pH, hypertonic contents and AA/FA presence lead to CCK and secretin release as well as neural reflexes
what are enterogastrones and what do they lead to?
CCK and secretin are. they increase pancreatic exocrine secretion
what does somatostatin turn off?
the process of forming proton pumps that gastrin, histamine and ACh stimulate via 2nd messengers
what parallels the secretion of HCl?
pepsinogen - its also mediated by ACh
what does pepsin come from?
when pepsinogen is activated in acidic conditions
pepsin also catalyses its own production - +ve feedback loop
function of pepsin?
breaks protein down into peptides
how is pepsin inactivated?
irreversibly by HCO3- in the small intestine
what increases gastric peristaltic waves?
gastrin and gastric distension
what decreases gastric peristaltic waves?
duodenal distension, duodenal fat, osmolarity, decrease pH, increased sympathetic drive
function of the duodenum
mixes stomach contents, bile and pancreatic exocrine secretions
3 important duodenal secretions
mucus (Brunner’s gland), CCK and secretin
what does jejunum absorb?
actively: glucose, AAs, small peptides, vitamins
passive: fructose
what does the ileum absorb?
bile salts, B12
where is calcium actively absorbed?
duo + jej
how is ileum different to jej?
payer’s patches and more mesenteric fat
2 types of motility in small intestine
segmentation
peristalsis
function of large intestine?
to complete absorption of water + few remaining carbs
movement: contraction in the circular muscle
how and where is vitamin b12 absorbed?
in the terminal ileum after pairing with IF
where is folate absorbed?
where is iron absorbed?
folate - jejunum
iron - duodenum
what do bile salts to do fat?
emulsify them into emulsion droplets
what does lipase break down?
breaks down emulsion droplets into free FAs and bile salts, which then combine to form micelles
where are micelles formed into chylomicrons?
in enterocyte cells, for transport in blood - released by exocytosis
what does lipoprotein lipase do?
breaks down triglycerides in chylomicrons into fatty acids and glycerol in the capillaries
what’s CCK and what stimulates it?
cholecystokinin
stimulated in the presence of fat in the duodenum, to release bile from GB and pancreatic enzymes from the pancreas
2 nerve plexuses of the intestine
Meisneer’s - submucosal
Auerbach’s (myenteric)
