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GI System (Cases (Colorectal cancer (dysplasia (low grade: abundant…
GI System
Cases
Peptic Ulcer
mainly in duodenum
also in antrum of stomach
imbalance of protective factors and aggressive factors, leading to damage to mucosa
protective: mucous, HCO3, prostaglandin E2
aggressive factor: HCl, enzymes (pepsin), NSAIDs,
H. pylori
, smoking (impairs blood flow
H pylori
Gram negative non-sporing rod bacteria
causes peptil ulcer in the stomach antrum
lives in the surface mucous layer = does NOT invade epithelium
causes peptic ulcer by:
producing
urease
, which converts urea into CO2 and NH3, increasing pH so making the environment hospitalizable
immune response
(T and B cell activaton) and intense inflammation, leading to release of interleukin from epithelial cells, which recruit and activate neutrophils
increases
gastrin
production => increases acid secretion
produces
phospholipase
which assist in mucous breakdown
produce Cag A gene, wrhich regulates production of vaculating toxin causing epithelial damage
all leads to damage to epithelial, causing leakage of nutrients and sustenance of bacteria
pathological features: :star:
red inflammation of mucosa = gastritis
smooth and clean base
punched out, straight wall
fibrotic contractions causes rugae folds coming out from central ulcer
histological features: :star:
4 layers: dnecrotic base, inflammation, granulation (vascular and fibrotic), fibrosis
thinning of wall at the base of ulcer
loss of muscle cell
treatment:
omeprazole = PPI to treat the gastritis, prevent further acid secretion
combination of antibiotics to kill H pylori
amoxicillin
clarithromycin
metaprozole
complications:
haemorrhage (ulcer hits a blood vessel)
perforation of the wall
penetration into adjacent organ
IBS
Ulcerative Colitis
involves
CD4 TH2
immune response
gross pathology:
reddened inflammed mucosa
broad base ulcers with regenerating epithelium bulging into lumen, forming pseudopolyp
affects mainly rectum, then continue proximally, even reaching terminal ileum
histology:
affects the mucosa only
regenerating epithelium
ulceration leading to inflammation
crypt abscess
= acute inflammatory exudate (abscess) in the crypt => decreased no. of goblet cells
complications:
toxic colon = due to severe inflammation where the mediators have caused neuromuscular dysfunction, with decrease in tone of SMC and loss of peristalsis, bowel dilates
development of dysplasia
haemorrhage
Crohn's disease
involves CD4
TH1
immune response
affects all of GIT, separated by normal mucosa = skip lesions
gross pathology:
serpentine linear ulcers, and normal mucosa intervening, forming a cobblestone appearance
histology:
thickening of wall due to fibrosis, fibrotic contractures causes narrowing of lumen, forming a stricture
transmural inflammation
fissure = deep ulceration and inflammation that extends down into the mesentery
fistula = abnormal communication between 2 adjacent organs
granulomatous formation = contains epitheloid cells, giant cells, amcropahges, lymphocytes but NO necrosis, occured due to Th1
complication: increased risk of carcinoma, fistula
treatment:
aminosalicylic acid = for mild-moderate IBD (anti-I)
glucocorticoid = symptom relief (anti-I)
immunomodulators = inhibit DNA synthesis of immune cells (only for CD)
antibodies = inhibit TNF
antibiotics
Colorectal cancer
2 pathways:
adenoma carcinoma sequence (APC-beta-catenine) = mutation in the APC- beta catenine gene that leads to loss of function of tumour suppressor genes
can change from benign lesion into polyp and as mutation accumulates, growth is less regulated and malignancy develops
mismatch repair gene = mutation in any of the 5 mismatch repair gene that causes microsatellite instability
adenomatous polyp can be:
sessile = raised, flat lesions
serrated = glandular, with a stalk
dysplasia
low grade:
abundant mitosis
high N:C ratio
nuclear pleomorphism
nuclear moulding
decreased goblet cells
nuclear polarity normal
architecture is normal
high grade dysplasia:
architecture is changed
loss of nuclear polarity
carcinoma in situ: dysplastic but no invasion of basement membrane
invasion
left side lesion = causes obstruction
narrowing of lumen
changes in bowel habit
right side lesion = anaemia
larger lumen so dilation
anaemia => dark stools, mainly liquid
desmosplastic stroma
:flag:
fibrovascular tissue that supports the tumour
produced due to cytokines produced by the tumour cells
suppply blood and nutrents
as it is fibrous tissue, can contract and causes thickening of bowel wall and narrowing of lumen, predominant in left side lesion
spread:
via lymph nodes
haematogenous (rare but most severe)
invasion into adjacent structures/organs
via serosal surface into peritoneal cavity
TNM staging system:
Tumour:
Tis = carcinoma in situ
T1 = into submucosa
T2 = into muscularis externa
T3 = into serosa
T4 = into adjacent tissue
Node
N1 = 1-3
N2 = 4 or more
M1 = metastasis
Jaundice
prehepatic = haemolytic or Gilbert's syndrome
increased urobilinogen
increased unconjugated bilirubin
increased AST
normal ALT
reticulocytes
decreased Hb
intracellular acute = hepatitis
increased conjugated bilirubin
increased urine bilirubin
normal serum albumin
very high ALT and AST
may have high GGT and ALP
intracellular chronic = cirrhosis
increased conjugated bilirubin
decreased albumin
high ALT and AST
increased urine bilirubin
increased PT time
no response to vitamin K
decreased plasma cholesterol
extrahepatic cholestasis
increased conjugated bilirubin
very high GGT and ALP
increased urine bilirubin
decreased urine urobilinogen
increased PT time
response to vitamin K
high plasma cholesterol (due to failure to excrete bile)
dark yellow urine = high urine bilirubin
pale stool = low urine urobilinogen
medically unexplained syndrome (e.g. IBS)
no diagnosis found yet
false negative
somatosization
low sensitivity/specificity test
Infectious gastroenteritis
bacteria = Campylobacter jejuni
viral = rotavirus
causes inflammatory diarrhoea
becomes hypokaelemic and metabolic acidotic
antibiotic associated diarrhoea =
Clostridium difficile
complications: :star::
Guillian Barre syndome
reactive arthiritis
bacteremia
IBS
Anatomy
Upper GIT
Oral Cavity
soft palate
covered by palatine apopneurosis
Muscles:
palatoglossus
palatopharyngeus
together, they depress the soft palate to close off the oral cavity
tensor veli palatini = tenses soft palate
levator veli palatini = elevate soft palate
musculus uvula
hard palate
palatine process of maxilla, palatine bone, hamulus of sphenoid bone
mucosa over it
anterior part is rough = rugae to hold fold
posterior part is smooth
muscles of the oral cavity floor
myohyoid
geniohyoid
both can alter the position of the hypoid, and thus pulls the attached larynx
vestibule
opposite upper 2nd molar is the opening of duct of parotid gland
Tongue
extrinsic muscles: :red_flag:
hyoglossus = depress
genioglossus = pull tongue forward
palatoglossus = elevate
styloglossus = pull tongue backward
intrinsic muscles of the tongue:
superior longitudinal
tranverse and vertical
inferior lonigitudinal
changes shape of the tongue
papilla:
circumvalate = just anterior to the terminal sulcus
filiform = more central
fungiform = more lateral
all except filiform have sensory taste buds
in pharyngeal part, there are many lingual tonsils
terminal sulcus = separates anterior (oral) part and posterior (pharyngeal) part
V-shaped, in the middle is foramen caecum
Frenulum = mucosa from base of oral cavity to the inferior side of tongue
at the base on both sides are
sublingual caruncle
beside the frenulum are
deep lingual veins
- visible
Salivary glands
Parotid
covered by a fibrous capsule, prevents expansion
structures that runs in it: :red_flag::
facial nerve
external carotid artery
retromandibular vein
auricotemporal
nerve runs between parotid and the auricle
supplies the parotid fascia, TMJ, skin over temporal area, auricle, external acoustic meatus
when the parotid gland swells and expands, it stretches the fascia and compresses the nerve = causes pain in the regions it innervates
duct pierces over the buccinator muscle, opens opposite the upper 2nd molar teeth into vestibule
secrete serous
Sublingual gland
secrete mucous
have short ducts that directly open into the sublingual fold into the oral cavity
Submandibular gland
secrete mucous + serous
have a very long duct = common site of stone
duct goes from the deep portion and opens into the sublingual caruncle
gland has deep and superficial portion
treatments to salivary stone:
give acidic to increase secretion to push the stone out, painful so give anaesthetic
ultrasound
surgery (invasive)
Pharynx
pharyngeal wall
mucous membrane
pharyngobasilar fascia
muscle: inner levator, outer constrictor
buccopharyngeal fascia
constrictors
superior
middle
inferior => thyropharyngeal and cricopharyngeal
pharyngeal diverticulum
= bulging of the wall in area of muscle weakness (in between thyropharyngeus and cricopharyngeaus)
levators:
stylopharyngeus
palatopharyngeus
salpinopharyngeus
verrucae = infront of epiglottis
piriform fossa = behind epiglottis
Oesophagus
upper sphincter = cricopharyngeal part of inferior constrictor muscle
lower sphincter = formed by right crus of diaphragm
constrictions:
arch of aorta 22cm
left main bronchus 27cm
right crus of diaphragm 38cm
start at C6 (where cricoid cartilage ends)
pierces diaphragm at T10
muscle
upper 1/3 is striated, rest is smooth
Lower GIT
Peritoneum
greater omentum
from the greater curvature of stomach to the bottom, then go back up to attach to transverse colon, then go to posterior wall
goes in front of small intestine
4 layers
(gastrocolic omentum only has 2)
lesser omentum
from the lesser curvature of stomach to the liver
2 parts: hepatogastric and hepatoduodenal
right free margin of lesser omentum forms the epiploic foramen
divided into quadrants and regions
regions:
divided by midclavicular lines vertically and subcostal and transtubercular plane horizontally
greater sac
divided into supracolic and infracolic by the transverse mesocolon
infracolic further divided into left and right by the mesentery of small intestine
supracolic and infracolic communicate via the left and right paracolic gutter
lesser sac
area behind the stomach and liver
give potential space of stomach to expand
left limit formed by splenorenal ligament and gastrosplenic ligament
access to lesser sac is through the omental foramen, cut through transverse mesocolon, gastrocolic omentum, hepatogastric ligament
retroperitoneal structures:
pancreas (except tail)
2+3 duodenum
A+D colon
kidney
stomach
opening:
gastro-oesophageal (cardia)
pyloric orifice
stomach bed:
left kidney
left ureter
spleen
neck, body, tail of pancreas
nerve innervation = T6-T9 sympathetic, referred pain to epigastric region and subcostal
hiatus hernia
formed by the weakening of right crus of diaphragm
GUT
Foregut
lower oesophagus, stomach, to upper 1/2 of descending (2) duodenum (major duodenal papilla)
supplied by celiac trunk
nerve: T6-T9 sympathetic
Midgut
lower 1/2 of 2nd part duodenum to the proximal 2/3 of transverse colon
supplied by superior mesenteric artery
nerve: T10-T12
Hindgut
distal 2/3 of TC to upper rectum
supplied by inferior mesenteric artery
nerve L1-L2
Small intestine
Duodenum
1st = superior
2nd = descending
3rd = transverse
4th = ascending
only 2nd and 3rd are retroperitoneal
C-shaped in the L2 vertebral region, where pancreas lies
major duodenal papilla at the postero-medial aspect of middle of descending duodenum
only the first 2.5cm don't have plicae circulares, rest do
DJ flexure is intraperitoneal
have Brunner's glands = secrete alkaline fluid and mucous
Jejunum
has the most plicae circulares
have long vasa recta with few arterial arcade
wider c.f. ileum
ileum
has least/no plicae circulares
short vasa recta, many arterial arcade
narrower lumen c.f. ileum
have peyer's patches = lymphoid aggregates
more fat in mesentery c.f. jejunum
histological features of small intestine:
villi
microvilli
intestinal glands
Large intestine
histological features:
simple tubular glands
plasma cells
epithelium has lots of absorptive cells (enterocytes) and goblet cells
gross features:
plicae circulares (thickened bands of longitudinal smooth muscle)
haustra pouches
appendices epiploica
appendix (can be in retrocaecal, subcaecal, pelvic, pre-iliac, post-iliac)
only transverse is intraperitoneal = transverse mesocolon
Rectum = transverse rectal folds to short faces and allow air through