Foregut + Midgut Flashcards
accessory digestive organs and their collective general function
Pancreas.
Gallbladder.
Liver.
Fxn: assist in digestion of food
main digestive organs and their functions
Esophagus (distal 1/3)
Stomach.
Intestines.
Fxn: Ingestion Propulsion mechanical digestion chemical digestion absorption defecation
secondary retroperitoneal organs
Originate in peritoneal space, then migrate to retroperitoneal space
Pancreas
Part of duodenum
Ascending/descending colon
primary retroperitoneal organs
kidneys
adrenal glands
ascites
Accumulation of protein-containing fluid within the abdomen.
Lose appetite, feel SOB, uncomfortable.
Tx: low sodium diet, diuretics
Causes: liver disease, cancer, heart failure, kidney failure, pancreatitis, tuberculosis
foregut
distal 1/3 of esophagus, 1.5 parts of duodenum, liver, gallbladder, pancreas, spleen
blood supply: celiac trunk
midgut
2.5 parts of duodenum, jejunum, ileum, cecum, appendix, ascending colon, proximal 2/3 transverse colon
blood supply: superior mesenteric artery
hindgut
Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum, upper 2/3 anal canal
blood supply: inferior mesenteric artery
esophagus passes thru diaphgragm at
T10
functions of esophagus
Secrete mucus.
Peristalsis
esophagus extends from _________ to _________
esophagus extends from pharynx to stomach
begins at level of the cricoid
GERD (general, symptoms, causes, risks)
Occurs when stomach acid flows back into esophagus.
Symptoms: heartburn, chest pain, difficulty swallowing, regurgitation of food, lump in throat
Causes: sphincter (LES) relaxes abnormal or weakens
Risks: obesity, hiatal hernial, pregnancy, scleroderma, delayed stomach emptying
complications of GERD
Esophageal ulcer.
Esophageal stricture.
Precancerous changes (Barrett’s esophagus)
functions of stomach
Temporary storage (2-4 hours). Mixing. Acidic pH. Mechanical/chemical digestion. Some nutrient absorption (water, electrolytes, alcohol, NSAIDs)
peptic ulcer disease (general, sx, cause)
Open sores that develop on inside of stomach lining (gastric) and upper portion of small intestine (duodenal).
Sx: stomach pain
Cause: H.pylori infection, long term use of aspirin/NSAIDs
stress/spicy foods do NOT cause ulcers, but do exacerbate them
hiatal hernia
Occurs when upper stomach bulges thru diaphragm (weakened).
Causes: age, injury, congenitally large hiatus, pressure from coughing/straining/lifting
widest part of small intestine
duodenum
location where duodenum becomes jejunum
L2
4 parts of duodenum
1) superior
2) descending
3) transverse
4) ascending
spleen functions
Early hematopoesis.
Mechanical filtration of senescent erythrocytes.
Infection control.
NO role in digestion, but is still intraperitoneal.
splenomegaly
Enlargement of spleen.
From disease like portal hypertension or infection
Cannot palpate normally, but can if enlarged.
ligament of Treitz
Suspensory ligament of duodenum.
2 parts
1. passes from R crus of diaphragm to CT surrounding coeliac a.
2. (muscular part) descends from CT to duodenum
^2nd pt actually suspends the duodenojejunal fixture
landmarks/directions associated with ligament of Treitz
Above: upper GI
Below: lower GI (usually w/ respect to bleeding)
Diagnosis of intestinal malrotation/ partial rotation.
accessory duct of pancreas
Duct of Santorini.
Empties directly into duodenum (does NOT combine with common bile duct).
main pancreatic duct
Duct of Wirsung.
Combines with common bile duct in ampulla of Vater.
ampulla of Vater
Enlargement where pancreatic and bile ducts come together.
major duodenal papilla
Sphincter of Oddi.
Releases content from common bile duct and pacreatic duct.
LANDMARK: above is foregut, below is midgut
endocrine function of pancreas
Release insulin to blood.
Regulates blood sugar.
Diabetes mellitus
exocrine function of pancreas
Release enzymes into pancreatic duct, into small intestine.
Loss = diarrhea, malnutrition.
blood supply of pancreas
HEAD:
anastamoses from branches of celiac trunk (foregut) and superior mesenteric (midgut). —- anterior/posterior superior pacreaticoduodenal AND anterior/posterior inferior pancreaticoduodenal [celiac > common hepatic > gastroduodenal].
Body: greater pancreatic a., dorsal pancreatic a. (both from splenic a.)
lymphatic drainage of pancreas
MAJOR:
celiac lymph nodes
superior mesenteric lymph nodes
MINOR:
superior pancreatic LN
pancreaticoduodenal LN
pyloric LN
clinical significance of head of pancreas
Common site for carcinoma.
Close to duodenum.
Numerous ducts/blood vessels.
Enlargement due to carcinoma can put pressure on duodenum (intestinal obstruction).
Jaundice due to pressure on bile duct (bilirubin flows back to liver, re-enters circulation).
Carcinoma erodes local vessels causing bleeding.
mucosal folds
In jejunum and ileum.
Increase surface area.
ileocecal junction
sphincter between ileum and cecum.
Endoscope here for gold standard diagnosis of Crohn’s disease.
large intestine
extends from ileocecal junction to upper part of anal canal
site where water, electrolytes, vitamin K is absorbed
cecum
large pouch forming the beginning of large intestine
connected to cecum is small blind tube or diverticulum (appendix)
colon
4 segments:
ascending
transverse
descending
sigmoid
rectum
pelvic pt of large intestine
anal canal
last subdivision of large intestine
vermiform appendix
contains lymphoid tissue, neutralizes pathogens
variable anatomical position, base of the appendix is attached to the cecum
most common cause of surgery in the abd
appendicitis (pain felt in periumbilical region T10)
perforation of inflamed appendix leads to
peritonitis (nflammation and infection of the peritoneum)
physical indications of appendicitis
pain worsened by pressure over the McBurney Point
+ Blumberg sign (REBOUND tenderness when palpating abd)
+ posas sign (irritation to illopsoas due to inflammed appendix)
external features of the large intestine (3)
omental (epiploic) appendices
taenia coli
haustra
omental (epiploic) appendice
small, fat filled pouches along large intestine
taenia coli
3 longitudinal smooth muscle bands (*not in rectum or anal canal)
haustra
sacculations of the colon from tightening of teniae coli
mass movements (peristaltic contractions)
circular muscles contract simultaneously w/ teniae coli of colon wall to move colon contents twd anus
dilatation at end of rectum
rectal ampulla
After the rectosigmoid junction, 3 transverse folds are found in the rectum
superior rectal fold
middle rectal fold
inferior rectal fold
anorectal junction
between rectum and anus
puborectalis m.
wraps around the posterior aspect of the rectum forming a sling that holds the rectum forward in the pelvis
celiac trunk
landmark, supplying…?
T12
foregut
superior mesenteric a.
landmark, supplying…?
L1
midgut
inferior mesenteric a.
landmark, supplying…?
L3
hindgut
Foregut blood supply comes from which branches of the celiac trunk?
- L gastric a.
- Splenic a.
- Common hepatic a.
- proper hepatic
- gastroduodenal
Midgut blood supply comes from which branches of superior mesenteric a.?
- Ileocolic a.
- R colic a.
- Middle colic a.
terminal end arteries of the superior mesenteric artery that reach the intestinal wall
vasa rectae (straight arteries)
Hundgut blood supply comes from which branches of the inferior mesenteric a.?
marginal artery (artery of Drummond)
L colic a.
sigmoid arteries
marginal artery (artery of Drummond)
formed by anastomosing ends of the branches of the superior and inferior mesenteric arteries
venous drainage of abd cavity
all drains into hepatic portal v. which accepts drainage from
superior mesenteric v.
inferior mesenteric v. (via splenic v.)
celiac lymph nodes receive lymph from
gallbladder duodenum pancreas spleen stomach
superior mesenteric lymph nodes receive lymph from
cecum
ascending and R half of transverse colon
jejunum
ileum
inferior mesenteric lymph nodes receive lymph from
hindgut
cisterna chyli
lowest portion of thoracic duct
all three lymph groups drain here (celiac, superior mesenteric, inferior mesenteric)
innervation from foregut to descending colon
visceral afferent pain fibers
SYMPATHETIC fibers (thoracic and lumbar splanchnic nerves T6-T12)
innervation from sigmoid to upper part of rectum and anal canal
visceral afferent pain fibers
PARASYMPATHETIC fibers (pelvic splanchnic nervers S2-S4)
sympathetic innervation of abd acts to
dec motility and secretions/contract sphincters
parasympathetic innervation of abd acts to
inc motility and secretions/relax sphincters
greater, lesser, least splanchnic n.
nerve roots?
ganglion?
paths of postsynaptic fibers?
T5-T12
synapse on celiac, superior mesenteric ganglion
postsynaptic fibers travel thru aortic and periarterial plexuses to viscera (foregut and midgut)
lumbar splanchnic n.
nerve roots?
ganglion?
paths of postsynaptic fibers?
L1-L2
synapse on inferior mesenteric, superior hypogastric ganglion
travel thru aortic and periarterial plexuses to viscera (hindgut)
vagus CNX
paths of presynaptic fibers?
ganglion?
paths postsynaptic fibers?
presynaptic fibers travel thru aortic and periarterial plexuses
synapse on enteric ganglion on the viscera (foregut and midgut)
postsynaptic fibers are lying on or w/i the abd viscera (foregut and midgut)
pelvic splanchnic n.
nerve roots?
paths of presynaptic fibers?
ganglion?
paths postsynaptic fibers?
S2-S4
presynaptic fibers travel through inferior hypogastric plexuses
synapse on enteric hanglion in the viscera (hindgut)
postsynaptic fibers are lying on or within the abd viscera (hindgut)
pectinate line
anatomic anorectal junction
remnant of anal membrane (during development)
above pectinate line –> endoderm (hindgut)
below pectinate line –> ectoderm
external anal sphincter
voluntary control
relaxation –> defecation
constriction –> maintains fecal continence
internal anal sphincter
involuntary control
modified extension of circular m. of rectum
relaxation –> defecation
constriction –> maintains fecal continence
above pectinate line, anal canal is receiving blood from
superior rectal a. (br. of inferior mesenteric a.)
below pectinate line, anal canal is receiving blood from
middle rectal a.
inferior rectal a.
(br. of internal iliac a.)
above pectinate line, anal canal venous drainage goes to
inferior mesenteric v. (to portal v.)
below pectinate line, anal canal venous drainage goes to
common iliac v. (to inferior vena cava)
venous blood from lower anal canal dumps into ________, while venous blood from upper anal canal (hindgut) goes __________.
venous blood from lower anal canal dumps into systemic circulation directly, while venous blood from upper anal canal (hindgut) goes to hepatic system first.
at anorectal junction, what time of anastomoses are present?
portacaval anastomosis
anastomoses between portal and systemic circulation
portacaval anastamoses locations
esophageal veins
retroperitoneal veins
anorectal veins
paraumbilical veins
hemorrhoids
normally, external/internal venous plexuses are cushions that help w/ stool control
disease when swollen or prolapsed
lymphatic drainage of the anal canal
above pectinate line –> inferior mesenteric nodes, cisterna chyli
below pectinate line –> superficial inguinal nodes
anal canal innervation above pectinate line
hindgut innervation (autonomic and visceral sensory) to mucosa and internal anal sphincter
anal canal innervation below pectinate line
somatic motor to external anal sphincter and somatic sensory to skin around anal region
Diverticulosis
false diverticula (external evaginations of mucosa of colon) develop along intestine
commonly found in sigmoid colon
infection/rupture –> diverticulitis (can erode arteries, cause hemorrhage)
tx: supportive, treat inflammation, surgery
middle-aged and elderly affected
volvulus of sigmoid colon
rotations/twisting of the mobile loop of sigmoid colon
result: obstruction of lumen of descending colon proximal to twisted segment
leads to…
constipation (may progress to fecal impaction)
ischemia/necrosis if untreated
tx: decompression or resection of the sigmoid
colorectal cancers
risk fx: FHx, IBD, old age, African American, low-fiber diet, alcohol, smoking, obesity
signs/sx: change in bowel habits rectal bleeding persistent abd discomfort pain weakness/fatigue unexplained weight loss
most cases begin as small, benign clumps of cells –> “adenomatous polyps”
dx: colonoscopy
3 primary tx: surgery, chemo, radiation
