SI Phys and Path again Flashcards
What are the 3 regions of the small intestine
Duodenum
Jejunum
Ileum
which region is the shortest and widest portion of the small intestine
duodenum
which region starts at the pyloric sphincter?
duodenum
which region is C-shaped and mostly retroperitoneal?
duodenum
which region is closely associated with the head of the pancreas?
duodenum
which region of the small intestine is the longest?
ileum (2 meters)
which region joins the large intestine at ileocecal sphincter?
ileum
the vast majority of the duodenum is ?
retroperitoneal
jejunum has what?
larger plicae circulares
the ileum has many ?
large lymphoid nodules (peyer’s patches)
the arterial supply for the first 2/3 of the duodenum comes from?
the hepatic artery of the celiac trunk
- Hepatic art. -> gastroduodenal art. -> superior pancreaticoduodenal art.
the arterial supply for the rest of the small intestine (last part of duodenum to ileum) comes from
the superior mesenteric artery
what receives venous blood from small intestine and portions of the large intestine, stomach, and pancreas
superior mesenteric vein
what are plica circulares?
folds of mucosa and submucosa, they are permanent ridges about 10 mm “tall”
what encourages mixing and cause chyme to spiral and slosh through the intestine
plica circulares
what are finger-like projections of mucosa that are 0.5-1 mm long and vastly increase the SA of epithelium
villi
what is too small to be seen individually and is called?
microvilli and brush border
what does L cells secrete?
Peptide YY
what does Peptide YY do?
inhibits gastric secretion and motility = slows gastric emptying
how is chyme propelled through the small intestine
peristaltic waves (peristalsis)
what is a peristaltic rush
a powerful wave of contractile activity that travels long distances down the small intestine
what causes a peristaltic rush
intense irritation or unusual distension
what is the “law of the gut”
distention in the alimentary canal causes distal parts of the canal to relax and proximal parts to contract
peristalsis is enhanced by?
- gastrin
- CCK
- serotonin
peristalsis is inhibited by?
- secretin
- peptide YY
- epinephrine
what are the requirements for gastric emptying into the small intestine (duodenum)
- food particles must by very small
- small volumes of low pH fluid
- gradual release
what is the major organ that regulates the rate of gastric emptying
duodenum
what are some duodenal hormones?
CCK and Secretin
what substances release the most CCK
fats
what is the major paracrine regulator of gastric emptying
CCK
- increased CCK release = slowed gastric emptying
secretin also has a mild impact on ?
gastric emptying slowing it
what is the major hormone that performs the role of the “ileal brake”
peptide YY
If undigested foods are reaching the distal small intestine, then ? “slows everything down” – not just gastric motility, but motility of the proximal intestines as well
peptide YY
when would the ileocecal valve forcefully close?
when excess pressure builds up in cecum
where are Brunner’s glands found?
found proximal to the sphincter of Oddi
what does brunner’s glands secrete
secrete alkaline mucous
what is the function of brunner’s glands
protect duodenal wall from digestion by gastric juice
what regulates the release of bile into the dudodenum fromt eh ampulla of vater
sphincter of Oddi
if the sphincter of Oddi is closed, then bile is stored where?
gall bladder
what are the protein digestion enzymes in the pancreas
- trysin
- chymotrypsin
- elastase
- carboxypeptidase
what is the inactive form of trypsin
trypsinogen
what is the activator for trypsinogen
enterokinase
what is the inactive form of chymotrpsin
chymotrypsinogen
what is the activator for chymotrypsinogen
trysin
what does chymotrypsin do?
cleaves peptide bonds next to a wide range of amino acids
what is the inactive form of elastase
proelastase
what is the activator of proelastase
trypsin
what does elastase do?
cleaves elastin
what is the inactive form of carboxypeptidase
procarboxypeptidase
what is the activator of procarboxypeptidase
trypsin
what does carboxypeptidase do?
cleaves the carboxy-terminal ends of peptides
what is the digestive enzyme for carbohydrate digestion in the pancreas
pancreatic amylase
what are the lipid digestion enzymes in the pancreas
pancreatic lipase/co-lipase
phospholipase A2
what is the activator of pancreatic lipase
co-lipase activates lipase at the micelle
what does pancreatic lipase do?
cleaves triglycerides to fatty acids and 2 monoacyl glycerol
what is the inactive form of phospholipase A2
prophospholipase
what activates prophospholipase
trypsin
what does phospholipase A2 do?
cleaves phospholipids
what is the enzyme called in the mouth that digest carbohydrates? and what secretes it?
ptyalin (salivary amylase) and parotid gland
what is the most important enzyme for digestion of starches
pancreatic amylase
The brush border formed by the microvilli contain 3 major enzymes that digest the major disaccharide sugars in our diet
- lactase
- maltase
- sucrase
what are the two things in the stomach that helps with protein digestion
- HCL
- Pepsin
what does HCL do to proteins in the stomach
denatures them which improves the “exposure” of peptide bonds to digestive enzymes
what has the ability to digest collagen
pepsin
33% of protein absorption as ?, 67% of protein absorption as ?
free amino acids and peptides
what does bile contain that help the formation of micelles
- lecithins
- bile salts
- cholesterol
“outside” of the micelle is what? “inside of the micelle is ?
hydrophillic
hydrophobic with the dieatary lipids
When absorption at the small intestine fails, nutrients remain in the lumen of the intestine. This can result in:
- diarrhea
- micronutrient deficiency
- macronutrient deficiencies
Types of malabsorption can be pathophysiologically organized into four major problems:
- disturbances in intraluminal digestion
- disturbances in terminal digestion
- disturbances in transepithelial transport
- disturbances in lymphatic transport
celiac disease is what type of malabsorption
terminal and trans-epithelial
explain basic celiac disease
Damage to the villi and microvilli results in loss of surface area and overall absorptive enterocyte function
explain basic chronic pancreatitis
Lack of major digestive enzymes from the pancreas leads to major impairment of absorption, diarrhea, and nutrient deficiencies
explain basic disaccharidase deficiencies (lactose intolerance)
Lack of disaccharide results in unabsorbed sugar in the lumen
->bacterial gas production and osmotic diarrhe
explain gastroenteritis
Damage to the brush border or dysregulation of electrolyte transport results in impaired ability to absorb nutrients
chronic pancreatitis is what type of malabsorption
intraluminal digestion
disaccharidase deficiencies is what type of malabsorption
terminal digestion
gastroenteritis is what type of malabsorption
terminal and trans-epithelial
