Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
43 Cards in this Set
- Front
- Back
|
How long does it take to traverse the small intestine?
|
2-5 Hours to traverse it
|
|
|
what are the 3 functions of the small intestine
|
mix, expose, propel
|
|
|
how are the walls of the jejunum compared to the ileum?
|
jejunum is much thicker walls, wider diameter
|
|
|
What does the PNS do to the small intestine? via what nevres?
|
the vagus nerve, acts to increase the contraction of intestinal smooth muscle.
(by ACH) |
|
|
What does the SNS do the small intestine? via what nerves?
|
this inhibits contraction of smooth muscle, from Celiac and superior mesenteric ganglia
|
|
|
how often are the duodenal contractions?
|
about every 12 min after food enters (local distention)
|
|
|
how often are the ileal contractions?
|
about 9min, due to gastrin (from chyme in stomach)
|
|
|
do segment contractions do much propulsion?
|
nope, mostly mixing
|
|
|
when does the migrating motility complex occur? how often are waves?
|
this happens when most of a meal is absorbed. about every 90 min
|
|
|
What contracts the muscle to push the food bolus along, what chemicals?
|
ACH and substance P
|
|
|
what relaxes the muscle ahead of the bolus to allow it to move forward?
|
VIP/ NO
|
|
|
how does the ileocecal sphincter respond to pressure in the cecum? in the ileum?
|
in cecum= closed sphincter
in ileum= open sphincter |
|
|
What do exocrine glands in the SI secrete?
|
succus entericus
an aqueous salt and mucus solution |
|
|
what are the folds in the SI called?
|
folds of kerckring
|
|
|
Where does absoprtion occur in the SI?
|
duodenum and jejunum
|
|
|
how much of the SI can be removed with little damage
|
about 50%
|
|
|
what is malabsorbed if the ileum is removed?
|
vit B12
|
|
|
Where does starch begin digestion?
|
in the mouth by alpha-amylase
|
|
|
What breaks down dietary polysaccharides? into what?
|
salivary amylase, pancreatic amylase
break it down into maltose (disaccardies) |
|
|
what breaks down the lactose/sucrose/maltose (dietary disaccharides)
|
maltase,lactase,sucrase in the Brush Border Ezymes
turns them into monosarccarides |
|
|
How does glucose and galactose absorbed?
|
these use Na+ dependent active transport into SI epithelial cells and into blood
|
|
|
how is Fructose absorbed?
|
by facilitated diffusion directly into blood
(GLUT 5) |
|
|
What transporter is used for facilitated diffusion of all sugars out of enterocytes?
|
GLUT 2
|
|
|
What enzymes are found in the brush border membrane?
|
Enterokinase
Aminopeptidases |
|
|
What does endopeptidase do?
|
this hydrolizes the interior protein bonds
(pepsin, trypsin, chymotrypsin) |
|
|
what does exopeptidase do?
|
this hydrolyzes one AA at a time from the end
(carboxypeptidase A/B) |
|
|
What activates ProColipase?
|
trypsin
|
|
|
What is the function of Colipase?
|
to bind to and activate pancreatic lipase
|
|
|
What emulsified dietary fat?
|
bile salts
|
|
|
what does Lipase do?
|
hydrolizes TG to MG and 2 FFA's
|
|
|
what carries water insoluble products from fat digestion?
|
micelles
|
|
|
how do micelles enter cells?
|
they passively diffuse through luminal plasma membrane
|
|
|
What do MG and FFA do in the cell?
|
they RE-esterify to form TG
|
|
|
What are apoproteins used for?
|
these are used to absorb lipids and CM's
|
|
|
How do TG's leave the cell?
|
they are incorporated into CMs which are coated with APO proteins
|
|
|
What is secreted in secretory diarrhea?
|
CI-
|
|
|
What kinds of things get lost during diarrhea?
|
H2O, HCO3, K+ (hypokalemia)
|
|
|
how does cholera lead to diarrhea?
|
this toxin permemently activates Alpha (somethign) receptors, this activates Adenylyl Cyclase, increasing cAMP signalling, increasing CFTR pumping out Cl-
|
|
|
What is mostly absorbed in the jejunum?
|
Na/HCO3
|
|
|
what is mostly absorbed in the ileum?
|
Na/Cl
|
|
|
What is Celiac disease?
|
damaged SI lining due to gluten. greatly decreased absorption.
High levels of anti-tissue transglutaminase Ab |
|
|
What things play a role in Celiac disease?
|
breast feeding time (longer is better)
age one starts eating gluten foods level of gluten eaten |
|
|
What region does chrons mostly affect?
|
the Ileum, this is an autoimmune disease
|
