exam 1 lecture 11 and 12 digestion Flashcards
4 salivary glands
parotid
mandibular
sublingual
zygomatic
Mumps
virus that effects the salivary glands
high fever and swelling of glands
A salivary___ is a collection of saliva that has leaked from a damaged salivary gland or salivary duct, and has accumulated in the tissues. Common in dogs
mucocele
parotid glands produce ___ , buccal glands produce ___
serous
mucus
there is large amount of ___ in ruminant saliva
bicarbonate (HCO3)
___ have isotonic saliva
ruminants
(which has a similar concentration of fluid, sugars and salt to blood)
___ have hypotonic saliva
non-ruminants
(lower salt, fluid and sugar concentration then in the blood)
___ breaks down starch in saliva
amylase (ptyalin)
___ breaks down fat in saliva
lingual lipase
___ which contain antimicrobial enzymes are found in saliva
lyzosymes
3 functions of saliva
- Moisten and lubricate food
- Antibacterial activity (oral hygiene)
- Evaporative cooling - cat and dog
ruminant saliva has a high amount of bicarbonate why?
to buffer forestomach digestion
makes low acidic pH higher
ion transporters on salivary ducts will ___
modify saliva secretion
acini salivary cells will secrete ___
duct cells will reabsorb ___
acini: secrete: bicarbonate, water, K+,Na+, Cl-
duct: secrete: bicarbonate, K+
absorb: Cl-, Na+ and water
the ___ rate of saliva determines the electrolyte concentration
flow
if very fast, Na, water and Cl can’t be reabsorbed as well (isotonic solution-concentration similar to that of blood)
if very slow, lots of Na, water and Cl leave, lots of bicarbonate and K are added (hypertonic solution- concentration lower than blood)
parasympathetic regulation of salivary secretion
- primary mode
- Pavlov’s dog - conditioned reflex
- Cholinergic receptors
- Atropine suppresses salivary secretion
•Atropine ____ salivary secretion
suppresses
what kind of receptors are used for parasympathetic regulation of salivary secretion?
cholinergic
what kind of receptors are used for sympathetic regulation of salivary secretion?
beta- adrenergic receptors
sympathetic regulation of salivary secretion
- Potentiate the effect of PNS
- b-adrenergic receptors
- Salivation and drooling in carnivores preparing to attack
what are the two functions of the pancreas?
- Exocrine secretion – digestion
- Endocrine secretion – insulin
acinar cells in the pancreas produce
zymogens (inactive)
amylase (active)
lipase (active)
electrolytes
the centroacinar cells, and duct cells of the exocrine pancreas produce ___
bicarbonate → enzymes have high pH (basic)
how is trypsinogen activated
in the small intestine
trypsinogen (enterokinase)→ trypsin
trypsin can activate ___
trypsinogen into trypsin
or activate other enzymes
enterokinase
not actually a kinase → acts like a protease
glycoprotein found in the small intestine (brush border of duodenal enterocytes), released from brush border by bile salts
trypsinogen (enterokinase)→ trypsin
acute pancreatitis is caused by
premature activation of pancreatic enzymes in the pancreas (pancreas eating itself)
three phases of pancreatic secretion
cephalic
gastric
intestinal
cephalic phase of pancreatic secretion
•vagal stimulation (sight and smell of food)
parasympathetic NS
gastric phase of pancreatic secretion
•vagovagal reflex (stomach distention)
intestinal phase of pancreatic secretion
- intestinal distension (Ach)
- chemical stimulation (CCK, secretin)
- Fat and protein stimulate CCK secretion
- H+ stimulates secretin secretion
Fat and protein stimulate ___ secretion
CCK
H+ in the small intestine stimulates ___ secretion
secretin
pavlov dog experiment stimulates ___
saliva secretion
cephalic and gastric pancreatic enzyme secretion
CCK stimulates ___ cells to secrete ___
acinar cells
zymogens, amylase, lipase and electrolytes
secretin stimulates ____ cells to produce ___
centroacinar and duct cells
bicarbonate
ACh stimulates which pancreas duct cells?
all three
acinar, centroacinar and duct cells
function of secretin
stomach produces acid which decreases the pH, this decrease in pH triggers secretin to stimulate pancreatic duct cells to produce bicarbonate which will increase the pH of the duodenum
liver is a __ gland that makes __
exocrine
bile
what is bile made of?
bile salts
- Phospholipids and cholesterol
- Electrolytes (HCO3-)
bile pigments (bilirubin)
metabolites of drug and toxins
bilirubin is made from ___ and excess can cause ___
bile pigment from breakdown of red blood cells
jaundice (liver failure)
bile acid is made from ___
cholesterol (hydrophobic)
bile acid aka cholic acid (amphipathic- both hydrophobic and hydrophilic)
amphiphilic
both hydrophobic and hydrophilic
like a detergent
example: bile acid/ cholic acid
what is the valve that controls bile into the small intestine?
sphincter of oddi
CCK does what to the gallbladder and sphincter of oddi
fat and protein in the SI triggers the release of CCK
CCK causes contraction of the gallbladder and relaxation of the sphincter of oddi → bile acid is released into the SI
bile secretion in ruminants and pig
sphincter of Oddi poorly defined leads to continuous secretion of bile
do horses have gallbladder?
no- leads to continuous secretion of bile acid
why does the body only need to make 6% of bile salts?
94% is reabsorbed from the small intestine back through through the liver into the gallbladder
6% is lost in feces and needs to be made from cholesterol
bile is released in reaction to __
fat and protein in the small intestine → CCK→ gall bladder contraction, Oddi opening → bile secretion
secretin will stimulate ___
bicarbonate secretion
bile acids help absorb ___
fat soluble vitamins (K,A,D,E)
fat absorption
biliary secretion provides additional buffer to ___ H+ in the duodenum
neutralize
Biliary secretion provides an excretory route for certain metabolites and ___
drugs
how does liver disfunction effect vitamin K?
vitamin K can not be stored in the body, must be provided by the diet
issues with liver will cause vit K deficiency (excessive bleeding)
how is bile acid reabsorped?
bile released into the small intestine, filtered through the portal vein and reabsorbed by liver cells (hepatocytes) back into the gallbladder
do not enter systemic circulation (unless things go wrong with the liver)
enterohepatic circulation
•Secretion of bile salts by ___ is proportional to hepatic portal vein concentration of bile salts.
hepatocytes
mastication leads to breakdown of particle size and increase of ___
surface area
chemical digestion involves splitting of chemical bonds: glycosidic linages (___), peptide bond (___) and ester bonds (___)
carbohydrates
proteins
fats
two phases of chemical digestion
luminal
membranous
luminal chemical digestion
enzymes active in the lumen of the gut (from the salivary, gastric and pancreatic glands)
large polymers(starch and proteins) are broken down into smaller polymers (polysaccharides and peptides)
membranous chemical digestion
small polymers (polysaccharides and peptides) are broken down into monomeric molecules suitable for absorption
enzymes active at surface of gut (from the enterocytes in the small intestine)
enzymes for the luminal phase of chemical digestion are from __
salivary, gastric and pancreatic glands
enzymes for the membranous phase of chemical digestion are from ___
enterocytes in the small intestine
carbohydrate digestion
luminal digestion (starch) enzymes form salivary, gastric and pancreatic glands
found on brush border oligosaccharidases
only monomers are absorbed
luminal phase of carbohydrate digestion
starch can be linear → amylose or branched → amylopectin
amylase is an enzyme that breaks the 1-4 bond will cleave starch into disaccharides (maltose) , trisaccharides (maltotriose) and oligosaccharides
what enzyme is used in the luminal stage of carbohydrate digestion?
amylase (can break 1-4 bond of starch→ disaccharides (maltose) , trisaccharides (maltotriose) and oligosaccharides)
membranous phase of carbohydrate digestion
lactose and sucrose skip luminal phase (they are both dimers)
starch has to go through luminal phase, breakdown by amylase into smaller pieces
enters membranous phase- each have their own enzyme (ex. lactose and lactase) → glucose and galactose
starch→ glucose
sucrose→ glucose and fructose
these monomers can then be absorbed
what is lactose broken into to be absorbed?
glucose and galactose
what is starch broken into to be absorbed?
glucose
what is sucrose broken into to be absorbed?
glucose and fructose
how is glucose and galactose absorbed
sodium dependent glucose transporter
Na+ has to be taking into the cell
then exported into the blood by glucose transporter 2
how is fructose absorbed
glucose transporter 5
then exported into the blood by glucose transporter 2
two types of enzymes for luminal phase protein digestion
endopeptidase- cuts through middle of protein → leads to short polymers
exopeptidase- removes one amino acid at a time from the end
enzymes for protein digestion come from two places
gastric glands and pancreas
endopeptidase-
cuts through middle of protein → leads to short polymers
exopeptidase
- removes one amino acid at a time from the end
enzyme for luminal phase of protein digestion
activation of pancreatic zymogens
membranous phase digestion of peptides
tripeptide, dipeptide and amino acids can be taken into the enterocyte or they can be broken down into amino acid using brush border peptidases
tripeptide and dipeptide are taken up by the H+ dependent peptide transporter 1
amino acid is taken up by the Na+ co-transporter
tripeptide and dipeptide have to be broken down more inside the enterocyte by peptidases into amino acids
___ are taken up into the enterocyte by the H+ dependent peptide transporter 1
tripeptide and dipeptide
amino acids are transported by ___ in the enterocyte
Na+ co-transporter
protein digestion
luminal: luminal digestion into smaller peptides by endopeptidase or exopeptidase from the gastric glands or the pancreas
membrane: broken down by brushborder peptidase into 3,2,or amino acids. (3 and 2 can be transported into the enterocyte and further broken down into amino acids by intracellular peptidases) (amino acids can be transported by Na+ co transporter)
carbohydrate digestion
luminal: starch into smaller molecules by amylase
membranous: lactose(lactase)→ glucose + galactose. starch (special enzyme) → glucose. sucrose (sucrase)→ glucose and fructose
absorption: glucose and galactose use Na+ glucose transporter then a GLUT2 transporter to go from enterocyte into the blood
fructose use GLUT5 transporter to get into enterocyte, then a GLUT2 transporter to go from enterocyte into the blood
fat will combine with bile acids to produce ___ when the concentration of bile salts is ___
micelles
2mM
what enzyme is used to breakdown triglyceride
lipase/co-lipase
what enzyme is used to breakdown cholesterol ester
cholesterol esterase
what enzyme is used to breakdown phospholipids?
phospholipase
triglyceride (pancreatic lipase)→
1 (2-monoglyceride) amphiphilic- hydrophobic and hydrophilic
and
2 (free fatty acids) amphiphilic- hydrophobic and hydrophilic
how does co-lipase work
moves bile acids away so lipase can bind to triglyceride and form micelle
lipase is secreted in the ___ form and is ___ by bile acids
secreted
inhibited
co-lipase is secreted in the ___ form and is __ by bile acids
inactive- pro-colipase
activated
binds to lipase and bile acids
(lipase and colipase in a 1:1 ratio)
how does fat get absorbed into enterocyte
broken down into fatty acids and glyceride by lipase and co-lipase to form micelle
glyceride, fatty acid, phospholipid and cholesterol are taken up into the enterocyte
bile acids are also absorbed in the ileum
inside the enterocyte: the glyceride and fatty acid reform triglyceride. triglyceride, phospholipid, cholesterol and protein from the ER form together to make the chylomicron
chylomicron is exported out of enterocyte into the ECM
which is bigger micelle or chylomicron
chylomicron (100s of nanometers)
micelle (nanoparticle)
lipids are moved out of the enterocyte by forming ___
chylomicron
where do chylomicrons go from the intestine
ECM → lymphatics → systemic circulation
(does not get filtered by the liver by the hepatic portal system like carbs and proteins)
lipemia
chylomicronemia
too much fat, causes lymphatics to turn milky yellow
fats are absorbed into enterocyte and then form chylomicrons which are exported into the EMC and taken up into the lymphatic system and go directly into the systemic circulation (skip the cleaning by the liver by the hepatic portal vein)
digestion of fats
triglycerides are broken down by lipase and co lipase. they combine with bile acids and form micelle
glyceride, free fatty acids, phospholipid and cholesterol are taken up into the enterocytes
glyceride and fatty acid reform triglyceride. Triglyceride, phospholipid, cholesterol and protein from the ER form the chylomicron
chylomicron gets transported out of the enterocyte and into the ECM, gets picked up by the lymphatic system and dumped into the systemic circulation without being filtered by the hepatic portal vein like carbs or proteins
•Lipids are absorbed through the apical membrane by carrier proteins and simple diffusion in the ___.
jejunum
•Absorbed lipids are re-esterified and re-packaged into ___ in the enterocytes.
chylomicrons
•Bile acids are ____ in the ileum by a sodium co-transport system.
re-absorbed
in neonates proteins are absorbed ___
intact, not broken down
in most livestock, antibodies (immunoglobulins- Ig) are not passed from damn to fetus
antibodies are acquired through colostrum
how are antibodies acquired for livestock
colostrum- proteins not digested, absorbed intact
how can a neonate absorb full proteins?
delay in acid secretion from the stomach, delay in pancreatic function
special enterocytes engulf soluble proteins, these special cells are lost after 24 hours (in livestock- gut closure in humans =6 months)
In neonate, Ig from colostral binds to what type of receptor
Fc receptor mediated
triggers pinocytic vesicle
at birth, there is more lactase activity then maltase activity because___
more milk at birth, less starch
switched in adult hood, if no lactase activity → lactose intolerance
___ failure to digest nutrients
Maldigestion
___ failure to absorb nutrients
(mucosal damage or bacterial overgrowth)
Malabsorption
•Carbohydrate absorption tests assess ____ (D-Xylose).
malabsorption
Rasco seems bright and friendly, but extremely thin with a dull, uneven hair coat. Laboratory analysis of feces collected over 24 hr shows that Rasco is passing 25g of fat in the feces per day (normal, < 5 g). blood test shows: a low value for trypsin-like immuoreactivity
Digestion problem
Juvenile Pancreatic Atrophy (Pancreatic exocrine insufficiency)
supplement with commercially prepared pancreatic enzymes
