SI and Pancreas (midterm) Flashcards
The ___________ is more dense CT than the areolar CT in the mucosa
submucosa
What cells are found in the intestinal glands?
1) absorptive cells
2) goblet cells
3) enteroendocrine cells
4) paneth cells
What is the function of absorptive cells inside of intestinal glands?
digest and absorb nutrients
What is the function of goblet cells?
test q
secretes mucus
What cells secrete hormones like secretin, CCK, and GIP?
enteroendocrine cells
What is the function of paneth cells?
test q
secretes lysozyme and is capable of phagocytosis to kill bacteria
Simple columnar cells are found in the mucosal layer of the SI and contains crypts of Lieberkuhn (deep to surface) which secretes ___________ and makes brush border enzymes
intestinal juice (note: this is slightly alkaline (7.6) whereas gastric juice is very acidic)
The submucosal layer of the SI has duodenal Brunner’s glands that secrete…
alkaline mucus to continue to raise pH of chyme
Intestinal juice provides a vehicle for absorption of substances from _______ as they come in contact with the villi. Some digestion will continue to occur in the lumen of the SI, especially until pH is neutralized
chyme
Brush border enzymes break down compounds on the surfaces of their microvilli. Peptidases like ______________________ attach remaining peptide bonds and nucleosideases and phosphatases continue to breakdown DNA and RNA
aminopeptidases or dipeptidases
Sucrose needs to be converted to what to be digested/absorbed?
glucose or fructose
Which hormone is secreted in the G cells of the antrum, duodenum, and jejunum, and stimulates gastric acid secretion and mucosal growth in the stomach?
test q
gastrin
Which hormone is secreted in the I cells of the SI and stimulates:
-pancreatic enzyme secretion
-pancreatic bicarbonate secretion
-gallbladder contraction
-growth of exocrine pancreas
(basically stimulates pancreas to release more exocrine cells)
and inhibits gastric emptying?
test q
CCK
Which hormone is secreted in the S cells of the SI and stimulates:
-pepsin secretion
-pancreatic bicarbonate secretion
-biliary bicarbonate secretion
-growth of exocrine pancreas
and inhibits gastric acid secretion?
test q
secretin
Which hormone is secreted in the K cells of the duodenum and jejunum and stimulates insulin release (carbs stimulate insulin release) while inhibiting gastric acid secretion?
test q
gastric inhibitory peptide (GIP)
What are the 3 parts of the pancreas?
head, body, and tail
The head of the pancreas is close to the curve in C-shaped ________
duodenum
The pancreas is connected to the duodenum via the main duct (duct of wirsung) and accessory duct (duct of santorini). The main duct joins the common bile duct from the liver and forms the ________________ duct. The hepatopancreatic sphincter (sphincter of oddi) on the hepatopancreatic ampulla (ampulla of vater) controls secretions (its close to the pyloric sphincter)
note: the location of pancreatic secretion release is relative to chyme released into duodenum
hepatopancreatic
The pancreatic acini are dark clusters that take up 99% of the gland and produce _____________________________. The islets of langerhans are 1% of the gland and are pale staining cells that produce many hormones
bicarbonate rich pancreatic juice
The islets of langerhans have alpha cells that produce what hormone? What is the function of this hormone?
glucagon
-raises the conc. of glucose in the bloodstream
-synthesis of glucagon is stimulated during fasting and is decreased during fed state
The islets of langerhans have beta cells that produce what hormones? What is the function of these hormones?
insulin
-promotes the absorption of glucose from the bloodstream
-synthesis of insulin is stimulated by IV glucose or feeding and is decreased by fasting
-insulin targets the liver, skeletal muscle and adipose tissue to store excess glucose
amylin
-slows gastric emptying and promotes satiety (feeling of fullness)
What cells are most common in the islets of langerhans?
beta cells are 70% of the cells there
The islets of langerhans have epsilon cells that produce what hormone? What is the function of this hormone?
the hunger hormone
-secreted when stomach is empty, and stops secretions once the stomach starts stretching from food
-secreted from adipocytes and works in the hypothalamus
Pancreatic juice is generated in response to ________ from the duodenum and jejunum
secretin
What does pancreatic juice contain and what does it do?
water, enzymes, and sodium bicarbonate
it fixes the pH of chyme exiting the stomach
What are the 5 types of enzymes in pancreatic juice?
1) pancreatic amylase
2) pancreatic lipase
3) trypsinogen
4) serine proteases
5) ribonuclease and deoxyribonuclease
Pancreatic ________ breaks down starch into glucose
amylase
Pancreatic ________ uses hydrolysis to break apart fats to MGs and free FAs
lipase
Trypsinogen is a zymogen activated by _______________ (a brush border enzyme)- ________ is the major protease
test q
enteropeptidase (initial enzyme that turns on whole cascade of pancreatic digestive enzyme release)
trypsin
All serine proteases are activated by….
test q
trypsin
trypsin is a huge activator!!!!
What are the 3 types of serine proteases?
1) chymotrypsinogen> chymotrypsin
2) procarboxypeptidase> carboxypeptidase
3) proelastase> elastase
Elastase is a serine protease that is specialized to break down….
elastin proteins
Which hormone combines with trypsin and is produced inside the pancreas? This hormone prevents self-digestion prior to secretion
trypsin inhibitor
Ribonuclease and deoxyribonuclease digest _____________
nucleic acids
Pancreatic juice secretion is high in bicarbonate, which ________ pH
increases (becomes more alkaline)
Acidic chyme arriving in the SI stimulates release of _________, which stimulates increased bicarbonate release in pancreatic juice
secretin
FAs and sugar in chyme causes increased insulin release with what hormone?
gastric inhibitory peptide (GIP)
Fats and proteins cause release of ____, which inhibits gastric emptying. This hormone increases gastric acid secretion and digestive enzymes release into pancreatic juice, which drives contraction of gallbladder
CCK
what is pancreatitis? What are the causes?
inflammation of the pancreas
-caused by gallstones, mumps, corticosteroids, trauma
What is acute pancreatitis most commonly associated with?
heavy alcohol intake or biliary tract obstruction (severity depends on activation level of trypsinogen and other proteolytic enzymes- if they are activated, the patient starts to digest themselves and this can be fatal)
Lingual lipase is more active in the __________ than the mouth
stomach
Absorption in the SI is the passage of the end products of digestion from the GI tract into…
blood or lymph
Monosaccharides are remnants of carb digestion and are absorbed into epithelial cells. Glucose and galactose go through a ________________, which is active transport. Fructose undergoes facilitated diffusion. Then they move out of epithelial cell into blood capillaries in villus through facilitated diffusion
sodium symporter (Na+/K+ pump)
What is the difference between primary and secondary active transport?
primary active transport generated energy directly there, while secondary got energy from elsewhere
AAs and dipeptides absorb into epithelium via secondary active transport with either Na+ or H+ ions (symporters). They are then transported out of epithelial cell into blood capillaries in the villus through_______________, but nothing greater than a tripeptide can get through. From the villus, it is transported to the liver via the hepatic portal vein
test q
simple diffusion
note: AAs go with Na+, di/tripeptides go with H+ into cell!!!!
Lipids are absorbed as small FAs and enter the epithelial cells and exit by _____________. Larger lipids exist only within micelles (bile salts coating) enter by simple diffusion (leaving bile salts behind in gut). Fat soluble vitamins enter with lipids also within micelles
simple diffusion
When lipids are being absorbed into epithelial cells, the fats are rebuilt and coated with lipoproteins to form _____________, which will leave the intestinal cells by _____________ into a lacteal which will travel to thoracic duct/lymphatic system to reach veins near the heart and be removed from the blood by the liver and adipose tissue
test q
chylomicrons, exocytosis
Many of the electrolytes absorbed by the SI come from GI secretions and some are a part of digested foods and liquids. Sodium and potassium are transported through Na+/K+ pump which is an active transporter. _________________ can passively flow through. _____________________ ions have to go through active transport.
test q
chloride, iodine, and nitrate
iron, magnesium and phosphate
Intestinal calcium absorption requires what?
test q
activated vit D and parathyroid hormone
What vitamins are absorbed with ingested dietary lipids and travel in micelles which are absorbed by simple diffusion?
fat soluble vitamins- vit K,A,D,E
What vitamins can be absorbed through simple diffusion?
water soluble vitamins- vit B and C
Which vitamin is absorbed with intrinsic factor (which comes from parietal cells of the stomach) before it is transported into the cells via receptor mediated endocytosis?
test q
vit B12
Water is absorbed mostly into SI but also the LI. The LI absorbs it by osmosis through cell walls into vascular capillaries inside villi. This allows the LI to….
finesse bowel movement composition and motility
What movement promotes absorption of food stuffs in the SI?
segmentation
What muscles are involved in promoting absorption of food stuffs in the SI?
muscularis mucosae, circular layer, and longitudinal layer
What structures are involved in the efficient absorption of food stuffs in the SI?
brush border
What happens in the digestive system when a lactose intolerant person consumes dairy?
undigested lactose retains fluid in feces and will result in bacterial fermentation and produce gas
symptoms:
-diarrhea
-gas
-bloating
-abdominal cramps
gets worse with age
Which hormones stimulate pancreatic bicarbonate secretion and growth of exocrine pancreas?
test q
CCK and secretin
Which hormones inhibit gastric secretion?
test q
secretin and GIP (gastric inhibitory peptide)
What is the path of carb digestion and absorption?
Which hormones are found in all 3 regions of SI?
secretin and CCK
Which hormone is found in duodenum and jejunum?
GIP
Which GLUT transporter is used to transport fructose from SI into an enterocyte?
GLUT5 (cotransporter with sodium)
Does protein digestion happen in mouth or esophagus?
NO
Does fat digestion occur in the esophagus?
NO
