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Flashcards in GI Deck (60)
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1
Q

functions of GI

A

digestion
absorption
excretion
endocrine

2
Q

what are the two secretions in the mouth

A

salivary amylase - breaks down carbs and starches

lingual lipase - breaks down fat

3
Q

what are the 3 gastric glands

A

mucosal or neck cells - secrete mucus and gastrin

chief cells - produce pepsinogen

parietal cells - produce HCL and intrinsic factor

4
Q

what cells secrete gastrin

what does it do

A

mucosal/neck cells - G cells

stimulate HCL gastric secretions

5
Q

what cells secrete pepsinogen

what does it do

A

chief cells

HCL converts pepsinogen to activated pepsin which breaks down proteins and collagen

6
Q

what cells secrete HCL and intrinsic factor

what does it do

A

parietal cells

HCL - destroy bacteria and activate pepsinogen

intrinsic factor - absorbs B12 in terminal ileum

7
Q

mixture of food and gastric secretions is called

A

chyme

8
Q

chyme is propelled through SI by

A

peristaltic waves

9
Q

presence of chyme in the SI stimulates release of what

A

secretin

10
Q

what cells and where is secretin secreted

what does it do

A

S cells found in duodenum

stimulates pancreatic acinar cells to secrete bicarbonate and water

also decreases gastric motility

11
Q

what glands secrete bicarbonate

where

what does it do

A

brunners glands in duodenum

neutralizes the gastric acid
makes PH more alkaline in SI

12
Q

what protects the duodenal wall from digestion from highly acidic gastric juices

A

bicarbonate

13
Q

the presence of fat in the duodenum stimulates the release of what

A

CCK

14
Q

what cells release CCK

where

what does it do

A

I cells in the duodenum

causes gall bladder to contract
causes sphincter of oddi to relax - allows bile excretion into the duodenum
stimulates pancreas to secrete enzymes

15
Q

what pancreatic enzyme completes the break down of of starches into maltose

what is it secreted by

A

pancreatic amylase

exocrine cells / acinar cells

16
Q

what does maltase do

A

breaks down maltose to 2 molecules of glucose

17
Q

what does lactase do

A

breaks down lactose to glucose and galactose

18
Q

what does sucrase do

A

breaks down sucrose into glucose and fructose

19
Q

where are maltase, surcase, and lactase found

A

brush border of enterocytes

20
Q

starches break down into what

A

maltose

21
Q

some digested fat is absorbed into the lacteals and drain into what

A

thoracic duct

22
Q

what enzymes digest polypeptides to produce amino acids

A

intestinal peptidases

23
Q

what are the final products of breaking down fat, starch, and protein in the SI

A

fats - fatty acids and glycerol
starch, sucrose, lactose - glucose, fructose, galactose
proteins - amino acids

24
Q

breakdown products (fat, starches, proteins) are __ by the small intestine and transported to the __ except what

A

absorbed
liver

except some fat travels in lacteals to thoracic duct

25
Q

is the pancreas an endocrine, exocrine, or both gland

A

both

26
Q

what are the endocrine cells of the pancreas

what are the exocrine cells of the pancreas

A

endocrine - islets of langerhans
glucagon - alpha cells
insulin - beta cells
somatostatin - delta cells

exocrine - acinar cells 
trypsinogen 
chyotrypsin 
carboxypolypeptidase 
proelastase 
pancreatic amylase 
lipase
27
Q

what creates the bulk of the pancreas

A

exocrine cells - acinar cells

28
Q

trypsinogen is activated by __ and converted to __

where is the activation enzyme secreted

A

activated by enterokinase - secreted from enterocytes

converted to trypsin

29
Q

most of the water and food is absorbed where

A

large intestine

30
Q

what produces vitamins in the large intestine

and what vitamin

A

bacteria produce vitamin k in large intestine

31
Q

the large intestine contains many __ which secrete mucus to aid in passage of feces

A

goblet cells

32
Q

carbs and amino acids are absorbed where

fats are absorbed where

bile salts are absorbed where

A

duodenum and jejenum

ileum

distal ileum

33
Q

where is vitamin K produced in the GI

A

colon or large intestine by bacteria

34
Q

water soluble vitamins are absorbed how

fat soluble vitamins are absorbed how

A

water soluble - secondary active transport using Na amino acid co transporters - then exit enterocytes via passive diffusion

fat soluble - same as fat

35
Q

iron is absorbed where

A

jejunum

36
Q

iron combines with __ in the blood to form __

iron combines with __ in the cells to form __

A

apotransferrin –> transferrin

apoferritin –> ferritin

37
Q

what does transferrin do

A

transfers iron to liver, spleen, bone marrow

38
Q

iron is released by cells to form what

A

hemoglobin and myoglobin

39
Q

vitamin B12 and intrinsic factor form a complex that is delivered to the ____ where it is bound to __ receptors on the enterocytes and transported to portal vein

A

terminal ileum

cubulin receptors

40
Q

what is the livers role in fat, protein, and carb metabolism

A

makes fat and cholesterol

builds proteins

carbohydrate metabolism

41
Q

what substances and vitamins does the liver store

A

glycogen

vitamin A, D, and B12

42
Q

what organ detoxifies toxic substances such as drugs and alcohols

A

liver

43
Q

where does bilirubin conjugation occur

A

liver

44
Q

what liver cells are associated with immune function

A

kupffer cells

45
Q

what organ makes clotting factors and forms red blood cells in the fetus

A

liver

46
Q

bilirubin is a byproduct of ___ breaking down in the ___

A

RBC

spleen

47
Q

how long do RBCs live

A

120 days or 4 months

48
Q

old RBCs are broken down into __ and __

A

heme and globin

49
Q

heme is broken down into __ and __

A

biliverdin and iron

50
Q

biliverdin is converted to __ which is carried in the blood by __

A

bilirubin

albumin

51
Q

the unconjugated form of bilirubin is __ soluble

the conjugated form of bilirubin is __ soluble

A

fat soluble

water soluble

52
Q

where is bilirubin conjugated in the body

bilirubin is conjugated to what by what enzyme

A

liver

glucoronide by glucuronyl transferase

53
Q

once bilirubin is conjugated it is secreted into the ___ , where __ (bilirubin + bile salts) is released that saponifies fat to make it more digestable

A

gall bladder or biliary tree

bile

54
Q

bilirubin in the gut is converted to what

A

urobilinogen

55
Q

urobilinogen is converted to __ which is then excreted in the __

the rest of the urobilinogen in the gut is converted to __ which is oxidized to __ which is excreted in the __

A

urobilin (gives urine its color)

urine

stercobilinogen

sterobilin (gives stool its color)

stool

56
Q

what percent of bile salts are reabsorbed and sent back to the liver through enterohepatic circulation

A

95%

57
Q

what are the roles of the gall bladder?

when is bile secreted from gall bladder?

A

stores bile - 50 cc
concentrates bile

excretes bile when fat is present in duodenum (CCK)

58
Q

what is the gall bladder controlled by

A

CCK - released when fat is present in duodenum

causes contraction of gallbladder which releases bile

59
Q

what causes the gall bladder to contract and secrete bile

A

CCK

60
Q

what are the endocrine secretions for the gut in charge of

gastrin 
somatostatin 
gastric inhibitory peptide 
CCK
secretin 
glucagon like peptide 1 
ghrelin 
motilin
A

gastrin - G cells in pyloric antrum of stomach - HCL secretion, gastric motility, delay gastric emptying - stimulated by vagal and alcohol

somatostatin - D cells in stomach and delta cells in islet of langerhans in pancreas - inhibits HCL secretion, gallbladder contraction, pancreatic secretion - stimulated by acidic PH

gastric inhibitory peptide - K cells in SI - decreases HCL secertion, increases insulin secretion - stimulated by glucose and fat in duodenum

CCK - I cells in SI - increase bile release from gallbladder, pancreatic enzymes, contraction of gall bladder, relax sphincter of oddi and lower (cardiac esophageal sphincter - stimulated by fat in duodenum

secretin - S cells in crypts of lieberkuhn in intestine - increase bicarbonate release from pancreas, decrease HCL secretion - stimulated by acidic PH

glucagon like peptide 1 - K cells in duodenum and jejunum - inhibits gastric emptying

ghrelin - P cells in stomach - increased before meals and decreased after meals - stimulates hunger

motilin - M cells in duodenum - controls cyclical movement of the gut and increases during fasting state