GI I

Question 1

bolus

Answer 1

food ball made from saliva and chewing in mouth

Question 2

what does the large intestine absorb?

Answer 2

fluid and electrolytes

Question 3

liver blood supply

Answer 3

25% from celiac artery

75% from portal vein (drains from GI system)

Question 4

how much blood pools in the liver

Answer 4

10%, 500mL

Question 5

how much nutrients does the liver take (first pass)

Answer 5

1/3-1/2 of nutrients

not fat or suppositories

Question 6

how is the GI wall organized?

Answer 6

inner layer is absorptive/secretory cells
submucosa: motility and endocrine responses
muscularis externa: motor innervation

Question 7

what 3 elements are the control mechanism for GI functiin

Answer 7

hormonal
neuronal
myogenic

Question 8

what are the 6 gastric hormones and their source?

Answer 8

gastrin- G cells (stom, duo)
CCK- I cells (duo, jej)
Secretin- S cells (duo, jej)
GLIP/GLP- K cells, L cells (duo, jej)
Motillin- M cells (duo, jej)
Somatostatin- D cells (pancreatic islets, GI mucosa)

Question 9

what does gastrin do?

Answer 9

increases acid secretion, mucosa growth, motility

Question 10

what does CCK do?

Answer 10

increase pancreatic bicarb, contraction of gallbladder/relax oddi
decrease gastric emptying

Question 11

what does secretin do?

Answer 11

increases pancreatic and billiary bicarb secretion

decrease gastric acid secretion, growth of mucosa

Question 12

what does GIP/GLIP do?

Answer 12

increases pancreatic insulin secretion

decrease gastric acid secretion

Question 13

what does motillin do?

Answer 13

increases migrating motor complex during fasting

so no SIBO

Question 14

what does somatostatin do/?

Answer 14

decrease gastric acid secretion
decrease pancreatic bicarb
decrease gallbladder contraction

Question 15

does sym NS or para NS have direct connection with GI muscles and cells?

Answer 15

sym NS

for fight or flight response

Question 16

what are the 3 enteric NT? fx?

Answer 16

Ach- parasym effects
VIP relax smooth muscle
GRP- increase gastrin secretion

Question 17

are ICPs coupled to themselves or SMCs?

Answer 17

BOTH

Question 18

what are the pacemakers in the GI system?

Answer 18

ICCs innervated by ENS
slow wave mechanism, contraction when threshold achieved (spike)
more spikes= larger contraction

Question 19

what are the three things that control GI blood supply

Answer 19

arteriole control
ANS command
local events

Question 20

what are the vasodilators for the GI arterioles?

Answer 20

NO
VIP
Ach
Substance P

Question 21

when you are in shock what does that do to your absorption

Answer 21

ischemic villus (impaired)

Question 22

what are the two local events that can change blood supply?

Answer 22

metabolic (changes in oxygen)

myogenic (stretch/tension)

Question 23

what are the three things that make up peyers patch?

Answer 23

m cell- IGA secretions
SED (subepithelial dome) and SIGA secretion
TDA (thymus dependent area) t cells enzymes and secretions

Question 24

what can radiation cause in GI?

Answer 24

low surface area (less absorbtion)

low goblet cell (less mucous)

Question 25

does sympathetic or parasympathetic make saliva more protein rich?

Answer 25

sympathetic

Question 26

when is the saliva more hypotonic?

Answer 26

low flow rates 155mEq less basic

Question 27

when is saliva less hypotonic?

Answer 27

high flow rates 220mEq more basic (pH8)

Question 28

why does flow rate effect Na and Cl so much?

Answer 28

contact time

Question 29

why does flow rate effect HCO3 so much?

Answer 29

selectively stimulated by parasympathetics, levels at 2mL/min

Question 30

what are the key cells for gastric secretion

Answer 30

``` mucous (mucous) parietal (Hcl, instinsic factor) ECL (histamine) chief cell (pepsinogen, gastric lypase) D cell (somatostatin) G cell (gastrin) ```

Question 31

what is imperitive for gastric secretions?

Answer 31

vagus innervation stimulates all

Question 32

what is the optimal pH for pepsin?

Answer 32

1.8-3.5pH

Question 33

what pH is pepsin REVERSIBLY inactivated?

Answer 33

at pH 5

Question 34

what pH is pepsin IRReversibly inactivated?

Answer 34

>pH7-8

Question 35

what is the vago-vagal reflex?

Answer 35

like you are eating a bAGEL: | stomach distension, vagel afferents send to CNS then vagal efferents increase digestion

Question 36

what 3 substances stimulate gastric acid (HCl) release?

Answer 36

Ach (vago vagal) hormone gastrin ( two pathways) local histamine release (ECL cells)

Question 37

what stimulates somatostatin?

Answer 37

H+ stimulate D cells to release SS and inhibit all 3 cells types G cell, ECL, parietal to stop gastric acid

Question 38

histamine receptor antagonism effect?

Answer 38

block histamine from ECL from binding to parietal cell | decrease gastric acid

Question 39

NSAIDs effect?

Answer 39

blocks prostaglandins and "inhibit the inhibitor" | increase gastric acid

Question 40

proton pump inhibitor effect?

Answer 40

blocks proton pump and decrease in acid

Question 41

what are the factors that protect the stomach from digesting itself?

Answer 41

``` mucins (gels) trefoil factor family (stabilize mucosa) bicarb epithelial replacement tight junctions ```

Question 42

what is the pH of pancreatic juice?

Answer 42

8.6, isotonic to plasma

Question 43

compare and contrast the composition of saliva vs pancreatic juices

Answer 43

see notes

Question 44

what breaks down protein, carbs and fat in pancreas?

Answer 44

protein- protease carbs- amylase fat- lipase/colipase

Question 45

why dont the pancreatic enzymes digest itself?

Answer 45

they are stored in inactive form

Question 46

what is secreted during oral glucose load

Answer 46

GIP

Question 47

what is inhibited in very acidic conditions (<1.5)

Answer 47

gastrin

Question 48

what 2 things cause bile to go into gallbladder?

Answer 48

hepatic secretion pressure | pressure from closure of oddi

Question 49

how is the bile concentrated?

Answer 49

Cl and bicard are pumped out with water

Question 50

what is the ideal bile:lectin:cholesterol ratio?

Answer 50

10:3:1

Question 51

why does the bile:lectin:cholestrol ratio matter?

Answer 51

to maintain solubility | increased cholesterol, decreased bile or lectin cause gallstones

Question 52

describe the process of gallbladder releasing bile

Answer 52

see chart

Question 53

what % of bile acid pool is reabsorbed in the ileum?

Answer 53

95%

Question 54

what absorbs bile in the ileum?

Answer 54

apical sodium dependent bile salt transporter

Question 55

describe the circulation of bile salts

Answer 55

see chart

Question 56

what percent of bile is lost in feces?

Answer 56

5%

Question 57

what are the 5 functions of the liver?

Answer 57

``` carb metabolism synthesis of plasma proteins synthesis of lipoproteins immunity inactivation of toxins ```

Question 58

what is the liver triad?

Answer 58

portal venule portal arterioles bile duct

Question 59

what does the liver do for immunity?

Answer 59

kupffer cells produce lymph

Question 60

what is kernicterus?

Answer 60

brain damage in children from the build up of bilirubin

Question 61

how is bilirubin made?

Answer 61

degredation of heme

Question 62

unconjugated bili

Answer 62

toxic | binds albumin, lipid soluble (enters cells)

Question 63

conjugated bili

Answer 63

non toxic water soluble bili glucuronide

Question 64

what does the liver do with bili?

Answer 64

uptakes and traps with Y&Z protein conjugates with glucuronic acid secrets through bile to SI

Question 65

where is bile exreted?

Answer 65

bile/gut 80% urobilinogen liver 18% reuptakes kidney 2% exretes as urine urobillnogen

Question 66

what does cirrhosis cause?

Answer 66

ascites