Phys 64

Front 1

tubular glands in the stomach/upper duodenum

Back 1

acid and pepsinogen-secreting gland of stomach

Front 2

what local epithelial stimulations activate the enteric nervous system

Back 2

tactile stimulation, chemical irritation, distention

Front 3

what does secretion of the distal small intestine and first 2/3 of large intestine depend on

Back 3

local neural and hormonal stimuli in each segment of the gut (little parasympathetic innervation)

Front 4

sympathetic stimulation causes what in the gut

Back 4

slight/moderate increase secretion by some glands; constriction of blood vessels-usually causes reduced secretion if copious secretion already occuring

Front 5

what type of hormones are GI hormones

Back 5

polypeptides or polypeptide derivatives

Front 6

where are secretory substances made in glandular cells

Back 6

ER and golgi complex

Front 7

how are secretory granules released

Back 7

control signal increases cell membrane permeability to Ca2+ causing vesicle usion with apical cell membrane

Front 8

water and electrolyte secretion in glandular cells step 1

Back 8

nerve stimulates basal cell to cause active transport of Cl- to cell interior

Front 9

water and electrolyte secretion in glandular cells step 2

Back 9

negative Cl- causes positve ions like Na+ to move into cell

Front 10

water and electrolyte secretion in glandular cells step 3

Back 10

excess ions in interior causes water to follow (osmosis), cell swells

Front 11

water and electrolyte secretion in glandular cells step 4

Back 11

P in cell initiates minute openings of secretory border of cell, causing flushing of water, electrolytes, and organic materials out of secretory end of glandular cell

Front 12

mucus composition

Back 12

water, electrolytes, mix of several glycoproteins (large polysaccarides bound with much smaller quantities of protein)

Front 13

mucus important properties

Back 13

1) adhere tightly to food/particles and spread as thin film over surfaces 2) coats wall of gut 3) low resistance for slipage 4) causes fecal particles to adhere to one another 5) resists degredation by GI enzymes 6) amphoteric properties (can buffer)

Front 14

principle glands of salivation

Back 14

parotid, submandibular, sublingual (and buccal)

Front 15

normal daily secretion of saliva

Back 15

800-1500 ml

Front 16

2 types of protein secretion of saliva

Back 16

1) serous secretion containing ptyalin (alpha-amylase) 2) mucus secretion with mucin for lubrication and surface protection

Front 17

secretion of parotid glands

Back 17

almost entirely serous

Front 18

submandibular and sublingual glands secretion

Back 18

serous and mucus

Front 19

buccal gland secretion

Back 19

only mucus

Front 20

pH of saliva

Back 20

btwn 6 and 7-favorable for ptyalin

Front 21

ions in saliva

Back 21

large quantities of K+ and bicarb; low Na+ and Cl-

Front 22

acini of salivary glands

Back 22

primary secretion that contains ptyalin and/or musin in a soln of ions not greatly different than typical ECF

Front 23

ducts of salivary glands

Back 23

Na+ actively reabsorbed with exchange of K+; bicarb secreted by ductal epithelium into lumen of duct

Front 24

Na+ reabsorption and K+ excretion in salivary gland ducts

Back 24

more Na+ absorbed than K+ excreted creating electrical negativeity of -70 in ducts; thus Cl- reabsorbed passively

Front 25

how are bicarb ions secreted by ductal epithelium

Back 25

passive exchange of bicarb for Cl- ions, some from active secretory process

Front 26

saliva during maximal secretion

Back 26

NaCl rises to one half to 2/3 plasma and K+ rises only 4 times plasma-flow through ducts rapidly

Front 27

what does saliva contain to destroy bacteria

Back 27

thiocyanate ions, several pproteolytic enzymes, and lysozyme; also protein antibodies

Front 28

what nuclei are involved in salivation

Back 28

superior and inferior salvitory nuclei-jxn of medulla and pons

Front 29

sympathetic nerve stimulation of salivary glands

Back 29

can slightly increase salivation; originate in superior cervical ganglia, travel along blood vessels to salivary glands

Front 30

kallikrein

Back 30

vasodilation effect; secreted by salivary glands-acts as enzyme to split blood protein (alpha-2-globulin)to form bradykinin

Front 31

esophageal secretions

Back 31

mucous-provide lubrication

Front 32

oxyntic glands aka gastric glands of stomach

Back 32

secrete HCl, pepsinogen, intrinsic factor, and mucus

Front 33

pyloric glands secrete

Back 33

mainly mucus for protection from stomach acid, also gastrin

Front 34

where are oxyntic glands located

Back 34

inside surfaces of body anf fundus (80% stomach)

Front 35

pyloric gland location

Back 35

antral portion, distal 20%

Front 36

3 cell types in oxyntic gland

Back 36

1) mucus neck cells-mucus 2) peptic/chief cells-pepsinogen 3) parietal/oxyntic cells-Hcl and intrinsic factor

Front 37

HCl secretion in parietal cells step 1

Back 37

Cl- ion actively transported from cytoplasm into lumen of canaliculus, Na+ actively transported out (created -40 to -70 potential in canaliculus), K+ passively diffuse (and some Na+) into canaliculus

Front 38

HCl secretion in parietal cells step 2

Back 38

water dissociated into H+ and OH- in cytoplasm; H+ actively secreted into canaliculus in exchange for K+; Na+ actively reabsorbed into cytoplasm; HCl secreted outward through open end of cancaliculus into lumen of gland

Front 39

HCl secretion in parietal cells step 3

Back 39

water passes into canaliculus via osmosis, thus final secretion contains water with HCl concentration of ~150-160 mEq/L

Front 40

HCl secretion in parietal cells step 4

Back 40

CO2 formed during metabolism or entering cell from blood combines with hydroxyl ions to form bicarb-diffuse into ECF in exchange for Cl-

Front 41

pepsin fxns

Back 41

active proteolytic enzyme at pH 1.8-3.5, almost no fxn above pH 5

Front 42

surface mucous cells

Back 42

btwn glands; secrete very viscid mucus that coats stomach mucosa with gel layer often more then 1 mm thick-alkaline

Front 43

enterochromafin-like cells (ECL cells) primary fxn

Back 43

secrete histamine (which stimulates gastric HCl secretion from parietal cells)

Front 44

where are ECL cell located

Back 44

deep recesses of oxyntic glands, release histamine in direct contact with parietal cells of glands

Front 45

how can ECL cells be secreted to release histamine

Back 45

1) gastrin 2) acetylcholine released from stomach via vagus nerve endings 3) hormonal substances secreted by enteric nervous system of stomach wall

Front 46

gastrin forms

Back 46

large form called G-34 and small form G-17 (more abundant)

Front 47

stimulation of pepsinogen secretion by peptic cells in oxyntic glands

Back 47

1) stimulation of peptic cells by acetylcholine via vagus or enteric NS 2) in response to acid in the stomach

Front 48

3 phases of gastric secretion

Back 48

cephalic, gastric, and intestinal phase

Front 49

cephalic phase of stomach

Back 49

occurs b4 food enters due to sight, smell, thought, taste; 20 % secretion associated with eating a meal

Front 50

where do cephalic phase signals originate

Back 50

cerebral cortex and in appetite centers of amygdala and hypothalamus-transmitted via dorsal motor nuclei of vagi

Front 51

gastric phase of stomach

Back 51

food enters and excites 1) long vagovagal reflexes 2) local enteric reflexes 3) gastrin mechanism; 70% gastric secretion with eating a meal

Front 52

intestinal phase of stomach

Back 52

presence of food in upper small intestine causes stomach to continue secretion, partly due to small amount of gastrin released by duodenal mucosa

Front 53

how does intestinal phase result in inhibition of gastric secretion

Back 53

1) reverse enterogastric reflex via myenteric nervous system, extrinsic sympathetic and vagus 2) release of intestinal hormones inhibit

Front 54

what intestinal hormones are released that inhibit stomach secretions

Back 54

secretin-pancreatic secretion and opposes stomach secretion; gastric inhibitory peptide, vasoactive intestinal polypeptide, and somatostatin-moderate to slight effects in inhibiting gastric secretion

Front 55

gastric secretion composition btwn meals

Back 55

mainly mucus, little pepsin, almost no acid; few ml each hour

Front 56

pentagastrin

Back 56

synthetic gastrin composed of terminal four aas of natural gastrin plus alanine; same physiological properties as natural gastrin

Front 57

most important pancreatic enzymes for digesting proteins

Back 57

trypsin (most abundant), chymotrypsin, and carboxypolypeptidase

Front 58

trypsin and chymotrypsin fxn

Back 58

split whole and partially digested protein into peptides of various sizes-don't cause release of individual aas

Front 59

pancreatic enzyme for carbs

Back 59

pancreatic amylase-hydrolyzes starches, glycogen, and most other cars (except cellulose) to form di and trisaccharides

Front 60

pancreatic enzymes for fat

Back 60

lipase-hydrolyze neutral fat into fatty acids and monoglycerides; cholesterol esterase-hydrolysis of cholesterol esters; phospholipase-splits fatty acids from phospholipids

Front 61

what activates tripsinogen

Back 61

enterokinase-secreted by untestinal mucosa when chyme comes into contact with it; autoactivated by trypsin

Front 62

what activates chymotrypsinogen

Back 62

trypsin, as is procarboxypolypeptidase

Front 63

trypsin inhibitor

Back 63

formed in cytoplasm of glandular cells and prevents activation of digestive enxymes within pancreas

Front 64

pancreatic bicarb

Back 64

mainly via epithelial cells of ductules and ducts that lead from the acini

Front 65

mechanism of bicarb secretion in pancreas step 1

Back 65

CO2 diffuses to interior of cell from blood; carbonic anhydrase forms H2CO3 which dissociates into bicarb and H+; bicarb actively transported in association with Na+ through luminal border into duct

Front 66

mechanism of bicarb secretion in pancreas step 2

Back 66

H+ exchanged for Na+ ions through blood border of cell by secondary active transport

Front 67

mechanism of bicarb secretion in pancreas step 3

Back 67

osmotic P gradient of water into pancreatic duct forming almost isosmotic bicarb soln

Front 68

3 basic stimuli that cause pancreatic secretion

Back 68

acetylcholine, cholecystokinin, secretin

Front 69

cholecystokinin is secreted where

Back 69

duodenal and upper jejunal mucosa when food enters small intestine

Front 70

acetylecholine and cholecystokinin stimulation of pancreas

Back 70

stimulate acinar cells causing production of large quantities of digestive enzymes, but small quantities of water-thus temporarily stored in acini and ducts until more fluid washes them out

Front 71

secretin stimulation of pancreas

Back 71

stimulates larege quantities of water solution of Na-bicarb by pancreatic ductal epithelium

Front 72

phases of pancreatic secretion

Back 72

cephalic (20%, stored in acini), gastric (another 5-10%), intestinal-copious

Front 73

secretin is released by

Back 73

S cells in mucosa of duodenum and jejunum-stimulated by chyme pH less than 4.5 to 5

Front 74

cholecystokinin is secreted by

Back 74

I cells in the mucosa of the duodenum and upper jejunum-release in presence of proteoses and peptones (products of partial protein digestion) and long-chain fatty acids in chyme

Front 75

how do cholecystokinin and secretin reach pancreas

Back 75

via blood

Front 76

total pancreatic secretion per day

Back 76

~1 liter

Front 77

bile acid fxns in digestion

Back 77

emusification and absorption; also serves in excretion of waste products (bilirubin, excess cholesterol)

Front 78

bile flow

Back 78

canaliculi toward interlobar septa into terminal bile ducts, into progressively larger ducts and finally the hepatic duct and common bile duct

Front 79

what is secondary secretion of watery Na+ and bicarb stimulated by in the liver

Back 79

secretin

Front 80

gallbladder absorption

Back 80

active transport of sodium through epithelium, followed by secondary absorption of Cl-, water, and most other diffusible constituents

Front 81

most potent stimulus for gallbladder contractions

Back 81

cholecystokinin-mainly released due to presence of fatty foods; also stimulated by acetylcholine from vagi and intestinal enteric nervous system

Front 82

bile salt synthesizes by liver daily

Back 82

~6 grams

Front 83

cholesterol to bile salts

Back 83

converted to cholic acid or chenodeoxycholic acid which combine with glycine (sometimes taurine) to form glyco or tauro-conjugated bile acids

Front 84

what do bile acids help absorption of

Back 84

fatty acids, monoglycerides, cholesterol, and other lipids via micelles

Front 85

reabsorption of bile acids

Back 85

half diffuse through mucosa in early small intestine, remaining active transport in distal ileum; total 94% reabsorbed

Front 86

Brunner gland location

Back 86

wall of the first few cm of duodenum; mainly btwn pylorus of stomach and papilla of Vater

Front 87

what stimulates Brunner glands secrete

Back 87

tactile/irritating stimuli of mucosa; vagal stimulation; GI hormones, especially secretin

Front 88

fxn of Brunner's glands

Back 88

protect duodenal wall from digestion by highly acidic gastric joice from stomach

Front 89

where are crypts of Lieberkuhn

Back 89

entire surface of small intestine btwn intestinal villi

Front 90

what provides flow of fluid for absorption

Back 90

secretions from enterocytes of crypts reabsorbed by villi

Front 91

two active secretory processes of enterocytes in crypts

Back 91

1) active secretion of cl- into crypts 2) active secretion of bicarb

Front 92

what splits disaccarides into monosaccharides

Back 92

sucrase, malase, isomaltase, lactase

Front 93

life cycle of an intestinal epithelial cells

Back 93

~5 days

Front 94

enzymes of villi cells

Back 94

peptidases, monosaccharide producing enzymes, intestinal lipase (neutral fats into glycerol and fatty acids)