salivary and gastric secretions

Question 1

what secretions are added to the lumen of the GI tract (exocrine)

Answer 1

saliva
gastric acid and secretions
pancreatic secretions
bile

Question 2

describe the characteristics of saliva

Answer 2

high bicarbonate
high potassium
hypotonic
contains alpha amylase and lingual lipase

1 L per day

Question 3

what factors increase salivary secretion

Answer 3

primarily parasympathetic but also sympathetic

No hormonal control

Question 4

what factors decrease secretion

Answer 4

sleep
dehydration
atropine

Question 5

what is the function of saliva

Answer 5

Initial digestion of starches and lipids
Dilution and buffering of ingested foods
Lubrication of ingested foods with mucous (mucin)

Question 6

describe the function of the parotid glands

Answer 6

• Serous cells secreting an aqueous fluid composed of water,
ions and enzymes

very high blood flow

Question 7

what makes up mucin

Answer 7

glycoprotein for lubrication

Question 8

what do acinar cells produce

Answer 8

an initial
isotonic saliva composed of
water, ions, enzymes and
mucus

Question 9

what do myoepithelial cells do

Answer 9

stimulated by neural input to eject saliva

Question 10

what do ductal cells do

Answer 10

modify the initial
saliva by altering electrolyte
concentrations

Question 11

how is saliva modified

Answer 11

– Absorption of Na+ and Cl-
– Secretion of K+ and HCO-
3
– Becausemore NaCl is absorbed
than KHCO3 secreted there is net
absorption of solute so hypotonic
– Low water permeability of ductal
cells means that the final saliva is
hypotonic

Question 12

what substances are secreted by the acinar cells

Answer 12

amylase
Lingual lipase-digestion of lipids
Mucus-lubricant
Kallikrein
enzymatic cleavage of kininogen to bradykinin (potent
vasodilator)

Question 13

how does neural stimulation affect the salivary glands

Answer 13

increased saliva
production, HCO-
3 production, enzyme secretion and
myoepithelial cell contraction

Question 14

what substances digest protein

Answer 14

HCl and pepsinogen

Question 15

what is the function of intrinsic factor

Answer 15

vitamin B12 absorption in the ileum

Question 16

what is the function of mucus

Answer 16

protects mucosa and lubrications

Question 17

what increases secretion of HCl

Answer 17

gastrin

Question 18

what increases and decreases secretion of pepsinogen

Answer 18

acetylcholine

chyme in duodenum

Question 19

what increases secretion of intrinsic factor

Answer 19

histamine and parasympathetic NS

Question 20

what decreases secretion of intrinsic factor

Answer 20

Somatostatin
Atropine
Cimetidine
Omeprazole

Question 21

where are stomach parietal cells found

Answer 21

body

Question 22

where are chief cells found

Answer 22

body

Question 23

where are G cells found

Answer 23

antrum

Question 24

what are invaginations of the stomach called

Answer 24

gastric glands

they increase surface area

Question 25

describe the layers of the stomach (inside to out)

Answer 25

``` mucosa and epithelia lamina propria muscularis mucosae submucosa muscularis externa ``` also submucosal plexus and myenteric plexus

Question 26

name the cells in an oxyntic (gastric) gland

Answer 26

surface epithelium mucous neck cells parietal cells peptic/chief cells

Question 27

what cells release HCl and intrinsic factor

Answer 27

oxyntic/ parietal cells

Question 28

what cells release pepsinogen

Answer 28

chief cells aka peptic cells

Question 29

what pH is the stomach

Answer 29

1-2

Question 30

what is responsible for conversion of pepsinogen to pepsin

Answer 30

low pH

Question 31

what is carbonic anhydrase

Answer 31

CO2 + H2O > carbonic acid

Question 32

how is HCl secreted through the apical membrane

Answer 32

– H+ is secreted into the lumen via the H+-K+ ATPase | – Cl- follows by diffusion through an apical channel

Question 33

describe the events at the basolateral surface in order to secrete HCl

Answer 33

bicarbonate ion is exchanged for Cl- via an exchanger (no ATP needed) Na+ is swapped for K+ using ATP

Question 34

what is the cephalic phase of HCl release

Answer 34

30% of secretion – Smell, taste, chewing, swallowing, conditioned reflex in anticipation of food * Direct stimulation of the parietal cells by the vagus * Indirect stimulation of the parietal cells by gastrin

Question 35

what peptide stimulates gastrin release from G cells

Answer 35

Vagal gastrin releasing peptide (GRP) | this enters the circulation and stimulates parietal cells

Question 36

what causes the gastric phase of HCl secretion

Answer 36

60% of secretion – Distension of the stomach and the presence of breakdown products of proteins, amino acids and small peptides in the stomach

Question 37

how does distension lead to HCl release

Answer 37

– direct vagal stimulation of parietal cells – indirect stimulation via gastrin – local reflexes in the antrumthat stimulate gastrin release

Question 38

what neurotransmitter is responsible for vagal activation of parietal cells via the direct pathway

Answer 38

ACh

Question 39

what is the indirect vagal pathway

Answer 39

Vagal stimulated release of gastrin fromG cells (byGRP neuropeptide transmitter )

Question 40

how do amino acids and peptides stimulate Hcl release

Answer 40

they cause gastrin to be released

Question 41

what is the intestinal phase of HCl secretion

Answer 41

10% of secretion – presence of breakdown products of proteins in the duodenum

Question 42

what messengers are used in vagal stimulation of parietal cells

Answer 42

ACh and IP3/ Ca2+ muscarinic 3 receptors on parietal cells

Question 43

how does histamine stimulate Hcl secretion

Answer 43

secreted by Enterochromaffin like cells (ECL) in the gastric mucosa Diffuses to and binds to H2 receptors on parietal cells second messenger is cyclic AMP

Question 44

what receptors does gastrin bind to on parietal cells

Answer 44

CCKB receptors IP3/Ca2+ is the second messenger

Question 45

what does somatostatin do

Answer 45

inhibits Hcl secretion – Direct pathway – binds to receptors on parietal cells and inhibits adenylate cyclase via Gi protein – Indirect pathway – inhibits histamine release from ECL cells and gastrin release from G cells

Question 46

what causes secretion of pepsinogen from chief and mucous cells

Answer 46

vagal stimulation and H+ triggers local reflexes which stimulate chief cells

Question 47

what causes pernicious anaemia

Answer 47

lack of intrinsic factor

Question 48

what cells release mucoprotein containing intrinsic factor

Answer 48

parietal cells

Question 49

what is a gastrinoma

Answer 49

a tumor in the pancreas or duodenum that secretes excess of gastrin leading to ulceration in the duodenum, stomach and the small intestine. There is hypersecretion of the HCl acid into the duodenum, which causes the ulcers. also causes hypertrophy and inactivation of pancreatic lipases

Question 50

how many lumbar veins are there

Answer 50

4 joining the IVC and one joining the common iliac

Question 51

what do the sublingual glands produce

Answer 51

mucus

Question 52

what is cimetidine

Answer 52

histamine 2 antagonist that inhibits stomach acid production | used in heart burn and peptic ulcers

Question 53

what is omeprazole

Answer 53

PPI | GERD and peptic ulcers not heartburn

Question 54

what is zollinger ellison syndrome

Answer 54

gastrin secreting tumour in the pancreas

Question 55

what is the difference between pepsin and trypsin

Answer 55

pepsin is produced in the stomach and trypsin is made in the pancreas

Question 56

where does omeprazole act

Answer 56

H/K atp ase

Question 57

where does cimetidine act

Answer 57

H2 receptors

Question 58

where is pepsinogen secreted from

Answer 58

cheif cells