gastric function: git hormones

Question 1

hormones and communication:
- Digestive motility and secretion are carefully regulated to — digestion and absorption of ingested food.
- GI tract is the largest — organ in the body - produces < — substances that have a diverse range of roles: gastrointestinal motility, absorption, and growth; control of glucose homeostasis, appetite, and metabolism
-Hormones are stored in specific — storage granules cells, which are subsequently released by —

❑ AUTOCRINE– communicate within the — cell
▪ Some cells possess — for their own messengers
❑ PARACRINE– communicate with — cells
❑ ENDOCRINE – communicate with — cells
▪ Secreted into —

Answer 1

maximise
endocrine
20
peptide
exocytosis
same
cell surface receptors
nearby
distant
bloodstream

Question 2

HORMONES AND THE GASTROINTESTIONAL TRACT
❑ Major GIT Hormones:
▪ — and — (CCK)
▪ –
▪ Various others

❑ Non-gastric actions
▪ Pancreatic — cells and —
▪ — glands

❑ Regulation of —

Answer 2

gastrin and cholecystokinin
secretion
pancreatic acinar and bile
duodenal brunners
food intake

Question 3

GASTRIN AND CHOLECYSTOKININ (CCK)
❑ Structurally-related — hormones
▪ Share a — aa — terminal sequence essential for receptor— - both act on — receptors
▪ CCK1 (CCKA) — specific receptor
▪ CCK2 (CCKB) — and — are CCK2R ligands with similar — and —

Answer 3

peptide
four aa
c terminal
receptor activation
CCK receptors
CCK
CCK and gastrin
affinity and potency

Question 4

GASTRIN
RELEASE
❑— in the — of the stomach, some in —
1- Stimuli that increase gastrin secretion:
▪ — and —
▪ Gastric —
▪ — stimulation
▪ Presence of —

2- Stimuli that inhibit
gastrin secretion
▪ Accumulation of — in
stomach ( — pH)
▪ —
▪ — , — , — , —

Answer 4

g cells
pyloric antrum
duodenum
peptides and amino acids
gastric distension
vagal
gastrin-releasing peptides GRP
acid
decreasing
somatostatin
secretin , GIP , VIP , glucagon

Question 5

GASTRIN
FUNCTIONS
❑ Acts to — secretion of — from — cells
➢ directly binding to — receptors on — cells
➢ Indirectly stimulating release of — from — cells ( — effect)
- Increased H+ feeds back to — of the antrum to release — to turn off — release
❑ Enhances gastric —
❑ Stimulates the — of stomach mucosa ( —- effects) - helps maintain well-developed,
functionally viable digestive tract lining

Answer 5

increase
acid
oxyntic
CCK2
parietal cells
histamine
ECL
paracrine
d cells
somatostatin
gastrin
motility
growth
proliferative

Question 6

GASTROINTESTINAL HORMONES
CHOLECYSTOKININ (CCK):

RELEASE
❑ From— in — ( — , — )
❑ Stimulated by increased levels of — / — & — (fats & protein) in —
FUNCTIONS:
❑ Most actions are on — and —
▪ Stimulates — of the — with simultaneous — of the — of — (allows bile and —- to flow between the pancreas and the small intestine)
▪ Stimulates secretion of— enzymes: lipases, amylase, and proteases
▪ Secretion of —- from the —
❑ Inhibits —-

❑ Effects on oxyntic cells:
▪ Indirectly — secretion of acid – binding to — receptors on D cells, stimulating release of —
▪ Some action at CCK2 (very – effect on acid secretion)

Answer 6

I cells
small intestine ( duodenum and jejunum )
FA , monoglycerides , aa
duodenum
pancreas and gallbladder
contraction of gallbladder
relaxation
sphincter of oddi
pancreatic juices
pancreatic enzymes
bicarbonate
pancrease
gastric emptying
decreases
CCK1
somatostatin
weak

Question 7

GASTROINTESTINAL HORMONES
SECRETIN
RELEASE
❑ Released from — mostly in the — .
❑ Stimulated in response to the presence of — in duodenum and to a lesser extent, — .

FUNCTIONS
❑ Main function is to — acid in the intestine by effects on secretions from the pancreas and gallbladder
▪ Secretion of large volumes of —- from the pancreas
▪ Stimulates — to secrete bicarbonate-rich bile which assists in —- process.
❑ inhibit gastrin, gastric motility & acid secretion (via — )
▪ Inhibits — in order to prevent further acid from entering
duodenum until acid already present is —
▪ Inhibits gastrin secretion to reduce amount of acid being —

Answer 7

s cells
duodenum
acid
fatty acids
neautralise acid
aqueous bicarbonate
liver
neautralization
somatostatin
gastric emptying
neutralise
produced
check slide 12 for summary

Question 8

GASTROINTESTINAL HORMONES
SOMATOSTATIN
RELEASE
❑ — cells of the — , — and —
▪ CCK ( — receptor) and — (muscarinic receptor) stimulate release in response to presence of — in duodenum, —- blood glucose/amino acids
FUNCTIONS
❑ Mainly — actions: —- all the activities of the gastrointestinal tract,decreases motility and gastric secretion, suppresses hormone release.
❑ In response to increased acid (decreasing pH), D cells to secrete — and reduce the amount of acid being produced:
▪ Directly: inhibitory effects on — cells (decreased cAMP production → — H+ secretion)
▪ Indirectly via inhibition of — and — release. D cells in close
proximity to gastrin-producing cells secrete somatostatin and inhibit gastrin release by a — effect.
▪ Inhibits gastric emptying in order to prevent further acid from entering duodenum until acid already present is neutralized.

Answer 8

delta cells
stomach , dududeum , pancreatic islets
CCK1
ACh
acid
increased
inhibitory
suppresses
somatostatin
oxyntic
decreased
gastric anf histamine
paracrine

Question 9

MOTILIN
❑ Peptide released from — cells of the mucosa during — to stimulate gastrointestinal —
▪ During the fasting state, plasma levels of motilin fluctuate, released in ~ — min cycles and increases gastrointestinal motility by stimulating the migrating — complex in the absence of food that moves through the fasting stomach and small intestines (‘ —-’).
▪ This — release and action get inhibited by the — of food requires — presence of food
▪ — role → helps clear intestine of — & residual — material.

Answer 9

endocrine cells
fasting
gastrointestinal motility
90 min
migrating motor complex
rumbling
cyclical
ingestion
physical
housekeeping role
forge in bodies and residual indigested

Question 10

SEROTONIN (5-HT)
❑ Released from — cells in response to mechanical or chemical — of GI tract- e.g.
presence of — and —
▪ Increased — activity e.g. emptying of a noxious substance from the GIT
❑ Excessive activation of — sensory afferent 5-HT3 receptors in — trigger zone induces — and —
▪ Blocking of 5-HT-3 receptors is very effective as an —

Answer 10

enterochromaffin
irritation
drugs or toxins
contractile
vagal
chemoreceptors
nausea and vomitting
anti emetic

Question 11

GASTRIC INHIBITORY POLYPEPTIDE (GIP)
❑ Released from — ( —mucosa) in response to the presence of food in the — small
intestine.
❑ Also known as —-dependent insulinotropic polypeptide
▪ Major action is the stimulation of — secretion (insulinotrophic peptide).
▪ Lesser (weak) roles: Inhibits gastric acid secretion and motility – slows gastric emptying when
the upper small intestine is full of food products – requires higher than normal physiological
levels.

Answer 11

k cells
duodenal
upper small intestine
glucose
insulin

Question 12

VASOACTIVE INTESTINAL PEPTIDE (VIP)
❑ Vasoactive peptide hormone
❑ Induces smooth muscle — (lower esophageal sphincter, stomach, sphincter of Oddi) –
mediates —-induced reflexes
❑ — of gastric acid secretion
❑ Stimulates pancreatic — secretion

Answer 12

relaxation
smooth
distention
inhibition
bicarbonate

Question 13

exocrine pancreatic secretions:
PANCREATIC SECRETIONS

Pancreas has both — and — secretions
❑ Endocrine secretions (in the —): — and —
❑ Exocrine (into — ): can be thought of as an —-
component and a —/— component

EXOCRINE SECRETIONS
❑ — — cells
▪ Produce – volumes of — solution, mainly — , —

❑ Acinar cells
▪ Produce – volumes of —-rich “juice”
▪ Inactive precursors of the digestive enzymes, — , — etc.

Answer 13

endocrine and exocrine
blood
glucagon anf insulin
ducts
aqueous
proteinaceous/enzymatic
ductal epithelial cells
large
aqueous
Na+ and HCO3-
smaller
protein rich
tryspisnogen anf chymotrypsinogen

Question 14

stimulation of exocrine pancreatic secretions:
Cephalic (Reflex) and Gastric Phases

1- Cephalic phase
Sight, taste, or smell of food ( — nerve)
❑ Stimulates pancreatic — cells to release — enzymes
❑ Stimulates —- cells to secrete —- and —

2-Gastric phase
Presence of food in the — ( — and — ) stimulates — secretions—primarily from the — cells—through two routes:
❑ Distention of the stomach activates a —- reflex
❑ Protein digestion products (—) stimulate —in the antrum of the stomach to release—.

Answer 14

vagus nerve
pancreatic acing
digestive enzymes
duct cells
HCO3- and fluid
stomach
stretch anf chemoreceptors
pancreatic secretions
acinar cells
vagovegal
peptones
g cells
gastrin

Question 15

STIMULATION OF EXOCRINE PANCREATIC SECRETIONS
Intestinal Phase
CCK
▪ Increased levels of — & — in duodenum stimulates secretion of CCK
Results in:
▪ Increased — production (by — cells).

Secretin
▪ Increased — in duodenum stimulates secretion of secretin
Results in:
▪ Increased secretion of —
solution (by 000 cells).
▪ Increases — and —

Answer 15

fatty and amino acids
enzyme production
acing cells
acid chime
aquaous bicarbonate
ductal cells
volume and pH
check slide 20

Question 16

regulation of bile secretion:
❑ Bile is secreted by — , stored in
the — and released into —
❑ Crucial for — digestion, consists of — , — , — , — , —

Answer 16

hepatocytes
gall bladder
duduemon
fat digestion
water, bilirubin,
cholesterol, bile salts
and other fats

Question 17

brunners gland:
❑ — -secreting glands in the — layer of the —
▪ Secrete — and — that protects the duodenum from — content of the stomach.
❑ Mucus secretion in response to:
▪ Presence of — in the duodenum (distension, irritation)
▪— stimulation.
▪ Also — , — , released by the arrival of food into
the duodenum.
▪ Secretion is decreased by — stimulation

Answer 17

mucuous
submucosusal
duodenum
mucus and HCO3-
acidic
food
vagal
cck , secretin
sympathetic

Question 18

CONTROL OF FOOD INTAKE
❑ Central regulation of food intake occurs in the — .
❑ The hypothalamus receives signals from various — pathways, those involved in digestion but
also emotion / behaviour / reward.
❑ Hormones that regulate food intake can be separated into those that act — to influence individual meals, and those that act more slowly to promote the —- of body fat stores.
❑ The two efferent pathways from the hypothalamus are:
▪ Inhibition of food intake and — metabolism
▪ Stimulation of food intake and — of metabolism (— )

Answer 18

hypothalamus
neurhumoral
rapidly
stability
increase
inhibition ( orexigenic)

Question 19

control of food intake:
GASTRIC CONTROL
Local gastric stimuli pass information back to the —
▪ — -duration, meal-related ‘satiety’ signals released from the gastrointestinal tract during
eating.
▪ Distension of the stomach stimulates — afferents and inhibition of feeding.
CCK
▪ Released due to presence of food in the — stimulates satiety both by stimulating — afferents and — release.
Peptide YY
▪ Released by — cells by —
products stimulates satiety – direct inhibition of — nerves.

Answer 19

hypothalamus
short
bagel
small intestine
vagal and insulin
enteroendocrine cells
digestion products
NYP orxigenic

Question 20

control of food intake:
1- INHIBITORY ( —- ) PATHWAY
▪ Releases melanocortins derived from proopiomelanocortin ( — ), a precursor molecule
that can be cleaved in different ways to produce several — products.
▪ Melanocortins — appetite, thus leading to — food intake and —
2-STIMULATORY ( — ) PATHWAY
▪ Releases —- ( — ) – neurotransmitter leads to — food intake. One of the most potent appetite — ever found.
The two pathways are mutually exclusive – stimulation of
the POMC pathway — NPY and vice versa.

Answer 20

MELANOCORTIN
POMC
hormone
suppress
reduced
weight loss
orexigenic
neuropeptide Y (NYP)
increased
stimulators
inhibits

Question 21

control of food intake:
PERIPHERAL CONTROL
Vagus nerve contains numerous — fibres that rely information back to the —
▪ Vagal stimulation induces — and — feeding.
▪ Blocking of the vagal afferent eliminates — .

Insulin
▪ Released from pancreatic — cells — a meal, acts
directly on the — to induce —.

Leptin
▪ Released from — , stimulates the — pathway and inhibits the — pathway.
Insulin and leptin act as —-term — released into
the — in proportion to the amount of body fat and exert
sustained inhibitory effects on food intake while increasing
energy expenditure.

Answer 21

afferent
brain
satiety anf inhibits feeding
satiety
pancreatic beta cells
following
hypothalamus
satiety
adipocyte
POMC
NPY
long term regulators
blood

Question 22

control of food intake:
STIMULANTS
❑ Ghrelin ( — hormone)
▪ Released from — glands in the stomach (likely extra-gastric sites too) when the stomach is —
▪ Ghrelin acts — on — neurons.
▪ Ghrelin release is not affected by — intake or — .
❑ — pathways (dopaminergic neurons from the
ventral tegmental area (VTA) of the midbrain) in response to sight, smell taste of food etc.
These can both influence the — but are also
equally affected by — etc.

Answer 22

hunger
oxyntic
empty
directly
orexigenic NPY
protein intake or distension
reward
hypothalamus
leptin