Lecture 5 Part 2 Flashcards
what are ways to describe a hormone
- composition
- source
- stimulus
- target
- action
what is a hormone
substance secreted from ductless gland from source to target tissue
when you eat something, what will most likely be produced
gastrin
gastrin
- composition: polypeptide
- source: gastric mucosa
- stimuli: stomach distention, dietary proteins, fats, carbs, alcohol and caffeine, vagus nerve
- target: gastric glands
- action: secretion of HCl and pepsin
gastric mucosa
stomach lining
stomach distention
causes stretching
- when you eat something
what causes the most stimulation of gastrin
dietary proteins
what is vagus nerve stimulation
- stimulated when you eat
- most closely interacted nerve of gastro intestinal system
what inhibits gastrin production
acid feedback
- negative feedback system
- HCl raises because gastrin stimulates it
- negative feedback regulates this action so don’t burn hole in stomach
pepsin
breaks down peptide bonds
vagus nerve and gastrin relationship
- parallel pathways
- vagus nerve stimulates HCl and pepsin
- vagus nerve turns on gastrin
what is the difference between vagus stimulation and gastrin production
vagus stimulation is short term (immediate) and gastrin production is long term
secretin
- composition: polypeptide
- source: SI mucosa
- stimuli: presence in SI of Hcl, polypeptides of dietary origin
- target: pancreas
- action: secretion of water and bicarbonate (pancreatic and bile)
what does the action of secretin do
- secretion of water
- secretion of bicarbonate
- neutralizes gastric acid
- adds liquid to lumen
CCK
cholecystokinin
what is another name for cholecystokinin (CCK)
pancreozymin
CCK
- composition: polypeptide
- source: SI mucosa and brain
- stimulus: presence in SI of peptides and fats
- target: several organs and tissues
- multiple actions (another slide for this)
SI mucosa
small intestine lining
action of CCK
- empties gall bladder
- stimulates synthesis of pancreatic enzymes
- inhibits HCL
- delays gastric emptying
- regulates blood glucose
- produces satiety
how does CCK empty the gall bladder
contracts gall bladder and pancreas
- bile helps break down
why would CCK be beneficial in slowing gastric emptying
- slows down food briefly
- want to give time for enzymes to work
how is the regulation of blood glucose from CCK helpful
enhances insulin release
what does producing satiety do
provides feeling of being full/not hungry
why do dietary fats and fiber delay gastric emptying
- these usually take longer to digest
- allows for more time to for digestion in SI
- effect of this may be medicated by CCK
what is the meaning of GIP
gastric inhibitory polypeptide
GIP
- composition: polypeptide
- source: duodenum (small intestine)
- stimulus: presence in SI of fats, glucose, and bile
- target: stomach
- action: HCl production and gastric mobility
what do fats do
stimulate release of fats
what is the main action of GIP
HCl production
motilin
- composition: polypeptide
- source: duodenum and jejunum (small intestine)
- stimulus: will vary (on other cards)
- target: entire GIT
- action: housekeeping during fasting (90-100 minutes) and stimulates gastric motor activity
what are the stimulus of motilin
- nerve stimulus
- species differences between meal stimulus (fats and proteins)
how does motilin perform “housekeeping”
- pattern
- sweeping/moving food through intestinal track so it doesn’t just sit
- cause contractions of intestine
somatostatin
- master controller
- secreted at end
1. composition: polypeptide
2. source: abomasal antrum, duodenum, nerve cells in GIT
3. stimulus: vagal stimulation
4. target: pancreas
5. action: turn off all other GIT hormones
what are some of the actions of somatostatin
turn of all other GIT hormones by inhibiting the following:
- acid production
- gastrin
- secretion
- CCK
- GIP
- motilin
- ion transport in intestines
