Regulation 5 Flashcards
How does the gut thins
- what does it sense
By chemoreceptors
—) senses changes in
- nutrient concentration
- nutrient degradation products
- osmotic pressure
- pH
And by mechanoreceptors
- sense stretch
What kind of cells are involved in sensing gut stretch (chemoreceptors)
What group of cells is it a part of (what kind of cells are they close to)
What are the black dots at the bottom of the cell
What exactly happens to these when they sense stretch (black dots)
Enteroendocrine cells
It is beside absorptive columnar epithelial cells
They are secretory granules that store hormones and release them when they sense stretch
They fuse with the basolateral membrane and allow hormones to enter the blood stream
Describe how endocrine hormones control GI function
Give examples of endocrine hormones (4)
What are the three kind of cells that release endocrine hormones (4)
- they have specificity by binding to a specific receptor (to a target receptor)
1. Gastrin
2. CCK (cholocystokinin)
3. Secretin
4. Motility
Cell Types
1. Paracrine: diffuse through extracellular space 2 target tissue
2. Autocrine: released substance regulates cells own function
3. Neurocrine: sensory cells secrete neurotransmitter
4. Endocrine: hormones enter blood and bind to target tissue
How does somatostatin act as and acid secretion inhibitor
In a paracrine fashion
What are two regulatory hormones that are only found in the small intestine
- CCK
- Secretin
What activates CCK
what activates secretin
CCK: amino acids and fatty acids
Secretin: activated by acid
What does secretin act on?
What does this do?
It acts on the pancreas
Specifically the duct cells of the pancreas to neutralize acid
They release bicarbonate
What is the downstream response to fatty acids and amino acids entering into the small intestine
- CCK is activated
- Digestive enzymes are released (for amino acids)
- Gull bladder is activated and Acinar cells release bile salts
What regulatory molecule reduces emptying of the stomach and relaxation of the sphincter of odi
CCK
Where is the sphincter of odi located
By the duodenum and is where the pancreas and the bile duct connect to the duodenum
What 4 things does CCK target in the small intestine, what does it do to them??
- Stomach —) causes reduction of emptying
- Pancreas —) targets Acinar cells to produce digestive enzymes
- Sphincter of odi —) relaxes (closes)
- Gall bladder —) release of bile salts
What are incretins what do they do
Give 2 examples
They are hormones that stimulate insulin production
GIP and GLP-1
What are two ways that we preform the glucose tolerance test
What are the results of the two tests
- Consumption of glucose —) production of incretins
- Injection into small intestine —) NO production of incretins
Why are second messengers sometimes used in endocrine hormones transport
Hydrophilic hormones can’t cross lipid by layer —) when needs to pass lipid by layer it uses a second messenger that activate transmembrane proteins
give two examples of secondary messengers that were discussed in class
Cyclic AMP
IP3