Secretion I Flashcards
What are R- binders?
- are proteins in the saliva that bind vitamin B12 and protect it from proteases in the stomach (pepsins)
What does ghrelin stimulate in the brain?
Neuro Peptide Y
Salivation is stimulated by
PNS – facial and glossopharyngeal nerves, NOT the vagus! Control by:
- autonomic: [parasymp: ACh, VIP] [sympath: beta and alpha adrenergics (NE)]
- central NS: afferents/efferents to salivary nucleus
What stimulates ghrelin?
empty stomach
What does NYP do?
Stimulates hunger
Where is ghrelin secreted from?
epsilon cells of the pancreas and P/D1 cells of the fundus
What is released when chyme enters the duodenum and upper jejunum?
Peptide YY and GLP-1
What does peptide YY and GLP-1 do?
suppress NPY
What does leptin do?
Suppresses NPY
What produces saliva?
Parotid glands, submaxillary glands, sublingual glands
What is in serous fluid?
amylase, R-binders
What is very important and limiting to the production of saliva?
Blood flow to the salivary gland
What is responsible for reclamation of electrolytes from the acinar excretions?
Striated and excretory duct cells
Is saliva hypo or hyper tonic compared to blood plasma?
hypotonic
What ion is in higher concentraiton in saliva than it is in the plasma?
K+
What is secreted from the tounge?
Lingual lipase
What PNS controls salivary function?
Glossopharyngeal and facial nerves
What function do SNS nerves have in the production of saliva?
Very small contribution in helping the acinar ducts constrict and spurt out their contents
What do glands in the esophagus do?
Produce some mucin
What produces HCl in the stomach?
Parietal cells
What produces Intrinsic factor?
Parietal cells
What does intrinsic factor do?
Helps bind B12 protecting it from proteases
What produces pepsinogen?
Chief cells
What % of digestion is done pre-duodenally?
25-30%
What produces gastrin?
G cells
Where are G cells located?
in the antrum
What role does gastrin play in the stomach?
Secretagogue for HCl
What stimulates gastrin production?
Chyme in the stomach
What produces lipase?
The tongue, Chief cells, pancreas
What is somatostatin’s role in the stomach?
suppresses production of HCl
What is the role of Histamine in the stomach
Secretogogue for HCl
What are three roles of mucus?
Protection, lubrication and attracts bicarb
Where are parietal cells located?
Only in the body of the stomach
What are the channels in the PM of the parietal cells called?
Canaliculi
What is the rate limiting step to acid production in the stomach
How many H+ pumps there are
How does gastrin help increase acid production?
It sitmulates the upregulation of H+ pumps to the cell surface of parietal cells
What is pumped into the capilaries for every H+ exported to the lumen of the stomach?
A bicarb ion
What keeps H+ out of the basolaminar side of the parietal cells?
tight junction
What is imported in exchange for H+ excretion?
K+
Why would there be a slight increase in K+ in the lumen of the stomach?
Some would start to come out fo the parietal cell as the intracellular concentrations rose
What happens to the gastric concentration of Na+ on Gastrin stimulation?
It goes down
What happens to the gastric concentration of Cl- upon Gastrin Stimulation?
Goes up
What causes 95% of gastric ulcers?
H. Pilori
What does the H. Pilori bug do that causes ulcers?
neutralizes the acid in the stomach with urea which is toxic to the epithelial lining and disrupts the mucus layer allowing the low pH fluid to destroy the delitcate enetrocytes
What stimulates HCl production?
PNS, Gastrin, histamine
What supresses HCl production
SNS, somatostatin, GIP, Peptide YY, prostoglandins
What produces mucus in the stomach?
Mucus Neck cells
What is the main function of secretin?
To stimulate the secretion of pancreatic and duodenal buffers, as well as open CTFR channels
What is CCK’s function?
To stimulate pancreatic enzymes, relax the sphincter of oddi, and induce contractions in the gall bladder.
What are the two things GIP stands for?
Gastric Inhibitory Peptide, and Glucose insulinotropic peptide
What are the functions of GIP?
Decreases gastrin–>HCl, stimulates insulin secretion
What induces the release of GIP?
macronuirents entering the duodenum
Where and what secretes Gastrin?
G Cells in the pyloric antrum and duodenum
Where and what secretes Secretin?
S cells in the duodenum
Where and what secretes CCK?
I ells of the duodenum and Jejunum
Where and what secretes GIP?
K cells of the duodenum and Jejunum
Where and what secretes Motilin?
M cells of the duodenum
Where and what secretes Peptide YY?
L cells of the terminal ilium and colon
Where and what secretes Ghrelin?
P/D1 cells of the fundus and episolon cells of the pancreas
What are the duodenal bound enzymes produced by the pancreas?
Trypsinogen, Chymotripsinogen, elastase, Pancreatic prolipase, ProCo-lipase, pancreatic amylase
What activates Trypsinogen?
Enteropeptidase
What secretes enteropeptidase?
Enterocytes in the duodenum
What does the pancrease secrete in order to prevent trypsin from destroying the pancreas?
Trypsin inhibitor
What induces secession of pancreatic secretions?
Lack of vegal stimulation, Peptide YY, Somatostatin, glucagon, pancreatic polypeptide
how does the colon reabsorb water and nutrients from the chyme?
Na+ pumps
What provides the slow wave function in the lower intestines?
Interstitial cells of cajal
Saliva is always _____ to plasma, contains …..
hypotonic - remember O
alpha-amylase (starch digestion)
lingual lipase (lipid digestion)
R-binders
