Control and regulation of gastric, pancreatic, intestinal, hepatobiliary secretions (12906)
Terms in this set (32)
From the surface of the stomach which glands are you going to see?
1- Cardiac glands: located in cardiac region, secrete mucus.
2- Mucus Secreting gland: secrete mucus alkaline to protect surface of stomach 1mm thick.
3- Tubular glands: are more specialized and have a tube.
What are the two types of tubular glands and what are their main difference?
1-Oxyntic or Gastric Glands: located in the proximal 80% of the stomach.
2-Pyloric glands: located in the distal 20% of the stomach.
Cells that oxyntic gland contains
1-Mucus neck cells: secrete mucus
2-Peptic or Chief cells: secrete pepsinogen
3-Parietal cells: secrete HCl and Intrinsic Factor
Cells that Pyloric Gland contains
2-Gastrin: stimulates HCl release from Parietal cells
Describe the process by which HCl is produced in the Parietal cell.
H2O gets inside the cell and once in there it separates into H and OH
H: H is taken out to the lumen by the H+/K+ pump
OH: meets CO2 from metabolism and become HCO3.
HCO3/Cl pump takes out of the cell HCO3 and introduces into the cell Cl, then Cl enters the lumen via the uniporter channel.
In the lumen H + Cl meet.
3 factors that stimulate HCl secretion
What 3 things does Ach stimulate to be released?
Direct pathway for HCl secretion
Ach, Gastrin or histamine stimulate directly parietal cell.
Indirect pathway for HCl secretion
Ach, Gastrin stimulate ECL cell and this one release Histamine then stimulating Parietal cell
Intrinsic Factor of Parietal cells
transports vitamin B-12 to ileum where it is absorbed.
Peptic Chief Cell
Secrete pepsinogen that is broken down by HCl to pepsin and this is a proteolytic enzyme
What cell does the pyloric gland lacks?
Pyloric glands lack of parietal cells.
Main secretion of Pyloric cells?
1- Mucus from mucous cells,
2-Gastrin from gastrin cells which stimulates production of HCl.
40% Mechanoreceptos and chemoreceptors in oral and nasal cavity..... engages neural responses.
Ach--> Parietal cell, ECl cells(histamine), G cells (gastrin)
50% When food enters the stomach..... engages neural and hormonal responses.
Proteins, peptides and aminoacids stimulates G cells, H in D cells stimulates somatostatin that inhibit acid production. and gastrin release
10% When food enters duodenum: mainly hormonal but also neural and paracrine (near) responses
Distention of the intestine release Gastric Inhibitory peptides which inhibit parietal acid secretion.
What stimulate pancreatic secretions?
Chyme in small intestine.
-Enzymes for digesting lipids
-Enzymes for digesting carbohydrates
-Enzymes for digesting Proteins
How are the enzymes synthesized in the acini?
-Mitochondria in acinar cell gives energy to produce protein-enzyme
-ER-Golgi App-Excreted by acinar cell exocytosis
How is the pancreatic activity and what regulates it in the digestive phases?
Cephalic: 25% Vagus Ach and VIP
Gastric:10% Vaso-Vagal reflexes (stomach distentions)
Intestinal:65% hormonal control of secreting and CCK in response to amino acids, FA and monoacylglycerols.
What is the main function of the Liver?
Secretion of bile.
lipid digestion via bile acids.
Excretion of waste product including bilirubin and cholesterol
What does hepatocytes secrete?
Bile acids, cholesteros and organic product into canaliculi.
When is bile produced?
Bile is constantly produced by liver and stored by gall bladder.
Primary mediator of bile release
CCK from duodenum and upper jejunum (long chain fatty acids and (products of protein digestion stimulates CCK release)
Inhibitory effects of CCK
Somatostatin and Norepinephrine
secrete mucus and bicarbonate
Crypts of lieberkuhn
secrete digestive juices
secrete water and electrolyes