Gi Hormones – Gastrointestinal System

by Thad Wilson, PhD

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    00:00 Now, besides neural signalling molecules, we also have hormones.

    00:06 There are five primary hormones And these we need to have identified because as we go through the various GI lectures, these will come up over and over again.

    00:15 The first is cholecystokinin and these are released by I cells.

    00:20 And these increase enzymatic secretions, contraction of the gallbladder as well as causing the pyloric sphincter to constriction Gastrin is released from G cells and these causes increase in acid secretion.

    00:38 Gastroinhibitory peptide, these cause the inhibition of acid secretion as well as it also increases insulin.

    00:48 And so sometimes this is called glucose insulinotropic peptide.

    00:52 Motilin is released by M cells.

    00:54 And this increases contractions of the various smooth muscle.

    00:59 It also does something called an increase in this motility complex that will help move food stuff from the top of the GI system down to the bottom.

    01:13 And these migrating motor complexes help really move food stuff along the GI tract.

    01:19 Secretin is released by S cells and this increases bicarbonate secretion as well as pepsin secretion We have a few other items that we need to deal with besides the GI hormones and that is local signalling molecules.

    01:37 These local signalling molecules are called paracrine signalling molecules.

    01:42 But before we do that, let’s first talk through a little bit about where the GI hormones come from.

    01:49 I gave you all the cells types that they come from, but now let’s talk more in generality about where anatomically they come from.

    01:59 Gastrin is started off by some release from those G cells in the bottom portion of the stomach, the duodenum, and it tapers off the jejunum.

    02:11 Glucose or gastric-inhibiting peptide is released in the duodenum and jejunum.

    02:18 Motilin is released in the same locations from M cells.

    02:22 Cholecystokinin is released throughout the small intestine, but tapers off in the ileum.

    02:28 And finally, secretin follows a very similar pattern of being primarily released in the duodenum, jejunum, and then tapering in the ileum.

    02:38 I promised you paracrine signalling molecules and here they are.

    02:42 Histamine is one of the primary ones.

    02:45 Histamine is released from ECL cells as well as mast cells and these increase acid secretion.

    02:54 Nitric oxide is released by many, many different molecules and by cells in the system.

    02:59 And mostly, this involves increasing both blood flow as well as relaxing smooth muscle.

    03:06 Prostaglandins are also released by many different cell types and these increase both mucus and bicarbonate secretion as well it decreases the secretion of hydrogen ions.

    03:19 Our final cell type of signalling molecule that we have is somatostatin.

    03:22 These are released by D cells and this inhibits most secretions and these are our four paracrine signalling molecules.

    About the Lecture

    The lecture Gi Hormones – Gastrointestinal System by Thad Wilson, PhD is from the course Gastrointestinal Physiology.

    Included Quiz Questions

    1. GIP is released for K cells in the stomach and pancreas to inhibit acid secretion and release insulin.
    2. Gastrin is released from I cells in the stomach to increase acid secretion.
    3. CCK is released from I cells in the liver to increase gall bladder contractions.
    4. Secretin is released from M cells in the pancreas to increase migrating motor complexes.
    5. Motilin is secreted by M cells in the pancreas to increase bicarbonate secretion.
    1. Histamine is released from the enterochromaffin-like cells to increase acid secretion.
    2. Nitrous oxide is released by mast cells to caused constriction of smooth muscles.
    3. Prostaglandins are released by G cells in the stomach to increase acid secretion.
    4. Somatostatin is released by D cells in the gall bladder to inhibit secretions.
    5. Histamine is released by mast cells to decrease acid secretion.

    Author of lecture Gi Hormones – Gastrointestinal System

     Thad Wilson, PhD

    Thad Wilson, PhD

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    Comprehensive Review
    By Joseph A. on 24. September 2017 for Gi Hormones – Gastrointestinal System

    Very Comprehensive lecture and lecture notes, covering a vast area within 3 to 4 mins