Gastric Oxyntic Gland: Structure and Functions – Upper Gastrointestinal Secretion

00:01 Mucous neck cells are the ones that are going to be protecting the system.

00:06 The G cells are going to be secreting gastrin.

00:10 D cells are secreting something called somatostatin, which is going to decrease the amount of acid production.

00:17 Chief cells are producing the pepsin.

00:20 And here we go, parietal cells, these are increasing the intrinsic factor, as well as hydrogen ion production.

00:28 So let’s look at these hydrogen ion production cells.

00:36 So here is our basic parietal cell.

00:39 We have a multiple step process in which we can get the hydrogen ions pumped out into the interstitial space.

00:47 The first thing that has to happen is we have normal metabolism that is occurring within the cell.

00:53 This normal metabolism produces carbon dioxide.

00:56 As carbon dioxide is produced, it’s combined with water to form carbonic acid.

01:01 Then that dissociates into a hydrogen ion and a bicarb.

01:04 That hydrogen ion that’s produced during metabolism is what is going to get kicked out into the intestinal lumen, and that particular process we’ll get to in a moment.

01:13 But the bicarb leaves the cell via the basolateral membrane in an exchange format for chloride.

01:22 The hydrogen ion gets kicked out into the stomach lumen in a pump format, meaning that it requires ATP.

01:32 And potassium is allowed to enter the cytosol.

01:37 Potassium then exits through just a normal potassium channel.

01:44 And then finally, what happens is that chloride that was brought across the basolateral membrane with bicarb, that is also allowed to leave the apical membrane into the stomach lumen.

01:58 So our end result is that we have hydrogen ions being secreted, and chloride being secreted, and potassium to a very small level.