Functions Of The Stomach Flashcards

1
Q

What are the basic functions of the stomach?

A

Receive food as part of a short term storage facility, and disrupt food, via vigorous contractions of the smooth muscle, and continue digestion mainly by using proteins as well as dinsinfect

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2
Q

What are the different areas of the stomach (top to bottom)

A

Cardia, fundus, the body, and the antrum

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3
Q

What are some of the features of the histology of the stomach?

A

Abrupt transition of stratified squamous to columnar, due to the features of secretion, the mucosa and the submucosa are thrown into folds known as rugae, and there are lots of little holes in the submucosa

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4
Q

What are the different types of cells found in the stomach?

A

The mucous cells, teh parietal cells, the chief cells and the g cells

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5
Q

What are some of the features of the smooth muscle of the stomahc?

A

There is an extra oblique layer of muscle, contractions, mix grin contents, and move contents along,upper stomach has sustained contractions and helps to create a basal tone

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6
Q

What are some of the functions of stomach smooth muscle?

A

Strong perstaislis mixes the stomahc contents, there are coordinate mvpovemtents with contractions about every 20 minutes, proximal to distal, and the shape of the stomach is larger proximal to smaller at the distal end and these causes the contents to accelerate and leave the lumps and stuff behind

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7
Q

What is the proccess of receptive relaxation?

A

vagally mediated relaxation of the oral stomach, swallows food to enter the stomach withourpt raising the intra gastric pressure too much, prevents reflux of the stomach contents during swallow and the gastric mucosal folds maintain distension

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8
Q

What substances kt the stomach secrete?

A

HCL, intrinsic factor, mucous, HCO3 and pepsinogen which then becomes pepsin

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9
Q

What do parietal cells in the sotmahc secrete?

A

HCL and intrinsic factor

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10
Q

What do g cells in the stomach secrete?

A

Gastrin

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11
Q

What do enterochromffin like cells in the stomahc secreete?

A

Histamine

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12
Q

What do chief cells in the stomach secrete?

A

Pesinpogen

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13
Q

What do the d cells in the stomach secrete?

A

Somatosatitn

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14
Q

What do the muclus cells of the surface and nexl of the stomach produce?

A

Stomachn

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15
Q

What are some of the features of the gastric pits and the gastric glands?

A

There are surface mucous cells, mucous neck cells then pertial cells, chief cells and the eneteroendocrine cells spit into the gastric pit at the top and the gastric glands at the bottom

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16
Q

What are the different secretory products of different oarts of the stomach?

A

The cardia is predominately involved in mucus secretion, the fundus and body is involved in the secretion of mucus, hcl and pepsinogen, pylorus is involved in the secretion of gastrin and somatostatin however there is lots of cross over

17
Q

What are the pariteal cells of the stomach stimulated by?

A

Gastrin, histamine and ACh

18
Q

What are the features of the control of HCl production?

A

Gastrin is released form the bloodstream, stimulates CCK production and the eneterochromfin like cells produce histamine, which stimulates the H2 receptors, the vagus nerve produces ACh and this stimulates the Mcr receptors

19
Q

How does the body inhibit HCl production?

A

Essentially by inhibiting g cells, when food leaves the stomach the pH drops as the food behaves as a buffer, the low pH activates the d cells that produce somatastatin that inhibits the G cells, and the reduction in stomach distension reduces the vagal activity

20
Q

How is gastrin secretion controlled?

A

By g cells, that are stimulated to produce gastrin by peptides and amino acids in the stomach lumen, and gastrin releasing peptide

21
Q

How is HCl produced fpby the stomach cells?

A

Water is split into H+ and OH-, H+ is moved into the lumen from the cells, and Cl- from the ecf is moved from cells into the lumen, and Co2 combines with OH- to from HCO3- and is moved into the bloodstream, the alakline tide

22
Q

What are the three phases of digestion?

A

The celphalic, the gastric and the intestinal phase of digestion

23
Q

What happens in the celphalic stage of digestion?

A

30% of the totalHCl is produced, parasympatheic stimuli from smelling chewing and swallowing, direct stimulation of the parietal cell by the vagus nerve, meaning stimulation of the G cells by the vagus nerve meaning the GRP is produced

24
Q

What happens in the gastric phase of digestion?

A

60% of HCl is produced, distension of the stomach stimualtes the vagus, stimulates the parietal and the g cells, presence of amino acids and peptides stimualte the g cells, food acts as a buffer increases the pH and therefore removes the inhibition on HCl production

25
Q

What happens in the intestinal phase of digestion?

A

10% of HCl production, the presence of chyme initially stimulates the gastrin secretion, but is soon overtaken by the inhibition of g cells, presence of lipids activates the enetrogastric reflux, adn therefore reduced the vagal stimulation, chyme stimulates CCk and secretin and therefore this helps to suppress secretion

26
Q

What are some of the features that protect the stomach from stomach acid?

A

Mucous and HCO3- are reasleased by the mucous cells and the neck cells and gastrin glands and help to create an alkaline layer, high turnover of epitehral cells, prostaglandins are used to help maintain the blood flow to the epithelial cells to supply them with nutrei t supply

27
Q

What are some of the forces that break the stomach defences?

A

Alchol dissolves the mucus layer, helicobacterpylori, NSAiDs as they stop the sytehsis of prostagladins

28
Q

What things can happen when the stomach defences aren’t working correctly?

A

Gastrtis, which can result in atriphy and dysplasia, ulceration commonly along the lesser curvature of the stomach, chromoc reflux due to dysfunction of the lower oesphageal spincther that can predispose a patient to metaplasia

29
Q

What do PPIs target and name one.

A

Omeprazole, targets the proton pumps in the parietal cells

30
Q

Name a H2 blocker and what do they target?

A

Cimitemine and ratinidome, target the H2 pump which normally is affected by histaimine that is produced by the enterochromaffin cells