Gastric Secretions

Created by: Becca
Created on: 23-12-13 22:03

What are the 2 secreting regions of the stomach & where are they?

Oxyntic mucosa in the fundus & body. Pyloric gland area in the antrum. Mucosal gland cells are found in gastric pits.

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What are the 4 cell types in the stomach & what do they produce?

Parietal cells: HCL, intrinsic factor that binds vitamin B12 to enable its absorption. Surface epithelia: mucous. Mucous neck cells: mucous. Chief cells: pepsinogen

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HCl does not digest material. How does aid digestion?

Activation of pepsin, provides an acid medium for optimal pepsin activity, aids the breakdown of connective tissue & muscle fibres

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What is the major digestive constituent of gastric secretions?

Pepsinogen produced by chief cells

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What are the 3 phases of gastric secretion?

Cephalic, gastric & intestinal phases

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Describe the cephalic phase of gastric secretion

Secretion stimulated (thought/expectation/sight/taste/chewing/swallowing) prior to food, contributes 30-50% secretions, dependent on activity of the vagus nerve (CNS involved)

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Describe the gastric phase of gastric secretion

50-60% secretions, local vago-vagal reflexes in response to mechanical stimulation due to food in antrum (no CNS involved), stimulation of gastric release from G-cells by peptide fragments of partially digested proteins (major mechanism)

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Describe the intestinal phase of gastric secretion

5% maybe due to circulating amino acids or gastrin

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What are the mechanisms of gastric circulation?

Local metabolite production (prostaglandins maintain capillary network, provide enough fluid for secretions), release of vasoactive intestinal polypeptide (VIP) from local nerves causing vasodilatation

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How is gastric secretion inhibited?

Removal of peptide fragments (no longer stimulates gastrin release). Removing food decreasing pH, pH

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How is gastric mucosa protected from gastric secretions?

Luminal membranes are impermeable to H+, -ve feedback: pH

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Card 2

Front

What are the 4 cell types in the stomach & what do they produce?

Back

Parietal cells: HCL, intrinsic factor that binds vitamin B12 to enable its absorption. Surface epithelia: mucous. Mucous neck cells: mucous. Chief cells: pepsinogen

Card 3

Front

HCl does not digest material. How does aid digestion?

Back

Card 4

Front

What is the major digestive constituent of gastric secretions?

Back

Card 5

Front

What are the 3 phases of gastric secretion?

Back

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Gastric Secretions