Secretatory/Regulation

Where is the cardia located?

The entryway to the stomach

What is the body of stomach called?

Corpus

What is the part of the stomach called?

Antrum

What cells are located in the corpus of the stomach?

Parietal Cell

What does parietal cell secret?

HCL and Intrinsic Factor

What pump lives in the parietal cell?

H+/K+ ATPase

What is the main purpose of H+/K+ ATPase in the stomach?

To pump H+ ions into stomach lumen, which will make the environment more acidic.

What stimulates the parietal cell in the stomach?

• Acetylcholine

• Gastrin

• Histamine

What effect does the HCL have in the gastric lumen?

1. Kills food-derived bacteria

2. Facilitates digestion

3. Promotes absorption of phosphate, calcium, and iron

What nerve stimulates the parietal cells?

Vagus Nerve (CN V)

What inhibits the HCL?

1. GIP (Gastric Inhibitory Polypeptide)(Hormone)

2. Prostaglandins (liquid compounds, acts like hormone)

3. Secretin (Hormone)

4. Somatostatin (Peptide Hormone + NT)

5. Cholecystokinin (Peptide Hormone)

What does intrinsic factor do?

B12 will bind to promote absorption at TERMINAL ILEUM

With autoimmune destruction with intrinsic factor, what does it cause?

Pernicious Anemia

1. Reversible Dementia

2. Megaloblastic Anemia

3. Subacute Combined Degeneration

When does pepsinogen convert to pepsin?

When there is a low pH environment

What are the roles of pepsin?

1. Optimized protein digestion

2. Initially inactive zymogen, pepsinogen

3. Pepsin → Pepsinogen

Where are the G-Cells located?

In the antrum of the stomach

What does gastrin do?

1. Promotes gastric acid secretin

2. Increase gastric motility

3. Supports gastric mucosa proliferation

What factors stimulate gastrin?

1. Vagus Nerve

2. High pH

3. High stomach distention

What inhibits gastrin?

1. Somatostatin

2. Low pH level

What cell releases histamine?

ECL (Enterochromaffin-like cell)

What affect does histamine have on the parietal cell?

It diffuses with parietal cell to increase HCL

What stimulates histamine?

Gastrin

What inhibits histamine?

Somatostatin

Where is I-Cells located?

Proximal small intestine

• Duodenum

• Jejunum

What does I-Cell secrete?

Cholecystokinin (CCK)

What are the roles of CCK?

1. CONTRACTION of gallbladder

2. Relaxes SPHINCTER of ODDI

3. Secretion of pancreatic digestive enzymes

4. Reduce GASTRIC emptying

What stimulates CCK?

1. Fatty Acids (Fats)

2. Amino Acids (Protein)

What inhibits CCK?

1. Somatostatin

2. Fasting

What cells secrete D-Cells?

Somatostatin

Where is somatostatin secreted in?

• Jejunum

• Pancreas

What is the role of somatostatin?

1. Inhibits GI secretions

2. Inhibits gallbladder contraction

3. Decreases GI motility

4. Causes splanchnic vasocontriction

5. Inhibits GH & TSH secretion

What stimulates somatostatin?

• Gastric acid

• Fatty Acids

• Amino Acids

What is somatostatin inhibited by?

Vagus Nerve (CN V)

What specific GI secretions is somatostatin inhibiting?

• HCL

• Gastrin

• Pepsinogen

• CCK

• Secretin

• VIP

• Glucagon

• Insulin

What cell secrets secretin?

S-Cell

Where is secretin secret from?

Duodenum

What does secretin do?

1. Increase bile secretion

2. Increase pancreatic bicarbonate secretion (Pancreatic enzyme doesn’t work otherwise)

3. Decrease gastric acid secretion

Why does secretin get stimulated by gastric acid and fatty acids in intestine?

Because secretin wants to break down the chyme in the intestine.

What stimulates secretin?

• Gastric Acid

• Fatty Acids

What inhibits secretin?

Somatostatin

What does K-Cell secrete?

GIP (Gastric Inhibitory Polypeptide)

Where does GIP secret from?

Duodenum

What is the role of GIP?

1. Increase insulin secretion

2. Decreases gastric acid secretion

What is GIP stimulated by?

• Glucose

• Amino

• Fatty Acid

What is GIP inhibited by?

Fasting

What is the role of VIP (Vasoactive Intestinal Peptide)?

1. Increases H2O and electrolyte secretion

2. Intestinal smooth muscle relaxation

What secrets VIP?

Parasympathetic Ganglia

What stimulates VIP?

• GI Distention

• Parasympathetics

What inhibits VIP?

Sympathetics

What is the role of Motilin?

Increases intestinal motility

Where is motilin secreted in?

Small Intestine

What stimulates motilin?

Fasting

What cell secrets nitric oxide?

Smooth Muscle Cell

What is the role of Nitric Oxide (NO)?

1. Relaxes smooth muscle/sphincters

2. Vasodilation

What happens with the lumen with nitric oxide?

Vasodilation