Final Exam: High Yield

Name the 2 major plexuses of the enteric nervous system.

1. Myenteric Plexus (AKA Auerbach's Plexus)

2. Submucosal Plexus (AKA Meissner's Plexus)

Myenteric Plexus

• Nervous system division

• Location

• Function

• Part of ENS (in walls of GIT)

• L: b/w the inner circular & outer longitudinal layers of the muscularis

• F: motility/peristalsis

Submucosal Plexus

• Nervous system division

• Location

• Function

• Part of ENS (in walls of GIT)

• L: w/in submucosa

• F: local regulation of secretion & blood flow

Name the 3 plexuses of the autonomic nervous system that supply the digestive organs.

1. Celiac plexus

2. Inferior mesenteric plexus

3. Superior mesenteric plexus

The largest autonomic plexus in the body is the…

Celiac plexus

The largest cranial nerve is the…

Vagus nerve

The major parasympathetic nerve supplying GIT is…

Vagus nerve

Segmentation

Emulsification of fats by bile is an example of…

(a) mechanical digestion

(b) chemical digestion

(a) mechanical digestion → because it is a process of physically breaking down food

Pepsin digesting proteins is an example of…

(a) mechanical digestion

(b) chemical digestion

(b) chemical digestion

What question should you ask yourself to determine if a physiological process is a form of mechanical v.s. chemical digestion?

Are chemical bonds being broken? If yes → chemical digestion

Chief cells secrete pepsinogen, whose main purpose is protein digestion.

Chief cells secrete pepsinogen, whose main purpose is protein digestion.

Parietal cells in the stomach secrete intrinsic factor whose main purpose is B12 absorption.

Parietal cells in the stomach secrete intrinsic factor whose main purpose is B12 absorption.

Describe the activation process of pepsin.

Chief cells → pepsinogen

Parietal cells → HCl → stomach becomes acidic (pH 1-2)

High acidity → structural change in pepsinogen

Inactive pepsiogen → Active pepsin

Active pepsin rapidly activates remaining pepsinogen

Which cells secrete HCl?

Parietal cells

_________ release gastrin which stimulates gastric secretion.

G cells release gastrin which stimulates gastric secretion.

Mucous Neck Cells — Function

• Secrete acidic mucous

• Prevents neutralization of acid in proximal stomach which consequently protects stomach lining from _____

• Also lubricates travelling food

INCOMPLETE

CCK

Produced by duodenal enteroendocrine cells

→ Stimulates pancreatic acinar cells to release digestive enzymes.

Secretin

Produced by duodenal cells

→ Stimulates pancreatic duct cells to release bicarbonate.

T or F: CCK produces bile.

False. (CCK stimulates gallbladder to contract & release bile)

What does “emulsification of lipids” mean?

Bile salts emulsify lipids.

That means they physically break large lipid droplets into smaller droplets, increasing surface area for digestive enzymes.

Form of mechanical digestion

NOT enzymatic/chemical digestion!!!

T or F: Emulsification of lipids is a form of chemical digestion.

False.

Emulsification = physical breakdown of large lipid droplets into smaller droplets

CCK stimulates the gallbladder to contract and release bile.

CCK stimulates the gallbladder to contract and release bile.