What is the primary function of the muscularis mucosae in the GI tract?

To alter the shape of the mucosa, creating ridges and valleys to modify the absorptive or secretory surface area.

Fill in the blank: The ______ is a nerve network in the submucosa that regulates local secretions and blood flow.

Submucosal (Meissner’s) plexus

True or False: The entire epithelium of the small intestine is replaced every 10-12 days.

False. The entire epithelium is replaced every 3-6 days.

What is the main role of the interstitial cells of Cajal?

They generate the Basic Electric Rhythm (BER) in the GI tract.

Riddle: I create waves in the gut, moving food along with a push and pull, but I am not a wave in the ocean. What am I?

Peristalsis

Which hormone is primarily responsible for inhibiting gastric emptying?

Cholecystokinin (CCK)

Fill in the blank: The gastric secretions include HCl, pepsinogen, and ______.

Intrinsic factor

True or False: Segmentation is a propulsive movement in the GI tract.

False. Segmentation is a non-propulsive mixing movement.

What type of muscle layers are responsible for GI motility?

Smooth muscle layers consisting of an inner circular layer and an outer longitudinal layer.

Riddle: I can be a reflex, a contraction behind a stretch, and I help move food through the gut. What am I?

Peristalsis

What initiates mass movement in the colon?

Colon distension and the gastrocolic reflex.

Fill in the blank: The primary pacemaker of the GI tract is located in the ______.

Mid-portion of the stomach

True or False: Villi in the small intestine increase the surface area for absorption.

True.

Which two ions are primarily involved in the spike potentials of GI smooth muscle?

Calcium (Ca²⁺) and Potassium (K⁺)

Riddle: I help to clear the intestines and ensure motility during fasting, but I am not a meal. What am I?

Migrating Motor Complex (MMC)

What is the effect of secretin on pancreatic secretion?

It stimulates the secretion of bicarbonate (HCO₃⁻) from ductal cells.

Fill in the blank: The absorption of iron occurs primarily in the ______.

Duodenum

True or False: The gallbladder contracts rhythmically within 30 minutes post-meal primarily stimulated by gastrin.

False. It is primarily stimulated by cholecystokinin (CCK).

What is the role of motilin in gastrointestinal motility?

It stimulates motility during fasting.

Riddle: I am a hormone that signals fullness, released by fat stores, but I am often ignored in obesity. What am I?

Leptin

What is the typical daily secretion volume of bile?

~500 mL/day

Fill in the blank: The primary site for bile salt absorption is the ______.

Terminal ileum

True or False: The jejunum is primarily responsible for the absorption of water-soluble vitamins.

True.

Which neurotransmitter increases spike potential frequency in the GI tract?

Acetylcholine

Riddle: I am a carbohydrate-rich layer that protects and aids absorption in the intestine. What am I?

Glycocalyx

What factors inhibit gastric emptying?

Duodenal distension, acidity (pH < 4),="" and="" high/low="" osmolality="" of="">

Fill in the blank: The primary site of absorption for carbohydrates in the intestine is the ______.

Proximal small intestine

True or False: Ruminants have a faster gastric emptying time compared to humans.

False. Humans typically have a faster gastric emptying time.

What is the role of the crypt cells in the intestine?

They are proliferative cells responsible for intestinal epithelium renewal.

What is the primary role of the muscularis mucosae in the GI tract wall?

The muscularis mucosae alters the shape of the mucosa, creating ridges and valleys to modify the absorptive or secretory surface area.