Gastrointestinal Tract Anatomy Quiz

Questions and Answers

What type of tissue supports the mucosa of the gastrointestinal tract?

Epithelial tissue

Dense regular connective tissue

Loose collagenous connective tissue (correct)

Adipose tissue

What is the function of the muscularis propria in the gastrointestinal tract?

Responsible for peristaltic contraction (correct)

Acts as a barrier to pathogens

Facilitates nutrient absorption

Produces digestive enzymes

Which junction is NOT mentioned as an abrupt transition point in the gastrointestinal tract?

Gastrooesophageal junction

Rectoanal junction

Gastroduodenal junction

Jejunoileal junction (correct)

How is the adventitia characterized when the gut lies within the abdominal cavity?

It becomes serosa Signup and view all the answers

What role does the autonomic nervous system play in the gastrointestinal tract?

It regulates secretory activity and peristalsis Signup and view all the answers

Which layer of the gastrointestinal tract contains the inner oblique layer of muscle?

Muscularis propria Signup and view all the answers

What type of muscle contraction follows voluntary muscular action in the gastrointestinal tract?

Peristaltic contraction Signup and view all the answers

What is the role of goblet cells within the gastrointestinal tract?

Secrete mucus Signup and view all the answers

What hormone is secreted by G cells in the gastric antrum in response to rising gastric pH?

Gastrin Signup and view all the answers

Which cells in the gastric glands secrete hydrochloric acid?

Parietal cells Signup and view all the answers

What is the primary role of mucous cells in the gastric epithelium?

Protection against autodigestion Signup and view all the answers

How is acid production by parietal cells physiologically controlled?

Through both the autonomic nervous system and hormones Signup and view all the answers

Which receptor type does acetylcholine act on in parietal cells?

M3 receptors Signup and view all the answers

In response to increased acid production, which hormone do D cells release to inhibit gastrin secretion?

Somatostatin Signup and view all the answers

What is essential for the absorption of vitamin B12 in the terminal ileum?

Glycoprotein intrinsic factor Signup and view all the answers

Which cell type in the gastric glands is primarily involved in the secretion of digestive enzymes?

Chief (zygomatic) cells Signup and view all the answers

What characterizes the muscularis propria in the oesophagus?

An outer longitudinal layer and an inner circular layer Signup and view all the answers

What is the primary role of the myenteric plexus?

It coordinates peristalsis between the muscle layers Signup and view all the answers

What initiates the swallowing process?

Skeletal muscles of the oropharynx Signup and view all the answers

Which factor does NOT influence sphincter control?

Pressure from the lungs Signup and view all the answers

What type of epithelium is found at the junction of the oesophagus and the stomach?

Stratified squamous epithelium Signup and view all the answers

What happens to the muscularis mucosae at the oesophago-gastric junction?

It remains continuous, but is less distinct Signup and view all the answers

What is the primary function of the glandular secretory mucosa in the stomach?

Secretion of digestive enzymes Signup and view all the answers

What structural feature is associated with the muscularis propria in the large intestine?

Pale-stained parasympathetic ganglion cells Signup and view all the answers

What initiates the contraction of the smooth muscle in the bowel?

Interstitial cells of Cajal Signup and view all the answers

Where are parasympathetic ganglia concentrated in the gastrointestinal tract?

In the submucosal plexus Signup and view all the answers

Which plexus is responsible for supplying the smooth muscle between the two layers of the muscularis propria?

Auerbach plexus Signup and view all the answers

What is the primary mechanism by which food is propelled along the GI tract?

Peristalsis Signup and view all the answers

What type of hormones do the diffuse neuroendocrine cells produce?

Locally acting hormones Signup and view all the answers

Which layer of muscle is responsible for constriction of the luminal diameter in the GI tract?

Circular muscle layer Signup and view all the answers

In the enteric nervous system, what structure do parasympathetic efferent fibres primarily synapse with?

Effector neurons in small ganglia Signup and view all the answers

What role does the longitudinal muscle layer play in the gastrointestinal tract?

Facilitates lengthening of the GI tract Signup and view all the answers

What are the circularly arranged folds in the mucosa and submucosa called?

Plicae circulares Signup and view all the answers

Which cell type is primarily responsible for the absorption of nutrients in the small intestine?

Enterocytes Signup and view all the answers

Where do reconstituted triglycerides enter after absorption in the small intestine?

Into intestinal lymphatics Signup and view all the answers

What is the primary function of Goblet cells in the small intestine?

Secretion of mucin for lubrication Signup and view all the answers

Which cell type is characterized by prominent eosinophilic apical granules?

Paneth cells Signup and view all the answers

What separates the muscularis mucosae from the base of the crypts in the small intestine?

Lamina propria Signup and view all the answers

Which type of cells are mostly T cells and help provide defense against invasive organisms?

Intraepithelial lymphocytes Signup and view all the answers

What role do neuroendocrine cells play in the small intestine?

Regulation of gastrointestinal motility and secretion Signup and view all the answers

Study Notes

Gastrointestinal Tract Structure

Abrupt mucosal transitions occur at four junctions: gastrooesophageal, gastroduodenal, ileocaecal, and rectoanal.
Submucosa consists of loose collagenous connective tissue and houses larger blood vessels, lymphatics, and nerves.
Muscularis propria features an inner circular and outer longitudinal smooth muscle layer; stomach also includes an inner oblique layer for enhanced peristalsis.
Adventitia, the outer layer, contains major vessels and nerves and merges with retroperitoneal tissues; lined by serosa (visceral peritoneum) in the peritoneal cavity.

Gastrointestinal Motility

Food moved primarily by peristalsis, with voluntary muscle action in the mouth, pharynx, and upper oesophagus.
Peristalsis is involuntary, driven by smooth muscle contractions controlled by the autonomic nervous system and various hormones from neuroendocrine cells.
The enteric nervous system mediates autonomic regulation, featuring both postganglionic sympathetic and parasympathetic fibers.

Smooth Muscle Control and Function

Contraction of bowel smooth muscle initiated by interstitial cells of Cajal, primarily modulated by the parasympathetic nervous system.
Parasympathetic fibers synapse in local ganglia, forming the submucosal (Meissner) and myenteric (Auerbach) plexuses, allowing intricate control of gut motility and secretion.

Oesophagus Structure and Function

Swallowing initiates voluntarily, involving skeletal muscles, followed by peristaltic reflex to push food to the stomach.
Gastrooesophageal sphincter function is influenced by diaphragmatic contraction, intra-abdominal pressure, and unidirectional peristalsis.

Mucosal Characteristics

Oesophago-gastric junction features a transition from stratified squamous epithelium to glandular secretory mucosa, enhancing secretion.
Gastric glands secrete hormones like serotonin, with stem cells in the neck replenishing various cell types continuously.

Gastric Mucosa Details

Gastric pits lined with surface mucous cells protect the epithelium from digestion by acid.
Parietal cells secrete hydrochloric acid and intrinsic factor for vitamin B12 absorption.

Gastric Acid Regulation

Acid secretion is controlled by the autonomic nervous system and hormones: acetylcholine (via vagus nerve), gastrin (from G cells), and histamine (via H2 receptors).
Somatostatin produced by D cells modulates gastrin secretion in response to gastric pH changes.

Small Intestine Structure and Absorption

Mucosa has circular folds (plicae circulares) and villi, with enterocytes responsible for absorption through microvilli.
Peyer’s patches in the lamina propria are significant in immune function within the small intestine.

Cell Types in Small Intestine Epithelium

Enterocytes (absorptive cells), goblet cells (mucus production), Paneth cells (defense), neuroendocrine cells (motility regulation), and epithelial stem cells (regenerative capacity).
Intraepithelial lymphocytes (mostly T cells) provide immune defense.

Nutrient Absorption Pathways

Amino acids and monosaccharides enter capillaries, while triglycerides enter lymphatics (lacteals) bypassing the liver before entering circulation.

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Description

Test your knowledge on the anatomy of the gastrointestinal tract, focusing on the transitions at key junctions and the layers of the gut wall. Learn about the mucosa, submucosa, and muscularis propria while discovering the importance of these structures in digestive health.