Digestive System

What is the function of the epithelial tissue in the GI tract?

It covers exposed surfaces, lines internal passageways, and produces glandular secretions.

What is the pyloric sphincter?

A muscular valve that regulates the passage of chyme from the stomach to the duodenum.

Define peristalsis.

Peristalsis is the coordinated contraction and relaxation of muscles that moves food through the digestive tract.

What is the greater omentum?

A large, fatty fold of peritoneum that drapes over abdominal organs, providing insulation, protection, and immune function.

What are the four layers of the GI tract?

Mucosa, Submucosa, Muscularis Externa, and Serosa/Adventitia.

What is the function of Brunner’s glands?

They secrete alkaline mucus to neutralize stomach acid in the duodenum.

Where are Peyer’s patches located and what is their function?

In the ileum, they help protect against pathogens in the digestive system.

What are the main functions of the large intestine?

Reabsorption of water, vitamins, and electrolytes; propulsion of feces; and synthesis of vitamins by gut flora

What is the difference between internal and external hemorrhoids?

Internal hemorrhoids occur inside the anal canal, while external hemorrhoids protrude outside the anus.

What are the muscles of mastication?

Masseter, Temporalis (jaw closure); Lateral Pterygoid (jaw opening); Medial & Lateral Pterygoids (grinding movement).

How does the histology of the esophagus differ from the stomach?

The esophagus has stratified squamous epithelium, while the stomach has simple columnar epithelium with gastric glands.

What are the three parts of the small intestine and their functions?

• Duodenum: Chemical digestion & enzyme secretion.

• Jejunum: Major site of nutrient absorption.

• Ileum: Absorption of vitamin B12 and bile salts.

How does the rectum function in the digestive system?

IIt temporarily stores feces and triggers the urge to defecate.

How does the histology of the stomach allow for digestion?

• Parietal cells secrete HCl for protein digestion.

• Chief cells release pepsinogen, which becomes pepsin.

• Mucous cells produce mucus for protection.

What is the importance of microvilli in the small intestine?

They increase surface area for nutrient absorption.

What are the three structural modifications of the small intestine that increase absorption?

Plicae circulares, villi, and microvilli.

What is the difference between intraperitoneal and retroperitoneal organs?

• Intraperitoneal: Almost entirely covered by peritoneum (e.g., stomach, small intestine).

• Retroperitoneal: Partially covered, located behind the peritoneum (e.g., kidneys, pancreas).

What causes gastroesophageal reflux disease (GERD)?

The improper closing of the lower esophageal sphincter, allowing stomach acid to enter the esophagus.

What are taenia coli and haustra in the large intestine?

• Taenia coli: Longitudinal bands of smooth muscle.

• Haustra: Pouch-like structures that slow fecal movement.

What are the six essential digestive processes?

Ingestion, mechanical digestion, propulsion, chemical digestion, absorption, and defecation.

What is the difference between mechanical and chemical digestion?

• Mechanical digestion: Physical breakdown of food (e.g., chewing, churning).

• Chemical digestion: Enzymatic breakdown into smaller molecules.

What is the role of saliva in digestion?

It contains amylase for carbohydrate digestion and lubricates food for easier swallowing.

What is the role of the mesentery?

It connects the intestines to the abdominal wall, providing blood supply and structural support.

What is the function of the serous membrane in the digestive tract?

It reduces friction between organs and allows smooth movement within the abdomen.

What is the function of the tongue in digestion?

It moves food, aids in chewing and swallowing, and contains taste buds.

What is the lingual frenulum?

A small fold of mucous membrane that secures the tongue to the floor of the mouth.

What muscle helps keep food within the mouth?

The orbicularis oris muscle.

What is the uvula’s function during swallowing?

It closes off the nasal passages to prevent food from entering the nasal cavity.

What is the role of the pharyngeal constrictor muscles?

They propel food from the oropharynx into the esophagus during swallowing.

What type of epithelium lines the esophagus?

Stratified squamous non-keratinized epithelium (protection against abrasion).

What is the function of the gastroesophageal sphincter?

Prevents acid reflux by controlling the passage of food from the esophagus into the stomach.

What is the function of rugae in the stomach?

They allow the stomach to expand when food enters.

What are the three layers of stomach muscles?

• Outer longitudinal layer

• Middle circular layer

• Inner oblique layer

What are the four main regions of the stomach?

Cardia, fundus, body, and pylorus.

What is the primary function of the small intestine?

Digestion and absorption of nutrients.

What is segmentation in digestion?

A process that moves food back and forth to enhance mixing and absorption.

How do villi and microvilli aid in absorption?

They increase surface area for maximum nutrient absorption.

What are the three parts of the small intestine?

Duodenum, jejunum, and ileum.

What is the function of the lacteal in each villus?

It absorbs dietary fats (lipids) into the lymphatic system.

What are the main functions of the large intestine?

Water absorption, vitamin production, and feces formation.

What is the function of gut microbiota in the large intestine?

They help in digestion, produce vitamins (B-complex & K), and aid in immune function.

What is the ileocecal valve?

A valve that prevents backflow from the large intestine into the small intestine.

What are the taenia coli?

Longitudinal muscle bands in the colon that create haustra (pouches).

What is the difference between the internal and external anal sphincter?

• Internal sphincter: Involuntary (smooth muscle).

• External sphincter: Voluntary (skeletal muscle).

What is the pectinate line in the anal canal?

A boundary that separates visceral (autonomic) and somatic (conscious) nerve innervation.

What are hemorrhoids?

Swollen veins in the anal canal that can be internal (inside the rectum) or external (outside the anus).

What causes appendicitis?

Bacterial infection and blockage of the appendix leading to inflammation.

What is Gastroesophageal Reflux Disease (GERD)?

A condition where stomach acid regurgitates into the esophagus, causing heartburn.