Anatomy and Physiology II: Anatomy of the Digestive System

Comprehensive vocabulary flashcards covering the structural organization, histology, organs, secretions, and common clinical pathologies of the human digestive system.

Mucosa

The innermost layer of the gastrointestinal tract wall.

Submucosa

The layer of the gastrointestinal tract wall containing numerous glands, blood vessels, and parasympathetic nerves.

Muscularis

The thick layer of muscle tissue within the gastrointestinal tract wall responsible for motility.

Serosa

The outermost layer of the gastrointestinal tract wall.

Oral Fissure

The line of contact formed between the closed lips.

Buccinator Muscle

The primary muscle forming the lateral boundaries (cheeks) of the oral cavity, covered externally by adipose tissue.

Hard Palate

The bony anterior portion of the roof of the mouth, consisting of portions of four bones: two maxillae and two palatines.

Soft Palate

The muscular arch partition separating the mouth from the nasopharynx.

Uvula

A conical tissue structure suspended from the midpoint of the posterior border of the soft palate arch.

Lingual Frenulum

The midline mucous membrane fold that anchors the tongue to the floor of the mouth.

Parotid Glands

The largest paired salivary glands, which produce a watery saliva containing digestive enzymes.

Submandibular Glands

Compound salivary glands containing both enzyme- and mucus-producing secretory elements.

Sublingual Glands

The smallest of the paired salivary glands, which produce a primarily mucous type of saliva.

Crown (Tooth)

The exposed portion of a tooth, covered by durable enamel to withstand abrasion during mastication.

Neck (Tooth)

The narrow region of a tooth that joins the crown to the root and is surrounded by the gingivae.

Root (Tooth)

The lower portion of a tooth that fits into the alveolar process socket, suspended by a fibrous periodontal membrane.

Dentin

The calcified tissue making up the greatest portion of the tooth shell, covered by enamel at the crown and cementum at the root.

Pulp Cavity

The central chamber within the dentin containing connective tissue, blood vessels, lymphatic vessels, and sensory nerves.

Deciduous Teeth

The initial set of $20$ baby teeth that erupt early in life and are later replaced.

Permanent Teeth

The complete adult set of $32$ teeth that replace the primary dentition.

Deglutition

The physiological process of swallowing that moves a food bolus from the mouth through the pharynx into the esophagus.

Esophagus

A muscular tube lined with stratified squamous epithelium extending from the pharynx to the stomach, encircled by sphincters at both ends.

Lower Esophageal Sphincter (LES)

The circular muscle ring (also known as the cardiac sphincter) controlling the opening of the esophagus into the stomach.

Cardia

The collarlike region of the stomach situated immediately at the junction with the esophagus.

Fundus (Stomach)

The enlarged, dome-shaped portion of the stomach located to the left of and above the esophageal opening.

Pylorus

The lower, narrow portion of the stomach that connects to the duodenum.

Pyloric Sphincter

The muscular valve controlling the outlet of the pyloric portion of the stomach into the duodenum.

Rugae

Coarse mucosal folds in the epithelial lining of the stomach that flatten to allow distension as the stomach fills.

Gastric Pits

Depressions in the gastric mucosa where the openings of gastric glands are located.

Chief Cells

Secretory cells of the gastric glands that synthesize and secrete the digestive enzymes of gastric juice.

Parietal Cells

Gastric gland cells that secrete hydrochloric acid ($\text{HCl}$) and produce intrinsic factor essential for vitamin $\text{B}_{12}$ absorption.

Gastric Muscularis

A modified muscularis layer consisting of three distinct sublayers of smooth muscle (longitudinal, circular, and oblique) arranged in a crisscrossing pattern.

Duodenum

The uppermost, roughly C-shaped division of the small intestine, measuring approximately $25\,\text{cm}$ in length.

Jejunum

The middle section of the small intestine, measuring approximately $2.5\,\text{m}$ in length.

Ileum

The terminal division of the small intestine, measuring approximately $3.5\,\text{m}$ in length.

Intestinal Villi

Fingerlike mucosal projections of the small intestine containing an arteriole, venule, and lacteal, designed to amplify surface area.

Lacteal

A specialized lymph capillary located at the core of an intestinal villus, responsible for absorbing dietary lipids.

Brush Border

A dense surface layer composed of approximately $1700$ ultrafine microvilli per epithelial cell lining the small intestine.

Crypts of Lieberkühn

Tubular glands located between intestinal villi containing stem cells that proliferate, differentiate, and migrate to renew the villus epithelium.

Cecum

A blind pouch measuring $5$ to $8\,\text{cm}$ located in the lower right quadrant of the abdomen, forming the first part of the large intestine.

Ileocecal Valve

A muscular valve that prevents contents from refluxing from the large intestine back into the ileum.

Transverse Colon

The horizontal segment of the large intestine extending across the abdomen between the hepatic flexure and splenic flexure.

Vermiform Appendix

An $8$ to $10\,\text{cm}$ accessory digestive organ communicating with the cecum that serves as a reservoir for beneficial gut bacteria.

Retroperitoneal

An anatomical classification designating structures located outside and posterior to the parietal peritoneum along the abdominopelvic wall.

Mesentery

A projection of parietal peritoneum that tethers intestinal coils, permits intestinal mobility, and prevents strangulation of the bowel.

Transverse Mesocolon

A broad fold of peritoneum that attaches and supports the transverse colon to the posterior abdominal wall.

Falciform Ligament

A peritoneal reflection that separates the liver into its left lobe and larger right lobe.

Hepatic Lobules

The hexagonal anatomical units of the liver, each pierced through the center by a branch of the hepatic vein (central vein).

Common Bile Duct

The duct formed by the confluence of the common hepatic duct and cystic duct that conveys bile into the duodenum.

Gallbladder

A pear-shaped sac on the undersurface of the liver measuring $7$ to $10\,\text{cm}$ long, which stores and concentrates bile fivefold to tenfold.

Acinar Units

The exocrine secretory units of the pancreas arranged in compound acini that produce and secrete digestive enzymes.

Pancreatic Islets

Endocrine cell clusters constituting about $2\%$ of total pancreatic mass, containing hormone-producing alpha cells and beta cells.

Sjögren Syndrome

An autoimmune disease targeting the salivary and lacrimal glands, resulting in xerostomia (dry mouth) and keratoconjunctivitis sicca (dry eyes).

Mumps

A viral infection characterized by painful inflammation and swelling of the parotid glands, which in $25\%$ of male cases can spread to cause orchitis.

Periodontitis

Inflammation of the periodontal membrane or ligament anchoring a tooth, potentially causing bone destruction and tooth loss.

Leukoplakia

A precancerous condition of the oral cavity characterized by thick, white patches of tissue typically arising on the cheeks or gums.

GERD

Gastroesophageal reflux disease, characterized by the backward flow of stomach acid into the esophagus, potentially leading to Barrett esophagus.

Helicobacter pylori

A spiral-shaped bacterium that causes inflammation, loss of protective mucus, and tissue erosion leading to peptic ulcers.

Pylorospasm

A condition in infants where the pyloric sphincter fails to relax, obstructing stomach emptying and precipitating projectile vomiting.

Diverticulosis

The presence of abnormal saclike outpouchings of the intestinal wall that become inflamed, predominantly seen in older adults on low-fiber diets.

Colitis

Any inflammatory condition of the large intestine, commonly presenting with diarrhea, constipation, and abdominal cramping.

Crohn's Disease

A chronic inflammatory bowel disease that can affect any part of the alimentary tract, occurring most frequently in the ileum and proximal colon.