Digestion: Study Notes Review

Vocabulary flashcards covering key terms and concepts related to the human digestive system, its anatomy, histology, and physiology, based on the provided lecture notes.

Digestion

The process of breaking down food into smaller molecules that can be absorbed into the body.

GI Tract

A long, continuous tube extending from the mouth to the anus where digestion occurs.

Accessory Organs (GI System)

Organs like the liver, pancreas, and gallbladder that support digestion but are not part of the continuous GI tract.

Mucosa

The innermost layer of the GI tract, responsible for protection and absorption.

Submucosa

A layer of the GI tract histology containing glands.

Muscularis

A layer of the GI tract histology responsible for moving food via peristalsis.

Serosa

The outermost layer of the GI tract, composed of connective tissue that provides shape and position.

Ingestion

The process of taking food into the body.

Absorption

The process where digested nutrients move into the bloodstream.

Excretion

The elimination of undigested waste from the body.

Oral Cavity (Mouth)

The entry point to the GI tract.

Hard Palate

Formed by the maxilla and palatine bones, used for mastication and speech.

Soft Palate

Composed of muscles and glands, ending in the uvula; involved in swallowing and preventing aspiration.

Incisors

Front teeth primarily used for biting food.

Canines

Pointed teeth used for tearing food.

Molars

Back teeth primarily used for crushing food.

Papillae

Structures on the tongue that grip food and contain taste buds.

Salivary Glands

Glands that produce saliva containing mucous, water, bicarbonate, and amylase.

Amylase

An enzyme that breaks down carbohydrates.

Pharynx

The intersection of the GI tract and airway, connecting the mouth, nose, esophagus, and trachea.

Epiglottis

A flap of tissue that covers the trachea during swallowing to prevent food from entering the lungs.

Esophagus

A long tube connecting the pharynx to the stomach, moving food by peristalsis.

Peristalsis

The rhythmic contraction and relaxation of muscles in the digestive tract that propels food forward.

Stomach

A J-shaped organ that performs physical and chemical digestion and can hold about 1 gallon of food.

Pyloric Sphincter

A muscular valve that controls the rate of stomach emptying into the small intestine.

Oblique Smooth Muscle

An additional muscle layer in the stomach wall, aiding in churning food.

Gastric Glands

Glands in the stomach lining that excrete gastric juice.

Gastric Juice

The acidic fluid secreted by the stomach glands, containing hydrochloric acid, pepsin, and other enzymes.

Hydrochloric Acid (HCl)

A component of gastric juice, giving it a pH of 1.5-2.

Gastrin

A hormone that stimulates gastric motility and HCl excretion.

Pepsin

An enzyme in gastric juice that breaks down protein.

Pepsinogen

The inactive precursor to pepsin.

Ghrelin

A hormone that regulates hunger.

Small Intestine

A ~10-foot-long organ where the majority of digestion and absorption occur.

Villi

Small, finger-like projections lining the small intestine that increase the surface area for absorption of nutrients.

Microvilli

Even smaller projections on villi that further increase the surface area for absorption.

Duodenum

The first 10 inches of the small intestine, where bile and pancreatic juice are released for digestion.

Hepatopancreatic Ampulla

The junction where the bile duct and pancreatic duct join in the duodenum.

Jejunum

The middle section of the small intestine (~3 feet), where digestion continues and absorption intensifies.

Ileum

The final 6 feet of the small intestine, primarily responsible for nutrient absorption.

Somatostatin

A hormone that inhibits digestion in the stomach.

Large Intestine

The last section of the GI tract (~5 feet long), primarily responsible for water, nutrient, and vitamin absorption, and feces formation.

Large Intestine Histology

Characterized by no enzyme-secreting glands/ducts, no villi but presence of microvilli, and epithelium that secretes mucus.

Bacterial Flora (Large Intestine)

Approximately 700 species of bacteria that facilitate chemical digestion, nutrient access, immune response, and compete with invaders.

Liver

The largest internal organ, responsible for filtering nutrients and toxins, producing bile, and storing glycogen.

Glycogen

Chains of carbohydrates stored by the liver.

Gallbladder

An accessory organ that stores bile produced by the liver and secretes it into the duodenum.

Bile

A fluid that emulsifies lipids for enzyme digestion, produced by the liver.

Pancreas

An organ that produces and secretes enzymes (pancreatic juice) into the duodenum and produces insulin.

Sodium Bicarbonate

A component of pancreatic juice that counteracts the acidity of gastric juice.

Lipase

An active enzyme produced by the pancreas that digests lipids.

Trypsin

An inactive enzyme produced by the pancreas, activated in the duodenum to digest proteins.

Insulin

A hormone produced by the pancreas that allows glucose to enter cells.

Hypothalamus

A brain region that regulates hunger and satiety and responds to ghrelin.

Thyroid

A gland crucial to metabolism; its hormone stimulates the sympathetic nervous system and increases metabolism.

Chyme

The pulpy acidic fluid that passes from the stomach to the small intestine, consisting of gastric juices and partly digested food.

Enzyme

A protein that acts as a biological catalyst to speed up chemical reactions.

Hormone

A chemical messenger produced by the body that travels through the bloodstream to regulate various bodily functions.