Digestion: Study Notes

Flashcards covering key vocabulary related to the 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 tube from mouth to anus where digestion occurs.

Accessory Organs

Organs that support digestion (e.g., liver, pancreas, gallbladder).

Mucosa

The innermost layer of the GI tract; protects and absorbs.

Submucosa

A layer of GI tract histology that contains glands.

Muscularis

A layer of GI tract histology that moves food via peristalsis.

Serosa

The outermost layer of GI tract histology; connective tissue for shape and position.

Ingestion

The process of taking food into the body.

Absorption

The process where nutrients move into the bloodstream.

Excretion

The elimination of undigested waste.

Vestibule

The space inside the mouth.

Hard Palate

Formed by 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

Teeth used for biting.

Canines

Teeth used for tearing.

Premolars

Teeth used for grinding.

Molars

Teeth used for crushing.

Tongue

Skeletal muscle attached to the hyoid bone; moves food, aids swallowing, crucial for speech.

Papillae

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

Salivary Glands

Glands that produce saliva (mucous, water, bicarbonate, 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; moves food by peristalsis.

Peristalsis

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

Stomach

A J-shaped organ where physical and chemical digestion occur and which expands to hold food.

Pyloric Sphincter

Controls the rate of stomach emptying into the small intestine.

Oblique Smooth Muscle

An additional muscle layer in the stomach wall for churning.

Gastric Glands

Glands in the stomach 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 with a pH of 1.5-2.

Gastrin

A hormone that stimulates gastric motility and HCl excretion.

Pepsin

An enzyme that breaks down protein in the stomach.

Pepsinogen

The precursor to pepsin.

Ghrelin

A hormone that regulates hunger.

Somatostatin

A hormone that inhibits digestion in the stomach.

Small Intestine

A ~10 feet long organ that is the primary site of digestion and absorption.

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 surface area for absorption.

Chyme

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

Duodenum

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

Hepatopancreatic Ampulla

The junction where the bile duct and pancreatic duct join.

Jejunum

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

Ileum

The final 6 feet of the small intestine, more vascular, with more villi and microvilli, primarily involved in absorption.

Large Intestine

The last section of the GI tract (~5 feet long), primarily responsible for absorbing water, nutrients, and vitamins, and forming feces.

Rectum

Part of the large intestine that holds feces until excretion.

Bacterial Flora

Approximately 700 species of harmless bacteria in the large intestine that facilitate chemical digestion, nutrient access, and immune response.

Liver

The largest internal organ, filters nutrients and toxins, produces bile, and stores glycogen.

Gallbladder

Stores bile produced by the liver and secretes it into the duodenum to emulsify lipids.

Pancreas

Produces and secretes enzymes (pancreatic juice) into the duodenum and produces insulin.

Sodium Bicarbonate

Produced by the pancreas to counteract the acidity of gastric juice.

Lipase

A pancreatic enzyme that digests lipids.

Trypsin

An inactive pancreatic enzyme that digests proteins, activated in the duodenum.

Chymotrypsin

An inactive pancreatic enzyme that digests proteins, activated in the duodenum.

Carboxypeptidase

An inactive pancreatic enzyme that digests proteins, activated in the duodenum.

Insulin

A hormone produced by the pancreas, released into the bloodstream, allowing glucose to enter cells.

Hypothalamus

Part of the brain that regulates hunger and satiety and responds to ghrelin.

Thyroid

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

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.