Digestion Lecture Notes

Vocabulary flashcards based on the digestion lecture notes.

Intracellular Digestion

Digestion inside the cell where phagocytosis occurs; cell engulfs food. Example: single-celled organisms like paramecium and amoeba.

Extracellular Digestion

Digestion outside the cells where food enters a tube and exits from the other end. Example: most animals, including the human digestive tract.

Filter Feeders

Aquatic animals that use a filter basket-like structure to gather small organisms suspended in the water. Examples: flamingoes, tube worms, clams, barnacles, and baleen whales.

Fluid Feeders

Organisms that obtain food by sucking or licking nutrient-rich fluids from live plants or animals. Examples: mosquitoes, ticks, aphids, spiders, bees, butterflies, vampire bats, and hummingbirds.

Substrate Feeders

Organisms that live in or on their food source and eat their way through it. Examples: caterpillars and earthworms.

Bulk Feeders

Organisms that ingest fairly large pieces of food, using tentacles, pincers, claws, fangs, or jaws and teeth. Examples: great blue heron.

Mechanical Digestion

The physical breakdown of large food particles into smaller ones through chewing, mashing, and breaking. This increases the surface area for enzyme contact.

Chemical Digestion

The chemical breakdown of large molecules into smaller ones (e.g., carbohydrates to monosaccharides, proteins to amino acids, lipids to fatty acids and glycerol, nucleic acids to nucleotides), facilitated by enzymes.

Bolus

A ball of food formed in the mouth by the tongue, which is then swallowed.

Peristalsis

A wave of muscular contractions that pushes the bolus down the esophagus towards the stomach.

Lower Esophageal Sphincter

A bundle of muscles that keeps stomach acid out of the esophagus.

Rugae

Folds in the stomach that allow it to expand.

Chyme

The digested bolus mixed with gastric juice in the stomach.

Pyloric Sphincter

The sphincter through which chyme leaves the stomach to enter the small intestine.

Duodenum

The first part of the small intestine where bile and pancreatic juice enter.

Bile

A substance that breaks down fats, entering the duodenum through the bile duct.

Jejunum

The middle part of the small intestine where the majority of absorption takes place.

Villi

Tiny finger-like projections lining the jejunum that increase the surface area for absorbing nutrients.

Microvilli

Tiny finger-like projections on each villus that further increase the surface area for absorption.

Ileum

The terminal part of the small intestine that compacts leftovers to pass into the large intestine.

Large Intestine (Colon)

Absorbs water from waste material and produces vitamin K and some B vitamins.

Rectum

The end of the large intestine where leftover waste is compacted and stored.

Anus

The opening through which feces pass out of the body.

Enzymes

Special proteins made at ribosomes that chemically break down food into small nutrients.

Carbohydrases

Enzymes that break down carbohydrates.

Proteinases

Enzymes that break down proteins.

Lipases

Enzymes that break down lipids.

Nucleases

Enzymes that break down nucleic acids.

Substrate

The item that an enzyme breaks down.

Salivary Amylase

An enzyme in saliva that begins to break down carbohydrates.

Pepsin

An enzyme in the stomach that breaks down proteins.

Lipase

An enzyme in the stomach that breaks down lipids.

Pancreatic Amylase

An enzyme produced in the pancreas that breaks down carbohydrates.

Trypsin

An enzyme produced in the pancreas that breaks down proteins.

Bile

A substance made by the liver that aids in fat digestion.

Gall Bladder

Stores the bile produced in the liver and releases it into the small intestine.

Gastrin

A hormone that stimulates the digestive glands around the stomach.

Secretin

A hormone that stimulates the pancreas to release enzymes which help neutralize the stomach contents.

Motilin

A hormone in the duodenum which stimulates the production of pepsin.

Cholecystokinin (CCK)

A hormone that stimulates the release of gastric juice.