BIOL 182: Form, Function, and Animal Digestion

Flashcards covering animal form and function constraints, physical scaling laws, surface exchange, and the mechanics of digestion.

Square-Cube Law

A physical principle stating that as an object increases in size without changing shape, its surface area increases proportional to the square of its linear dimensions ($2^2 = 4$), while its volume increases proportional to the cube ($2^3 = 8$).

Essential Nutrients

Required chemical elements and compounds that an animal cannot synthesize from simple organic molecules and must obtain directly through its diet.

Hydrolysis

The chemical breakdown of a macromolecule into smaller subunits mediated by enzymes during digestion.

Types of Ingestion

The four main mechanisms by which animals take in food: filter feeding, substrate feeding, fluid feeding, and bulk feeding.

Intracellular Digestion

The processing of food inside cellular organelles called food vacuoles, which fuse with lysosomes containing hydrolytic enzymes.

Extracellular Digestion

The breakdown of food in specialized body compartments that are continuous with the outside environment of an animal.

Gastrovascular Cavity

A central digestive compartment with a single opening that serves for both food ingestion/digestion and nutrient distribution.

Alimentary Canal

A complete digestive tract consisting of a tube running between a mouth and an anus, containing specialized compartments for digestion and nutrient absorption.

Peristalsis

Rhythmic waves of muscular contraction that push food through the esophagus and remaining parts of the digestive tract.

Chyme

A liquid suspension produced in the stomach through the mechanical churning of ingested food mixed with acidic gastric juice.

Small Intestine

The major site of enzymatic hydrolysis of macromolecules and nutrient absorption, measuring approximately $20\,\text{feet}$ in humans.

Villi and Microvilli

Finger-like foldings and microscopic cell surface projections in the small intestine that dramatically increase surface area for nutrient uptake.

Large Intestine

The organ system segment comprising the colon, cecum, and rectum, measuring about $5\,\text{feet}$ in humans; lacks villi and microvilli and specializes in final water recovery and feces formation.

Hepatic Portal Vein

A major blood vessel that channels nutrient-laden blood from the digestive tract directly to the liver for nutrient distribution and toxin processing.

Salivary Amylase

An enzyme secreted in the oral cavity that begins chemical breakdown of carbohydrates during mechanical processing.