Comparative Anatomy and Physiology of Different Types of Digestive Systems (Vocabulary)

Vocabulary flashcards covering key terms related to comparative digestive anatomy and physiology across pigs, cattle, poultry, and pets, including omnivore/carnivore classifications, monogastric vs ruminant systems, major stomach compartments, and digestive organs and processes.

Omnivores

Animals that eat both plant-based and animal-based foods (examples: pigs, chickens, ducks, humans).

Carnivores

Animals that primarily eat animal-based foods with minimal or no plant material (examples: cats; dogs are facultative carnivores).

Monogastric

A simple, single-stomach digestive system; typical of humans, pigs, and many other non-ruminants.

Simple stomach

One-chamber stomach; contrasts with multi-chambered (ruminant) stomachs.

Ruminant

An animal with a four-chambered stomach that uses microbial fermentation to digest fiber (e.g., cattle, sheep, goats).

Four-chambered stomach

Polygastric stomach consisting of rumen, reticulum, omasum, and abomasum in ruminants.

Rumen

The largest rumen chamber where microbial fermentation occurs, producing volatile fatty acids (VFAs) used for energy.

Reticulum

Second stomach chamber with a honeycomb structure; traps foreign objects and aids digesta movement.

Omasum

Third stomach chamber that absorbs water and minerals; acts as a filter.

Abomasum

The true stomach; secretes gastric juices (acid and enzymes) for digestion.

Reticular groove

Esophageal groove in young ruminants that shunts milk directly to omasum/abomasum, bypassing the reticulorumen.

Rumination

Process of regurgitating and rechewing swallowed food; also known as second chewing.

Poultry (modified monogastric)

A monogastric digestive system with specialized organs: crop, proventriculus, gizzard.

Beak

Beak in birds; no teeth; used for swallowing and initial mechanical processing.

Crop

Storage and softening organ in poultry before grinding in the digestive tract.

Proventriculus

Glandular stomach of birds where enzymes and hydrochloric acid are secreted.

Gizzard (ventriculus)

Muscular grinding organ in birds that crushes food with grit (stones).

Cloaca

Single multipurpose exit/entry in birds for feces, urine, and reproductive tract.

Cattle (Cow) – Ruminant

A ruminant with a four-chambered stomach enabling microbial fermentation of fibrous feed.

Ruminant development

Immature ruminants are functionally nonruminants and develop rumen/omasum/reticulum with age.

Mouth (in pigs)

Mouth opens the digestive tract; teeth for grinding; saliva begins digestion.

Esophagus (pig)

Muscular tube that transports food via peristalsis; in ruminants also involved in rumination.

Stomach (pig)

Single-chamber stomach where mechanical and chemical digestion begins; ~8 L capacity in pigs.

Small intestine (pig)

Main site of nutrient absorption; composed of duodenum, jejunum, and ileum.

Large intestine (pig)

Water absorption and some fermentation; ends at the anus.

Duodenum

First section of the small intestine; receives bile and pancreatic secretions; site of chyme mixing.

Jejunum

Middle section of the small intestine; major site of nutrient absorption; brush border.

Ileum

Final section of the small intestine; absorption of nutrients; contains brush border.

Brush border

Microvilli-covered surface of intestinal cells (villi) increasing absorption area.

Villi

Finger-like projections in the small intestine that increase surface area for absorption.

Pancreas

Gland that secretes digestive enzymes and sodium bicarbonate; also produces insulin/glucagon.

Liver

Organ that produces bile for fat digestion and absorption; bilirubin metabolism; fat-soluble vitamins.

Gall bladder

Bile storage organ that releases bile into the small intestine as needed.

LARGE INTESTINE

Section including cecum, colon, rectum, and anus; reclaims water and electrolytes and forms feces.

Cecum

Pouch where bacterial fermentation of undigested material occurs; part of the large intestine.

Colon

Part of the large intestine where water absorption and fermentation occur; houses feces formation.

Rectum

Final section of the large intestine; stores feces before defecation.

Anus

External opening of the digestive tract at the end of the large intestine.

Chyme

Semi-fluid mass of partly digested food formed in the stomach.

Pyloric sphincter

Muscular valve regulating digesta passage from stomach to the duodenum.

Pyloric region (stomach)

Last part of the stomach; secretes mucus to protect lining and regulates emptying.

Cardiac area (stomach)

Upper portion of the stomach where mucus mixes with food.

Fundic area (stomach)

Section of the stomach where gastric glands secrete acid and pepsinogen.

Protein digestion (pepsin/pepsinogen)

Proteins are digested in the stomach by pepsin activated from pepsinogen by HCl.

HCl (hydrochloric acid)

Acid produced in the stomach that lowers pH and activates enzymes like pepsin.

VFA (volatile fatty acids)

Short-chain fatty acids (acetate, propionate, butyrate) produced by microbial fermentation; main energy source for ruminants.

Bile salts

Components of bile that emulsify fats, aiding fat digestion and absorption.