AGRI 1319: Gastrointestinal Tract (GIT) of Livestock Animals

Vocabulary flashcards covering the anatomical structures, digestive processes, and terminology of livestock gastrointestinal systems.

Digestion

The physical, chemical, and enzymatic means the body uses to render a feedstuff ready for absorption.

Mechanical Digestion

The breakdown of feedstuff mostly referring to chewing (mastication) as well as muscular contractions throughout the gastrointestinal tract.

Chemical Digestion

The breakdown of feedstuffs achieved through acid and enzymatic activity.

Microbial Digestion

The breakdown of feedstuffs by microbes that produce enzymes the host animal cannot synthesize on its own.

Absorption

The passage of digested nutrients through the mucous membrane of the gastrointestinal tract into the blood or lymphatic system.

Prehension

The means or mechanism by which an animal brings food to its mouth.

Dental Pad

A flat tissue structure present in ruminants like cattle and sheep in place of upper front teeth.

Mastication

The process of grinding feed with the teeth in the mouth.

Salivation

The secretion of saliva from salivary glands and its mixing with food in the mouth.

Bolus

The rounded mixture of ground feed and saliva formed in the mouth for swallowing.

Deglutition

The act of swallowing a bolus to pass it from the mouth into the esophagus.

Peristalsis

Involuntary muscular contraction and relaxation that moves a bolus or digestive contents along the gastrointestinal tract.

Chyme

The fluid mixture of partially digested food and secretions that exits the monogastric stomach into the small intestine.

Parietal Cells

Stomach cells responsible for producing Hydrochloric acid (HCl).

Chief Cells

Stomach cells that secrete pepsinogen, an inactive enzyme converted to pepsin for protein breakdown.

Gastric Juice

The combination of hydrochloric acid (HCl), enzymes (such as pepsin and gastric lipase), and other stomach secretions.

Papillae

Finger-like projections lining the inner wall of the rumen that enlarge its total surface area for nutrient absorption.

Cellulase

An enzyme produced by rumen microorganisms that digests cellulose, an ability host livestock animals lack.

Volatile Fatty Acids (VFAs)

Major energy-yielding fatty acids produced by microbial fermentation of fibrous feedstuff in ruminants and hindgut fermenters.

Rumination

The process in ruminants of regurgitating, re-chewing, and re-swallowing feed to reduce particle size for enhanced microbial and enzymatic action.

Reticulum

The second compartment of the ruminant stomach, easily identified by its distinctive honeycomb inner surface.

Omasum

The third compartment of the ruminant stomach, functioning primarily in the absorption of water, electrolytes, and volatile fatty acids.

Abomasum

The fourth compartment of the ruminant stomach, referred to as the true stomach because it performs chemical and enzymatic digestion.

Enterocytes

Specialized absorptive epithelial cells covering the intestinal villi, containing microvilli that form the brush border.

Goblet Cells

Intestinal epithelial cells that secrete protective mucus along the lining of the digestive tract.

Paneth Cells

Specialized cells in the small intestine crypts that secrete anti-microbial peptides to maintain intestinal defense.

Enteroendocrine Cells

Specialized cells located within the intestinal epithelium that release gastrointestinal hormones.

Lacteals

Lymphatic capillaries found inside each intestinal villus that absorb digested lipids into the lymphatic system.

Digesta

The fully processed intestinal contents leaving the ileum after undergoing extensive digestion and absorption in the small intestine.

Ileocecal Junction

The site of connection where the ileum of the small intestine meets the cecum of the large intestine.

Hindgut Fermenters

Animals (such as horses and rabbits) that rely on extensive microbial fermentation located in an enlarged cecum and colon behind the stomach.

Coprophagy

The act of consuming one's own feces to absorb nutrients and microbial end-products created in the hindgut.

Defecation

The physiological process of discharging fecal waste from the gastrointestinal tract via the rectum.