Ruminant and Bird Digestive Systems

This set of vocabulary flashcards covers the anatomical structures and physiological functions of the ruminant and avian digestive systems based on the lecture notes.

Saliva (Ruminant)

Produced at rates up to $190\,liters$ ($50\,gallons$) per day; it contains no starch-digesting enzymes but is rich in bicarbonate and phosphate buffers to neutralize acids.

Dental Pad

A thick, fibrous, keratinized pad on the top jaw of ruminants that replaces upper incisors.

Diastema

The toothless gap between the front teeth and premolars in ruminants used as a working space to feel and pull grass.

Hypsodont teeth

Teeth characterized by extreme high crowns and deep roots, found in ruminants.

Rumen

The massive fermentation vat on the left side of the abdominal cavity lined with papillae; it serves as a continuous flow bioreactor where microbes use cellulase to break down cellulose.

Papillae

Finger-like projections lining the rumen that increase the surface area for absorption.

Reticulum

A small pouch-like compartment that traps heavy objects like nails or wire and initiates the rumination reflex for cud formation.

Omasum

A chamber that acts as a physical filter and grinder, responsible for absorbing water, bicarbonate, and volatile fatty acids.

Abomasum

The 'true glandular stomach' of ruminants, equivalent to the human stomach, which secretes $HCl$, pepsin, and rennin.

Crop

An expansion of the esophagus used for food storage and softening; in pigeons, it produces 'crop milk' to feed chicks.

Proventriculus

The glandular stomach of a bird where chemical digestion begins via the secretion of $HCl$ and pepsinogen.

Gizzard (Ventriculus)

The muscular mechanical stomach of a bird used to crush and grind seeds and grains.

Pancreas (Bird)

An accessory gland that dumps digestive enzymes (amylase, lipase, and protease) and bicarbonate into the small intestine.

Caeca

Two blind pouches at the junction of the small and large intestine that house fermenting bacteria to break down fibrous plant material.

Large Intestine (Bird)

A very short organ in birds designed to keep body weight light for flight; its primary function is absorbing water and electrolytes.

Cloaca

A common chamber in birds where the digestive, urinary, and reproductive tracts meet.

Vent

The external opening through which both feces and urine are expelled together in birds.