Ch_17_-_Digestive_System__2025_

Digestive System

A long tube consisting of specialized structures like the stomach and intestines, responsible for breaking down food and absorbing nutrients.

Luminal Microbes

Microorganisms, such as bacteria, present in the inner portion (lumen) of the digestive tract, which is connected to the outside environment.

Mechanical Digestion

The physical breakdown of food into smaller pieces without altering their chemical composition.

Chemical Digestion

The breakdown of food particles through enzymatic reactions that convert them into simpler chemical forms.

Alimentary Canal

The long tube that extends from the mouth to the anus, serving as a passageway for food.

Accessory Organs

Organs that aid in digestion but do not pass food directly; includes salivary glands, liver, gall bladder, and pancreas.

Mucosa

The innermost epithelial layer of the digestive tract that secretes mucus.

Peristalsis

Wave-like contractions in the digestive tract that propel food along the canal.

Segmentation

Rhythmic contractions that mix food in the small intestine without propelling it in one direction.

Gastric Juice

A digestive fluid produced in the stomach that contains hydrochloric acid and digestive enzymes.

Bile

A yellowish-green fluid produced by the liver that aids in the digestion of fats.

Cholecystokinin (CCK)

A hormone that stimulates the gallbladder to release bile and the pancreas to secrete digestive juices.

Intestinal Villi

Tiny projections in the small intestine that increase surface area for absorption of nutrients.

Pepsin

A protein-digesting enzyme produced in the stomach that breaks down proteins into polypeptides.

Microvilli

Small projections on the surface of epithelial cells in the small intestine that further increase surface area for absorption.

Gallstones

Solid crystals formed from excess bile concentration or cholesterol in the gall bladder.

Feces

Waste material composed of undigested food, water, bacteria, and other substances eliminated from the body.

Peritoneum

A double-layered membrane that lines the abdominal cavity and covers the organs within it.

Autonomic Control of Digestive Activity

Regulation of digestive processes by the autonomic nervous system; includes parasympathetic and sympathetic impulses.