Physio - 1st Lecture

Primary responsibility of the digestive system

Breaking down food into nutrients that the body can absorb and use for energy and bodily functions.

Motility

Movement of food through the digestive tract.

Secretion

Release of enzymes and acids in the digestive process.

Digestion

Physical and chemical breakdown of food.

Absorption

Taking in nutrients into the bloodstream.

Storage and Elimination

Holding waste and removing it from the body.

Immune Barrier

Serving as a defense against pathogens in the digestive system.

Alimentary tract

A continuous 9-meter tube extending from the mouth to the anus, including oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.

Mucosa

The innermost layer of the alimentary tract responsible for absorption and secretion.

Submucosa

A vascular layer containing blood vessels, lymphatics, and nerve plexuses.

Muscularis

Layer consisting of inner circular and outer longitudinal smooth muscle responsible for peristalsis.

Serosa

The outermost protective layer of the alimentary tract.

Accessory organs

Organs that aid digestion without being part of the main tube, including teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Extrinsic Regulation

Control of the digestive system by the autonomic nervous system and endocrine system.

Intrinsic Regulation

Management of the digestive system by the enteric brain (enteric nervous system) and paracrine regulators.

Mastication

The process of chewing that mixes food with saliva and salivary amylase to begin starch digestion.

Deglutition

The coordinated process of swallowing food.

Peristalsis

Wave-like contractions of muscles that move food through the digestive tract.

Intrinsic factor

A protein required for the absorption of vitamin B12 in the small intestine, crucial for survival.

Pepsin

An enzyme that breaks down proteins into smaller peptides, activated by HCl.

Rugae

Visible folds on the inner surface of the stomach that increase surface area.

Gastric Pits

Microscopic openings in the mucosa that lead into the gastric glands.

H+/K+ ATPase pumps

Molecular pumps in parietal cells that transport H+ into the stomach lumen and K+ out.

Hydrochloric Acid (HCl)

An acid produced in the stomach that creates a low pH, denatures proteins, and activates pepsin.

D Cells

Cells in the gastric glands that secrete somatostatin, a regulatory hormone.

Brunner’s glands

Glands that secrete bicarbonate in the duodenum to protect it from stomach acid.

Clinical cause of peptic ulcers

Primarily caused by infection from Helicobacter pylori.

Phases of deglutition

The oral, pharyngeal, and esophageal phases involved in swallowing.