Main Points Digestive System

Ingestion

The process of food intake in the digestive system.

GI tract

The gastrointestinal tract, which has four layers and is responsible for digesting and processing food.

Mechanical breakdown

The physical process of breaking down food into smaller pieces to aid digestion.

Alimentary Canal

The continuous tube that runs through the body, starting at the mouth and ending at the anus, involved in the digestion and absorption of food.

Optimal Conditions for Digestion

The ideal environmental factors necessary for the digestive processes to occur efficiently, including appropriate temperature, pH, and enzyme activity.

Digestive Signals

Chemical or hormonal messages that initiate or regulate the digestive processes, signaling for the release of digestive juices and enzymes.

Intrinsic Factors of Digestion

Biological mechanisms inherent to the digestive system that facilitate the process of digestion, including muscular contractions and secretion of digestive fluids.

Functional Anatomy

The study of the structure and function of body systems, specifically how the parts of the digestive system work together to process food.

Epithelium

A tissue layer that covers the body surfaces and lines cavities.

Salivary Glands

Glands that produce saliva, including major glands (parotid, submandibular, sublingual) and many minor glands.

Saliva

A largely water-based fluid that contains proteins and enzymes such as lysozyme, defensins, IgA, salivary amylase, and mucin.

Deciduous Teeth

The first set of teeth (baby teeth) that begin to be shed around the age of 6 and are replaced by permanent teeth.

Mucosa

The moist tissue lining of various cavities in the body, including the mouth, which is covered by epithelium.

Mastication

The process of chewing food to break it down mechanically.

Incisors

Type of tooth primarily used for cutting food.

Pharynx

The passage that food travels through after the mouth, consisting of the oropharynx and laryngopharynx.

Gastroesophageal sphincter

Muscle that surrounds the opening between the esophagus and the stomach, controlling the passage of food.

Salivary amylase

Enzyme in saliva that begins the digestion of starch.

Peristalsis

The wave-like muscle contractions that move food through the digestive tract.

Bolus

A mass of food that has been chewed and mixed with saliva, ready to be swallowed.

Gastroesophageal sphincter

The muscle that relaxes to allow food to enter the stomach from the esophagus.

Cardia

The region of the stomach adjacent to the esophagus.

Muscularis

The layer of the stomach that contains an additional oblique layer of smooth muscle.

Gastric Mucosa

The stomach lining composed of epithelial cells that include gastric pits leading into gastric glands.

Pepsinogen

An inactive enzyme produced by gastric glands that is activated to pepsin in acidic conditions.

Neck Cells

Cells within the gastric glands that produce mucus to protect the stomach lining from self-digestion.

HCL

Hydrochloric acid secreted by gastric cells that creates the acidic environment necessary for digestion.

Cephalic Phase

The first phase of gastric secretion triggered by sight, smell, or thought of food, stimulating gastric secretory activity.

Pylorus

The muscular valve controlling food movement from the stomach to the duodenum.

Hepatocytes

The main functional cells of the liver, responsible for bile production, detoxification, and metabolism.

Bile

A digestive fluid produced by the liver that helps emulsify fats in the intestine.

Peristalsis

The wave-like muscle contractions that move food through the digestive tract.

Gallbladder

A muscular sac beneath the right liver lobe that stores bile.

Bile

A fluid that contains electrolytes, fatty substances, bile salts, and bile pigments in an aqueous medium.

Bile salts

Emulsifying agents in bile that disperse fats and form water-soluble micelles.

Pancreatic juice

A HCO3-rich fluid produced by the pancreas, containing enzymes that digest all categories of foods.

Hepatopancreatic ampulla

The junction where the bile duct and pancreatic duct meet to empty secretions into the duodenum.

Cholecystokinin

A hormone released by the small intestine that stimulates gallbladder contraction and relaxation of the hepatopancreatic sphincter.