Digestive System

What are the two major categories of organs in the digestive system?

• Alimentary canal organs: The continuous muscular tube that food actually passes through.

• Accessory organs: Organs like salivary glands, liver, gallbladder, and pancreas that assist in digestion but aren't part of the direct tube.

Name the main organs of the alimentary canal in order from top to bottom.

Mouth (oral cavity), Pharynx, Esophagus, Stomach, Small intestine (Duodenum, Jejunum, Ileum), Large intestine, Anus.

List the six main activities/processes of the digestive system.

1. Ingestion

2. Propulsion

3. Mechanical breakdown

4. Digestion (Chemical)

5. Absorption

6. Defecation.

Define Ingestion

An active, voluntary process whereby food is physically placed into the mouth (commonly known as eating).

What is the difference between Swallowing and Peristalsis in propulsion?

• Swallowing: A voluntary movement involving skeletal muscle to push food into the esophagus.

• Peristalsis: An involuntary alternating wave of smooth muscle contraction and relaxation that propels food along the rest of the tract.

What is Segmentation and what is its purpose?

A mechanical process in the small intestine where local rhythmic constrictions mix food with digestive juices and push it back and forth to increase absorption efficiency

What takes place during Mechanical Breakdown?

The physical preparation of food for digestion by fragmenting it into smaller pieces. Examples include chewing (mastication) in the mouth, churning in the stomach, and segmentation in the small intestine.

Define Chemical Digestion.

The sequence of steps in which large food molecules are chemically broken down into their building blocks (monomers) by enzymes.

What is Absorption and where does most of it occur?

The transport of digested end products from the lumen of the GI tract through its mucosal cells into the blood or lymph. The small intestine is the major site for this process.

What is Defecation?

The elimination of indigestible residues from the body via the anus in the form of feces.

Where does Carbohydrate digestion begin, and what are its final products?

It begins in the mouth with salivary amylase and is completed in the small intestine. The final monosaccharide products are galactose, glucose, and fructose.

Where does Protein digestion begin, and what are its final products?

It begins in the stomach via pepsin and continues in the small intestine via pancreatic enzymes. It breaks down into large polypeptides, small peptides, and finally amino acids

Where does Fat digestion primarily take place, and what assists it?

It takes place in the small intestine. It requires bile salts from the liver to emulsify the fats, which are then chemically broken down by pancreatic lipase into monoglycerides and fatty acids.