Digestive System: Macromolecules Overview

Digestive System Quiz

• Macromolecules: Large molecules formed from smaller ones, essential nutrients for energy, cellular regulation, and tissue repair. These include carbohydrates, lipids, proteins, and nucleic acids. Metabolism is the sum of all chemical reactions in an organism.

Four Major Categories of Macromolecules

• Carbohydrates: Provide quick energy for cells. These include monosaccharides (single sugars), disaccharides (two sugars), and polysaccharides (many sugars). Examples include glucose and starch.
• Lipids: Store energy, cushion organs, and build cell membranes. Examples include fats and oils.
• Proteins: Build tissues, muscles, blood cells and aid in immune response and transports ions. Examples include enzymes (catalysts that speed up reactions) and hormones.
• Nucleic Acids: Contain genetic information. Examples include DNA (genetic information) and RNA (directing organism's growth and function).

Hydrolysis

• Chemical reaction that breaks apart macromolecules using water. Macromolecules must be broken down to smaller, absorbable molecules for cells.

Enzymes

• Enzymes help break down macromolecules by acting as catalysts. Enzymes aren't used up in the reaction and increase reaction rate. Enzyme names generally end in "ase".

Importance of Water in the Body

• Water transports nutrients, removes waste, lubricates tissues, regulates body temperature, and is a major component of bodily fluids.

Animals Obtaining Food

• Filter Feeders: Filter small organisms from water (e.g. tube worms).
• Substrate Feeders: Live on or in a food source and eat it (e.g., earthworms, caterpillars).
• Fluid Feeders: Consume nutrient-rich fluids (e.g., butterflies).
• Bulk Feeders: Consume large chunks of food (e.g., humans).

Four Stages of Food Processing

• Ingestion: Taking in food.
• Digestion: Breaking down food mechanically and chemically into smaller molecules.
• Absorption: Transporting digested nutrients from the digestive system to the circulatory system to be used throughout the body.
• Elimination: Removal of undigested waste.

The Alimentary Canal

• Long tube where food passes and is processed, starting at the mouth and ending at the anus. Different organs process food in different ways. Mechanical digestion includes physical breakdown from larger chunks to smaller pieces via teeth and muscle contractions.

Chemical Digestion

• Breaks down macromolecules into functional units using enzymes.

Human Digestive System

• Mouth: Mechanical and chemical digestion occurs here. Saliva contains amylase to break down carbohydrates, and lubricates the food for swallowing.

• Esophagus: Muscular tube connecting the mouth to the stomach, moving food via peristalsis. The esophageal sphincter is a muscular valve at the bottom of the esophagus to prevent backflow to the mouth.

• Stomach: Mechanical and chemical digestion which holds food and churns it with gastric juices. Gastric juices include hydrochloric acid and enzymes like pepsin to break down proteins.

• Small Intestine: Chemical digestion continues and absorption occurs. The small intestine is lined with villi and microvilli to increase surface area for absorption. Accessory organs such as the pancreas, liver, and gallbladder contribute enzymes and bile to aid digestion .

• Large Intestine (Colon): Water is reabsorbed, bacteria continue food breakdown and produce vitamins, and waste forms feces.

• Rectum: Stores feces before elimination through the anus.

Accessory Organs

• Pancreas: Produces digestive enzymes and the hormone insulin.
• Liver: Produces bile to aid fat digestion.
• Gallbladder: Stores bile until needed.

Factors Affecting Enzyme Activity

• Temperature and pH affect enzyme function (each enzyme has optimal conditions). Enzymes denature when conditions are not optimal.

Test your knowledge about the digestive system and its macromolecules with this quiz. Explore the four major categories: carbohydrates, lipids, proteins, and nucleic acids, along with their functions and examples. Assess your understanding of metabolism and hydrolysis processes involved in digestion.