The Digestive System

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Digestion Noun

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[dy-jes-chun]

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Digestion

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The process by which the body breaks down food into smaller molecules that can be absorbed and used for energy.

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Example: This diagram shows digestion as the process of breaking down a large, complex food molecule (starch) into many small, simple molecules (glucose).

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Ingestion Noun

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[in-jes-chun]

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Ingestion

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The process of taking food or drink into the body by swallowing or absorbing it, typically through the mouth.

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Example: This diagram highlights the epiglottis, a part of the throat involved in the digestive process after food has been ingested and is being swallowed.

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Mechanical Digestion Noun

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[muh-kan-i-kuhl dy-jes-chun]

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Mechanical Digestion

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The physical breakdown of large food pieces into smaller pieces through actions like chewing and stomach churning.

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Example: This image shows that mechanical digestion is the physical breakdown of food, which starts in the mouth through actions like biting, tearing, and chewing.

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Chemical Digestion Noun

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[kem-i-kuhl dy-jes-chun]

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Chemical Digestion

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The process where complex food molecules are broken down into simpler molecules by chemical reactions involving enzymes and acids.

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Example: This diagram shows chemical digestion by illustrating how a large, complex protein molecule is broken down into smaller peptides and finally into individual amino acids.

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Absorption Noun

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[ab-sorp-shun]

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Absorption

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The process where nutrients from digested food pass from the small intestine into the bloodstream for transport to cells.

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Example: This diagram shows an enlarged intestinal villus, where digested nutrients are absorbed from the small intestine into the body's blood capillaries and lymphatic system (lacteal).

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Peristalsis Noun

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[per-uh-stal-sis]

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Peristalsis

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The involuntary, wave-like muscle contractions that move food through the digestive tract, from the esophagus to the rectum.

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Example: This diagram shows how wave-like muscle contractions push food through the esophagus. Muscles contract behind the food and relax in front of it.

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Enzyme Noun

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[en-zahym]

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Enzyme

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A protein that acts as a biological catalyst to speed up the rate of specific chemical reactions in the body.

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Example: An enzyme (the lock) has a specific active site that fits a substrate (the key), causing a chemical reaction that creates new products.

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Epiglottis Noun

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[ep-i-glot-is]

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Epiglottis

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A flap of cartilage at the root of the tongue that covers the windpipe opening during swallowing to prevent choking.

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Example: This diagram shows the epiglottis, a flap in the throat that covers the windpipe (trachea) when you swallow, directing food to the esophagus.

Front

Esophagus Noun

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[ih-sof-uh-guhs]

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Esophagus

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The muscular tube connecting the pharynx (throat) with the stomach, which transports food via peristalsis.

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Example: This diagram shows the esophagus as the muscular tube connecting the mouth to the stomach, highlighting its position within the upper digestive system.

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Hydrochloric Acid Noun

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[hy-dro-klor-ik as-id]

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Hydrochloric Acid

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A highly corrosive acid produced by the stomach to break down food and kill ingested pathogens.

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Example: This image shows a model of a hydrochloric acid (HCl) molecule, made of one hydrogen (H) atom and one chlorine (Cl) atom.