About Digestion & Nutrition
Nutrition depends on digestion and absorption. The digestive system breaks food into smaller molecules, moves nutrients across the intestinal wall, and sends them into blood or lymph for processing and delivery.
Mouth
Chewing and saliva begin digestion.
Learn MoreStomach
The stomach mixes food with acid and enzymes.
Learn MoreSmall Intestine
Most nutrient absorption occurs in the small intestine.
Learn MoreLiver
The liver processes, stores, and redistributes nutrients.
Learn MoreLarge Intestine
The colon absorbs water and houses dense microbial communities.
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Blood and lymph carry absorbed nutrients.
Learn MoreCell Use
Cells use nutrients as fuel and building material.
Learn MoreMicrobiome
Gut microbes are part of the nutrition story.
Learn MoreMouth
Teeth break food into smaller pieces, while saliva moistens food and begins digesting some carbohydrates. The tongue forms a swallowable mass and moves it toward the throat.
Stomach
Acid helps unfold proteins and control many microbes. Muscular contractions mix food into a liquid mixture that gradually enters the small intestine.
Small Intestine
Folds, villi, and microvilli create a huge surface area. Sugars, amino acids, vitamins, minerals, and many other nutrients enter blood or lymph.
Liver
It stores glycogen, processes fats, makes blood proteins, regulates many chemicals, and produces bile for fat digestion.
Large Intestine
Gut microbes ferment some fibers and produce compounds that can be used by intestinal cells or absorbed.
Transport
The cardiovascular system distributes nutrients to tissues, while hormones help control whether molecules are used, stored, or transformed.
Cell Use
Glucose can make ATP, amino acids build proteins, fats build membranes and store energy, and micronutrients help enzymes and signals work.
Microbiome
Microbial communities differ between people and respond to diet, age, environment, medicines, and health. Research is active and there is no single perfect microbiome.