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Nutrient

Any substance taken in by an organism that is needed for survival, growth, development, tissue repair, or reproduction.

Nutrition

The process of consuming and using food and nutrients.

Five categories of organic nutrients

Carbohydrates, Proteins, Lipids, Nucleic acids, Vitamins.

Inorganic nutrients

Nutrients that include water and minerals.

Essential nutrients

Compounds that cannot be synthesized from any ingested or stored precursor molecule and must be obtained through diet.

Essential amino acids

Nine amino acids that must be available for protein synthesis in humans.

Essential fatty acids

Fatty acids that must be obtained through diet because the body cannot synthesize them.

Vitamins

Organic molecules required in small amounts as nutrients and often serve as coenzymes.

Minerals

Inorganic molecules needed by organisms in small amounts.

Herbivores

Animals that eat only plants.

Carnivores

Animals that consume animal flesh or fluids.

Omnivores

Animals that eat both plant and animal material.

Ingestion

The phase of food processing where food is taken into the body.

Digestion

The phase of food processing where food is broken down into smaller molecules.

Absorption

The phase where ions, water, and small molecules diffuse or are transported into the circulatory system.

Egestion

The phase where undigested materials and wastes are expelled from the body.

Intracellular digestion

Digestion that occurs inside a cell, typically found in simple invertebrates like sponges.

Extracellular digestion

Digestion that occurs in a digestive tract, allowing consumption of large food items.

Gastrovascular cavity

A simple form of extracellular digestion occurring in invertebrates, where one opening serves as both entry and exit.

Alimentary canal

A single elongated tube with openings at both ends, containing smooth muscle and epithelial cells for digestion.

Passive absorption

Absorption of nutrients without the use of energy, typically through simple diffusion.

Active absorption

Absorption that requires energy expenditure, often involving transport proteins.

Ruminants

Herbivores that can digest cellulose with the help of microorganisms in their digestive tract.

Small intestine

The major site for digestion and absorption of nutrients and water.

Villi

Finger-like projections in the small intestine that increase surface area for absorption.

Chylomicrons

Fat droplets that form inside intestinal cells and are transported into the lymphatic system.

Bile

A digestive fluid produced by the liver that emulsifies fats to aid in digestion.

Hydrochloric acid

A strong acid secreted in the stomach that helps kill microbes and dissolves particulate matter.

Pepsinogen

An inactive precursor of pepsin that is converted in the stomach to begin protein digestion.

Pancreas

An accessory organ that secretes digestive enzymes and bicarbonate into the small intestine.

Cecum

A pouch located at the junction of the small and large intestine, containing microorganisms.

Digestion of carbohydrates

Involves breaking down polysaccharides into monosaccharides primarily in the small intestine.

Digestion of proteins

Involves breaking down polypeptides into amino acids through the action of enzymes.

Digestion of lipids

Mainly occurs in the small intestine where triglycerides are emulsified and broken down into fatty acids.

Neural control of digestion

Local control of muscular and glandular activity by the nervous system, influencing digestion.

Hormones in digestion

Hormones released in response to food signaling that regulate various digestive processes.

Health issues related to digestion

Conditions such as diarrhea, heartburn, and ulcers that affect digestive health.