Subject:
Applied Science, Life Science, Biology
Material Type:
Module
Level:
Community College / Lower Division, College / Upper Division
Provider:
Rice University
Tags:
Alimentary Canal, Amino Acid, Aminopeptidase, Amylase, Animal Digestion, Anus, Avian Digestion, Bile, Bolus, Carbohydrate Digestion, Carboxypeptidase, Carnivore, Cephalic Phase, Cholecystokinin, Chylomicron, Chyme, Chymotrypsin, Digestion, Digestion Regulation, Digestive Process, Digestive System, Duodenum, Elastase, Elimination, Endocrine System, Esophagus, Essential Nutrient, Fat Digestion, Food Energy, Food Requirements, Gallbladder, Gastric Inhibitory Peptide, Gastric Phase, Gastrin, Gastrovascular Cavity, Gizzard, Herbivore, Hormonal Response, Ileum, Ingestion, Intestinal Phase, Jejunum, Lactase, Large Intestine, Lipase, Liver, Maltase, Mineral, Monogastric, Neural Response, Nutrition, Obesity, Omnivore, Pancreas, Pepsin, Pepsinogen, Protein Digestion, Proventriculus, Pseudo-ruminant, Rectum, Roughage, Ruminant, Salivary Amylase, Secretin, Small Intestine, Somatostatin, Sphincters, Stomach, Sucrase, Trypsin, Villi, Vitamin
License:
Creative Commons Attribution-NonCommercial 4.0
Language:
English

Introduction

Introduction

Section 1

Photo shows a variety of fresh vegetables being sold at a market.
For humans, fruits and vegetables are important in maintaining a balanced diet. (credit: modification of work by Julie Rybarczyk)

All living organisms need nutrients to survive. While plants can obtain the molecules required for cellular function through the process of photosynthesis, most animals obtain their nutrients by the consumption of other organisms. At the cellular level, the biological molecules necessary for animal function are amino acids, lipid molecules, nucleotides, and simple sugars. However, the food consumed consists of protein, fat, and complex carbohydrates. Animals must convert these macromolecules into the simple molecules required for maintaining cellular functions, such as assembling new molecules, cells, and tissues. The conversion of the food consumed to the nutrients required is a multi-step process involving digestion and absorption. During digestion, food particles are broken down to smaller components, and later, they are absorbed by the body.

One of the challenges in human nutrition is maintaining a balance between food intake, storage, and energy expenditure. Imbalances can have serious health consequences. For example, eating too much food while not expending much energy leads to obesity, which in turn will increase the risk of developing illnesses such as type-2 diabetes and cardiovascular disease. The recent rise in obesity and related diseases makes understanding the role of diet and nutrition in maintaining good health all the more important.