BIOCHEM 9:nutrition, absorption, and digestion

• the small intestine is the site where most nutrient absorption occurs
• Nutrition is the process of providing or obtaining the food necessary for health and growth.
• Nutrition is the sum of the processes by which an animal or plant takes in and utilizes food substances.
• Nutrients are substances that are not synthesized in sufficient amounts in the body and therefore must be supplied by the diet.
• Absence of nutrients leads to growth impairment, organ dysfunction, and failure to maintain adequate status of other nutrients.
• Proteins are digested through Mechanical Digestion and Chemical Digestion.
• Absorption of proteins occurs through Mechanical Digestion and Chemical Digestion.
• Fats are digested through Mechanical Digestion and Chemical Digestion.
• Function of lipids is not known.
• Carbohydrates are digested through Mechanical Digestion and Chemical Digestion.
• Absorption of carbohydrates occurs through Mechanical Digestion and Chemical Digestion.
• Water is essential for the body.
• Fiber is essential for the body.
• Vitamins and minerals are essential for the body.
• Water-soluble vitamins and fat-soluble vitamins are essential for the body.
• Malnutrition is a disorder related to nutrition.
• Malnutrition refers to inadequate or unbalanced intake of nutrients, impaired assimilation or utilization, and can lead to deficiencies, excesses or imbalances in a person's intake of energy and/or nutrients.
• Recommended Dietary Allowance (RDA) is the average daily dietary intake level that meets the nutrient requirements of nearly all healthy persons of a specific sex, age, life stage, or physiologic condition (pregnancy, lactation).
• Excessive food consumption can lead to obesity, diabetes, cardiovascular diseases, cancers, reduced health and longevity, and chronic diseases
• The body requires nutrients sufficient to provide energy to manufacture our daily requirement, which includes high energy phosphate (mainly ATP) to power all body functions.
• Undernutrition can lead to stunting, wasting, and underweight, and micronutrient deficiencies or insufficiencies.
• Undernutrition is a disorder related to nutrition.
• Excessive food consumption is a disorder related to nutrition.
• The quantity of proteins is affected by protein quality, energy intake, and physical activity.
• The importance of proteins includes growth, pregnancy, lactation, rehabilitation after injury/malnutrition.
• The Recommended Daily Allowance (RDA) for protein is 0.6/kg body mass/day.
• Large peptides may be absorbed intact by uptake into mucosal epithelial cells (transcellular) or passing between epithelial cells (paracellular).
• Essential amino acids include Phenylalanine/Tyrosine, Valine, Threonine, Tryptophan, Isoleucine, Methionine/Cystine, Histidine, Arginine, and Leucine.
• The digestion of dietary protein begins in the stomach with the action of pepsin and continues in the small intestine with the action of trypsin, chymotrypsin and elastase along with a series of exopeptidases and dipeptidases, some derived from the pancreas and some from the intestinal mucosal cells.
• Energy intake, particularly carbohydrate and fat intake, affects protein requirements because it spares the use of protein as an energy source.
• Protein quality is measured by comparing the proportions of essential amino acids in a food with the proportions required for good nutrition.
• Proteins provide the body's requirement for amino acid nitrogen to maintain nitrogen balance.
• Proteins provide specific amino acids used for growth and development like tissue repair after injury, recovery from an illness, pregnancy and lactation.
• Physical activity increases nitrogen retention from dietary protein.
• Free amino acids, the end product of digestion, are absorbed across intestinal mucosa through sodium-dependent active transport.
• Energy is essential for the body.
• Diseases are related to nutrition.
• Fats are a concentrated source of energy, providing 34% of calories in usual diets.
• Carbohydrates make up 45 - 55% of total caloric intake, with the brain requiring approximately 100g of glucose per day for fuel and other tissues consuming 50g/day.
• Some carbohydrates remain in the intestinal lumen and act as a substrate for bacterial fermentation.