CH18 & 19--nutrition

Nutrition

Study of nutrients and how body uses them

Nutrients

Chemicals from the environment that organisms need for survival. Used to give energy to fuel metabolic processes

Macronutrients

Required in large quantities, such as carbohydrates, lipids, proteins; provide energy

Micronutrients

Required in small amounts, such as vitamins and minerals; help extract energy from macronutrients

Essential nutrients

Nutrients that the body cannot synthesize or cannot synthesize in sufficient quantity (Must be obtained from the diet)

Calories

Units of heat used to express amount of energy in foods

Carbohydrates— name the 3 carbohydrate sources

Organic compounds, such as sugars and starches

1. polysaccharides

2. disaccharides

3. Monosaccharides

Polysaccharides

Complex carbohydrates, such as starch from plant foods and glycogen from meats

Disaccharides

Double sugars: milk sugar, cane sugar, beet sugar, molasses

Monosaccharides

• what processes breaks down carbohydrates into monosaccharides so that they’re absorbed?

Single sugars: from honey and fruits

• digestion

Cellulose

A complex carbohydrate abundant in our food; not digested, but provides fiber

Glycolysis

The process where glucose is oxidized to produce energy

Glycogenesis

The process of converting excess glucose into glycogen for storage in liver and muscle cells

Name 3 types of monosaccharide absorbed from the digestive tract

fructose, galactose, and glucose

Glycogenolysis

Process of breaking down glycogen into glucose when glucose is needed for energy.

Lipogenesis

Conversion of excess glucose into fats, which are stored in adipose tissue.

Gluconeogenesis

Conversion of noncarbohydrates (amino acids, glycerol) to glucose for cells that require glucose as an energy source.

Carbohydrate Requirements

Carbohydrates are the primary source of fuel for cellular processes, with minimal requirements likely being at least 125 to 175 grams/day.

Average Diet in the United States

Includes 200 to 300 grams of carbohydrates per day.

Lipids

Organic compounds that include fats, oils, phospholipids, and cholesterol, supplying energy for cellular processes.

Triglycerides

Composed of glycerol and 3 fatty acids; the most common dietary lipids, also known as 'fats'. Most found in plant based and animal based foods

Saturated Fats

Fats with no double bonds between carbon atoms in fatty acids, mainly found in animal-origin foods and associated with increased cardiovascular disease risk.

Unsaturated Fats

Fats that contain one or more double bonds between carbon atoms, found in seeds, nuts, and plant oils.

Cholesterol

Abundant in liver and egg yolk, and found in whole milk, butter, cheese, and meats; not found in foods of plant origin.

Functions of Lipids

Mainly supply energy, containing more than twice as much chemical energy per gram as carbohydrates or proteins. Triglycerides are broken down to glycerol and fatty acids in order to release energy. Glycerol and fatty acids can be used to synthesize storage fats in adipose tissue

Essential Fatty Acids

Fatty acids that cannot be synthesized by the liver and must be obtained from the diet.

Lipoproteins

Formed when lipids combine with proteins, classified based on density for lipid transport to specific target cells.

VLDLs

Very low density lipoproteins with high triglyceride content.

LDLs

Low density lipoproteins with high cholesterol content.

HDLs

High density lipoproteins with high protein content.

Lipid Requirements

American Heart Association advises that fat intake should not exceed 30% of total daily calories. And fat intake should suffice absorption of fat soluble vitamins

Proteins

Chains of amino acids that have many functions, including building new proteins, enzymes, hormones, antibodies, clotting factors and supplying energy.

Deamination

Process where amino groups (-NH2) are removed from amino acids, resulting in the formation of urea, which is excreted in urine.

Essential Amino Acids

Amino acids that cannot be synthesized by the body and must be provided in the diet.

Complete Proteins

High-quality proteins that contain adequate amounts of essential amino acids for good health, found in meat, milk, and eggs.

Incomplete Proteins

Low-quality proteins that do not contain adequate amounts of essential amino acids, typically found in many plant proteins.

Amino Acids in Foods

Eight essential amino acids cannot be synthesized by human cells and must be provided in the diet.

Average Carbohydrate Intake

The average diet in the United States includes 200 to 300 grams of carbohydrates per day.

Nitrogen Balance

A state in which the amount of nitrogen taken in equals the amount excreted.

Negative Nitrogen Balance

Develops from starvation when excretion exceeds dietary intake.

Positive Nitrogen Balance

Develops in growing children, pregnant women, or athletes in training when protein being built into new tissue exceeds energy usage and excretion.

Dynamic Equilibrium

A state where overall gain equals overall loss in protein metabolism.

Protein Requirements

The need for dietary protein intake that varies according to body size, metabolic rate, and nitrogen balance condition.

Non-Essential Amino Acids

Amino acids that can be produced by the body and do not need to be obtained from the diet.

Dietary Protein Intake

Typically recommended to be 10% of a person's diet, equating to 0.8 g/kg of body weight or 0.4 g/lb.

Nitrogenous Substances

Certain non-protein substances that require nitrogen for their production.

Metabolic Rate

The rate at which the body uses energy, influencing protein intake needs.

Calorie

The amount of potential energy a food contains (units of heat).

Basal Metabolic Rate (BMR)

Rate at which body expends energy under basal conditions (awake and at rest, after overnight fasting, in comfortable environment).

Positive Energy Balance

Caloric intake exceeds output; tissues store excess nutrient, leading to weight gain.

Negative Energy Balance

Caloric expenditure exceeds intake; tissues are broken down for energy, leading to weight loss.

Appetite

Drive that compels us to seek food.

Insulin

Hormone secreted by the pancreas after eating; stimulates adipocytes to take up glucose and store fat, and other cells to take up glucose and store glycogen.

Leptin

Hormone secreted by adipocytes while eating; acts on hypothalamus to suppress appetite, by inhibiting release of Neuropeptide Y.

Neuropeptide Y

Neurotransmitter secreted by the hypothalamus in response to the hormone ghrelin; stimulates appetite.

Ghrelin

Hormone secreted by the stomach; enhances appetite by causing secretion of Neuropeptide Y.

Vitamins

Organic compounds that are required in small amounts for normal metabolic processes.

Fat-Soluble Vitamins

Vitamins A, D, E, and K that dissolve in fats and are stored in various tissues.

Water-Soluble Vitamins

B vitamins and vitamin C that are destroyed by cooking and food processing.

B Vitamins

Essential for normal cellular metabolism and usually found together in the same foods.

Minerals

Inorganic elements required in metabolism, usually extracted from the soil by plants.

Characteristics of Minerals

Make up about 4% of body weight; most concentrated in the bones and teeth.

Iron

An example of a mineral incorporated into organic molecules, such as hemoglobin.

Calcium Phosphate

An example of a mineral that exists as parts of inorganic compounds.

Free Ions

Some minerals exist as free ions in the blood (e.g., Na+, Cl-).

Homeostatic mechanisms

Regulate the concentration of minerals in body fluids.

Mineral toxicity

Can result from ingestion of too much of a mineral, or from overexposure to industrial pollutants, household chemicals, or certain drugs.

Major Minerals

Account for 0.05% or more of body weight.

Calcium

A major mineral that is essential for various bodily functions.

Phosphorus

A major mineral that is essential for various bodily functions.

Potassium

A major mineral that is essential for various bodily functions.

Sulfur

A major mineral that is essential for various bodily functions.

Sodium

A major mineral that is essential for various bodily functions.

Chlorine

A major mineral that is essential for various bodily functions.

Magnesium

A major mineral that is essential for various bodily functions.

Trace Elements

Also called microminerals, essential minerals found in minute amounts; each makes up less than 0.005% of body weight.

Manganese

A trace element that is essential for various bodily functions.

Copper

A trace element that is essential for various bodily functions.

Iodine

A trace element that is essential for various bodily functions.

Cobalt

A trace element that is essential for various bodily functions.

Zinc

A trace element that is essential for various bodily functions.

Fluorine

A trace element that is essential for various bodily functions.

Selenium

A trace element that is essential for various bodily functions.

Chromium

A trace element that is essential for various bodily functions.

Dietary supplements

Not classified as either a food or a drug; may contain ingredients that function like pharmaceuticals in the body.

Malnutrition

Poor nutrition that results from a lack of essential nutrients or inability to use them.

Undernutrition

Malnutrition resulting from deficiency of essential nutrients.

Overnutrition

Malnutrition resulting from excess of nutrient intake.

Starvation

A healthy human can survive 50 to 70 days without food; during starvation, the body will begin to digest itself.

Obesity

Body weight 20% or more above the ideal weight for a person's height.

Bulimia Nervosa

Can coexist with either obesity or anorexia nervosa; involves binge eating, then purging.

Anorexia Nervosa

Morbid fear of gaining weight; individuals have a distorted self-image and all the symptoms of starvation.

Gas exchange

Major function of the respiratory system.

Pulmonary ventilation

Movement of air into and out of the lungs.

External respiration

Exchange of gases between the air and blood in the lungs.

Internal respiration

Exchange of gases between blood and body cells.

Transport of gases

Movement of oxygen and carbon dioxide between lungs and tissues.

Nose

Provides openings for air to enter and leave the nasal cavity.

Nasal cavity

Hollow space behind the nose, separated into left and right portions by the nasal septum.

Nasal conchae

Turbinate bones that curl in from lateral walls of the cavity, separating the nasal cavity into passageways.