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Adenosine Triphosphate (ATP)
This is the primary fuel used by cells to generate the biochemical reactions essential for life.

The glands located on the top of the kidneys that are responsible for the production of stress-related hormones, such as cortisol, DHEA, and adrenaline.

Adrenocortiotrophic Hormone (ACTH)
The hormone released from the pituitary gland that interacts with receptors on the adrenal gland to begin the process of cortisol and DHEA production. ACTH uses the second messenger cyclic AMP to signal target cells in the adrenal gland.

Advanced Glycosylation Endproduct
The polymerized end products of protein cross-linked with glucose. AGE’s tend to adhere to capillaries and arteries increasing the risk of heart disease, blindness, and kidney failure. AGE’s are best estimated by the levels of glycosylated hemoglobin in the bloodstream.

Aerobic Capacity
The body’s ability to process oxygen. It is a combination of lung capacity, the size of the capillaries, the pumping action of the heart, and the transfer of oxygen from red blood cells to target tissues.

Aerobic Exercise
Exercise with a low enough intensity to facilitate adequate oxygen transfer to the muscle cells so that no buildup of lactic acid is observed. This type of exercise is useful for reducing insulin levels and lowering blood glucose.

The general deterioration of the body with increasing age.

Amino Acids
These are the building blocks of protein. There are eight essential amino acids the body cannot make and, therefore, must be included in the foods you eat.

The portion of the limbic system in the brain that processes emotions.

Anabolic Steroids
Synthetic analogs of testosterone that maintain the anabolic (i.e. muscle-building effects) state while reducing the virilization effects of testosterone.

Anaerobic Exercise
Exercise at an intensity that exceeds the ability to supply oxygen to the muscle cells leading to the buildup of lactic acid. Anaerobic exercise stimulates the synthesis of both growth hormone and testosterone.

Anti-aging Zone Lifestyle Pyramid
The combination of the Zone Diet, moderate exercise, and meditation that interact to reduce the four pillars of aging (excess insulin, excess blood glucose, excess free radicals, and excess cortisol). Of the three components of the Anti-aging Zone Lifestyle Pyramid, the Zone Diet is by far the most important.

Arachidonic Acid
An essential fatty acid that is the immediate precursor to “bad” eicosanoids found in fatty red meats, egg yolks, and organ meats.

Autocrine Hormones
Hormones that act upon the secreting cell. They are used to sample the immediate environment surrounding the cell. Eicosanoids are the best-known example of autocrine hormones.

Binding Proteins
Proteins that bind to water-soluble hormones, such as sex hormones, cortisol, and thyroid; or certain water-soluble proteins, such as insulin-like growth factor to maintain stable circulating levels of the hormone in the bloodstream.

Biological Marker of Aging
Any physiological marker that appears to be universal in an aging population.

Biological Response Modifier
Any molecule that can modify the biological response of cells to changes in its external environment.

Blood Glucose
The primary source of energy for the brain. Elevated blood glucose levels cause diabetes and accelerate aging.

Calorie Restriction
The reduction of calories that maintains adequate levels of protein and essential fats while also supplying adequate amounts of micronutrients (vitamins and minerals).

Corticotropin-Releasing Hormone (CRH)
The hormone released from the hypothalamus that interacts with the pituitary to produce ACTH. This hormone uses cyclic AMP for its second messenger.

The hormone released from the adrenal glands in response to stress or low blood glucose. Its primary mode of action in times of stress is to shut down eicosanoid synthesis. Its synthesis in the adrenal gland requires the second messenger, cyclic AMP.

Cyclic AMP
A second messenger that begins the biological response initiated by a hormone. Cyclic AMP is derived from ATP. Many endocrine hormones use cyclic AMP as their second messenger.

Cyclic GMP
A second messenger that begins the biological response initiated by a hormone. Cyclic GMP is the second messenger induced by nitric oxide.

Dehdroepiandrosterone (DHEA)
A steroid hormone produced in the adrenal glands. Its primary function is to inhibit the binding of cortisol.

A condition in which blood glucose is not well controlled. Type I diabetics make no insulin, whereas Type II diabetics are characterized by the overproduction of insulin with inability of the target cells to respond to the insulin.

A neurotransmitter that works in an axis with serotonin.

A hormone derived from a 20-carbon atom, polyunsaturated fat. Eicosanoids are made by every cell in the body. As autocrine hormones, they are constantly produced by the cell to sample the external environment. “Good” eicosanoids generate AMP.

Endocrine Hormones
Hormones that are secreted from a discrete gland and then travel through the bloodstream to target tissues.

The study of hormones. A more inclusive definition would be the study of biological communications.

The process by which extracellular molecules (including hormones) enter a cell.

Endothelial Cells
The cells that line the vascular system. They act as a barrier between the bloodstream and target cells that hormones must pass through in order to reach their receptors and exert their biological action.

Essential Fatty Acids
These are the fats the body cannot make and therefore must be part of the diet. Essential fatty acids are also the building blocks of eicosanoids. There are two groups, omega-3 and omega-6 fatty acids, each gives rise to a different group of eicosanoids.

A group of three steroid hormones that convey female characteristics and control fertilization. The production of estrogen is stimulated by follicle-stimulating hormone (FSH), which uses cyclic AMP as its second messenger.

The process by which intracellular chemicals (including hormones) are released.

Follicle-Stimulating Hormone (FSH)
The hormone released from the pituitary that stimulates estrogen production in females, and sperm production in males. FSH uses cyclic AMP as its second messenger.

Free Radical
Any molecule that contains an unpaired electron. Free radicals are unstable and will extract electrons from other biological molecules, which generates more free radicals.

The ability to live in an unassisted fashion.

A discrete organ responsible for the secretion of hormones. There are nine separate glands in the body: three are in the brain (hypothalamus, pineal, and pituitary), three are in the throat area (thyroid, thymus, and parathyroid), two are in the midsection (pancreas and adrenals), and one is in the gonad area (testes for males and ovaries for females).

The hormone from the pancreas that causes the release of stored carbohydrate in the liver to restore blood glucose levels. Glucagon uses the second messenger cyclic AMP to exert its biological action.

The only simple carbohydrate that circulates in the bloodstream. Glucose is the primary fuel used by the brain. It can also be stored in the liver and muscles in a polymer form known as glycogen.

Glucose Tolerance
The ability of muscle cells and the liver to remove glucose from the bloodstream. As you age, glucose tolerance decreases.

Glycemic Index
A measure of the rate at which a carbohydrate will enter the bloodstream as glucose. Some simple sugars, like table sugar, will enter the bloodstream slower than many complex carbohydrates, such as bread, rice, and potatoes. The faster a carbohydrate enters the bloodstream, the higher its glycemic index. The higher the glycemic index of a carbohydrate, the greater the increase in insulin levels. Fruits and vegetables tend to have a low glycemic index, whereas breads, pasta, grains, and starches tend to have a high glycemic index.

The storage form of glucose. Only glycogen from the liver can be used to restore blood glucose levels.

Glycosylated Hemoglobin
A measure of the long-term control of blood glucose determined by the amount of carbohydrate-modified hemoglobin in the red blood cells. The higher the amount of glycosylated hemoglobin, the worse the control of blood glucose levels.

Growth Hormone
The hormone released from the pituitary that interacts with fat cells to release fatty acids and also the liver to produce insulin-like growth factors.

Growth Hormone-Releasing Hormone (GHRH)
The hormone released from the hypothalamus that causes the release of growth hormone from the pituitary. GHRH uses cyclic AMP as its second messenger.

High Density Lipoprotein (HDL)
The “good” cholesterol that helps remove cholesterol from cells. If insulin levels go up, then HDL levels go down. The lower your HDL level, the more likely you are to suffer cardiovascular complications.

The portion of the limbic system in the brain that integrates incoming nerve impulses to the hypothalamus, and is also the memory center of the brain.

Hormone Releasing Factors
Hormones released from the hypothalamus that directly affect the pituitary and initiate the release of other hormones into the bloodstream. Many hormone releasing factors use cyclic AMP as their secondary messengers.

Biological compounds that communicate information at a distance. Hormones require specific receptors to begin their biological action and use second messengers to initiate the cellular process that uses that information.

The excess production of insulin. This is usually a consequence of insulin resistance in which the cells do not respond to insulin to reduce blood glucose levels.

The portion of the brain’s limbic system that integrates incoming information and either increases or decreases the release of certain hormones that instruct the pituitary gland to release hormones.

The hormone that drives incoming nutrients into cells for storage. Excess insulin is the primary pillar of aging.

Insulin Resistance
A condition in which the cells no longer respond well to insulin. As a result, the body secretes more insulin into the bloodstream in an effort to reduce blood glucose levels.

Insulin-like Growth Factor (IGF)
The hormone released from the liver in response to growth hormone. IGF-1 is the hormone responsible for building muscle.

Interstitial Space
The space between the endothelial cells and target cells, such as the liver or the smooth muscle cells that line the vascular bed.

Lean Body Mass
The total body weight minus the fat mass. Lean body mass consists of water, bones, collagen, and muscle.

Life Expectancy
The average age at which 50 percent of newborn children survive.

Limbic System
The part of the brain that is concerned with more primitive impulses and maintaining biological homeostasis.

The percentage of the maximum life span that an organism will reach before it dies.

Luteinizing Hormone (LH)
The hormone released from the pituitary gland that stimulates the production of testosterone in males and the production of progesterone in females. This hormone uses cyclic AMP as its second messenger.

Any food that contains calories and, therefore, can generate hormonal responses. Protein, carbohydrate, and fat are macronutrients.

Maximum Life Span
The longest period of life that an animal can expect to reach.

The hormone made in the pineal gland that controls circadian rhythms. It is also a powerful antioxidant for hydroxyl free radicals.

Vitamins and minerals that have no caloric value and little direct impact on hormonal response.

Mortality Doubling Time
The amount of time required for the death rate to double after reaching adulthood.

Nitric Oxide
A protohormone that generates cyclic GMP. Nitric oxide is a free radical.

Omega-3 Fatty Acids
A special type of polyunsaturated essential fatty acids found primarily in cold-water fish and purified fish oils. This type of fat is exceptionally beneficial to your cardiovascular system because of its effect on promoting the formation of “good” eicosanoids.

Omega-6 Fatty Acids
The type of polyunsaturated fatty acids found in protein and most seed oils. This type of fat can generate both “good” and “bad” eicosanoids.

Percentage Body Fat
This describes the percentage of your total weight that is composed of fat. The higher your percentage of body fat, the greater the likelihood of chronic disease, such as heart disease, cancer, or diabetes.

The gland located within the brain that synthesizes melatonin.

A hormone produced in response to luteinizing hormone (LH) released from pituitary gland. It is required to flush out the uterus if an egg is not fertilized. It is also useful for stimulating the growth of new bone mass.

A hormone produced in response to luteinizing hormone (LH) released from pituitary gland. It is required to flush out the uterus if an egg is not fertilized. It is also useful for stimulating the growth of new bone mass.

Synthetic analogs of progesterone that have some of the properties of natural progesterone.

A molecule that recognizes a unique hormone. Once that hormone is bound to the receptor, the information carried by the hormone can now exert its biological action.

Second Messenger
Molecules that are synthesized in response to hormones binding to their receptors. Second messengers initiate the biological action of the hormone.

A neurotransmitter important in filtering out information. If its levels are low, it can be the underlying cause of depression and violence.

The active form of T4 synthesized in the peripheral tissue.

The thyroid hormone that is released from the thyroid gland in response to TSH, which generates cyclic AMP.

A small segment at the end of nuclear DNA that becomes shorter with every replication of the DNA. DNA will no longer replicate beyond a certain point of telomere reduction.

The hormone that promotes the building of muscle mass in males and libido in both sexes.

The gland responsible for the production of certain white cells known as T-lymphocytes that are important for immune function. The thymus is very sensitive to excess cortisol.

The gland in the throat that synthesizes thyroid hormones that affect metabolism.

Thyroid-Releasing Hormone (TRH)
The hormone released from the hypothalamus that instructs the pituitary to release TSH.

Thyroid-Stimulating Hormone (TSH)
The hormone released from the pituitary that causes the thyroid gland to produce T4 hormone. TSH uses the second messenger cyclic AMP to initiate the synthesis of T4.

Triglycerides (TG)
The form of fat found in various lipoproteins in the bloodstream. High levels of triglycerides are usually indicative of high levels of insulin. The ratio of TG/HDL is a powerful indicator of insulin levels and is strongly predictive of future cardiovascular events.

Type 2 Diabetes
A diabetic condition characterized by the overproduction of insulin (hyperinsulinemia), increased AGE production, and decreased longevity.

Ventromedial Nucleus (VMN)
The part of the hypothalamus sensitive to excess glucose.

Zone Diet
A calorie-restricted diet that provides adequate protein, moderate levels of carbohydrates along with essential fats, and micronutrients spread throughout the day into three meals and two snacks that approximately maintain the protein-to-carbohydrate ratio throughout the day.