The Science of Nutrition - Chapter 11

Trabecular Bone

(spongy or cancellous bone) A porous bone tissue that makes up only 20% of the skeleton and is found within the ends of the long bones, inside the spinal vertebrae, inside the flat bones (breastbone, ribs, and most bones of the skull), and inside the bones of the pelvis.

Hypercalcemia

A condition marked by an abnormally high concentration of calcium in the blood.

T-Score

A comparison of an individual's bone density to the average peak bone density of a 30-year-old healthy adult.

Hypocalcemia

A condition characterized by an abnormally low concentration of calcium in the blood.

Hypomagnesemia

A condition characterized by an abnormally low concentration of magnesium in the blood.

Female Athlete Triad

A condition characterized by the coexistence of three disorders in some athletic females: an eating disorder, amenorrhea, and osteoporosis.

Calcium Tetany

A condition in which muscles experience twitching and spasms due to inadequate blood calcium levels.

Hypermagnesemia

A condition marked by an abnormally high concentration of magnesium in the blood.

Fluorosis

A condition marked by staining and pitting of the teeth; caused by an abnormally high intake of fluoride.

Osteoporosis

A disease characterized by low bone mass and deterioration of bone tissue, leading to increased bone fragility and fracture risk.

Calcium Rigor

A falure of muscles to relax, which leads to a hardening or stiffening of the muscles; caused by high levels of blood calcium.

Calcitonin

A hormone secreted by the thyroid gland when blood calcium levels are too high. _____ inhibits the actions of vitamin D, preventing reabsorption of calcium in the kidneys, limiting calcium absorption in the intestines, and inhibiting the osteoclasts from breaking down bone.

Fluorohydroxyapatite

A mineral compound in human teeth that contains fluoride, calcium, and phosphorus and is more resistant to destruction by acids and bacteria than hydroxyapatite.

Collagen

A protein that forms strong fibers and connective tissue.

Matrix Gla Protein

A vitamin K-dependent protein that is located in the protein matrix of bone and also found in cartilage, blood vessel walls, and other soft tissues.

Osteocalcin

A vitamin K-dependent protein that is secreted by osteoblasts and is associated with bone turnover.

Osteoclasts

Cells that erode the surface of bones by secreting enzymes and acids that dig grooves into the bone matrix.

Osteoblasts

Cells that prompt the formation of new bone matrix by laying down the collagen-containing component of bone that is then mineralized.

Cortical Bone

Compact bone; a dense bone tissue that makes up the outer surface of all bones, as well as the entirety of most small bones of the body.

DEXA

Dual energy x-ray absorptiometry/DXA; currently the most accurate tool for measuring bone density.

Parathyroid Hormone

PTH; a hormone secreted by the parathyroid gland when blood calcium levels fall. It is also known as parathormone, and it increases blood calcium levels by stimulating the activation of vitamin D, increasing reabsorption of calcium from the kidneys, and stimulating osteoclasts to break down bone, which releases more calcium into the bloodstream.

Bone Density

The degree of compactness of bone tissue, reflecting the strength of the bones. Peak bone density is the point at which a bone is strongest.

Bioavailability

The degree to which our bodies can absorb and utilize any given nutrient.

Phylloquinone

The form of vitamin K found in plants.

Menaquinone

The form of vitamin K produced by bacteria in the large intestine.

Calcitriol

The primary active form of vitamin D in the body.

Resorption

The process by which the surface of bone is broken down by cells called osteoclasts.

Remodeling

The two-step process by which bone tissue is recycled; includes the breakdown of existing bone and the formation of new bone.

Osteomalacia

Vitamin D-deficiency disease in adults, in which bones become weak and prone to fractures.

Rickets

Vitamin D-deficiency disease in children. Symptoms include deformities of the skeleton such as bowed legs and knocked knees.

Ergocalciferol

Vitamin D2, a form of vitamin D found exclusively in plant foods.

Cholecalciferol

Vitamin D3, a form of vitamin D found in animal foods and the form we synthesize from the sun.