Bone Physiology & Bone Disorders Flashcards

Vocabulary flashcards covering bone physiology, mineral deposition/resorption, calcium and phosphate homeostasis, fracture classifications, and bone disorders from the lecture notes.

Mineralization

The process in which calcium, phosphate, and other ions are extracted from the blood and deposited into bone tissue.

Ectopic Ossification

The abnormal calcification of otherwise soft tissue.

Mineral Resorption

The process of dissolving bone and releasing minerals into the blood, carried out by osteoclasts using hydrogen pumps that create hydrochloric acid at $\text{pH } 4$ to dissolve bone minerals and acid-tolerant proteases to break down collagen.

Calcitriol

The most active form of Vitamin D, produced by sequential actions of the skin, liver, and kidneys, which acts to raise blood calcium levels by enhancing intestinal calcium absorption, supporting bone resorption, and promoting renal calcium reabsorption.

Calcitonin

A hormone produced by the thyroid gland and secreted when blood calcium levels are elevated; it lowers blood calcium levels by stimulating osteoblasts and inhibiting osteoclasts.

Parathyroid Hormone (PTH)

A hormone secreted by the parathyroid glands in response to low blood calcium levels; it raises blood calcium levels by stimulating osteoclast production via RANKL, promoting renal calcium reabsorption, completing calcitriol synthesis, and inhibiting osteoblast collagen synthesis.

Hypocalcemia

A deficiency of calcium in the blood that lowers the charge gradient across cell membranes, causing muscle and nerve hyperexcitability, tetany, and potentially fatal laryngospasm.

Hypercalcemia

An excess of calcium in the blood that increases the electrical charge difference across cell membranes, rendering nerves and muscles less excitable and resulting in sluggish reflexes and muscle weakness.

Orthopedics

The branch of medicine concerned with the prevention and correction of injuries and disorders of bones, joints, and muscles.

Stress Fracture

A bone break caused by abnormal external trauma, such as a fall.

Pathological Fracture

A break in a bone that has been weakened by a pre-existing disease, such as osteoporosis or brittle bone disease.

Transverse Fracture

A fracture line that extends straight across perpendicular to the long axis of the bone.

Linear Fracture

A fracture line that runs parallel to the long axis of the bone, or a single-line fracture in the skull.

Oblique Fracture

A fracture in which the break occurs diagonally along a slant relative to the bone's axis.

Open Fracture

A fracture in which the broken bone pierces through the skin.

Closed Fracture

A fracture in which the broken bone remains entirely contained beneath intact skin.

Non-displaced Fracture

A fracture where the anatomical alignment of the bone fragments is maintained.

Displaced Fracture

A fracture in which the bone fragments shift out of their normal anatomical alignment.

Comminuted Fracture

A fracture in which the bone is splintered or broken into $3$ or more pieces, common in elderly individuals with brittle bones.

Compressed Fracture

A fracture in which a bone collapses or is crushed under compressive pressure, commonly occurring in vertebrae.

Greenstick Fracture

An incomplete fracture in which one side of the bone breaks while the opposite side remains intact and bends.

Osteoporosis

The most common bone disease, characterized by severe loss of bone mass and density, destruction of organic matrix and inorganic minerals, and heightened bone fragility primarily affecting spongy bone.

Kyphosis

An exaggerated thoracic curvature of the spine (widow's hump) resulting from vertebral bone loss and collapse due to osteoporosis.

Amenorrhea

The cessation of menstruation and ovulation due to extremely low body fat, leading to reduced estrogen levels and early onset of osteoporosis.

Fracture Repair Stages

The four sequential stages of bone healing: hematoma formation, soft callus formation, hard callus formation, and bone remodeling.