Bones Flashcards
(28 cards)
What is the epiphysis?>
The flared bone at the end of a long bone covered by hyaline cartilage
What is the diaphysis?
The shaft of the long, a hollow cylinder that contains bone marrow in the marrow cavity
What is the metaphysis?
The region between epiphysis and diaphysis; the region of growth in childhood.
What is the periosteum?
A fibrous connective tissue sheath covering external surfaces; contains fibroblasts, mesenchymal cells, and osteoclasts.
What is the function of the nutrient foramen?
To supply blood to the bone.
What are the two major kinds of bone?
Trabecular (cancellous) bone and cortical (compact) bone.
What is trabecular bone?
Spongy and porous bone that gives supporting strength to the ends of weight-bearing bone.
What is cortical bone?
Solid bone on the outside forming the shaft of long bone; provides stiffness and strength.
What is the anatomical/functional unit of compact bone?
The osteon.
What is the anatomical/functional unit of trabecular bone?
The trabecula.
What do trabeculae do?
Distribute stress and have a high surface area for metabolism (e.g., Ca²⁺ regulation).
What is an osteoblast?
A bone-forming cell that forms osseous matrix and becomes enclosed as an osteocyte.
What is an osteoclast?
A large, multinucleated cell that resorbs bone matrix by demineralisation.
What is an osteocyte?
A mature bone cell (trapped osteoblast) embedded in lacunae; maintains matrix and senses mechanical stress.
What are osteoprogenitor cells?
Stem cells that give rise to osteoblasts and other cells.
What hormone decreases osteoclast activity?
Calcitonin (↓ blood Ca²⁺ levels)
What hormone increases osteoclast activity?
Parathyroid hormone (↑ Ca²⁺ release)
What increases bone mass and density?
Excessive mechanical stimulation.
What decreases bone mass and density?
Non-weight bearing, sex-hormone deficiency (e.g., menopause), endocrine/nutritional disorders.
What is Wolff’s Law?
Bone adapts to the load under which it is placed.
What is the first step in fracture healing?
Inflammation and additional blood flow lead to callus formation.
What is woven bone?
Bone quickly formed by osteoblasts with irregular collagen; weak and temporary.
What is lamellar bone?
Bone with collagen arranged in regular sheets, giving strength and resilience.
What final step restores bone shape after a fracture?
Remodelling by osteoclasts.
