Chapter 7 Bone Tissue

Flashcards for reviewing bone tissue lecture notes.

Osteology

Study of bone.

Cartilage

Forerunner of most bones and covers many joint surfaces of mature bone.

Ligaments

Hold bones together at joints.

Tendons

Attach muscle to bone.

Bone (osseous tissue)

Connective tissue with the matrix hardened by calcium phosphate and other minerals.

Mineralization or calcification

The hardening process of bone.

Flat bones

Thin, curved plates that protect soft organs (e.g., cranial, sternum).

Long bones

Longer than wide, rigid levers acted upon by muscles for movement (e.g., limbs).

Short bones

Approximately equal in length and width, glide across one another in multiple directions (e.g., wrist).

Irregular bones

Elaborate shapes that do not fit into other categories (e.g., hip, vertebrae).

Compact bone

Dense outer shell of bone (~80%).

Spongy (cancellous) bone

Loosely organized bone tissue found in center of ends and center of shafts of long bones and in middle of nearly all others (~20%).

Diaphysis

Shaft that provides leverage in long bones.

Medullary cavity (marrow cavity)

Space in the diaphysis of a long bone that contains bone marrow.

Epiphyses

Enlarged ends of a long bone that strengthen joint and anchor ligaments and tendons.

Articular cartilage

Layer of hyaline cartilage that covers joint surface, allowing joint to move more freely.

Nutrient foramina

Minute holes in bone surface that allow blood vessels to penetrate.

Periosteum

External sheath covering most of bone with outer fibrous layer of collagen and inner osteogenic layer of bone-forming cells.

Endosteum

Thin layer of reticular connective tissue lining marrow cavity with cells that dissolve osseous tissue and others that deposit it.

Epiphyseal plate (growth plate)

Area of hyaline cartilage that separates epiphyses and diaphyses of children’s bones, enabling growth in length.

Epiphyseal line

In adults, a bony scar that marks where growth plate used to be.

Osteogenic cells

Stem cells found in endosteum and inner layer of periosteum that multiply continuously and give rise to most other bone cell types.

Osteoblasts

Bone-forming cells that synthesize soft organic matter of matrix which then hardens by mineral deposition and secrete hormone osteocalcin.

Osteocytes

Former osteoblasts that have become trapped in the matrix they deposited; some reabsorb bone matrix while others deposit it and act as strain sensors.

Lacunae

Tiny cavities where osteocytes reside.

Canaliculi

Little channels that connect lacunae, allowing for passage of nutrients, wastes, signals.

Osteoclasts

Bone-dissolving cells found on bone surface that develop from same bone marrow stem cells that give rise to blood cells.

Resorption bays

Pits in bone surface where osteoclasts often reside

Matrix of osseous tissue

By dry weight, about one-third organic (collagen, carbohydrate-protein complexes) and two-thirds inorganic matter (hydroxyapatite, calcium carbonate, other minerals).

Hydroxyapatite

Crystallized calcium phosphate salt that makes up 85% of the inorganic matter in bone.

Rickets

Disease caused by mineral deficiency resulting in soft, deformed bones.

Osteogenesis imperfecta

Brittle bone disease resulting from a defect in collagen deposition.

Lamellar bone

Adult bone made up of layers (lamellae) of collagen in parallel surrounded by mineralized matrix.

Lamellus

The unit of bone structure

Histology of compact bone reveals osteons (haversian systems)

Concentric lamellae surround a central (haversian) canal running longitudinally.

Perforating (Volkmann) canals

Transverse or diagonal passages in compact bone.

Circumferential lamellae

Fill outer region of dense bone

Interstitial lamellae

Fill irregular regions between osteons.

Spongy bone

Lattice of bone covered with endosteum; slivers of bone called spicules and thin plates of bone called trabeculae, spaces filled with red bone marrow.

Bone marrow

Soft tissue occupying marrow cavities of long bones and small spaces of spongy bone.

Red marrow (myeloid tissue)

Contains hemopoietic tissue—produces blood cells; found in nearly every bone in a child; in adults, found in skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of humerus and femur.

Yellow marrow

Fatty marrow that does not produce blood; can transform back to red marrow in the event of chronic anemia.

Ossification or osteogenesis

The formation of bone.

In the human fetus and infant

Bone develops by two methods, intramembranous and endochondral ossification

Epiphyseal plate

Enables growth in length

Epiphyseal plate

Cartilage transitions to bone and functions as growth zone where bone elongates.

Appositional growth

Continual growth in diameter and thickness of bone.

Wolff’s law of bone

Architecture of bone determined by mechanical stresses placed on it.

Mineral deposition (mineralization)

Process in which calcium, phosphate, and other ions are taken from blood and deposited in bone.

Solubility product

Critical level of calcium times phosphate concentration at which hydroxyapatite crystals form.

Mineral resorption

Process of dissolving bone and releasing minerals into blood performed by osteoclasts at ruffled border.

Calcitriol

Most active form of vitamin D produced by actions of skin, liver, and kidneys that raises blood calcium level.

Calcitonin

Secreted by C cells (clear cells) of thyroid gland when blood calcium levels rise too high; lowers blood calcium concentration.

Parathyroid hormone (PTH)

Secreted by parathyroid glands on posterior surface of thyroid when calcium levels low in blood; raises calcium blood level.

Stress fracture

Break caused by abnormal trauma to a bone.

Pathological fracture

Break in a bone weakened by disease.

Comminuted fracture

Three or more pieces.

Closed reduction

Procedure in which bone fragments are manipulated into their normal positions without surgery.

Open reduction

Involves surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments.

Osteoporosis

Severe loss of bone density; bones lose mass and become brittle due to loss of organic matrix and minerals.

Kyphosis (widow’s hump)

Deformity of spine due to vertebral bone loss.