Chapter 7: Skeletal System - Bone Structure and Function

Comprehensive vocabulary flashcards covering the anatomy, physiology, and pathology of the skeletal system based on Chapter 7 lecture notes.

Skeletal system

The body system composed of bones, cartilages, and ligaments.

Cartilage

The forerunner of most bones that covers joint surfaces of mature bone.

Ligaments

Connective tissues that hold bones together at joints.

Tendons

Connective tissues that attach muscle to bone.

Electrolyte balance

The skeletal function of maintaining calcium and phosphate levels.

Blood formation

The skeletal function where red bone marrow acts as the chief producer of blood cells.

Bone (osseous tissue)

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

Mineralization

The hardening process of bone, also known as calcification.

Flat bones

Thin, curved plates used to protect soft organs, such as the brain and heart.

Long bones

Bones that are longer than they are wide and serve as rigid levers for movement.

Short bones

Bones that are approximately equal in length and width and glide across one another.

Irregular bones

Bones with elaborate shapes that do not fit into other shape categories.

Compact bone

The dense outer shell of bone that makes up three-fourths of the skeleton by weight.

Spongy (cancellous) bone

Loosely organized bone tissue found in the center of bone ends and shafts; makes up one-fourth of the skeleton by weight.

Diaphysis

The shaft of a long bone that provides leverage.

Medullary cavity

The space in the diaphysis of a long bone that contains bone marrow.

Epiphyses

The enlarged ends of a long bone that strengthen joints and anchor ligaments and tendons.

Articular cartilage

A layer of hyaline cartilage covering joint surfaces to allow free movement.

Nutrient foramina

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

Periosteum

The external sheath covering most of the bone.

Endosteum

A thin layer of reticular connective tissue lining the marrow cavity.

Epiphyseal plate

An area of hyaline cartilage separating the epiphyses and diaphyses in children to enable growth in length.

Osteogenic cells

Stem cells found in the endosteum and periosteum that multiply continuously and give rise to other bone cell types.

Osteoblasts

Nonmitotic, bone-forming cells that synthesize the soft organic matter of the matrix.

Osteocytes

Former osteoblasts trapped in the matrix that reside in lacunae and act as strain sensors to regulate bone remodeling.

Lacunae

Tiny cavities where osteocytes reside.

Canaliculi

Little channels that connect lacunae and allow for passage of nutrients and signals.

Osteoclasts

Large, multi-nucleated bone-dissolving cells that develop from bone marrow stem cells.

Hydroxyapatite

Crystallized calcium phosphate salts that make up $85\%$ of the inorganic matter in bone matrix.

Osteon

The functional unit of compact bone, consisting of concentric lamellae surrounding a central canal.

Trabeculae

Thin plates of bone that form the lattice structure of spongy bone.

Ossification

The formation of bone, also known as osteogenesis.

Endochondral ossification

Bone development method where bone replaces hyaline cartilage; forms most bones inferior to the skull.

Intramembranous ossification

Bone development within fibrous connective tissue membranes; forms the frontal, parietal, occipital, and temporal bones.

Interstitial growth

Lengthwise growth of long bones at the epiphyseal plate.

Appositional growth

The process by which bones increase in thickness.

Mineral deposition

The process in which calcium, phosphate, and other ions are taken from blood and deposited in bone by osteoblasts.

Mineral resorption

The process of dissolving bone and releasing minerals into the blood, performed by osteoclasts using hydrochloric acid ($pH\,4$).

Wolff’s law

The principle stating that bones grow or remodel in response to the mechanical demands placed on them.

Osteomalacia

An adult bone disease where bones are poorly mineralized and weak due to Vitamin D deficiency.

Rickets

A form of osteomalacia in children that results in bowed legs and bone deformities.

Osteoporosis

The most common bone disease, characterized by severe loss of bone density where resorption exceeds deposit.

Achondroplastic dwarfism

Condition where long bones stop growing in childhood, resulting in a normal torso but short limbs.

Pituitary dwarfism

Condition caused by a lack of growth hormone, resulting in short stature with normal proportions.

Hypocalcemia

A condition of deficient calcium levels in the blood.

Hypercalcemia

A condition of excessive calcium levels in the blood.

Calcitriol

The most active form of vitamin D that raises blood calcium levels by increasing intestinal absorption.

Calcitonin

A hormone secreted by the thyroid gland that lowers blood calcium levels by inhibiting osteoclasts.

Parathyroid hormone (PTH)

A hormone released when blood calcium is low that increases osteoclast population and bone resorption.