Bone and Muscle Physiology Exam Review

Vocabulary flashcards covering skeletal ossification, histology, calcium regulation, and the sliding filament mechanism of muscle contraction.

Osteogenesis (Ossification)

The process of bone formation, wherein bone is deposited by osteoblasts and resorbed by osteoclasts when reinforcement is needed or when bone is broken.

Rickets

A condition analogous to osteomalacia occurring exclusively in children that results in the softening and bowing of the bones.

Epiphyseal Plate

A region visible in a growing bone that forms new cartilage which is subsequently replaced by bone tissue.

Epiphyseal Line

The vestigial remnant of the epiphyseal plate present in a mature bone after growth has ceased.

Postnatal Bone Growth

The two modes of bone growth after birth: appositional growth (increase in thickness) and interstitial growth (increase in length).

Concentric Contraction

A muscle contraction where the muscle shortens while producing force, such as the bicep curling a weight upward.

Eccentric Contraction

A muscle contraction where the muscle lengthens while resisting a load, such as slowly lowering a weight downward during a bicep curl.

Voltage-Gated Calcium Channels

Channels at the motor neuron axon terminal that open during excitation-contraction coupling to stimulate acetylcholine release.

Axial Skeleton

The central skeletal division comprising the skull, vertebral column, and rib cage, excluding appendicular components like the pelvic girdle.

Fast-Glycolytic Fibers (Type IIb / IIx)

Muscle fibers that operate via anaerobic respiration and are recruited for rapid, explosive movements.

Intercalated Discs

Specialized junction sites between cardiac muscle cells that facilitate mechanical and electrical coupling in cardiac tissue.

Parathyroid Hormone (PTH)

A hormone that activates osteoclasts to degrade bone matrix and release stored calcium into the bloodstream.

Calcitonin

A hormone that signals osteoblasts to deposit calcium into the bone matrix, promoting new bone formation.

End Plate Potential

A local, depolarizing graded potential that occurs in the sarcolemma of skeletal muscle at the neuromuscular junction.

Intramembranous Ossification

A type of bone formation wherein bone develops from a fibrous membrane to form flat bones, such as cranial and facial bones.

Four Steps of Intramembranous Ossification

The sequential stages of flat bone development: Development of Ossification Center, Calcification, Formation of Trabeculae, and Development of Periosteum.

Sharpey's Fibers

Bundles of dense irregular connective tissue that firmly secure the periosteum to the underlying cortical bone.

Spongy Bone

A porous network of trabecular bone tissue found primarily within the epiphyses or ends of long bones.

Hydroxyapatites

Inorganic mineral calcium phosphate crystals that form the hard matrix of bone tissue.

Tendons

Dense regular connective tissue structures that attach skeletal muscles to bones.

Endomysium

The delicate sheath of areolar connective tissue that wraps around each individual muscle fiber.

Central (Haversian) Canal

A central structural conduit within an osteon containing blood vessels, lymphatic vessels, and nerves.

Sliding Filament Model Sequence

The cyclical stages of cross-bridge cycling: Cross-bridge formation, Power stroke, Cross-bridge detachment, and Cocking of myosin head.

Lacunae

Small cavities within the bone matrix that house mature osteocytes.

Osteoblasts

Bone-building cells responsible for synthesizing and secreting the unmineralized organic bone matrix.

Sarcoplasmic Reticulum

A specialized smooth endoplasmic reticulum in muscle fibers that regulates intracellular calcium storage and release.

Direct Phosphorylation Pathway

A metabolic pathway that transfers a phosphate from creatine phosphate to ADP, producing creatine and $1\,\text{ATP}$ per creatine phosphate molecule.

Creatine Kinase

The enzyme responsible for transferring a high-energy phosphate group from creatine phosphate to ADP to regenerate ATP.

Tropomyosin

A regulatory filamentous protein that physically covers and blocks the myosin-binding sites on actin filaments at rest.

DHP and Ryanodine Receptors

Voltage sensor proteins (DHP) in the t-tubule mechanically linked to calcium release channels (ryanodine) in the sarcoplasmic reticulum.