Chapter 7 - Skeletal System: Bone Structure & Function

Vocabulary flashcards covering bone structure, types, functions, growth processes, and common fractures as detailed in Chapter 7 notes.

Skeletal System

A system consisting of bones, cartilage, ligaments, and the connective tissues that stabilize or connect the bones.

Compact Bone

Also known as dense or cortical bone; it is rigid, white, smooth, and solid, making up 80% of total bone mass.

Spongy Bone

Also known as cancellous or trabecular bone; it is porous and located deep to compact bone, making up 20% of total bone mass.

Hyaline Cartilage

A semirigid connective tissue that includes costal, articular, and epiphyseal cartilage; it also forms the model for the development of the fetal skeleton.

Fibrocartilage

A weight-bearing cartilage found in intervertebral discs, the pubic symphysis, and the cartilage pads of knee joints (menisci).

Ligaments

Dense regular connective tissue that connects bone to bone.

Tendons

Dense regular connective tissue that connects muscle to bone.

Hematopoiesis

The process of producing blood cells, which occurs in the red bone marrow connective tissue.

Calcium

A mineral stored in bone essential for body functions, blood clotting, and neurotransmitter release; it is pulled from bones into the bloodstream by parathyroid hormone.

Phosphate

A mineral stored in bone that serves as a structural component of $ATP$, other nucleotides, and phospholipids.

Yellow Bone Marrow

Connective tissue that serves as a site for lipid storage.

Long Bones

Bones that are longer than they are wide with a cylindrical shaft (diaphysis); examples include the humerus, femur, palms, and fingers.

Short Bones

Bones with a length nearly equal to their width; examples include carpal and tarsal bones.

Sesamoid Bones

Small, sesame seed-shaped bones along the tendons of some muscles, such as the patella.

Flat Bones

Bones with flat, thin surfaces that may be curved; examples include the roof of the skull, scapulae, sternum, and ribs.

Irregular Bones

Bones with elaborate or complex shapes, such as the vertebrae, ossa coxae, and several skull bones like the ethmoid and sphenoid.

Diaphysis

The long central shaft of a bone, mainly made of compact bone, which surrounds the medullary cavity.

Epiphysis

The enlarged proximal and distal ends of a long bone, mostly composed of spongy bone.

Metaphysis

The region between the diaphysis and epiphysis that contains the growth plate in growing bones.

Epiphyseal Plate

A layer of hyaline cartilage where bone lengthening occurs during childhood and adolescence; also called the growth plate.

Epiphyseal Line

The remnant of the epiphyseal plate after growth stops and the cartilage is replaced by bone.

Articular Cartilage

A smooth layer of hyaline cartilage covering the ends of bones at joints to reduce friction and absorb shock.

Medullary Cavity

The hollow space inside the diaphysis containing bone marrow.

Endosteum

A thin membrane lining the medullary cavity and internal bone surfaces containing bone-forming and bone-remodeling cells.

Periosteum

A tough connective tissue membrane covering the outer surface of bone (except at articular cartilage) containing blood vessels, nerves, and bone-forming cells.

Diploë (Diploe)

The spongy (cancellous) porous layer of bone found between the inner and outer compact bone layers of certain skull bones.

Red Bone Marrow (Myeloid Tissue)

A soft connective tissue containing reticular connective tissue, developing blood cells, and adipocytes; it is the site of hematopoiesis.

Axial Skeleton

The central axis of the body including the skull, vertebral column, ribs, and sternum.

Appendicular Skeleton

The limbs (arms, hands, legs, feet) and their attachments (pectoral and pelvic girdles) mainly used for movement.

Osteoprogenitor Cells

Bone stem cells derived from mesenchyme that are mitotically active and differentiate into osteoblasts.

Osteoblasts

Bone-forming cells that secrete osteoid and help mineralize bone; they may become osteocytes or inactive lining cells.

Osteoid

The unmineralized organic bone matrix made mostly of collagen.

Osteocytes

Mature bone cells derived from osteoblasts, found in lacunae, which maintain and monitor the bone matrix.

Canaliculi

Tiny channels through which osteocytes communicate and sense mechanical stress.

Osteoclasts

Large, multinucleated, bone-resorbing cells derived from monocyte/macrophage lineage that break down bone by secreting acids and enzymes.

Hydroxyapatite

Inorganic salt crystals ($Calcium\,phosphate + Calcium\,hydroxide$) that give bone its hardness.

Bone Resorption

The process where osteoclasts release enzymes to digest organic components and $HCl$ to dissolve calcium and phosphate crystals.

Intramembranous Ossification

Bone growth within a membrane that produces flat bones of the skull, some facial bones, the mandible, and the central clavicle.

Endochondral Ossification

Bone development that begins with a hyaline cartilage model; produces the limbs, pelvis, vertebrae, and ends of the clavicle.

Interstitial Growth

Growth in bone length dependent upon the growth of cartilage within the epiphyseal plate.

Appositional Growth

Growth in bone diameter or thickness occurring within the periosteum.

Zone of Proliferating Cartilage

The microscopic zone where chondrocytes undergo rapid mitotic cell division and align into longitudinal columns.

Bone Remodeling

The continuous process of renewing and reshaping bone, with 20% of the adult human skeleton replaced yearly.

Calcitriol

The active form of Vitamin D produced via the kidneys that increases the absorption of calcium from the small intestine.

Osteopenia

A condition of insufficient ossification resulting in thinner, weaker bones due to a decline in osteoblast activity during aging.

Osteoporosis

A reduction in bone mass sufficient to compromise normal function, often found in elderly individuals.

Fracture Hematoma

A blood clot that forms at the site of a bone fracture.

Fibrocartilaginous Callus

A 'soft' callus that forms during the second stage of bone fracture repair.

Colles Fracture

A fracture of the distal end of the radius (lateral forearm) that produces a 'dinner fork' deformity.

Comminuted Fracture

A fracture where the bone is splintered into several small pieces between the main parts.

Greenstick Fracture

A partial fracture where one side of the bone breaks and the other side is bent; common in children.

Pott Fracture

A fracture involving the distal ends of both the tibia and the fibula.