Osseous Tissue Lecture Review

Flashcards covering the classification, functions, anatomy, histology, development, and hormonal regulation of osseous tissue based on Chapter 6 lecture notes.

Axial skeleton

The long axis of the body, including the skull, vertebral column, and rib cage.

Appendicular skeleton

Bones of the upper and lower limbs and the girdles attaching limbs to the axial skeleton.

Support (Bone function)

One of the primary functions of bones, providing a framework for tissues and organs.

Storage of Minerals and Lipids (Bone function)

One of the primary functions of bones, serving as an important reserve of calcium, phosphate ions, and yellow marrow (lipids).

Blood Cell Production (Bone function)

One of the primary functions of bones, where blood cell formation occurs within the red marrow.

Protection (Bone function)

One of the primary functions of bones, where the axial skeleton and pelvic girdle protect internal organs.

Leverage (Bone function)

One of the primary functions of bones, where bones act as levers on which force can be applied to cause movement.

Sutural bones (Wormian bones)

Small, irregular bones found in the skull, in-between the flat bones.

Long bones

Bones that are longer than they are wide, e.g., humerus.

Short bones

Cube-shaped bones found in the wrist and ankle.

Flat bones

Thin, flat, slightly curved bones like the sternum, scapulae, ribs, and most skull bones.

Irregular bones

Bones with complicated shapes, such as vertebrae and coxal bones.

Sesamoid bones

Small bones associated with tendons and muscles.

Bone Markings

Sites on external surfaces of bones for muscle, ligament, and tendon attachment, joint surfaces, and conduits for blood vessels and nerves.

Projections (Bone Markings)

Bone markings that usually indicate stresses created by muscle pull or joint modifications.

Depressions/Openings (Bone Markings)

Bone markings that usually allow nerves and blood vessels to pass.

Head (Bone Marking)

An expanded articular end of an epiphysis, often separated from the shaft by a narrower neck.

Neck (Bone Marking)

A narrow connection between the epiphysis and diaphysis.

Facet (Bone Marking)

A small, flat articular surface.

Condyle (Bone Marking)

A smooth, rounded articular process.

Trochlea (Bone Marking)

A smooth, grooved articular process shaped like a pulley.

Sulcus (Bone Marking)

A narrow groove.

Fossa (Bone Marking)

A shallow depression.

Trochanter (Bone Marking)

A large, rough projection.

Crest (Bone Marking)

A prominent ridge.

Spine (Bone Marking)

A pointed process.

Line (Bone Marking)

A low ridge.

Tubercle (Bone Marking)

A small, rounded projection.

Tuberosity (Bone Marking)

A rough projection.

Compact bone

The dense outer layer of bone; smooth and solid.

Spongy bone (Cancellous or Trabecular bone)

Internal bone tissue composed of a honeycomb of flat pieces (trabeculae) of bone deep to compact bone.

Trabeculae

Flat pieces of bone that make up spongy bone, aligning along lines of stress to help resist it.

Diaphysis

The tubular shaft that forms the long axis of a long bone, composed of compact bone surrounding the medullary cavity.

Epiphysis

The bone ends of a long bone, with external compact bone and internal spongy bone, covered by articular cartilage.

Articular cartilage

Hyaline cartilage that covers the articular surfaces of the epiphyses.

Epiphyseal line

A remnant of childhood bone growth at the epiphyseal plate, visible in mature bones.

Epiphyseal plate (Epiphyseal cartilage)

A cartilaginous region that separates the epiphysis from the diaphysis in growing bones, where bone lengthening occurs.

Medullary cavity

The central cavity of the diaphysis of a long bone, containing yellow marrow.

Red bone marrow

Site of blood cell formation, found within the spongy bone.

Yellow marrow

Fat/adipose storage reserve, found mainly in the medullary cavity of long bones.

Metaphysis

The area or region between the diaphysis and epiphysis.

Endosteum

A thin membrane inside the medullary cavity, composed of a single layer of bone-forming cells, active in bone growth and repair.

Periosteum

The outer membrane (connective tissue) sheath found on all bones (except at joint cavities), functioning to protect bone, heal fractures, provide nourishment, and aid in tendon/ligament attachment.

Perforating fibers (Sharpey’s fibers)

Thick collagen fibers that attach the periosteum to the bone beneath.

Osteon (Haversian system)

The structural unit of compact bone; an elongated cylinder parallel to the long axis of bone, composed of lamellae surrounding a central canal.

Lamellae

Each ring of an osteon; collagen fibers in each ring run in different directions to give added strength.

Central (Haversian) canal

Runs through the core of an osteon, containing blood vessels and nerve fibers.

Osteocytes

Mature bone cells in lacunae; monitor and maintain bone matrix, and act as stress or strain sensors.

Canaliculi

Hairlike canals that connect lacunae to each other and the central canal, allowing communication and nutrient/waste relay.

Perforating (Volkmann's) canals

Canals lined with endosteum at right angles to the central canal, connecting blood vessels and nerves of the periosteum, medullary cavity, and central canal.

Interstitial lamellae

Incomplete lamellae not part of a complete osteon, filling gaps between forming osteons or remnants of osteons cut by bone remodeling.

Circumferential lamellae

Lamellae just deep to the periosteum, extending around the entire surface of the diaphysis to resist twisting of long bones.

Osteogenic cells (Osteoprogenitor cells)

Unspecialized bone stem cells derived from mesenchyme; mitotically active cells found in the endosteum that differentiate into osteoblasts.

Osteoblasts

Bone-forming cells that synthesize and secrete unmineralized bone matrix (osteoid).

Osteoid

Unmineralized bone matrix secreted by osteoblasts, including collagen and calcium-binding proteins.

Bone lining cells

Cells thought to help maintain the matrix and are found on bone surfaces where bone remodeling is not occurring.

Osteoclasts

Giant, multinucleate cells derived from hematopoietic stem cells, specialized for bone resorption (breakdown).

Bone resorption

The breakdown of bone matrix by osteoclasts, a process part of normal development, maintenance, and growth.

Resorption bay

A depression where active osteoclasts rest.

Ruffled border (Osteoclast)

An increased surface area of active osteoclasts for enzyme degradation of bone and sealing off the area from the surrounding matrix.

Hydroxyapatite

Crystals formed from calcium phosphate and calcium hydroxide, incorporating other calcium salts and ions, making up two-thirds of the bone matrix.

Osteogenesis

The process of bone formation.

Ossification

The process of replacing other tissues with bone.

Calcification

The process of depositing calcium salts, occurring during bone ossification and in other tissues.

Endochondral ossification

A form of ossification that ossifies bones originating as hyaline cartilage; most bones develop through this process.

Intramembranous ossification (Dermal ossification)

A form of ossification that occurs in the dermis, producing dermal bones such as the mandible and clavicle.

Primary ossification center

The region where fibroblasts differentiate into osteoblasts and begin producing spongy bone during endochondral ossification.

Secondary ossification centers

Regions where capillaries and osteoblasts migrate into the epiphyses during endochondral ossification, creating new centers of bone formation.

Epiphyseal closure

The event at puberty when epiphyseal cartilage production slows and osteoblast activity accelerates, causing the epiphyseal cartilage to disappear, forming the epiphyseal line.

Dermal bones

Bones formed through intramembranous ossification, such as the mandible and clavicle.

Spicules

Small struts of developing bone that grow outward from the ossification center during intramembranous ossification.

Nutrient artery and vein

A single pair of large blood vessels that enter the diaphysis through the nutrient foramen, supplying blood to the bone.

Nutrient foramen

An opening in the diaphysis through which the nutrient artery and vein enter.

Metaphyseal vessels

Blood vessels that supply the epiphyseal cartilage, where bone growth occurs.

Periosteal vessels

Blood vessels that supply superficial osteons and secondary ossification centers.

Calcitriol

A hormone made in the kidneys that helps absorb calcium and phosphorus from the digestive tract; its synthesis requires vitamin D3.

Vitamin D3 (Cholecalciferol)

A vitamin required for the synthesis of calcitriol.

Vitamin C

A vitamin required for collagen synthesis and stimulation of osteoblast differentiation.

Vitamin A

A vitamin that stimulates osteoblast activity.

Vitamins K and B12

Vitamins that help synthesize bone proteins.

Growth hormone

A hormone that stimulates bone growth and osteoblast activity.

Thyroxine

A hormone that, with growth hormone, stimulates osteoblast activity and the synthesis of bone matrix.

Estrogens

Sex hormones that stimulate osteoblast activity, synthesis of bone matrix, and accelerate epiphyseal closure.

Androgens

Sex hormones that stimulate osteoblast activity and the synthesis of bone matrix.

Calcitonin

A hormone secreted by C cells in the thyroid gland that decreases calcium ion levels by inhibiting osteoclast activity and increasing calcium excretion at the kidneys.

Parathyroid Hormone (PTH)

A hormone produced by parathyroid glands that increases calcium ion levels by stimulating osteoclasts, increasing intestinal absorption of calcium, and decreasing calcium excretion at the kidneys.

Calcium homeostasis

The process of closely regulating calcium ion levels in body fluids, maintained by calcitonin and parathyroid hormone (PTH).

Fractures

Cracks or breaks in bones caused by physical stress.

Bleeding (Fracture repair step)

The first step in fracture repair, which produces a blood clot or fracture hematoma.

Fracture hematoma

A large blood clot that develops immediately after a fracture.

Calluses (Fracture repair)

Formed by cells of the endosteum and periosteum, stabilizing the break; includes external and internal calluses.

External callus

A callus of cartilage and bone that surrounds the outer edges of a bone break during fracture repair.

Internal callus

A callus that develops in the medullary cavity during fracture repair, uniting the inner edges of the break.

Transverse fracture

A fracture that occurs straight across the bone.

Displaced fracture

A fracture where the bone ends are out of normal alignment.

Compression fracture

A fracture where the bone is crushed, common in vertebrae.

Spiral fracture

A fracture in which the bone has been twisted apart.

Epiphyseal fracture

A fracture that occurs where the bone matrix is calcifying and chondrocytes are dying, within the epiphyseal plate.

Comminuted fracture

A fracture in which the bone breaks into three or more pieces.

Greenstick fracture

An incomplete fracture where only one side of the shaft breaks, and the other side bends.