Chapter 6 - Anatomy - The Skeletal System: Bone Tissue and Homeostasis

Vocabulary flashcards covering bone tissue, skeletal organization, histology, ossification, bone growth, remodeling, calcium homeostasis, and skeletal disorders based on lecture notes.

Osteology

The study of bones and the skeletal system.

Hemopoiesis

The formation and production of blood cells, which takes place in red bone marrow.

Yellow Bone Marrow

Material associated with bone composed of adipose tissue and scattered leukocytes that serves as a source of energy for the human body.

Osteocalcin

A hormone produced by bone tissue that helps regulate insulin secretion and sugar homeostasis in the body.

Axial Skeleton

Bones located along the central axis of the body that protect and support body structures.

Appendicular Skeleton

Bones of the extremities that are involved in movement.

Long Bones

Bones that are longer than they are wide, typically curved to withstand stress and reduce the chance of fracture.

Diaphysis

The shaft of a long bone.

Epiphyses

The ends of a long bone, covered and protected by hyaline cartilage.

Metaphysis

The region in a mature bone where the diaphysis meets the epiphysis, containing the epiphyseal plate.

Epiphyseal Plate

A layer of hyaline cartilage in the metaphysis of a growing bone where cartilage is replaced by bone during growth in length.

Hyaline (Articular) Cartilage

A layer of cartilage covering the ends of a long bone that serves as a shock absorber between bones.

Periosteum

A membrane surrounding the surface of a bone, composed of an outer fibrous layer and an inner osteogenic layer.

Sharpey's Fibers

Collagen fibers that anchor the periosteum to the bone, also known as perforating fibers.

Medullary (Marrow) Cavity

An open space within the diaphysis of a bone that contains yellow bone marrow.

Endosteum

A membrane that covers and lines the medullary cavity of a bone, containing osteoprogenitor cells and osteoclasts.

Diploe

Thin plates of spongy bone tissue enclosed between plates of compact bone in short, flat, and irregular bones.

Short Bones

Cube-shaped bones internally composed of diploe covered by compact bone, such as carpals and tarsals.

Flat Bones

Very thin bones composed of two plates of compact bone enclosing a layer of spongy bone (diploe), such as cranial bones, sternum, and ribs.

Irregular Bones

Bones with complex shapes composed of diploe, such as vertebrae and facial bones.

Sesamoid Bones

Small bones embedded in tendons, such as the patella.

Bone Matrix

Hardened tissue component composed of about $25\%$ water, $25\%$ protein (collagen), and $50\%$ mineral salts.

Calcification (Mineralization)

The formation of new matrix that occurs as mineral salts accumulate over collagen fibers.

Sacrificial Bonds

Bonds holding collagen fibers together in bone that easily break and reform to dissipate energy from force on bones.

Osteoprogenitor Cells

Unspecialized cells derived from mesenchyme capable of rapid cell division that develop into osteoblasts.

Osteoblasts

Cells located on the surface of bone tissue that secrete collagen and other materials needed to build bone tissue.

Osteogenesis

The process of secreting bone matrix performed by osteoblasts.

Osteocytes

Mature bone cells that regulate daily bone tissue activities, maintain bone homeostasis, and act as stress sensors to monitor overload.

Bone Lining Cells

Cells thought to help maintain the health of bone.

Osteoclasts

Cells involved in bone resorption that release acids and enzymes through a ruffled border to degrade bone tissue.

Osteolysis

The process of bone tissue degradation carried out by osteoclasts releasing acids and enzymes.

Compact Bone Tissue

Bone tissue forming the external layer over all bones and the diaphysis of long bones, composed of repeating osteons.

Haversian Systems (Osteons)

Repeating structural units that make up compact bone tissue.

Haversian (Central) Canals

Canals running longitudinally in bone tissue containing blood vessels and nerves.

Lamellae

Rings of matrix in bone composed of calcium carbonate and calcium phosphate.

Volkmann's Canals

Canals running horizontally in bone tissue containing blood vessels and nerves.

Lacunae

Small spaces within the lamellae of compact bone housing osteocytes.

Canaliculi

Small channels extending from lacunae that serve as passageways for nutrient and waste exchange.

Spongy Bone Tissue

Bone tissue containing open spaces composed of thin plates called trabeculae, lacking Haversian systems.

Trabeculae

Thin plates of bone that make up spongy bone tissue.

Spicules

Thin rods of spongy bone tissue that support trabeculae.

Hemopoietic Stem Cells

Cells within red bone marrow that can develop into all types of blood cells.

Nutrient Foramina

Openings in the diaphysis of long bones through which nutrient arteries enter.

Epiphyseal Arteries

Blood vessels that carry blood into the epiphyses of a bone.

Ossification

The process by which bone tissue is formed.

Intramembranous Ossification

Bone formation occurring directly on or over loose fibrous connective tissue without a cartilage stage.

Center of Ossification

A cluster of mesenchyme cells that differentiate into osteoprogenitor cells at the site of intramembranous ossification.

Fontanelles

True soft spots in the skull bones of newborns that formed via intramembranous ossification.

Endochondral Ossification

Bone formation over hyaline cartilage, which is how most human bones form.

Chondrification

The process where mesenchyme cells develop into chondroblasts that secrete hyaline cartilage matrix.

Zone of Resting Cartilage

The zone of the epiphyseal plate containing cells that anchor the plate to the compact bone of the epiphysis.

Zone of Proliferating Cartilage

The zone of the epiphyseal plate containing actively dividing chondrocytes that push epiphyses away from the diaphysis.

Zone of Hypertrophic Cartilage

The zone of the epiphyseal plate containing mature chondrocytes.

Zone of Calcified Cartilage

The zone of the epiphyseal plate containing osteoblasts that secrete matrix.

Epiphyseal Line

The remnant produced when cells in the epiphyseal plate stop dividing and bone replaces the cartilage.

Bone Growth in Thickness

Growth occurring as osteoblasts secrete new matrix over the periosteum of a bone.

Human Growth Hormone (HGH)

Hormone secreted by the pituitary gland that regulates bone growth prior to puberty.

Bone Remodeling

The ongoing replacement of old bone tissue by new bone tissue involving resorption by osteoclasts and synthesis by osteoblasts.

Alkaline Phosphatase

An enzyme needed in large supplies for bone remodeling that regulates the formation of calcium carbonate and calcium phosphate.

Wolff's Law

Principle stating that a bone grows or remodels in response to the demands placed on it.

Fracture Hematoma

A blood clot fully formed about $12\text{ hours}$ after a fracture due to broken blood vessels around the bone.

Procallus

A structure formed during fracture repair when capillaries and osteoprogenitor cells invade the fracture hematoma.

Callus

A cartilaginous mass of tissue formed from a procallus that bridges the ends of a broken bone.

Clavicle

The most commonly broken bone in the human body.

Parathyroid Hormone (PTH)

Hormone secreted by the parathyroid gland that increases blood calcium levels by stimulating osteoclasts and kidney calcium recovery.

Calcitonin

Hormone secreted by thyroid gland cells that reduces blood calcium levels by decreasing osteoclast activity and increasing osteoblast activity.

Osteoporosis

A condition of porous bone characterized by decreased bone mass and increased susceptibility to fracture.

Osteomalacia

Bone softening due to inadequate supplies of Vitamin D.

Paget's Disease

A disorder involving accelerated remodeling that causes weak areas in bone tissue.

Osteoarthritis

The degeneration of hyaline cartilage.

Rickets

A form of osteomalacia occurring in children usually associated with vitamin D deficiency.

Achondroplasia

A type of dwarfism involving defective cartilage and endochondral growth leading to abnormally short limb bones.

Bony Spur

An abnormal projection from a bone due to bone overgrowth.

Ostealgia

Pain in a bone.

Osteitis

Inflammation of bone tissue.

Osteomyelitis

Inflammation of bone and bone marrow caused by a bacterial infection.

Osteosarcoma

Bone cancer that usually metastasizes to the lungs and liver.

Osteogenesis Imperfecta

A genetic condition in which bone matrix does not contain enough collagen.

Traction

Placing tension on a body part to keep the parts in proper alignment during severe fractures or vertebral damage.

Pathologic Fracture

A fracture occurring in a diseased bone with slight or no physical trauma.