Ch. 7 Lecture

Bone tissue

The hard, dense connective tissue that makes up the skeleton.

Osteology

The study of bones.

Skeletal system

The system composed of bones, cartilages, and ligaments.

Cartilage

A flexible connective tissue that covers joint surfaces and acts as a precursor to most bones.

Ligaments

Connective tissues that hold bones together at joints.

Tendons

Connective tissues that attach muscles to bones.

Support

The function of the skeleton to provide support to the body and its organs.

Protection

The function of the skeleton to protect vital organs such as the brain, spinal cord, heart, and lungs.

Movement

The function of the skeleton to enable limb movements, breathing, and other movements.

Electrolyte balance

The function of the skeleton to regulate calcium and phosphate levels in the body.

Acid-base balance

The function of the skeleton to buffer blood against large pH changes.

Blood formation

The function of the skeleton to produce blood cells in the red bone marrow.

Bone (osseous tissue)

Connective tissue with a hardened matrix composed of calcium phosphate and other minerals.

Mineralization or calcification

The process of hardening bone tissue.

Compact bone

The dense outer shell of bone.

Spongy (cancellous) bone

Loosely organized bone tissue found in the center of ends and shafts of long bones.

Flat bones

Thin, curved plates that protect soft organs.

Long bones

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

Short bones

Bones that are approximately equal in length and width and allow for gliding movements.

Irregular bones

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

Epiphysis

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

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.

Articular cartilage

The layer of hyaline cartilage that covers joint surfaces.

Nutrient foramina

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

Periosteum

The external sheath covering most of the bone, consisting of an outer fibrous layer and an inner osteogenic layer.

Endosteum

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

Epiphyseal plate

The area of hyaline cartilage that separates the epiphyses and diaphyses of children's bones, enabling growth in length.

Epiphyseal line

In adults, a bony scar that marks where the growth plate used to be.1. Long bone:A type of bone characterized by its elongated shape, consisting of epiphyses and diaphysis.

Epiphyses

The ends of a long bone, composed of spongy bone and covered with articular cartilage.

Diaphysis

The shaft of a long bone, composed of compact bone and containing a marrow cavity.

Compact bone

Dense and hard bone tissue that forms the outer layer of bones.

Spongy bone

Porous bone tissue that forms the inner layer of bones, consisting of trabeculae.

Marrow cavity

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

Articular cartilage

Smooth and slippery cartilage that covers the surfaces of bones where they come into contact with each other in a joint.

Periosteum

A dense layer of connective tissue that covers the outer surface of bones.

Flat bone

A type of bone characterized by its flat and thin shape, consisting of two layers of compact bone enclosing a middle layer of spongy bone.

Diploe

The spongy middle layer of a flat bone, which absorbs shock and contains marrow spaces.

Osteogenic cells

Stem cells found in the endosteum and inner layer of periosteum, giving rise to most other bone cell types.

Osteoblasts

Bone-forming cells that synthesize the organic matter of the bone matrix.

Osteocytes

Mature bone cells that are trapped in the matrix they deposited, residing in lacunae and connected by canaliculi.

Osteoclasts

Bone-dissolving cells found on the bone surface, involved in bone remodeling.

Matrix

The extracellular substance of osseous tissue, consisting of organic and inorganic matter.

Hydroxyapatite

Crystallized calcium phosphate salt, the main inorganic component of bone matrix.

Rickets

A disease caused by mineral deficiency, resulting in soft and deformed bones.

Osteogenesis imperfecta

A genetic disorder characterized by brittle bones due to a defect in collagen deposition.

Osteon

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

Spongy bone

A type of bone tissue that consists of a lattice of bone covered with endosteum, containing spicules and trabeculae.

Trabeculae

Thin plates of bone that make up the lattice structure of spongy bone.1. Spongy Bone:A type of bone tissue that is porous and contains trabeculae.

Periosteum

A fibrous membrane that covers the outer surface of bones.

Marrow cavity

The central cavity of long bones that contains bone marrow.

Trabeculae

The branching, lattice-like structure found in spongy bone.

Compact bone

Dense bone tissue that forms the outer layer of bones.

Bone Marrow

Soft tissue found in the marrow cavities of long bones and small spaces of spongy bone.

Red marrow

Type of bone marrow that contains hemopoietic tissue and produces blood cells.

Yellow marrow

Fatty marrow that does not produce blood.

Ossification

The process of bone formation.

Intramembranous ossification

The formation of bone directly from mesenchymal tissue.

Endochondral ossification

The formation of bone from a pre-existing cartilage model.

Hyaline cartilage

A type of cartilage that provides support and flexibility.

Chondrocytes

Cartilage cells.

Epiphyseal plate

A cartilaginous plate in the metaphysis of long bones that allows for bone elongation.

Interstitial growth

Growth from within, such as the elongation of bones through cartilage growth in the epiphyseal plate.

Epiphyseal line

A line of spongy bone that marks the site of a former epiphyseal plate.

Metaphysis

The zone of transition between the epiphysis and diaphysis of a long bone.

X-Ray

A medical imaging technique that uses electromagnetic radiation to visualize the internal structures of the body.

Zones of the Metaphysis

Different zones in the metaphysis of long bones that represent different stages of cartilage growth and bone deposition.

Achondroplastic dwarfism

A type of dwarfism where long bones stop growing in childhood, resulting in a normal torso and short limbs.

Pituitary dwarfism

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

Appositional growth

The continual growth in diameter and thickness of bones that occurs at the bone surface.

Osteoblasts

Cells responsible for depositing osteoid tissue, which eventually becomes mineralized and forms bone.

Osteoclasts

Cells responsible for resorbing or dissolving bone tissue, releasing minerals into the blood.

Compact bone

Dense bone tissue that consists of osteons (haversian systems) and contains concentric lamellae, central canals, and perforating canals.

Bone remodeling

The process of absorption and deposition that occurs throughout life, repairing microfractures, releasing minerals into the blood, and reshaping bones in response to use and disuse.

Calcium homeostasis

The regulation of calcium levels in the blood, which is important for various physiological processes such as neuron communication, muscle contraction, blood clotting, and exocytosis.

Calcitriol

The most active form of vitamin D, produced by the skin, liver, and kidneys, and involved in maintaining normal blood calcium concentration.

UV-B

Ultraviolet-B radiation, a type of UV radiation that is responsible for the synthesis of vitamin D in the skin.

7-dehydrocholesterol

A precursor molecule in the skin that is converted to pre-vitamin D3 upon exposure to UV-B radiation.

Calcifediol

Also known as calcidiol, it is the intermediate form of vitamin D3 that is produced in the liver.

Calcitriol 25(OH)D

The active form of vitamin D that is produced in the kidneys from calcifediol.

Vitamin D receptor (VDR)

A protein that binds to calcitriol and acts as a transcription factor to upregulate genes involved in calcium metabolism.

Apoptosis

Programmed cell death.

TRPV6

A cation channel highly selective to calcium ions.

Calbindin

A calcium-binding protein.

Calcitonin

A hormone secreted by the thyroid gland that lowers blood calcium levels by inhibiting bone resorption and promoting calcium deposition into bone.

Parathyroid hormone (PTH)

A hormone secreted by the parathyroid glands that raises blood calcium levels by stimulating bone resorption, promoting calcium reabsorption by the kidneys, enhancing calcitriol synthesis, and inhibiting collagen synthesis by osteoblasts.

Phosphate Homeostasis

The regulation of phosphate levels in the body, which is influenced by calcitriol and PTH.

Estrogen

A hormone that has a stronger effect than testosterone on bone growth, especially in girls.

Growth hormone

A hormone that stimulates bone growth, especially during puberty and adolescence.

Orthopedics

A branch of medicine that deals with the prevention and correction of injuries and disorders of bones, joints, and muscles.

Pathological fracture

A break in a bone weakened by disease, such as bone cancer or osteoporosis.

Fractures classified by structural characteristics

Fractures can be classified based on the direction of the fracture line, whether there is a break in the skin, and whether there are multiple pieces. For example, a comminuted fracture refers to a fracture with three or more pieces.

Nondisplaced fracture

A fracture where the bone fragments remain in their normal positions.

Displaced fracture

A fracture where the bone fragments are not in their normal positions.

Comminuted fracture

A fracture with three or more pieces.

Greenstick fracture

A fracture where the bone is partially broken, resembling a green twig.

Closed reduction

A procedure where bone fragments are manipulated into their normal positions without surgery.

Open reduction

A surgical procedure that involves exposing the bone and using plates, screws, or pins to realign the fragments.

Cast

A device used to stabilize and immobilize a healing bone.

Traction

A treatment for fractures of the femur in children, where bone fragments are aligned by overriding the force of the thigh muscles.