Bone Tissue, Cell Connections, and Integumentary System Vocabulary

Comprehensive vocabulary flashcards covering bone tissue histology, cell junction types, gland classifications, tissue repair pathways, and integumentary anatomy.

Mineralization (calcification)

The deposition of calcium phosphate crystals (hydroxyapatite) within the organic bone matrix, making bone tissue hard and rigid.

Bone tissue (osseous tissue)

The specific connective tissue type composed of bone cells embedded within a mineralized matrix.

Diaphysis

The shaft portion of a long bone.

Epiphysis

An expanded end of a long bone.

Diploe

The interior layer of spongy bone sandwiched between two thin layers of compact bone in flat bones.

Osteoprogenitor cells

Stem cells in bone that divide and differentiate into osteoblasts.

Osteoblasts

Bone-building cells that secrete osteoid, the organic matrix that subsequently mineralizes.

Osteocytes

Mature bone cells housed inside lacunae that maintain the surrounding bone matrix.

Osteoclasts

Large, multinucleated cells originating from the monocyte lineage that resorb and break down bone matrix.

Compact bone

Bone tissue organized into densely packed osteons (Haversian systems) featuring concentric lamellae surrounding a central canal.

Spongy (cancellous) bone

Bone tissue organized as an open lattice of thin plates and rods called trabeculae, lacking osteons.

Red marrow

Hematopoietic tissue situated within spongy bone that actively produces blood cells.

Yellow marrow

Adipose tissue occupying the medullary cavity of adult long bone shafts that functions in energy and fat storage.

Intramembranous ossification

Bone development occurring directly within a mesenchymal connective tissue membrane without a precursor cartilage model.

Endochondral ossification

Bone formation process where a hyaline cartilage model is progressively replaced by bone.

Appositional growth

Growth of a bone in width, where osteoblasts deposit new bone beneath the periosteum while osteoclasts resorb bone from the medullary surface.

Parathyroid hormone (PTH)

Hormone that increases blood calcium levels by stimulating osteoclasts, increasing renal calcium reabsorption, and activating vitamin D.

Calcitonin

Hormone that decreases blood calcium levels by inhibiting osteoclast activity.

Tight junction

Cellular junction composed of interlocking claudin and occludin proteins that seals the intercellular space near the apical surface to prevent fluid passage.

Desmosome

Anchoring junction where cadherin proteins cross intercellular space to join intracellular plaques attached to intermediate keratin filaments, providing mechanical tensile strength.

Gap junction

Intercellular connection composed of connexon channels made of connexin proteins that allows direct passage of ions and small molecules between adjacent cells.

Hemidesmosome

Specialized junction using integrin proteins to anchor the basal surface of an epithelial cell to the underlying basement membrane.

Exocrine gland

Gland structure that releases its secretions through a duct onto an epithelial surface.

Endocrine gland

Ductless gland structure that secretes hormones directly into the interstitial fluid or bloodstream.

Merocrine secretion

Exocrine secretion mode in which secretory products are released via exocytosis while leaving the cell intact.

Apocrine secretion

Exocrine secretion mode where the apical region of the cell pinches off along with the secretory product.

Holocrine secretion

Exocrine secretion mode where the entire secretory cell disintegrates and becomes part of the secretion.

Hyperplasia

Tissue growth resulting from an increase in the total number of cells.

Hypertrophy

Tissue growth resulting from an increase in individual cell size without an increase in cell number.

Metaplasia

Transformation of one mature tissue type into a different mature tissue type, usually caused by chronic stress or irritation.

Regeneration

Tissue repair process that replaces damaged cells with the same functional cell type, fully restoring original tissue function.

Fibrosis

Tissue repair process that replaces damaged tissue with fibrous scar tissue, which does not restore original tissue function.

Atrophy

Reduction in tissue or organ size due to a decrease in cell size, cell number, or both.

Apoptosis

Programmed, genetically directed cell death of individual cells that occurs without triggering inflammation.

Stratum basale

Deepest layer of the epidermis, containing actively dividing stem cells and melanocytes.

Stratum lucidum

Epidermal layer found exclusively in thick skin areas, such as the palms of the hands and soles of the feet.

Papillary layer

Superficial zone of the dermis composed of thin areolar connective tissue that forms dermal papillae interlocking with the epidermis.

Reticular layer

Deep zone of the dermis composed of thick dense irregular connective tissue that houses blood vessels, nerves, glands, and hair follicles.

Melanin

Brown or black pigment produced by melanocytes that serves as the main determinant of skin tone and shields cells from UV damage.

Anagen

The active growth phase of the hair growth cycle, during which the follicle produces new hair.

Catagen

The short transitional phase of the hair growth cycle, during which hair growth stops and the hair follicle regresses.

Telogen

The resting phase of the hair growth cycle, where the fully formed hair is inactive while remaining attached inside the follicle.

Exogen

The shedding phase of the hair growth cycle, where the mature hair falls out of the follicle.

Piloerection

Contraction of the arrector pili muscle that pulls a hair follicle upright, occurring via sympathetic stimulation from cold or fear.

Eponychium

The cuticle fold of tissue that seals the proximal edge of the nail body.

Lunula

The pale, crescent-shaped visible region of the actively growing nail matrix at the base of a nail.

Eccrine sweat glands

Abundant cutaneous glands opening directly onto skin surfaces that produce watery sweat primarily for evaporative cooling.

Apocrine sweat glands

Cutaneous glands in the axilla, groin, and areola associated with hair follicles that secrete a fatty, protein-rich fluid broken down by bacteria to produce body odour.

Sebaceous glands

Dermal holocrine glands that produce oily sebum to lubricate hair and skin and resist water loss.

Ceruminous glands

Modified apocrine glands located in the external auditory canal that secrete cerumen (earwax) combined with sebum.

Myoepithelial cells

Contractile epithelial cells surrounding gland secretory units that contract to propel secretions into and out of ducts.

Insensible perspiration

Continuous, unperceived loss of water through evaporation across the skin surface.

Diaphoresis

Visible, profuse sweating triggered by factors such as heat, exertion, stress, or illness.