Integumentary and Skeletal Systems: Anatomy, Histology, and Pathologies

Vocabulary practice flashcards covering integumentary pathologies (burns and skin cancers) and skeletal biology (cartilage, bone histology, ossification, remodeling, and repair) based on lecture material.

Chemical, Physical, and Biological Barriers of Skin

The three protective barrier functions of the integumentary system that defend the body against physical abrasion, chemical irritants, pathogens, and radiation damage.

Blood Reservoir Function of Skin

The capacity of the extensive dermal vascular network to hold roughly $5\%$ of the body's total blood volume, which can be diverted to other organs when needed.

First-Degree Burn

A superficial burn in which cellular injury is strictly limited to the epidermis.

Second-Degree Burn

A superficial partial-thickness burn that damages both the epidermis and the superficial layer of the dermis, typically characterized by blistering.

Third-Degree Burn

A deep, full-thickness burn that destroys the entire depth of the skin, including the epidermis and dermis, extending down into underlying tissues.

Lund and Browder Chart

A burn assessment method used to estimate total body surface area burned in children, adjusting percentages because pediatric body proportions change significantly with age.

Superficial Spreading Melanoma

The most frequent form of melanoma, typically appearing as a flat lesion with irregular contours and multiple variations in coloration.

Nodular Melanoma

The second most frequent type of melanoma ($15\text{--}20\%$ of cases) and the fastest growing; presents as an elevated, often black mass on sun-damaged skin.

Lentigo Maligna

A type of melanoma representing $10\text{--}15\%$ of cases that develops predominantly in elderly individuals on chronically sun-exposed skin (such as the face and neck) as a large, flat, pigmented patch.

Acral Lentiginous Melanoma

A rare type of melanoma occurring on the palms of the hands, soles of the feet, or under the nails, which is not associated with sun exposure.

ABCD Rule of Melanoma

A clinical guideline for recognizing melanoma based on Asymmetry, Border irregularity, Color variegation, and Diameter greater than $6\,\text{mm}$.

Basal Cell Carcinoma (CBC)

The most common skin cancer; characterized by slow growth and appearance as a firm, pink, shiny nodule (pearly aspect) or a non-healing sore, almost never metastasizing.

Squamous Cell Carcinoma (CSC)

The second most common skin cancer; presents as a thick, red, scaly, or crusted nodule often arising from actinic keratosis, which grows more rapidly than basal cell carcinoma and can metastasize to lymph nodes if untreated.

Hyaline Cartilage

The most abundant skeletal cartilage; found at articular surfaces of movable joints, costal attachments of ribs, respiratory pathways (larynx, trachea), and the nose.

Elastic Cartilage

A resilient cartilage type containing plentiful elastic fibers, with a distribution restricted to the external ear and epiglottis.

Fibrocartilage

A highly compressible cartilage with high tensile strength distributed in high-stress zones such as the menisci, intervertebral discs, and pubic symphysis.

Appositional Growth (Cartilage)

Growth in thickness where chondrogenic cells in the perichondrium differentiate into chondroblasts that secrete new matrix onto the external face of the tissue.

Interstitial Growth (Cartilage)

Growth from within where internal chondrocytes divide and secrete new extracellular matrix, characteristic of embryonic development and length expansion.

Axial Skeleton

The division of the skeleton that forms the central longitudinal axis of the body, consisting of the skull (crâne), vertebral column (colonne vertébrale), and bony thorax (cage thoracique).

Appendicular Skeleton

The division of the skeleton consisting of the upper and lower limb bones along with the pectoral (ceinture scapulaire) and pelvic (ceinture pelvienne) girdles.

Long Bones

Bones that are significantly longer than they are wide, comprising a shaft and two expanded ends, fulfilling supportive roles (e.g., humerus, femur, phalanges).

Short Bones

Roughly cube-shaped bones designed to provide stability and limited motion, such as the carpal bones of the wrist and tarsal bones of the ankle.

Sesamoid Bones

Specialized short bones that form within tendons to alter tendon pull direction and reduce friction, such as the patella (rotule).

Flat Bones

Thin, flattened, and typically curved bones that serve protective functions, including the sternum, ribs, scapulae, and most cranial bones (e.g., parietal).

Irregular Bones

Bones with complicated, varied shapes and compositions that do not fit into other categories, such as vertebrae, coxal (hip) bones, and certain facial bones.

Diaphysis

The elongated, tubular main shaft of a long bone surrounding the central medullary cavity.

Epiphysis

The expanded proximal or distal extremity of a long bone, covered by articular cartilage on its joint surfaces.

Periosteum

The double-layered vascular connective tissue membrane that covers and protects external bone surfaces wherever articular cartilage is absent.

Sharpey's Fibers

Tufts of collagen fibers (fibres perforantes) that extend from the fibrous layer of the periosteum into the outer bone matrix to securely anchor it.

Endosteum

A delicate internal connective tissue membrane covering the medullary cavity, trabeculae of spongy bone, and the internal vascular canals.

Diploë

The internal spongy bone layer sandwiched between the inner and outer compact bone plates of flat, short, and irregular bones.

Osteogenic Cells

Mesenchyme-derived stem cells located in the periosteum and endosteum that undergo cell division to give rise to osteoblasts.

Osteoblasts

Immature bone-forming cells that synthesize and secrete the unmineralized organic components of the bone matrix known as osteoid.

Osteocytes

Mature, non-dividing bone cells residing within lacunae that monitor, maintain, and regulate the surrounding mineralized matrix.

Osteoclasts

Large, multinucleated cells that actively secrete acids and proteolytic enzymes to demineralize and digest the organic bone matrix during resorption.

Osteon (Haversian System)

The structural and functional unit of compact bone, composed of concentric lamellae of matrix surrounding a neurovascular central canal.

Canaliculi

Microscopic, hairlike canals radiating through the bone matrix that connect adjacent lacunae to each other and to the central canal, facilitating cellular communication.

Trabeculae

A lattice-like network of thin, pointed bone struts that make up spongy bone, aligned precisely along lines of mechanical stress.

Chemical Composition of Bone Matrix

Bone consists of $33\%$ organic material (mainly collagen fibers and osteoid) and $67\%$ inorganic mineral salts, of which calcium constitutes $39\%$ and phosphate $17\%$.

Endochondral Ossification

The process of bone formation wherein a pre-existing hyaline cartilage model is broken down, calcified, and systematically replaced by bone tissue.

Intramembranous Ossification

The bone formation mechanism in which mesenchymal cells directly differentiate into osteoblasts within a fibrous connective tissue membrane without a prior cartilage stage.

Epiphyseal Plate Zones

The four functional layers of cartilage governing longitudinal bone growth: the proliferation zone (mitosis), hypertrophic zone (cell enlargement), calcification zone (matrix calcification and cell death), and ossification zone (osteogenesis on calcified spicules).

Appositional Bone Growth

The growth mode expanding bone thickness and diameter, wherein osteoblasts beneath the periosteum deposit new matrix on the outer surface while osteoclasts resorb bone along the endosteum.

Bone Remodeling

The coupled, lifelong cyclical process consisting of bone resorption by osteoclasts and bone deposition by osteoblasts to maintain skeleton structure and mineral balance.

Parathyroid Hormone (PTH)

The hormone released by the parathyroid glands when blood calcium drops below normal ($2.2\text{ to }2.7\,\text{mmol/L}$), stimulating osteoclasts to dissolve bone matrix and return $Ca^{2+}$ into systemic circulation.

Phases of Fracture Consolidation

The four sequential stages of bone healing: hematoma formation, fibrocartilaginous (soft) callus formation, bony callus formation of spongy bone, and long-term bone remodeling.

Osteoporosis

A skeletal pathology characterized by an imbalance where bone resorption outpaces bone deposition, resulting in porous, fragile bones; affects $29\%$ of women and $18\%$ of men over age 45.