BIOL 2251 - Exam 2 Key Terms

A complete set of vocabulary flashcards covering the key terms for the Integumentary System, Bone Tissue, and Articulations (Joints) from the BIOL 2251 Exam 2 study sheet.

Integumentary system

Skin, hair, nails, and glands.

Epidermis

Outer epithelial layer of the skin.

Dermis

Connective tissue layer beneath the epidermis.

Hypodermis

Subcutaneous layer composed primarily of adipose and areolar connective tissue.

Stratum basale

Deepest epidermal layer; contains mitotically active stem cells.

Stratum spinosum

Several layers of keratinocytes connected by desmosomes that provide strength.

Stratum granulosum

Layer where keratin formation and keratinization begin.

Stratum lucidum

Thin layer found only in thick skin, such as the palms and soles.

Stratum corneum

Most superficial layer; composed of dead, flattened, keratinized cells.

Keratinocyte

Primary epidermal cell that produces keratin.

Melanocyte

Cell that produces the pigment melanin.

Melanin

Pigment that contributes to skin color and protects against ultraviolet radiation.

Carotene

Yellow-orange pigment that contributes to skin coloration.

Hemoglobin

Red pigment in blood that contributes to skin coloration.

Physical barrier

Protects against pathogens, mechanical damage, and excessive water loss.

Chemical barrier

Antimicrobial substances and secretions that help inhibit microorganisms.

Biological barrier

Immune cells, including macrophages and dendritic cells, that provide defense.

Thermoregulation

Regulation of body temperature.

Perspiration

Sweat production that assists with evaporative cooling.

Hair shaft

Visible portion of hair extending above the skin surface.

Hair follicle

Structure within the skin that produces hair.

Arrector pili muscle

Small smooth muscle attached to a hair follicle; contraction produces goosebumps.

Sebaceous gland

Gland that secretes oily sebum.

Sebum

Oily secretion produced by sebaceous glands.

Eccrine gland

Sweat gland involved primarily in thermoregulation.

Nail matrix

Region where new nail cells are produced.

Nail plate

Hard, visible portion of the nail.

Eponychium

Cuticle located at the proximal edge of the nail.

Mole (nevus)

Pigmented skin lesion.

Vitiligo

Loss of melanocytes resulting in areas of decreased pigmentation.

Albinism

Condition involving reduced melanin production.

Melanoma

Malignant cancer involving melanocytes.

ABCD rule

Method for evaluating suspicious pigmented lesions: Asymmetry, Border, Color, Diameter.

First-degree burn

Burn involving only the epidermis.

Second-degree burn

Burn involving the epidermis and part of the dermis.

Third-degree burn

Full-thickness destruction of the skin.

Osteon (Haversian system)

Cylindrical structural unit of compact bone composed of concentric lamellae surrounding a central canal.

Central (Haversian) canal

Channel at the center of an osteon containing blood vessels and nerve fibers.

Concentric lamellae

Ring-like layers of bone matrix surrounding the central canal that help resist twisting and compression.

Lacuna(e)

Small cavities in the bone matrix that house mature bone cells (osteocytes).

Osteocyte

Mature bone cell that maintains the bone matrix.

Canaliculi

Microscopic channels connecting lacunae that allow nutrients and wastes to pass between osteocytes.

Compact bone

Dense bone tissue forming the strong outer portion of bones.

Spongy bone

Porous bone composed of trabeculae that reduces skeletal weight and contains bone marrow.

Trabeculae

Thin plates or struts of spongy bone arranged along lines of stress.

Diaphysis

Shaft of a long bone composed primarily of compact bone.

Epiphysis

Expanded end of a long bone containing primarily spongy bone.

Epiphyseal plate (growth plate)

Hyaline cartilage plate that allows lengthwise bone growth during development.

Epiphyseal line

Bony remnant of the epiphyseal plate after growth has stopped.

Articular cartilage

Hyaline cartilage covering bone surfaces at joints; reduces friction and absorbs shock.

Periosteum

Double-layered connective tissue membrane covering the external surface of bone except at joint surfaces.

Endosteum

Thin connective tissue membrane lining internal bone surfaces.

Medullary cavity

Hollow cavity within the diaphysis containing yellow bone marrow in adults.

Osteogenic cells

Stem cells that divide and develop into osteoblasts.

Osteoblast

Bone-forming cell that secretes osteoid.

Osteoid

Organic, unmineralized portion of bone matrix composed primarily of collagen.

Osteoclast

Large multinucleated cell that breaks down bone matrix during remodeling.

Endochondral ossification

Bone formation that begins with a hyaline cartilage model; forms most bones of the skeleton.

Intramembranous ossification

Bone formation within fibrous connective tissue membranes; forms many flat bones of the skull and portions of the clavicle.

Interstitial growth

Lengthwise bone growth occurring at the epiphyseal plate.

Appositional growth

Increase in bone thickness through deposition of new matrix on the bone surface.

Hematopoiesis

Formation of blood cells in red bone marrow.

Mineral storage

Storage of calcium and phosphate within bone matrix.

Parathyroid hormone (PTH)

Hormone that raises blood calcium levels by promoting processes that increase bone resorption.

Calcitonin

Hormone that helps lower blood calcium levels by inhibiting osteoclast activity.

Joint (articulation)

Site where two or more bones meet.

Fibrous joint

Joint in which bones are connected by dense connective tissue and no joint cavity is present.

Cartilaginous joint

Joint in which bones are connected by cartilage and movement is generally limited.

Synovial joint

Freely movable joint containing a fluid-filled joint cavity.

Synovial fluid

Viscous fluid derived from blood plasma that lubricates a synovial joint.

Joint capsule

Fibrous and synovial membrane layers surrounding a synovial joint.

Synovial membrane

Inner portion of the joint capsule that produces synovial fluid.

Bursa

Small fluid-filled sac that reduces friction between moving structures.

Tendon sheath

Elongated bursa that reduces friction around a tendon.

Flexion

Movement that decreases the angle between two bones.

Extension

Movement that increases the angle between two bones.

Hyperextension

Extension of a joint beyond anatomical position.

Abduction

Movement away from the body's midline.

Adduction

Movement toward the body's midline.

Circumduction

Circular movement combining flexion, extension, abduction, and adduction.