BIO 201–202 Study Guide: Integumentary and Skeletal Systems

Comprehensive vocabulary flashcards covering the anatomy, cell types, layers, and physiological processes of the Integumentary and Skeletal systems.

Integumentary System

The body system consisting of the skin and its accessory structures, including hair, nails, sweat glands, and sebaceous glands.

Keratin

A strong, fibrous protein found in the epidermis that provides durability, strength, and waterproofing.

Melanin

A pigment produced by melanocytes that absorbs ultraviolet radiation and protects cellular DNA from mutation.

Dendritic Cells

Immune surveillance cells that patrol the epidermis to identify pathogens and activate the immune system.

Avascular

A term meaning 'contains no blood vessels,' which describes the epidermis.

Keratinocytes

The most abundant epidermal cells ($90\%$) which produce keratin and form a protective, waterproof barrier.

Merkel Cells

Specialized touch receptors in the skin associated with sensory neurons that help detect light touch and distinguish textures.

Stratum Basale

The deepest, single row of mitotically active cells in the epidermis containing stem cells, melanocytes, and Merkel cells.

Stratum Spinosum

An epidermal layer several layers thick where desmosomes connect cells to resist tearing; it contains many dendritic cells.

Stratum Granulosum

The epidermal layer where keratin production increases, organelles deteriorate, and the transition from living to dead cells occurs.

Stratum Lucidum

An additional epidermal layer for protection found only in thick skin on the palms of the hands and soles of the feet.

Stratum Corneum

The outermost epidermal layer consisting of dead, keratinized cells that provide protection and water resistance.

Papillary Layer

The superficial portion of the dermis made of areolar connective tissue that nourishes the epidermis and forms fingerprints via dermal papillae.

Reticular Layer

The deepest and thickest part of the dermis made of dense irregular connective tissue containing collagen and elastic fibers.

Hypodermis

Also called subcutaneous tissue, it consists of adipose and loose connective tissue used for energy storage, insulation, and shock absorption.

Eccrine Sweat Glands

The most numerous sweat glands that produce watery sweat primarily for cooling the body and excreting wastes.

Apocrine Sweat Glands

Glands located in the axillae and groin that produce thicker secretions rich in proteins and lipids starting at puberty.

Sebaceous Glands

Glands that produce sebum to lubricate hair, waterproof the skin, and prevent drying.

Third-Degree Burn

A medical emergency involving the destruction of both the epidermis and dermis; often painless due to destroyed nerve endings.

Hematopoiesis

The process of blood cell production (red cells, white cells, and platelets) which occurs in the red bone marrow.

Osteogenic Cells

Stem cells located in the endosteum and periosteum that generate osteoblasts.

Osteoblasts

Bone-forming cells that produce osteoid and initiate the mineralization process.

Osteocytes

Mature bone cells located in lacunae that maintain the bone matrix and sense mechanical stress.

Osteoclasts

Bone-resorbing cells that break down bone tissue to release calcium into the bloodstream.

Hydroxyapatite

Inorganic crystals in the bone matrix that provide hardness and resistance to compression.

Osteon

The primary structural unit of compact bone, consisting of a central canal, lamellae, lacunae, and canaliculi.

Trabeculae

The structural lattice-like components of spongy bone that align with lines of stress and house marrow.

Intramembranous Ossification

A bone development process where bones like the flat skull bones and mandible develop directly from mesenchymal tissue.

Endochondral Ossification

The process forming most bones in the body, which begins with a hyaline cartilage model.

Epiphyseal Plate

The site of longitudinal bone growth consisting of five zones: resting, proliferation, hypertrophic, calcification, and ossification.

Parathyroid Hormone (PTH)

A hormone released when blood calcium falls that activates osteoclasts to release calcium from bone.

Calcitonin

A hormone released when blood calcium rises that inhibits osteoclasts and encourages calcium storage in bone.

Hematoma

The first step in fracture repair involving the formation of a blood clot around the fracture site.