Anatomy and Physiology: Tissues, Integumentary System, and Skeletal System

Comprehensive vocabulary flashcards covering anatomical tissues, skin layers, skin appendages, body membranes, and the skeletal system.

Hematopoiesis

The process of blood cell formation that occurs within the red marrow cavities of certain bones.

Compact Bone

A dense, smooth, and homogeneous type of osseous tissue that forms the exterior of all bones and the bulk of long bone shafts.

Spongy Bone

Bone tissue composed of small, needle-like pieces of bone (trabeculae) and open spaces filled with marrow.

Diaphysis

The shaft of a long bone that accounts for most of its length, composed predominantly of compact bone.

Periosteum

A fibrous connective tissue membrane that covers the diaphysis and allows blood vessels and nerves to enter the bone.

Epiphysis

The expanded end of a long bone, consisting of an interior of spongy bone enclosed by a thin outer layer of compact bone.

Articular Cartilage

A layer of hyaline cartilage covering the external surface of the epiphyses that provides a smooth, slippery surface to decrease friction at joint articulations.

Epiphyseal Plate

A flat plate of hyaline cartilage found in young, growing long bones that provides the site for lengthwise growth until puberty ends.

Epiphyseal Line

The visible remnant of the epiphyseal plate in adult bones that forms once lengthwise bone growth has ceased.

Medullary Cavity

The internal cavity within the diaphysis of a long bone; it contains red marrow in infants until age $6$ or $7$, after which it is replaced with fat-storing yellow marrow.

Osteocyte

A mature bone cell situated within tiny matrix cavities called lacunae.

Lacunae

Tiny chambers within the bone matrix that house osteocytes.

Lamellae

Concentric rings of hard, calcified matrix arranged around the central canal in compact bone.

Central (Haversian) Canal

A longitudinal channel running lengthwise through the center of each osteon carrying blood vessels and nerves.

Osteon (Haversian System)

The fundamental structural and functional unit of compact bone, consisting of a central canal surrounded by concentric lamellar rings.

Canaliculi

Tiny canals radiating outwards from central canals to lacunae, creating a transport and communication network that links all bone cells to nutrients.

Appositional Growth

The process by which bones increase in diameter and width, driven by osteoblasts in the periosteum adding matrix to the outside while osteoclasts in the endosteum remove bone internally.

Parathyroid Hormone (PTH)

A hormone released into the bloodstream when calcium levels drop, activating osteoclasts to break down bone matrix and release calcium ions into the blood.

Fibrocartilage Callus

A temporary splint formed of cartilage matrix, bony trabeculae, and collagen fibers that closes the gap during the repair of a fractured bone.

Synarthrosis

An immovable joint category, typically represented by fibrous joints such as cranial sutures.

Amphiarthrosis

A slightly movable joint category, commonly represented by cartilaginous joints such as the pubic symphysis and intervertebral joints.

Diarthrosis

A freely movable joint category, represented by all synovial joints.

Cutaneous Membrane

The skin; a dry, external epithelial membrane composed of an outer keratinized stratified squamous epithelium and an underlying dense fibrous connective tissue dermis.

Mucous Membrane (Mucosa)

A moist epithelial membrane lining body cavities that open to the exterior, resting atop a loose connective tissue layer called the lamina propria.

Serous Membrane (Serosa)

A moist membrane consisting of simple squamous epithelium resting on areolar connective tissue that lines closed ventral body cavities and secretes lubricating serous fluid.

Parietal Layer

The specific portion of a serous membrane that lines the inner wall of a closed ventral body cavity.

Visceral Layer

The inner layer of a serous membrane that covers and adheres directly to the external surface of organs within a ventral body cavity.

Synovial Membrane

A connective tissue membrane composed solely of areolar connective tissue with no epithelial cells, lining fibrous capsules of joints, bursae, and tendon sheaths to secrete lubricating fluid.

Stratum Basale

The deepest epidermal layer containing stem cells that continually divide via mitosis, producing daughter cells pushed upward into superficial layers.

Stratum Lucidum

A clear, thin epidermal layer of dead cells found exclusively in the thick, hairless skin of the palms of the hands and soles of the feet.

Stratum Corneum

The outermost layer of the epidermis, consisting of $20$ to $30$ cell layers of dead, flat, scale-like sacs completely filled with protective keratin.

Keratinocytes

The predominant cells of the epidermis that produce keratin, a fibrous protein providing structural toughness and water resistance.

Melanocytes

Spider-shaped cells found primarily in the stratum basale that synthesize melanin pigment to shield keratinocyte nuclei from ultraviolet radiation.

Epidermal Dendritic Cells

Protective skin cells that patrol the epidermis to alert and activate the immune system against bacterial or viral invasions.

Merkel Cells

Epidermal cells associated with sensory nerve endings that function as sensitive touch receptors known as Merkel discs.

Dermal Papillae

Peg-like projections of the papillary layer of the dermis indenting the epidermis, containing capillary loops, pain receptors, and touch receptors that produce fingerprint ridges.

Sebaceous Glands

Cutaneous exocrine oil glands found throughout the skin (except the palms and soles) that secrete sebum, usually into hair follicles, activated at puberty by androgens.

Eccrine Glands

Coiled tubular sweat glands distributed body-wide that release clear, acidic perspiration via ducts to surface pores for body temperature regulation.

Apocrine Glands

Larger sweat glands localized to the axillary and genital regions whose ducts empty into hair follicles; they produce a milky or yellowish secretion containing fatty acids and proteins.

Arrector Pili

Small bands of smooth muscle cells connecting the hair follicle to the dermal tissue that contract when cold or frightened to pull hairs upright.

Lunule

The white crescent-shaped area over the thickened nail matrix at the proximal base of the nail body.

Erythema

Reddening of the skin caused by embarrassment, fever, hypertension, inflammation, or allergy.

Acid Mantle

The thin, acidic film of secretions on the skin's surface that prevents and inhibits bacterial and microbial multiplication.

Axial Skeleton

The division of the human skeleton forming the longitudinal axis of the body, comprising the skull, vertebral column, and bony thorax.

Appendicular Skeleton

The division of the skeleton composed of the $126$ bones of the limbs and the pectoral and pelvic girdles.

Fontanels

Fibrous membranes connecting cranial bones in the fetal skull that permit cranial compression during birth and intracranial expansion, typically ossifying by $2$ years of age.

Paranasal Sinuses

Air-filled, mucosa-lined cavities within the frontal, ethmoid, sphenoid, and maxillary bones that lighten the skull and amplify voice resonance.

Hyoid Bone

A horseshoe-shaped bone in the anterior neck that does not articulate with any other bone; it serves as a movable base for the tongue and aids in swallowing and speech.

Primary Curvatures

Spinal curvatures located in the thoracic and sacral regions that are present at birth, producing a $C$-shaped curve in newborns.

Secondary Curvatures

Spinal curvatures in the cervical and lumbar regions that develop after birth as a child begins to raise its head and walk, creating the adult $S$-shaped spine.

Atlas (C1)

The first cervical vertebra, which lacks a body and contains large superior articular facets that receive the occipital condyles to permit nodding.

Axis (C2)

The second cervical vertebra, characterized by an upright toothlike process called the dens (odontoid process) that serves as a pivot point for skull rotation.

True Ribs

The first seven pairs of ribs (pairs 1–7) that attach directly to the sternum through individual costal cartilages.

Floating Ribs

Rib pairs $11$ and $12$, classified as false ribs that lack any anterior sternal attachment.

Pseudostratified Columnar Epithelium

A single layer of columnar cells of varying heights where nuclei rest at different levels, giving the false impression of stratification; commonly ciliated in the respiratory tract.

Transitional Epithelium

A specialized stratified epithelium lining the organs of the urinary system that can stretch and alter its cell shape from rounded to flattened as organs distend.

Goblet Cells

Individual mucus-producing cells frequently interspersed within simple columnar epithelial linings.

Areolar Connective Tissue

A soft, pliable, loose connective tissue containing a network of all fiber types that functions as a universal packaging tissue and forms the lamina propria beneath mucous membranes.

Fibrocartilage

A highly compressible type of cartilage characterized by dense collagen fibers, forming cushionlike discs between the vertebrae of the spinal column and the pubic symphysis.

Intercalated Discs

Specialized cellular junctions containing gap junctions that connect branching cardiac muscle cells, allowing rapid ion flow and coordinated contractions.

Neuroglia

Nonconducting support cells in nervous tissue that insulate, protect, and support neurons.