Anatomy and Physiology: Cellular Function, Tissues, Integument, Bone, and Joints

Comprehensive vocabulary flashcards covering key structural, histological, cellular, and functional terminology across human tissues, the integumentary system, bone physiology, joints, and molecular genetics based on Kenneth S. Saladin's Anatomy & Physiology lectures.

Osseous Tissue

A connective tissue whose extracellular matrix is hardened by calcium phosphate and other minerals through the process of calcification or mineralization.

Diaphysis

The cylindrical shaft of a long bone that provides leverage during musculoskeletal movement.

Epiphysis

The expanded, enlarged head located at each end of a long bone, serving to strengthen joints and anchor ligaments and tendons.

Diploe

The central layer of spongy bone sandwiched between the inner and outer tables of compact bone in cranial flat bones.

Osteoblast

A bone-forming cell found in the endosteum and inner periosteum that synthesizes the soft organic components of bone matrix and promotes calcification.

Osteocyte

A mature bone cell trapped within a lacuna that maintains the matrix and acts as a mechanical strain sensor to regulate bone remodeling.

Osteoclast

A large, multinucleated bone-dissolving cell originating from hematopoietic stem cells that performs osteolysis along bone surfaces.

Osteon

The basic structural and functional unit of compact bone, consisting of a central (haversian) canal surrounded by concentric lamellae.

Hydroxyapatite

A crystallized calcium phosphate salt ($Ca_{10}(PO_4)_6(OH)_2$) that makes up approximately 85% of the inorganic matrix of osseous tissue.

Endochondral Ossification

The embryonic and juvenile process of bone development in which hyaline cartilage models are broken down and replaced by osseous tissue.

Wolff's Law of Bone

The physiological principle stating that the architecture and density of a bone are determined by the mechanical stresses and loads placed upon it.

Calcitriol

The active form of vitamin D produced sequentially by the skin, liver, and kidneys that raises blood calcium levels primarily by stimulating dietary absorption in the small intestine.

Parathyroid Hormone

A hormone secreted by the parathyroid glands during hypocalcemia that raises blood calcium by stimulating osteoclasts, promoting renal calcium reabsorption, and inhibiting osteoblasts.

Histology

The microscopic study of tissues and how they assemble into functional organs; also called microscopic anatomy.

Mesenchyme

A gelatinous embryonic tissue derived from mesoderm consisting of wispy collagen fibers and fibroblasts in a gel matrix, which gives rise to bone, cartilage, and blood.

Basement Membrane

A thin extracellular layer between an epithelium and the underlying connective tissue that anchors the epithelium and controls molecular exchange.

Pseudostratified Columnar Epithelium

An epithelial tissue that appears multilayered due to nuclei at varying depths, although every individual cell contacts the basement membrane.

Urothelium

A specialized stratified epithelium lining the urinary bladder and ureter whose apical cells transition from rounded to flattened as the organ distends.

Fibroblast

A large, flat branching cell in fibrous connective tissue that synthesizes the collagenous, elastic, and reticular fibers, as well as the ground substance.

Chondrocyte

A mature cartilage cell trapped within an extracellular cavity called a lacuna.

Intercalated Disc

A specialized junctional complex uniting adjacent cardiomyocytes end-to-end, containing mechanical linkages and gap junctions for electrical synchronization.

Desmosome

A patch-like intercellular junction that mechanically links intermediate filaments of adjacent cells, preventing them from pulling apart under physical tension.

Gap Junction

A communicating junction formed by six transmembrane proteins assembled into a ring-like connexon, allowing direct intercellular diffusion of ions and small molecules.

Holocrine Secretion

A mode of exocrine secretion in which mature secretory cells accumulate a product and completely disintegrate to release their contents.

Metaplasia

A reversible transformation of one fully differentiated, mature tissue type into another mature tissue type.

Synostosis

An immovable bony joint formed when the intervening gap between two separate bones ossifies, fusing them into a single bone.

Suture

An immovable or slightly movable fibrous joint in which short collagen fibers tightly bind together the bones of the skull.

Syndesmosis

A fibrous joint in which two adjacent articulating bones are bound together by relatively long collagenous fibers, such as an interosseous membrane.

Synchondrosis

A cartilaginous joint in which the articulating bones are joined rigidly together by hyaline cartilage, such as the temporary epiphyseal plate.

Symphysis

A cartilaginous joint in which two opposing bones are united by a fibrocartilaginous pad, such as the pubic symphysis or intervertebral discs.

Synovial Fluid

A viscous, albumin- and hyaluronic acid-rich fluid filling the joint cavity of a diarthrosis to lubricate articular surfaces and nourish cartilage.

Bursa

A fibrous sac lined with synovial membrane and filled with synovial fluid, situated between muscles, tendons, or bones to cushion and reduce friction.

Mechanical Advantage

The ratio of a lever's output force to its input force, mathematically expressed as the effort arm length divided by the resistance arm length ($L_E / L_R$).

First-Class Lever

A anatomical lever arrangement where the fulcrum is situated between the applied effort and the resisting load ($EFR$), as seen at the atlanto-occipital joint.

Glenoid Labrum

A fibrocartilaginous ring encircling the margin of the scapular glenoid cavity that deepens the socket for the head of the humerus.

Anterior Cruciate Ligament

An intracapsular ligament of the knee joint that passes obliquely from the anterior tibia to the femur, preventing hyperextension of the knee.

Gene

An information-containing segment of DNA that codes for the production of an RNA molecule, which typically participates in the synthesis of one or more proteins.

Histone

A disc-shaped cluster of eight proteins around which DNA coils in a regular repeating pattern to form chromatin core particles (nucleosomes).

Transcription

The nuclear enzymatic process carried out by RNA polymerase in which genetic nucleotide sequences from a DNA template strand are copied into pre-mRNA.

Alternative Splicing

A nuclear RNA-processing mechanism where exons of pre-mRNA are assembled in different combinations, allowing a single gene to code for multiple distinct proteins.

Codon

A three-nucleotide sequence in messenger RNA ($mRNA$) that specifies a particular amino acid or directs the initiation or termination of protein translation.

Anticodon

A triplet of three ribonucleotides on a transfer RNA ($tRNA$) molecule that base-pairs complementarily with a corresponding mRNA codon during translation.

Polyribosome

A cluster consisting of multiple ribosomes simultaneously engaged in translating a single messenger RNA strand into identical polypeptide chains.

Semiconservative Replication

The mechanism of DNA duplication in which each resulting double-stranded daughter DNA molecule retains one parental strand and one newly formed strand.

Contact Inhibition

The regulatory cessation of cell division that occurs when proliferating cells become crowded and make physical contact with surrounding cells.

Pleiotropy

A genetic condition in which a single mutant gene or allele causes multiple, seemingly distinct and unrelated phenotypic abnormalities in an individual.

Dendritic Cell

An antigen-presenting, macrophage-like immune cell found in the stratum spinosum and stratum granulosum of the epidermis that defends against pathogens.

Stratum Basale

The deepest epidermal layer, composed of a single row of actively dividing stem cells, keratinocytes, tactile cells, and melanocytes anchored to the basement membrane.

Stratum Lucidum

A pale, featureless layer of the epidermis found exclusively in thick skin, where dead, translucent keratinocytes are packed with the protein eleidin.

Papillary Layer

The superficial zone of the dermis composed of areolar connective tissue and dermal papillae, highly vascularized to supply nutrients and facilitate leukocyte motility.

Hair Matrix

A region of actively dividing epithelial cells immediately above the dermal papilla of the hair bulb that constitutes the mitotic growth center of a hair.

Nail Plate

The hard, visible keratinized portion of a fingernail or toenail, consisting of the free edge, nail body, and root.

Sebaceous Gland

A flask-shaped holocrine cutaneous gland whose short duct typically empties oily sebum into a hair follicle to lubricate the skin and hair.

Malignant Melanoma

A highly invasive skin cancer that originates from melanocytes, characterized by asymmetrical borders, irregular pigmentation, and high metastatic lethality.

Eschar

The nonviable, burned, and coagulated dead tissue produced by severe full-thickness burns, posing life-threatening risks of toxicity and infection.