Histology and Tissue Types Flashcards

Vocabulary flashcards covering histology concepts, tissue types, cell shapes, epithelial and connective tissues, muscle types, nervous tissue, cell junctions, and abnormal growth patterns based on the Anatomy & Physiology 1 Lab lecture notes.

Histology

The microscopic study of tissues and their cellular structures.

Tight Junction

A cell junction formed by the fusion of the outer phospholipid layers of adjacent plasma membranes that prevents fluids and most molecules from moving between cells.

Desmosome

A patch-like cell junction consisting of hook-like J-shaped proteins arising from the cytoskeleton that holds cells together to resist mechanical stress.

Hemidesmosome

A specialized cell junction that anchors basal epithelial cells to the basement membrane, preventing epithelium from easily peeling away.

Gap Junction

A communicating cell junction composed of six transmembrane proteins surrounding a water-filled pore (connexon) that allows ions, glucose, amino acids, and solutes to pass between cells.

Exocrine Glands

Glands derived from epithelia that secrete substances onto external surfaces or into internal passageways through a duct.

Endocrine Glands

Ductless glands derived from epithelia that secrete hormones directly into the interstitial fluid or bloodstream.

Exocrine Gland Structural Classification

Structural modes of exocrine glands categorized by duct branching (simple vs. compound) and secretory unit shape (tubular vs. acinar/alveolar).

Glandular Secretion Modes

The mechanisms by which exocrine glands release products: merocrine (exocytosis), apocrine (pinching off apical cytoplasm), and holocrine (entire cell destruction).

Merocrine Gland

A gland that releases its fluid secretory product through the cell membrane via exocytosis without damaging the cell.

Apocrine Gland

A gland in which a portion of the cell membrane and apical cytoplasm is pinched off along with the secretory product.

Holocrine Gland

A gland in which the entire cell ruptures and disintegrates to release its secretory product.

Carcinoma

A malignant neoplasm of epithelial origin, accounting for approximately $85\%$ of all cancers.

Sarcoma

A malignant neoplasm of connective tissue origin, accounting for approximately $10\%$ of all cancers.

Simple Squamous Epithelium

A single layer of thin, flattened cells with disc-shaped nuclei that allows material passage by diffusion and filtration in lung alveoli, capillary walls, and kidney glomeruli.

Simple Cuboidal Epithelium

A single layer of box-like cells with central spherical nuclei specialized for secretion and absorption in kidney tubules, ovary surfaces, and small glands.

Simple Columnar Epithelium

A single layer of tall cells with round to oval nuclei, often containing microvilli or goblet cells, specialized for absorption and secretion lining the stomach and intestines.

Pseudostratified Columnar Epithelium

A single layer of cells of differing heights with nuclei at different levels that appears multi-layered; often ciliated with goblet cells in the upper respiratory tract.

Transitional Epithelium

A specialized stratified epithelium with dome-shaped surface cells that flatten upon distension, lining the ureters and urinary bladder.

Fibroblast

The primary cell type of connective tissue proper that secretes collagen and elastic fibers into the extracellular matrix.

Adipose Tissue

A loose connective tissue composed of closely packed adipocytes filled with fat droplets that displace the nucleus and cytoplasm to the cell periphery.

Reticular Tissue

A loose connective tissue containing a network of dark-staining reticular fibers that form a soft internal framework (stroma) supporting cells in lymphoid organs.

Dense Regular Connective Tissue

Connective tissue consisting primarily of parallel bundles of collagen fibers produced by fibroblasts, providing high tensile strength in tendons and ligaments.

Dense Irregular Connective Tissue

Connective tissue made of irregularly arranged collagen fibers capable of withstanding tension in multiple directions, located in the dermis of the skin and organ capsules.

Osteoblast

A bone-forming cell that secretes the ground substance and organic matrix of bone tissue.

Osteoclast

A large multinucleated cell that breaks down and resorbs bone matrix, releasing calcium ($Ca^{2+}$) into the blood.

Osteocyte

A mature bone cell formed when an osteoblast becomes trapped within a lacuna in the calcified bone matrix.

Compact Bone Microstructure

The structural arrangement of osseous tissue consisting of osteons, osteonic (Haversian) canals, concentric lamellae, osteocytes in lacunae, and canaliculi.

Erythrocyte

A red blood cell (RBC) suspended in plasma that functions in transporting oxygen and carbon dioxide.

Leukocyte

A white blood cell (WBC) involved in immune defense against pathogens and foreign invaders.

Thrombocyte

A blood cell fragment (platelet) that functions in the blood clotting mechanism.

Hyaline Cartilage

A supporting connective tissue with an amorphous firm matrix and concealed collagen fibers that cushions ends of long bones, costal cartilages, and tracheal rings.

Elastic Cartilage

Flexible cartilage containing a dense network of elastic fibers in its matrix, maintaining structural shape in the external ear (pinna) and epiglottis.

Fibrocartilage

Cartilage with a matrix containing thick collagen fibers that provides high tensile strength and shock absorption in intervertebral discs and the pubic symphysis.

Skeletal Muscle

Voluntary, striated muscle tissue composed of long, non-branched, multinucleated cylindrical fibers attached to bones.

Cardiac Muscle

Involuntary, striated muscle tissue consisting of branched, single-nucleated cells connected end-to-end by intercalated disks in the heart wall.

Smooth Muscle

Involuntary, non-striated, non-branched muscle tissue composed of single-nucleated, fusiform (spindle-shaped) cells found in the walls of hollow internal organs.

Intercalated Disks

Specialized microscopic junctional structures connecting adjacent cardiac muscle cells to allow coordinated contraction.

Neuron

The functional conducting nerve cell responsible for generating and transmitting electrical impulses, consisting of dendrites, a cell body (soma), and an axon.

Neuroglia

Non-conductive, supportive cells of the nervous system that nourish, protect, and insulate neurons.

Myelin

An insulating sheath surrounding neuronal axons produced by Schwann cells to prevent electrical impulses from escaping.

Atrophy

An abnormal cellular growth pattern characterized by a decrease in both cell size and cell number.

Hypertrophy

An adaptive increase in cell size ONLY, without an increase in cell number.

Hyperplasia

An increase in cell number ONLY within a tissue.

Metaplasia

The reversible transformation of one fully differentiated adult cell type into another adult cell type to better endure chronic stress or irritation.

Dysplasia

A growth alteration producing atypical cells that vary in size, shape, and organization, which can potentially progress to neoplasia (malignancy).

Abnormal Cellular Growth Patterns

Variations in cell growth and differentiation including atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia, and neoplasia (malignancy).