Epithelial and Connective Tissues

Vocabulary flashcards covering epithelial and connective tissues, cell junctions, tissue classifications, gland secretion modes, tissue components, membranes, and abnormal growth patterns based on Anatomy & Physiology I lecture notes.

Tissue

A group of cells organized into groups or layers that have specialized function(s).

Epithelial Tissue

Tissue type that covers body surfaces (epithelia) and forms glands that produce fluid secretions.

Tight Junctions

Intercellular junctions that provide a strong bonding between neighboring cells and prevent leakage across tissues.

Adherens Junctions

Cell junctions that link the cytoskeleton from two adjacent cells together and transmit mechanical forces.

Gap Junctions

Cell junctions that facilitate the movement of ions and molecules across the tissue.

Apical Surface

The exposed top surface of an epithelial cell or tissue layer.

Basal Surface

The bottom surface of an epithelial cell attached to the basal lamina.

Microvilli

Projections on the apical surface of epithelial cells that increase surface area to maximize absorption or secretion.

Cilia

Surface structures on epithelial cells that beat in a coordinated fashion to move materials past the exterior of the cell.

Types of Epithelial Tissues

Classifications of epithelial tissues based on cell shape (squamous, cuboidal, columnar) and number of layers (simple, stratified, pseudostratified, transitional).

Simple Squamous Epithelium

A single layer of flat cells suited for diffusion, found in protected areas such as air sacs of lungs, kidney tubules, and lining of body cavities and blood vessels.

Stratified Squamous Epithelium

Multiple layers of flat cells; keratinized on exterior surfaces to prevent water loss and non-keratinized on moist interior surfaces like the esophagus.

Simple Cuboidal Epithelium

A single layer of cube-shaped cells adapted for absorption or secretion, commonly featuring microvilli in kidney tubules.

Stratified Cuboidal Epithelium

A rare stratified tissue composed of cube-shaped cells located in the ducts of sweat and mammary glands.

Simple Columnar Epithelium

A single layer of tall cells typically possessing microvilli and goblet cells, specialized for absorption or secretion in the digestive tract.

Pseudostratified Columnar Epithelium

A single layer of columnar cells that appears multi-layered because cell nuclei lie at various levels; frequently lined with cilia and goblet cells in the respiratory system.

Transitional Epithelium

A specialized stratified epithelium that changes shape to allow expansion and recoil, lining organs such as the urinary bladder.

Stratified Columnar Epithelium

A rare tissue type composed of multiple layers with columnar surface cells, functioning in absorption and secretion in areas such as salivary ducts.

Goblet Cells

Specialized epithelial cells interspersed in mucosal linings that secrete protective mucus.

Merocrine Secretion

Exocrine gland secretion method where cellular products are released via exocytosis without damaging the cell (e.g., sweat glands).

Apocrine Secretion

Exocrine gland secretion method where membrane-bound buds detach from the apical portion of the cell into the duct, losing part of the cell membrane (e.g., mammary glands).

Holocrine Secretion

Exocrine gland secretion method in which the entire cell ruptures to release its contents into the duct (e.g., sebaceous glands).

Connective Tissue

Body tissue type consisting of cells dispersed within an extracellular matrix of ground substance and fibers, functioning to bind, support, protect, and transport.

Fibroblasts

Connective tissue proper cells that secrete hyaluronic acid, proteins, collagen fibers, reticular fibers, and elastic fibers.

Fibrocytes

Connective tissue cells derived from fibroblasts that maintain extracellular fibers.

Macrophages

Phagocytic immune cells in connective tissue that scavenge pathogens and signal other immune cells; exists as fixed or free populations.

Adipocytes

Fat cells containing a single large lipid droplet that pushes the nucleus and organelles to the periphery, creating a signet ring appearance.

Mesenchymal Cells

Multipotent stem cells in connective tissue that divide and differentiate into specialized connective tissue cells upon injury or infection.

Mast Cells

Connective tissue cells that release histamine to promote inflammation and heparin to prevent blood clotting following tissue injury or infection.

Loose Connective Tissue Types

Packing materials of the body that cushion and support organs; includes areolar tissue, adipose tissue, and reticular tissue.

Areolar Tissue

A loosely organized, highly vascular connective tissue containing all cell and fiber types that can distort without damage.

White Fat vs. Brown Fat

White fat is nutrient-storing tissue found in adults with few blood vessels; brown fat is highly vascular tissue filled with mitochondria found in infants for heat production.

Reticular Tissue

Loose connective tissue containing abundant reticular fibers that forms the stroma or framework supporting functional cells in organs like the liver, kidney, and spleen.

Dense Regular White Connective Tissue

Dense connective tissue dominated by parallel collagen fibers aligned with applied stress to provide high tensile strength in tendons, ligaments, and aponeuroses.

Chondrocytes

Cartilage cells that reside in matrix spaces called lacunae.

Perichondrium

Membrane encapsulating cartilage, consisting of an outer fibrous layer for structural support and an inner cellular layer for cartilage growth and repair.

Hyaline Cartilage

The most abundant type of cartilage in the body, rich in collagen fibers and enclosed by a dense perichondrium.

Fibrous Cartilage

Exceptionally tough cartilage consisting mostly of collagen fibers with minimal matrix, serving to prevent bone-to-bone contact between spinal vertebrae and pubic bones.

Osteon

The basic structural and functional unit of compact bone tissue consisting of concentric lamellae surrounding a central canal.

Osteoblasts

Bone-forming cells that synthesize and build new bone matrix.

Osteoclasts

Large cells that resorb and chew up bone matrix.

Canaliculi

Microscopic channels traversing the calcified bone matrix that connect lacunae to each other and to the central canal.

Periosteum

A two-layered membrane surrounding bone with an outer fibrous layer and an inner cellular layer responsible for bone growth and repair.

Mucous Membrane

An epithelial membrane lining body cavities open to the exterior environment, consisting of epithelium with goblet cells and underlying connective tissue (lamina propria).

Serous Membrane

A double-layered membrane lining closed body cavities (pleura, pericardium, peritoneum) consisting of simple squamous epithelium and connective tissue that secretes serous fluid.

Synovial Membrane

Membrane lining joint cavities composed of fibrous and loose connective tissue that secretes lubricating synovial fluid.

Hyperplasia

An abnormal growth pattern characterized by an increase in the number of normal cells within a tissue.

Hypoplasia

Underdevelopment or incomplete development of a tissue or organ due to a decreased number of cells.

Metaplasia

A tissue transformation where normal, fully differentiated cells appear in an abnormal anatomic location.

Dysplasia

Disordered cell growth and maturation within a tissue, often considered pre-cancerous.

Neoplasia

New and uncontrolled growth of abnormal cells, classified as either benign or malignant.