Cell Physiology and Tissue Histology

Comprehensive vocabulary flashcards covering cell physiology, body fluid compartments, membrane transport mechanisms, cell division, protein synthesis, and tissue histology.

Metabolic Water

Water produced within the body as a result of cellular oxidation and metabolic processes, also known as water of oxidation.

Insensible Water Loss

Water loss that occurs passively through evaporation from the skin or during vocalization and respiration without conscious control.

Intracellular Fluid

Fluid residing inside the cells of the body, constituting the largest fluid compartment.

Extracellular Fluid

Body fluid located outside of cells, subdivided into intravascular fluid within blood vessels and interstitial fluid surrounding tissue cells.

Electrolytes

Solute particles in body fluids capable of conducting an electrical current, including cations, anions, acids, and bases, measured in concentration units of $mEq/L$.

Osmolality

The measurement of solute concentration in a body fluid, where higher osmolality reflects a greater total concentration of dissolved solutes.

Isotonic Fluid

A fluid solution with an osmolality comparable to that of normal blood, where extracellular dissolved substance concentration matches intracellular fluid (e.g., $0.9\%$ NaCl).

Hypotonic Fluid

A fluid solution with an osmolality lower than blood, causing water to shift into cells, leading to swelling and potential cellular lysis.

Hypertonic Fluid

A fluid solution with an osmolality greater than blood, causing water to shift out of cells into the extracellular space, leading to cell shriveling.

Edema

An abnormal, excess accumulation of fluid within tissue spaces, resulting from fluid shifting out of the vascular space into the interstitial space.

Crystalloids

Intravenous fluids composed of water rich with small solutes and electrolytes capable of freely crossing capillary walls.

Colloids

Intravenous fluids containing heavy, high-molecular-weight molecules suspended in an isotonic solution that are too large to cross vascular walls.

Diffusion

The passive kinetic movement of solute molecules down a concentration gradient from an area of higher concentration to lower concentration.

Facilitated Diffusion

A passive transport mechanism in which selective carrier proteins assist solute molecules across the cell membrane without cellular energy (ATP) expenditure.

Osmosis

The passive movement of water through a semipermeable membrane from a dilute solution into a more concentrated one to achieve concentration equilibrium.

Filtration

The passive movement of liquids and solutes through a membrane driven by a hydrostatic pressure gradient.

Oncotic Pressure

The difference between the osmotic pressure of blood plasma and the osmotic pressure of interstitial fluid or lymph, crucial for maintaining fluid balance.

Symport System

An active transport mechanism in which two or more transported substances are moved across the plasma membrane in the same direction.

Antiport System

An active transport mechanism in which transported substances are moved across the plasma membrane in opposing directions (e.g., $Na^+/K^+$ pump).

Phagocytosis

A form of endocytosis in which a cell extends pseudopodia to engulf solid extracellular material into an internal vesicle.

Pinocytosis

A form of endocytosis in which a cell engulfs liquid extracellular material through tiny infoldings of the plasma membrane.

Receptor-Mediated Endocytosis

A selective endocytic process where extracellular ligands bind to specific plasma membrane protein receptors before being internalized in a coated pit.

Exocytosis

The active process by which membrane-bound vesicles packaged by the ER and Golgi body fuse with the plasma membrane to export contents into extracellular space.

Resting Membrane Potential

The electrical potential difference across the cell membrane created by separated charges, with normal values ranging from $-20\,mV$ to $-22\,mV$.

Interphase

The metabolic period between cell divisions during which the cell grows and replicates its DNA, divided into G1, S, and G2 subphases.

Mitosis

The process of nuclear division in somatic cells consisting of prophase, metaphase, anaphase, and telophase, producing two genetically identical daughter cells.

Cytokinesis

The physical division of the cytoplasm that completes the cell division phase.

Transcription

The process occurring in the nucleus where a gene's DNA sequence is copied into a complementary strand of messenger RNA (mRNA).

Translation

The process occurring in the cytoplasm where ribosomes decode mRNA sequences into amino acid chains to form proteins.

Histology

The microscopic study of the structure and function of biological tissues, also referred to as microanatomy.

Tight Junction

A cell junction formed by the fusion of outermost plasma membrane layers of adjoining cells, creating an impermeable barrier against leaks.

Desmosome

A strong mechanical cell junction consisting of a plaque and tonofilaments that anchors adjacent plasma membranes in tissues subjected to repeated tension.

Gap Junction

A cellular attachment composed of tubular channel proteins called connexons that link cell cytoplasms to allow rapid passage of ions, nutrients, and electrical signals.

Basement Membrane

A nonliving network of fibers (basal lamina) that cements epithelial cells to underlying tissues and serves as a partial protective barrier.

Simple Squamous Epithelium

A single delicate layer of flattened, smooth cells adapted for liquid or gas passage, forming mesothelium in body cavities and endothelium in blood vessels.

Simple Cuboidal Epithelium

A single layer of cube-shaped cells with aligned central nuclei, located in regions where secretion and absorption occur.

Simple Columnar Epithelium

A single layer of tall, elongated cells with basal nuclei, specialized for absorption and secretion within digestive and respiratory lining.

Pseudostratified Columnar Epithelium

A single-layered epithelium that appears stratified due to nuclei at varying heights, where all cells contact the basement membrane; typically ciliated in the respiratory tract.

Transitional Epithelium

A stratified leak-proof epithelium capable of stretching and changing shape from cuboidal to squamous, lining organs that expand such as the urinary bladder.

Goblet Cell

A modified unicellular exocrine gland embedded in columnar epithelia that synthesizes and secretes mucin.

Merocrine Gland

An exocrine gland whose cells remain fully intact, releasing secretory products through exocytosis as they are synthesized.

Apocrine Gland

An exocrine gland that stores secretions at the apical cellular apex, releasing its product by pinching off the top portion of the cell into the duct system.

Holocrine Gland

An exocrine gland that accumulates secretions intracellularly until the entire cell lyses and dies to release the product.

Serous Secretion

A thin, watery exocrine fluid containing a high concentration of active digestive or protective enzymes.

Mucous Secretion

A thick, viscous exocrine secretion rich in glycoproteins (mucin) and electrolytes.

Extracellular Matrix

The nonliving material surrounding connective tissue cells, consisting of an amorphous ground substance and extracellular protein fibers.

Fibroblast

The predominant fixed cell type in connective tissue proper responsible for synthesizing matrix ground substance and fibers.

Diapedesis

The active movement of transient white blood cells squeezing in and out of blood vessels into surrounding connective tissues.

Areolar Tissue

A loose connective tissue comprising a random meshwork of fibers and cells suspended in thick ground substance that surrounds and supports organs.

Adipose Tissue

A vascular loose connective tissue dominated by lipid-filled adipocytes, functioning in energy storage, thermal insulation, and shock absorption.

Reticular Tissue

A loose connective tissue consisting of a delicate framework of reticular fibers and fibroblasts, forming the supportive internal stroma of cellular organs like the spleen.

Dense Regular Connective Tissue

A strong connective tissue of tightly packed parallel collagen fibers with rows of fibroblasts, providing high unidirectional tensile strength in tendons and ligaments.

Dense Irregular Connective Tissue

A connective tissue featuring thick bundles of collagen fibers interwoven into a multi-directional sheet, offering structural support to the dermis and organ capsules.

Hyaline Cartilage

The most common and rigid cartilage type, composed of densely packed collagen fibers surrounded by a perichondrium, located in tracheal rings, growth plates, and articular surfaces.

Fibrocartilage

A tough cartilage lacking a perichondrium that contains thick bundles of hyaline cartilage, designed to absorb high compressive forces between spinal vertebrae and pelvic bones.

Serous Membrane

A continuous sheet of simple squamous epithelium bound to loose connective tissue lining closed body cavities, producing a watery transudate (serosal fluid).

Synovial Membrane

A membrane lining joint cavities composed of connective and adipose tissue covered by collagen fibers and fibroblasts without an epithelial layer, manufacturing synovial fluid.

Granulation Tissue

A pink, vascular tissue formed during wound organization composed of newly branched capillary networks and collagen fibers synthesized by fibroblasts.

First-Intention Healing

A wound repair process where wound margins are closely apposed, enabling rapid healing without granulation tissue formation or significant scarring.

Second-Intention Healing

A wound repair process occurring in separated wound edges, requiring granulation tissue formation and resulting in fibrous scar tissue.