Cell Biology and Tissues Flashcards

Vocabulary flashcards covering epithelial tissue types and functions, mechanisms of endocytosis, lysosomal function, Tay-Sachs disease, and active transport processes.

Tissue

A structure composed of a number of cells, classified into four major types: epithelial, connective, muscle, and nerve tissue.

Epithelial Tissue

A major tissue type that covers all body surfaces, lines body cavities, forms major tissues of glands, lacks blood vessels, and attaches to underlying connective tissue by a basement membrane. Functions in protection, secretion, absorption, excretion, and sensory reception.

Simple Epithelium

Epithelial tissue composed of a single layer of cells.

Stratified Epithelium

Epithelial tissue composed of more than one layer of cells.

Squamous Epithelial Cells

Thin, flattened epithelial cells.

Cuboidal Epithelial Cells

Cube-like epithelial cells.

Columnar Epithelial Cells

Elongated epithelial cells.

Desmosomes

Structures that frequently attach epithelial cells to each other.

Simple Squamous Epithelial Cells

Single-layer, thin, flattened cells through which molecules pass easily. Found where diffusion and filtration take place, such as in alveoli and capillaries.

Simple Cuboidal Epithelial Cells

Single-layer, cube-like cells that cover ovaries and line kidney tubules and ducts of glands; functions in secretion and absorption.

Simple Columnar Epithelium

Tissue composed of tall, relatively thick cells with nuclei located near the basement membrane at the same level. Lines parts of the digestive tract and uterus to protect underlying tissues, secrete digestive fluids, and absorb nutrients.

Microvilli

Structures present on columnar cells involved in absorption that increase the surface area of the cell membrane exposed to substances to be absorbed.

Goblet Cells

Cells often scattered among columnar cells that secrete mucus onto the tissue surface for protection and lubrication.

Endocytosis

The process by which molecules too large to enter a cell by diffusion or active transport enter via clathrin-coated vesicles formed from the cell membrane.

Pinocytosis

A form of endocytosis, also known as bulk-phase or fluid phase endocytosis ("drinking"), in which a cell invaginates its membrane to take in a drop of fluid containing water and dissolved particles such as proteins.

Phagocytosis

A form of endocytosis ("eating") in which a cell engulfs attached solid matter, pinching off the cell membrane to form an internal vesicle.

Phagocytes

Cells that phagocytize particles, particularly bacterial cells.

Macrophage

A very large phagocytic cell.

Receptor-Mediated Endocytosis

A process that moves specific particles, such as hormones and blood proteins, into the cell by binding them to specific transmembrane protein receptors, triggering membrane invagination and vesicle formation.

Tay-Sachs Disease

An inherited disease with no known treatment where cell lysosomes lack an enzyme to digest certain lipids. These lipids accumulate in the nervous system, causing progressive retardation, paralysis, blindness, dementia, and usually death by age 3 or 4.

Active Transport

A process requiring energy in the form of ATP (released by cellular respiration) and carrier proteins to move particles such as $Na^+$, $K^+$, $Ca^+$, $H^+$, sugars, and amino acids across the cell membrane.

Carrier Proteins (Active Transport)

Membrane proteins with specific binding sites that change shape using energy released upon particle binding to transport molecules across the membrane, releasing them on the other side via enzymes.