Anatomy and Physiology: The Human Tissues

Vocabulary flashcards covering human tissue classifications, extracellular matrix components, epithelial characteristics and polarity, connective, nervous, and muscular tissues, cellular junctions, glandular types, and body membranes.

Tissue

A collection of similar cells that perform a specific structural or physiological role in an organ.

Histology

The study of tissues.

Extracellular Matrix (ECM)

Non-cellular component composed of fibrous proteins and a clear gel known as ground substance, tissue fluid, extracellular fluid (ECF), or interstitial fluid, differing in characteristics across the four primary tissue types.

Ground Substance

A clear gel in the extracellular matrix (also termed tissue fluid, ECF, or interstitial fluid) containing water, gasses, nutrients, wastes, minerals, and other chemicals.

Epithelial Tissue

Primary tissue type that covers the body surface, lines body cavities, forms external and internal linings of many organs, and constitutes most glandular tissue; functions in protection, secretion, excretion, absorption, filtration, and sensation.

Cellularity

A characteristic of epithelial tissue in which cells are closely packed together, rendering the extracellular material barely visible under a light microscope.

Avascular

The structural characteristic of lacking blood vessels, as observed in epithelial tissues.

Basement Membrane

A structure that anchors an epithelium to underlying connective tissue and controls the exchange of materials between epithelial and underlying tissues.

Basal Surface

The surface of an epithelial cell that faces toward the basement membrane.

Apical Surface

The surface of an epithelial cell that faces away from the basement membrane and toward the body exterior or the internal cavity lumen.

Connective Tissue

The most abundant, widely distributed tissues of the body; functions include binding of organs, support, physical protection, immune protection, energy storage, and transport.

Nervous Tissue

Tissue specialized for communication by means of electrical and chemical signals, comprising the majority of the brain, spinal cord, and nerves.

Neurons

Nervous tissue cells that detect stimuli, respond quickly, and transmit coded information rapidly to other cells.

Neuroglia

Cells in nervous tissue that protect and assist neurons.

Muscle Tissue

Tissue specialized to contract when stimulated, categorized into skeletal (voluntary), cardiac (involuntary), and smooth (involuntary) types.

Tight Junctions

Cellular junctions that act like seals to hold cells tightly together, such as between stomach cells to prevent digestive juices from seeping between epithelial cells and damaging underlying tissues.

Desmosomes

Cellular junctions that act like rivets, keeping cells from pulling apart and enabling a tissue to resist mechanical stress; found in locations such as the epidermis.

Gap Junctions

Cellular junctions formed by a connexon that creates a pore or channel to allow small substances to pass between two adjacent cells; found in cardiac and smooth muscle.

Endocrine Glands

Glands that secrete hormones directly into the blood, such as the thyroid, adrenal, or pituitary gland.

Exocrine Glands

Glands that release secretions to a surface, producing substances such as sweat, tears, mucus, or digestive enzymes.

Cutaneous Membrane

A membrane that covers the surface of the body (the skin), consisting of an outer epithelial layer called the epidermis and a deep layer of connective tissue called the dermis.

Mucous Membranes (Mucosae)

Membranes that line passageways opening to the external environment (digestive, respiratory, urinary, and reproductive tracts), often covered with mucus to trap pathogens and foreign particles and protect underlying tissue.

Serous Membranes

Membranes lining the pleural, pericardial, and peritoneal body cavities, composed of parietal and visceral layers.

Parietal Layer

The layer of a serous membrane that lines the wall of the body cavity.

Visceral Layer

The layer of a serous membrane that covers the internal organ.

Serous Fluid

Fluid located between the parietal and visceral layers of a serous membrane that reduces friction as organs move.