Chapter 5: Human Tissues Vocabulary

Comprehensive vocabulary flashcards covering human tissue types, germ layers, epithelial structures, connective tissues, muscular and nervous tissues, cellular junctions, glands, and tissue growth/repair.

Tissue

A group of similar cells working together to perform a specific function.

Histology

The microscopic study of tissues.

Epithelial Tissue

Tissue composed of layers of closely spaced cells that cover organ surfaces, form glands, and serve for protection, secretion, and absorption.

Connective Tissue

Tissue with usually more matrix than cell volume, often specialized to support and protect organs and to bind other tissues and organs to each other.

Nervous Tissue

Tissue containing excitable cells specialized for rapid transmission of coded information to other cells.

Muscular Tissue

Tissue composed of elongated, excitable muscle cells specialized for contraction.

Endoderm

The innermost primary germ layer that gives rise to the digestive and reproductive tracts including many organs.

Mesoderm

The middle primary germ layer that gives rise to muscles, bones, and other connective tissues.

Ectoderm

The outermost primary germ layer that gives rise to the epidermis, nervous system, hair, and nails.

Avascular

Lacking a direct blood supply; characteristic of epithelial tissues which are nourished by underlying connective tissue.

Simple Epithelia

Epithelial tissue containing one layer of cells in which all cells touch the basement membrane.

Stratified Epithelia

Epithelial tissue containing more than one layer of cells, where upper cells rest on top of others and do not touch the basement membrane.

Simple Squamous Epithelium

A single row of thin cells that permits rapid diffusion or transport of substances and secretes serous fluid.

Simple Cuboidal Epithelium

A single layer of square or cube-like cells specialized for absorption, secretion, and mucus production.

Simple Columnar Epithelium

A single row of tall, slender cells with oval nuclei in the basal half and a microvilli brush border; functions in absorption and secretion of mucus.

Pseudostratified Epithelium

An epithelium that looks multilayered but has all cells touching the basement membrane, typically featuring cilia and goblet cells to secrete and propel mucus.

Keratinized Stratified Squamous Epithelium

A multilayered epithelium covered with flat, scaly dead cells at the surface; resists abrasion, retards water loss through skin, and resists pathogen penetration.

Non-keratinized Stratified Squamous Epithelium

A multilayered epithelium lacking a surface layer of dead cells; resists abrasion and pathogen penetration in moist internal areas like the esophagus and vagina.

Stratified Cuboidal Epithelium

An epithelium consisting of two or more cell layers with square or round surface cells; secretes sweat, produces sperm, and produces ovarian hormones.

Urothelium

Transitional multilayered epithelium with surface cells that change from round to flat when stretched, allowing filling of the urinary tract.

Collagenous Fibers

Tough, flexible, and stretch-resistant protein fibers found in connective tissue matrix.

Reticular Fibers

Thin collagen fibers coated with glycoprotein that form a supportive network in connective tissue.

Elastic Fibers

Thinner connective tissue fibers made of elastin that allow tissues to stretch and recoil.

Ground Substance

The non-fibrous material of connective tissue matrix that ranges from watery to gelatinous, rubbery, or solid consistency.

Areolar Tissue

Loose connective tissue with loosely organized fibers and abundant blood vessels; found in the upper dermis and between muscles.

Reticular Connective Tissue

A mesh of reticular fibers and fibroblasts forming a supportive stroma for lymphatic organs like the spleen, lymph nodes, and bone marrow.

Dense Regular Connective Tissue

Connective tissue consisting of densely packed, parallel collagen fibers and compressed fibroblast nuclei; found in tendons and ligaments.

Dense Irregular Connective Tissue

Connective tissue with densely packed, randomly arranged collagen fibers that withstands unpredictable stresses; located in organ capsules and deeper dermis.

Adipose Tissue

Connective tissue composed of adipocytes with peripheral nuclei, serving functions in energy storage, thermal insulation, and cushioning.

Hyaline Cartilage

Cartilage with a clear, glassy matrix composed of fine collagen fibers; eases joint movement, holds airways open, and aids growth of juvenile long bones.

Elastic Cartilage

Cartilage containing an abundance of elastic fibers covered with perichondrium, providing flexible, elastic support to the external ear and epiglottis.

Fibrocartilage

Cartilage containing large, coarse bundles of collagen fibers that resists compression and absorbs shock in intervertebral discs and menisci.

Osteocytes

Mature bone cells situated within small chambers called lacunae.

Canaliculi

Delicate microscopic canals radiating from each lacuna to neighboring chambers in compact bone, enabling osteocytes to contact one another.

Erythrocytes

Red blood cells (RBCs) responsible for transporting $O_2$ and $CO_2$ in the blood.

Leukocytes

White blood cells (WBCs) that defend the body against infection and disease.

Thrombocytes

Platelets; cell fragments in blood involved in blood clotting.

Neurons

Nerve cells specialized for detecting stimuli, responding quickly, and rapidly transmitting electrical signals to other cells.

Neuroglia

Glial cells that protect and assist neurons, serving as the support system for nervous tissue.

Skeletal Muscle Tissue

Voluntary muscle tissue composed of long, striated, multinucleated muscle fibers mostly attached to bones.

Cardiac Muscle Tissue

Involuntary, striated muscle tissue restricted to the heart, featuring short, branched cardiomyocytes joined by intercalated discs.

Smooth Muscle Tissue

Involuntary, non-striated muscle tissue made of short, fusiform cells with a central nucleus, located mainly in the walls of hollow organs.

Exocrine Glands

Glands possessing ducts that release their secretions onto an internal or external surface.

Endocrine Glands

Ductless glands that release hormones directly into the bloodstream to act on distant target cells.

Serous Secretions

Thin, watery glandular secretions such as perspiration, tears, and digestive juices.

Mucous Secretions

Secretions containing glycoprotein and mucin produced by goblet cells, absorbing water to form mucus.

Eccrine Secretion

A mode of glandular secretion where secretory vesicles release their product via exocytosis.

Apocrine Secretion

A mode of glandular secretion where lipid droplets bud from the cell surface enveloped by a layer of plasma membrane and cytoplasm.

Holocrine Secretion

A mode of glandular secretion where entire secretory cells disintegrate and die to release their product.

Hyperplasia

Tissue growth through cell multiplication and an increase in cell number via mitosis.

Hypertrophy

Tissue growth through enlargement of pre-existing cells rather than an increase in cell number.

Atrophy

Shrinkage of a tissue through a loss in cell size or cell number, often resulting from aging or disuse.

Tissue Necrosis

Pathological tissue death resulting from physical trauma, toxins, or infections.

Regeneration

A tissue repair process that replaces dead or damaged cells with the same cell type, fully restoring normal tissue function.

Fibrosis

A tissue repair process that replaces damaged cells with scar tissue, binding organs together without restoring normal tissue function.