Four Basic Types of Human Tissue

Vocabulary practice cards covering the four basic types of human tissue, specific epithelium subtypes, connective tissue categories, bone cell types, and neuroglia.

Epithelial Tissue

Tissue made of cells arranged in a continuous sheet with one or more layers, featuring apical and basal surfaces.

Basement membrane

The attachment between the basal surface of the cell and the underlying connective tissue.

Stratified Squamous Epithelial Tissue

A tissue consisting of several layers with apical and basal surfaces, existing in both keratinized and non-keratinized forms.

Pseudostratified Columnar Epithelium

Epithelial tissue where all cells are anchored to the basement membrane, but not all cells reach the apical surface.

Simple Cuboidal Epithelium

A single layer of cubelike cells with large, spherical central nuclei, functioning in secretion and absorption.

Transitional epithelium

A type of epithelium with dome-shaped or squamous-like surface cells that stretch readily to permit distension of urinary organs.

Endocrine glands

Glands that release chemical substances known as hormones directly into the bloodstream or tissues of the body.

Exocrine glands

Glands that release chemical substances through ducts to the outside of the body or onto another surface within the body.

Fibroblasts

Cells responsible for making the extracellular matrix and collagen.

Connective tissue matrix

The substance made of two materials: Ground Substance (proteins and polysaccharides) and Fiber (reticular, collagen, and elastic).

Areolar Connective Tissue

A loose connective tissue with a gel-like matrix and all three fiber types; it wraps and cushions organs and forms the lamina propria.

Adipocytes

Also known as lipocytes or fat cells, these cells primarily compose adipose tissue and are specialized in storing energy as fat.

Hyaline cartilage

The weakest and most abundant type of cartilage, found at the ends of long bones, ventral ends of ribs, larynx, trachea, and bronchi.

Elastic cartilage

Cartilage that maintains structure shape while allowing flexibility; found in the epiglottis and the pinnae (external ear flaps).

Fibrous Cartilage

The strongest type of cartilage with dense collagen and little matrix; found in the pelvis, skull, and vertebral discs.

Hematopoiesis

The process where hematopoietic stem cells (HSCs) in the bone medulla give rise to all different mature blood cell types and tissues.

Osteoblasts

Bone-forming cells that secrete the bone matrix.

Osteoclasts

Giant multinucleate cells located at sites of cell resorption, generated from the same hematopoietic stem cells as macrophages.

Osteocytes

Mature bone cells that occupy lacunae and monitor and maintain the bone matrix.

White blood cells (WBCs)

Also called leukocytes, these cells of the immune system protect the body against infectious disease and foreign invaders.

Skeletal Muscle

Voluntary, striated muscle tissue mainly found attached to bones with striations perpendicular to the muscle fibers.

Cardiac Muscle

Involuntary, striated, and branched muscle tissue that contains intercalated discs.

Smooth Muscle

Involuntary, nonstriated, spindle-shaped muscle tissue found in blood vessels and the GI tract.

Astrocytes

Star-shaped glial cells in the brain and spinal cord that support the blood–brain barrier and maintain extracellular ion balance.

Oligodendrocytes

Neuroglia that provide support and insulation to axons in the CNS by creating the myelin sheath, which is $80\%$ lipid and $20\%$ protein.

Ependyma

The thin epithelial lining of the brain's ventricular system and the spinal cord's central canal; it is involved in producing cerebrospinal fluid (CSF).

Microglia

Resident macrophage cells in the CNS that act as the first and main form of active immune defense, accounting for $10-15\%$ of all brain cells.

Mesoderm

A primary germ cell layer that develops into epithelial tissue, connective tissue, and muscle tissue.

Tight Junctions

Junctions that form a seal between cells and define the apical and basal sides of an epithelial cell.

Hemidesmosomes

Junctions that anchor keratin fibers in epithelial cells to the basement membrane through integrin anchors.