Tissue level

Histology

The study of tissues, which are structures that consist of cells organized to fulfill a common function.

Epithelial Tissue

Tissues that line and cover surfaces of the body.

Connective Tissue

A broad class of tissues that connect different parts of the body together, including connective tissue proper, cartilage, bone, blood, and lymph.

Muscle Tissue

A type of tissue capable of producing movement or exerting force by contracting.

Nervous Tissue

A tissue that enables rapid communication of information within the body.

Avascular

Refers to tissues, such as epithelial tissue, that do not have their own blood supply.

Stem Cells

Less specialized cells that can regenerate tissues through cell division.

Intracellular Junctions

Structures that channel cells together in tissues, including gap junctions, tight junctions, and desmosomes.

Gap Junctions

Intracellular junctions that allow movement of ions and small molecules between adjacent cells.

Tight Junctions

Intracellular junctions that create a seal between adjacent cells, preventing leakage of substances.

Desmosomes

Reinforced intracellular junctions that bind cells together and allow them to withstand stress.

Simple Epithelium

A single layer of cells that is in contact with the underlying connective tissue.

Stratified Epithelium

Multiple layers of cells, with only some in contact with the underlying connective tissue.

Cuboidal Epithelium

Epithelial tissue composed of cube-shaped cells.

Columnar Epithelium

Epithelial tissue composed of tall, column-like cells.

Transitional Epithelium

A stratified epithelium that can stretch, found in the urinary tract.

Exocrine Glands

Glands that secrete onto surfaces through ducts.

Endocrine Glands

Glands that secrete hormones directly into the bloodstream.

Merocrine Secretion

A mode of secretion where products are released via exocytosis without damaging the cell.

Apocrine Secretion

A mode of secretion where the apical portion of the cell pinches off and releases a secretion.

Holocrine Secretion

A mode of secretion where entire cells disintegrate and release their contents as secretion.

Adipose Tissue

Connective tissue primarily composed of adipocytes, serving as an energy reserve and insulation.

Reticular Connective Tissue

A type of loose connective tissue that provides a scaffold to hold together soft tissues.

Collagen Fibers

Strong protein fibers that provide tensile strength to tissues.

Elastic Fibers

Fibers that allow tissues to stretch and then return to their original length.

Fibroblasts

Cells in connective tissue that produce and maintain protein fibers.