Tissue

Tissue

A group of similar cells and their extracellular matrix working together to perform a common function.

Matrix (extracellular matrix)

Nonliving material surrounding cells, consisting of ground substance and fibers.

Epithelial tissue

Tissue that covers body surfaces, lines cavities, and forms glands.

Connective tissue

Tissue that supports, binds, protects, and transports materials.

Nervous tissue

Tissue specialized for communication through electrical signals.

Muscular tissue

Tissue specialized for contraction and movement.

Fixation

Preservation of tissue to prevent decomposition and maintain structure.

Embedding

Infiltrating tissue with paraffin or resin to make it firm enough to cut.

Sectioning

Cutting thin slices of tissue for microscopic examination.

Staining

Applying dyes to tissue to improve visibility and contrast.

Mounting

Placing a tissue section on a slide with a coverslip.

Basement membrane

Thin layer that anchors epithelium to underlying connective tissue.

Basal surface

Side of the cell that faces the basement membrane

Apical surface

Side of the cell that faces away from the basement membrane

Pseudostratified epithelium

Epithelium that appears multilayered but all cells contact the basement membrane.

Cartilage

Firm, flexible connective tissue that supports and cushions structures.

Chondroblast

Immature cartilage-forming cell.

Lacuna

Small cavity in cartilage or bone that houses a mature cell.

Chondrocyte

Mature cartilage cell located in a lacuna.

Perichondrium

Connective tissue layer surrounding cartilage.

Osseous tissue

Bone tissue.

Spongy bone

Porous inner bone composed of trabeculae.

Compact bone

Dense outer layer of bone organized into osteons.

Lamella

Concentric layer of mineralized bone matrix.

Osteon

The basic structural unit of compact bone (Haversian system).

Osteocyte

Mature bone cell located in a lacuna.

Canaliculus

Microscopic channel connecting osteocytes.

Periosteum

Fibrous membrane covering the outer surface of bone.

Blood plasma

Liquid extracellular matrix of blood.

Formed elements

Cellular components of blood: erythrocytes, leukocytes, and platelets.

Erythrocyte

Red blood cell responsible for oxygen transport.

Leukocyte

White blood cell involved in immune defense.

Platelets

Cell fragments that function in blood clotting.

Neuron

Functional nerve cell that transmits electrical impulses.

Glial cell

Support cell that protects and nourishes neurons.

Soma

The cell body of a neuron.

Dendrite

Neuron process that receives incoming signals.

Axon

Neuron process that carries signals away from the cell body.

Sphincter

Circular muscle that closes or constricts an opening.

Striations

Alternating light and dark bands seen in skeletal and cardiac muscle.

Gland

Epithelial structure specialized for secretion.

Secretion

Useful substance released by a gland.

Excretion

Removal of waste products from the body.

Exocrine gland

Gland that secretes through ducts onto a surface or into a lumen.

Endocrine gland

Ductless gland that secretes hormones into the bloodstream.

Unicellular gland

A single secretory cell, such as a goblet cell.

Capsule

Outer connective tissue covering of an organ or gland.

Septa (trabeculae)

Connective tissue partitions extending inward from a capsule.

Lobes

Large subdivisions of a gland or organ.

Lobules

Smaller subdivisions within a lobe.

Stroma

Supporting connective tissue framework of an organ.

Parenchyma

Functional tissue of an organ.

Serous glands

Glands that secrete watery, enzyme-rich fluid.

Mucous glands

Glands that secrete thick mucus.

Mixed glands

Glands containing both serous and mucous secretory cells.

Cytogenic glands

Glands that release whole cells rather than fluid secretions.

Merocrine (eccrine) glands

Glands that release products by exocytosis with no loss of cell material.

Apocrine glands

Glands that release products with a portion of the cell membrane and cytoplasm.

Holocrine glands

Glands that release products by rupture of the entire cell.

Cutaneous membrane

The skin.

Mucous membrane (mucosa)

Membrane lining body passages open to the exterior.

Serous membrane (serosa)

Membrane lining closed body cavities and covering organs.

Synovial membrane

Membrane lining freely movable joints.

Synovial fluid

Lubricating fluid produced by synovial membranes.

Lamina propria

Connective tissue layer underlying the epithelium of a mucous membrane.

Muscularis mucosae

Thin layer of smooth muscle associated with mucous membranes.

Mesothelium

Simple squamous epithelium that forms serous membranes.

Endothelium

Simple squamous epithelium lining blood vessels and the heart.

Tunica interna (tunica intima)

Innermost layer of a blood vessel.

Endocardium

Inner lining of the heart chambers.

Serous fluid

Lubricating fluid found between visceral and parietal serous membranes.

Hyperplasia

Increase in the number of cells.

Hypertrophy

Increase in the size of cells.

Neoplasia

Abnormal uncontrolled growth of new cells resulting in a tumor.

Metaplasia

Replacement of one mature cell type by another mature cell type.

Regeneration

Replacement of damaged tissue with the same type of functional tissue.

Fibrosis

Replacement of damaged tissue with scar (connective) tissue.

Atrophy

Decrease in the size or mass of a tissue or organ.

Necrosis

Uncontrolled pathological cell death caused by injury or disease.

Infarction

Death of tissue due to loss of blood supply.

Myocardial infarction

Death of heart muscle due to blocked blood supply; a heart attack.

Cerebral infarction

Death of brain tissue due to blocked blood supply; an ischemic stroke.

Dry gangrene

Tissue death with drying and shriveling, usually without bacterial infection.

Wet gangrene

Tissue death with bacterial infection, causing swelling and moisture.

Apoptosis

Programmed, controlled cell death that is a normal physiological process.