Anatomy and Physiology Chapter 4: Histology Vocabulary

Tissue

Groups of cells that are similar in structure and perform a common or related function

Histology

the study of tissues

Epithelial Tissue

A sheet of cells that covers a body surface or lines a body cavity

Apical Surface

An upper free surface exposed to the body exterior or the cavity of an internal organ

Basal Surface

Lower attached (not free)

Microvilli

Finger-like extensions of the plasma membrane

Basal Lamina

Lies adjacent to the basal surface of an epithelium and is a thin supporting sheet

Reticular Lamina

This is deep to the basal lamina; a layer of extracellular material containing a fine network of collagen protein fibers

Basement Membrane

Made up of the basal and reticular lamina

Simple Epithelium

Consists of a single cell layer

Stratified Epithelium

Composed of two or more cell layers stacked one on top of the other (common in high abrasion areas where protection is important)

Squamous Cells

Flattened and scale-like

Cuboidal Cells

Boxlike, approximately as tall as they are wide

Columnar Cells

Tall and column shaped

Endothelium

Provides a slick, friction-reducing lining in lymphatic vessels and in all hollow organs of the cardiovascular system

Mesothelium

The epithelium found in serous membranes lining the ventral body cavity and covering its organs

Simple Squamous Epithelium

Flattened laterally, and their cytoplasm is sparse

Simple Cuboidal Epithelium

Consists of a single layer of cells as tall as they are wide (look like a string of beads)

Simple Columnar Epithelium

Seen as a single layer of tall, closely packed cells, aligned liked soldiers in a row (lines the digestive track through the rectum)

Pseudostratified Columnar Epithelium

Cells vary in height; all of these cells rest on the basement membrane, but only the tallest reach the surface

Stratified Squamous Epithelium

The most widespread of the stratified epithelia; composed of several layers and is thick and well-suited for its protective role in the body

Stratified Cuboidal Epithelium

Quite rare in the body; mostly found in some ducts of the larger glands (sweat glands and mammary glands)

Stratified Columnar Epithelium

Limited distribution in the body; found in the pharynx, male urethra, and lining some glandular ducts

Transitional Epitherlium

Forms the lining of hollow urinary organs, which stretch as they fill with urine (allows greater volume of urine to flow through a tube-like organ)

Gland

Consists of one or more cells that make and secrete a particular product

Secretion

An active process; can refer either to the gland's product or process

Endocrine Glands

Eventually lose their ducts (also known as ductless glands)

Hormones

Regulatory chemicals that are secreted by exocytosis directly into the extracellular space

Exocrine Glands

Secrete their products into body surfaces or into body cavities (muscle, sweat, oil, salivary glands, the liver, the pancreas, etc.)

Unicellular Glands

Mucous cells and goblet cells

Mucin

Secreted by unicellular glands (dissolves water when secreted)

Goblet Cells

Mucin makes the top of the cell look like glass (this distortion does not occur in mucous cells)

Multicellular Exocrine Glands

More structurally complex; two basic parts are the epithelium derived duct and a secretory unit consisting of secretory cells

Mucus

Covers and protects certain areas of the body; secreted by glands

Simple Glands

Have an unbranched duct

Compound Glands

Have a branched duct

Tubular

Gland with secretory cells form tubes

Alveolar

Gland with secretory cells that form small, flask like sacs

Tubuloalveolar

Gland with secretory cells with both small flask like sacs, and tube forming secretory cells

Acinar

Used interchangeably with alveolar

Merocrine Glands

Secrete their products by exocytosis as they are produced (pancreas, most sweat glands, and salivary glands)

Holocrine Glands

Accumulate their products within them until they rupture (replaced by underlying cells once ruptured)

Apocrine Glands

Humans are not known to have this gland type (only accumulate their products just beneath the free surface and repairs itself after rupture)

Connective Tissue

Found everywhere in the body; four main types: connective tissue proper, cartilage, bone tissue, and blood

Common Origin

All connective tissues arise from mesenchyme

Degrees of Vascularity

Cartilage is avascular

Dense connective tissue is poorly vascularized

Other connective tissues have a rich supply of blood vessels

Extracellular Matrix

Consists of nonliving things; separates the living cells of the tissue

Ground Substance

Unstructured material that fills the space between the cells and contains the fibers

Collagen Fibers

Constructed primarily of the fibrous protein collagen

Elastic Fibers

Long, thin fibers that form branching networks in the extracellular matrix

Reticular Fibers

Short, fine, collage nous fibers with a slightly different chemistry and form

Fibroblast

Connective tissue proper

Chondroblast

Cartilage

Osteoblast

Bone

Hematopoietic Stem Cell

Undifferentiated blast cell that produces blood cells

White Blood Cells

(Neutrophils, eosinophils, lymphocytes) and other cells concerned with tissue response to injury

Mast Cells

Cluster along blood vessels; act as active sentinels to detect foreign microorganisms and initiate local inflammatory responses against them

Macrophages

Large, irregularly shaped cells that avidly phagocytize a broad variety of foreign materials, ranging from foreign molecules to entire bacteria to dust particles

Mesenchyme

Common embryonic tissue that mature connective tissue arises from

Loose Connective Tissue

(Areolar, adipose, and reticular)

Dense Connective Tissue

(Dense regular, dense irregular, and elastic)

Areolar Connective Tissue

Supporting and binding tissue

Holding body fluids

Defending against infection

Strong nutrients as fat

Adipose Tissue

Similar to areolar tissue in structure and function, but it's nutrient-storing ability is much higher

Adipocytes

Commonly called adipose/fat cells; account for 90% of tissue's mass

Brown Adipose Tissue

Contain abundant mitochondria, which use lipid fuels to heat up the blood stream to warm the body

Reticular Connective Tissue

Resembles areolar connective tissue, but the only fibers in its matrix are reticular fibers, which form a delicate network along which fibroblasts (reticular cells) are scattered

Fibrous Connective Tissue

What dense connective tissue is often referred to as

Dense Regular Connective Tissue

Contains closely packed bundles of collagen fibers running in the same direction, parallel to the direction of pull

Dense Irregular Connective Tissue

Has the same structural elements as the regular variety, but bundles of collagen fibers are much thicker and are arranged irregularly

Elastic Connective Tissue

(Ligamenta nuchae and flava) specific structures in dense regular connective tissue

Cartilage

Stands up to both tension and compression; tough and flexible

Hyaline Cartilage

Most abundant type of cartilage in the body; provides firm support with some pliability

Elastic Cartilage

Nearly identical to hyaline cartilage, except there are many more elastic fibers

Fibrocartilage

Perfect structural intermediate between hyaline and dense regular connective tissue; contains rows of chondrocytes that alternate with rows of thick collagen fibers

Osseous Tissue

Has an exceptional ability to support and protect body structures

Osteocytes

Mature bone cells; reside in the lacunae within the matrix they have made

Neurons

Highly specialized nerve cells that generate and conduct nerve impulses

Muscle Tissues

Highly cellular, well-vascularized that are responsible for most types of body movement

Myofilaments

Elaborate versions of the actin and myosin filaments that bring about movement or contraction in all cell types

Skeletal Muscle

Packages connective tissue sheets into organs

Muscle Fibers

Long, cylindrical cells that contain many nuclei (also called skeletal muscles)

Cardiac Muscles

Found only within the walls of the heart

Intercalated Discs

unique junctions found between cardiac muscle cells

Smooth Muscle

Cells have no visible striations

Voluntary Muscle

Skeletal muscle

Involuntary Muscle

Not conscious movement

Cutaneous Membrane

Skin

Mucous Membrane (Mucosae)

Line body cavities that open to the exterior (digestive, respiratory, and urogenital tracts)

Lamina Propria

Loose connective tissue right under the epithelial tissue

Serous membranes (serosae)

Moist membranes found in closed ventral body cavities

Regeneration

Replacement of destroyed tissue with the same kind of tissue

Fibrosis

Involves proliferation of fibrous connective tissue called scar tissue

Scar Tissue

Used in fibrosis

Blood

the fluid within blood vessels

Granulation tissue

delicate pink tissue that has capillaries growing into it; found in healing tissues