Tissue: The Living Fabric

Connective Tissue

Connective tissue is found everywhere in the body.  

Each epithelium is given two names. First name indicates the number of cell layers present, and the second describes the shape of its cells. There could be; simple epithelia (single cell layer) typically found where absorption and filtration occur, stratified epithelia (two or more cell layers stacked on top of one another) commonly found in high-abrasion areas where protection is important like the skin surface and the lining of the mouth. Epithelial cells have six irregular sides that looks like a honeycomb. There are three common shapes of epithelial cells; squamous cells are flattened and scalelike their nucleus are flattened disc, cuboidal cells are boxlike approximately as tall as they are wide with a nucleus that is spherical, and columnar cells are tall and column shaped their nucleus is elongated from top to bottom and located towards the cell base.

Simple Squamous Epithelium
Function: allows passage of materials by diffusion and filtration in sites where protection is not important
Location: air sacs of lungs. lining of heart, blood vessels, lymphatic vessels
Two simple squamous epithelia in the body have special names that reflect their location. Endothelium "inner covering" and the Mesothelium "middle covering."

Simple Cuboidal Epithelium 
Function: secretion and absorption
Location: kidney tubules, ducts and secretory portions of small glands, ovary surface

Simple Columnar Epithelium
Function: absorption, secretion of mucus, enzymes, and other substances
Location: nonciliated type lines most of the digestive track (stomach to anal canal), gallbladder, and some regions of the uterus

Stratified Squamous Epithelium
Function: protects  underlying tissue in areas subjected to abrasion
Location: epidermis of the skin, lining of the esophagus, mouth, and vagina.

Stratified Cuboidal Epithelium
Location: quite rare in the body, mostly found in the ducts of some of the larger glands like the sweat and mammary glands with typically two layers of cuboidal cells

Stratified Columnar Epithelium
Location: rare in the body but small amounts found in the pharynx, the male urethra, and the lining some glandular ducts

Pseudostratified Columnar Epithelium
Function: secretion, particularly of mucus, propulsion of mucus by ciliary action.
Location: nonciliated type in males sperm-carrying ducts and ducts of large glands, lines the trachea, and most of the upper respiratory tract. The cell nuclei lie at different levels above the basement membrane, but only the tallest reach the free surface of the epithelium.

Transitional Epithelium 
Function: stretches readily and permits distension of urinary organ by contained urine.
Location: lines the ureters, bladder, and part of the urethra
The ability of transitional cells to change their shape or undergo "transitions" allows a greater volume of urine to flow through.

Muscle Tissue
Muscle tissues are highly cellular, well-vascularized tissues that are responsible for most types of body movement.

Skeletal Muscle
Function: voluntary movement, locomotion, manipulation of the environment, facial expression, voluntary control.
Location: in skeletal muscles attached to bones or occasionally to skin

Cardiac Muscle
Function: as it contracts, it propels blood into the circulation, involuntary control
Location: the walls of the heart

Smooth Muscle
Function: propels substances or objects (foodstuffs, urine, a baby) along internal passageways, involuntary control
Location: mostly in the walls of hollow organs

Nervous Tissue
Function: transmit electrical signals form sensory receptors and to effectors (muscles and glands) with control their activity
Location: brain, spinal cord, and nerves
The main component of the nervous system the brain, spinal cord, and nerves which regulates and controls body functions. Containing two major cell types.