BIOL2311 Histology

Epithelial

A body tissue that covers the surfaces of the body, inside and out

simple squamous epithelial tissue

flattened cells provided a short path length for rapid diffusion.

simple cuboidal epithelial tissue

cuboidal cells allow relatively short path length for passive transport, but increase cellular machinery allows for active absorption and secretion.

simple columnar epithelial tissue

two types, ciliated and non ciliated. Non ciliated has convoluted apical surface to increase surface area for absorption and secretion. Ciliated has specialized membrane bound organs lining the apical surface called cilia allowing for movement of material parallel to surface.

stratified squamous epithelium

Function: protects underlying tissues in areas subject to abrasion. Location: nonkeratinized type forms the moist lining of the esophagus, mouth, and vagina; keratinized type forms the epidermis of the skin, a dry membrane.

stratified cuboidal epithelium

Function: protection and transport of secretion. Location: Largest ducts of sweat glands, mammary glands, and salivary glands.

stratified columnar epithelium

Function: protection and secretion. Location: rare in the body; small amounts in male urethra and in large ducts of some glands

pseudostratified columnar epithelium

Function: secretion and propulsion of mucus. Location: ciliated found in trachea, non ciliated found in male ejaculatory ducts.

Transitional epithelial

Location: Urinary Bladder. Function: Stretches and permits dissension of urinary organ by contained urine

connective tissue

A body tissue that provides support for the body and connects all of its parts

areolar connective tissue (fascia)

Function: wraps and cushions organs; least specialized; contains mostly fibroblast, macrophages, mast cells, and some while blood cells. Location: widely distributed under epithelia of body

adipose connective tissue

Function: provides reserve fuel; insulates against heat loss; supports and protects organs. Location: under skin, around kidneys and eyeballs, within abdomen, in breasts.

reticular connective tissue

Function: supports soft structures of lymphoid organs. Location: walls of liver and spleen

dense connective tissue

protein fibers are arranged in dense bundles

dense regular connective tissue

Function: attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Location: tendons, most ligaments, aponeuroses

Dense irregular connective tissue

Function: able to withstand tension exerted in many directions; provides structural strength. Location: fibrous capsules of organs and joints; dermis of the skin; submucosa of digestive tract

Supporting connective tissue

cartilage and bone

Cartilage

A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together.

hyaline cartilage

Function: cushioning, support, reinforcement. Location: found on the ends of long bones, ribs, trachea, matrix relatively uniform

Elastic cartilage

cartilage with abundant elastic fibers; more flexible than hyaline cartilage (ear)

Fibrous Cartilage

more collagen fibers for high tensile strength and shock absorption; found in intervertebral disks and knee joint. Matrix; contains many parallel collagen fibers.

Bone

Dense, hard connective tissue composing the skeleton

Osseous Connective Tissue

Support and protection of internal organs. Found in bones in both compact and spongy form.

Fluid connective tissue

blood and lymph

blood

Connective tissue made of plasma, erythrocytes, leukocytes, and platelets.

lymph

lymphocytes found within a fluid matrix containing small amounts of dissolved proteins.

Primary muscle

long slender cells containing contractlie protein actin and myosin. . Function: movement of both skeletal elements and of material within hollow organs

skeletal muscle

long, multinucleated cells with obvious striations found in all skeletal muscles to provide voluntary movement

Smooth muscle

spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets. found in walls of all body organs, blood vessels and function to propel substances along internal passageways; involuntary movement.

cardiac muscle

appears striated, branched and uninucleated; found only in heart.

nervous tissue

A body tissue that carries electrical messages back and forth between the brain and every other part of the body.

lacunae

spaces which chondrocytes resides

chrondrocytes

Cartilage cells found in the spaces called lucunae

collagen

structural protein found in the skin and connective tissue

elastin

protein base similar to collagen that forms elastic tissue

reticulin

* Found in tissues where a network of overlapping fibers is necessary.
* Subunits form fine, heavily-branched strands.
* Functions to create a sieve-like net structure to trap debris or to support other tissues where strength is unnecessary.

elastic connective tissue

Function: allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: walls of large arteries; within certain ligaments associated with vertebral column, within the walls of the bronchial tubes

characteristics of epithelial tissue

polarity, specialized contracts, basement membrane, avascular, regenerative

polarity

sheets of epithelia always have an apical surface, facing the external or internal space, and a basal surface, facing the underlying connective tissue

specialized contracts

cells are joined together via specialized junctions to form sheets

basement membrane

forms from a basal lamina (epithelial cells) and reticular lamina (connective tissue)

avascular

epithelia do not have direct blood supply, but are supplied nutrients via blood supply of the underlying connective tissue

Regenerative

epithelial cells will readily divide and regenerate the epithelium. This is especially important for epithelia that form protective layers since they are often damage though friction or chemicals.

mesenchyme

embryonic connective tissue; gel like ground substance and fibers; give rise to other connective tissue types; found in embryo