What 5 characteristics are unique to epithelial tissue?
1. Polarity 2. Specialized contacts (like special junctions that connect tissue) 3. Supported by connective tissue (the retuclar lamina is the layer of fibers that hold epithelial tissue in place) 4. Avascular but innervated (no blood vessels, but has nerves) 5. Regeneration **
consist of single cell layer, tipically found where absorption, secretion, and filtration occur.
two or more cell layers stacked on top of one another, common in high-abrasion areas where protection is important such as the skin and mouth
flattened and scale-like epithelial cell
box like epithelial cell, approximately as tall as they are wide (kinda like justin)
tall and column shaped epithelial cell
most concerned with absorption, secretion, and filtration because they consist of a single cell layer and are very thin. These DO NOT provide much protection
Simple squamous epithelium
Single layer of flattened cell with disc-shaped central nuclei and sparse cytoplasm. This allows materials to pass by and diffuse through them.
Where is simple squamous epithelial tissue usually found?
Kidney glomeruli, air sacs of the lungs, lining of the heart, blood vessels, lymphatic vessels, lining of ventral body cavity.
provides a slick, friction-reducing lining in lymphatic vessels and in all hollow organs of the cardiovascular system.
is the epithelial tissue found in serous membranes lining the ventral body cavity and covering its organs.
Simple cuboidal epithelium
consist of a single layer of cells as tall as they are wide. Typically functions to secrete and absorb.
Where is simple cuboidal epithelium usually found?
kidney tubules, ducts and secretory portions of small glands, and ovary surface.
Simple columnar epithelium
seen as a single layer of tall closely packed cells, some of which have cilia and may have a layer containing mucus secreting unicellular glands known as goblet cells
Mucus secreting unicellular glands
Where is simple columnar epithelium usually found?
digestive tract, gallbladder, excretory ducts of some glands, small bronchi, uterine tubes, and some regions of the uterus.
Pseudostratified columnar epithelium
single layer of cells of differing heights, some not reaching the free surface. Functions include secretion of mucus and propulsion of mucus by ciliary action.
Where is pseudostratified columnar epithelium found/
Male-sperm carrying ducts, ducts of large glands, trachea, and upper respiratory tract.
two or more cells layers, considered more durable than simple epithelia, and protection is a key role.
stratified squamous epithelium
Thick membrane composed of several layers, the surface of the tissue is squamous and are full of keratin.
Where is stratified squamous epithelium found/
Esophagus, mouth, and vagina, epidermis of the skin, and dry membranes.
Resembles both stratified and squamous and stratified squamous cells, have the ability to stretch and distend. (these are in the bladder and ureters and parts of the urethra)
consists of one or more cells that make and secrete a particular product or secretion
an aqueous fluid that usually contains proteins, however some glands release a lipid or steroid-rich secretion
often times loose their ducts are are also known as ductless glands. They produce hormones and regulatory chemicals that are exocytosed into the extracellular space.
Secrete their products onto body surfaces like the skin or into body cavities. This includes mucous, sweat, oil, and saliva
What are the two unicellular exocrine glands?
Mucous cells and goblet cells
Multicellular exocrine glands
structurally more complex than unicellular. They have two basic parts: a ducts and a seceratory unit consisting of secretory cells.
multicellular exocrine glands that have an unbranched duct
multicellular exocrine gland that have a branched duct
multicellular exocrine gland secrete their products by exocytosis as they are produced. Generally pancreatic, sweat and salivary glands belong to this type.
multicellular exocrine glands that accumilate their product within them until they rupture which releases their secretion. A good example of this is the sebaceous (oil) glands of the skin.
How are multicellular glands classified?
according to their duct type.
the most abundant and widely distributed of the primary tissues.
Four types of connective tissue
connective tissue proper, cartilage, bone tissue, and BLOOD
Is blood a tissue?
YES, blood is a connective tissue (I know this sounds weird, but it is)
Three main characteristics of connective tissue
ground substance, fibers and cells
What is ground substance?
One of the characteristics of connective tissue that fills the space between the cells and contains fibers. It holds large amounts of fluid and functions as a molecular medium through which nutrients and other things diffuse between blood capillaries and the cell
What are fibers (connective tissue)?
Another characteristic of connective tissue which provide support
What are the three types of fibers in connective tissue?
Collagen, Elastic, and Reticular fibers
What are collagen fibers?
These are cross-linked fibers that are incredibly strong and provide tissue strength?
What are elastic fibers?
Long and thin fibers that form branching networks in the matrix. They contain a protein called elastin which allows the fobers to stretch and recoil like rubber bands. These fibers are found where the tissue is constantly expanding like the skin, lungs, and blood vessels.
What are reticular fibers/
short fine fibers that are collagen fibers, and they surround small blood vessels and support the soft tissue of organs. This is kind of a mixture of collagen and elastic fibers.
Where does mature connective tissue arise from?
From common embryonic tissue called mesenchyme?
What is mesenchyme?
This is a fluid ground substance containing fine sparse fibers and star-shaped mesenchymal cells. These arise during the early weeks of embryonic development and eventually become different types of connective tissue.
Connective tissue proper
has two subclasses: the loose connective tissues and dense connective tissue. exept for bone, cartilage, and blood, all mature connective tissues belong to this class?
Areolar connective tissue
Wraps and cushions organs; its macrophages eat bacterial plays an important role in inflammation and holds and conveys tissue fluid. Found widely distributed under epithelia of the body
Adipose connective tissue
Provide reserve food fuel, insulates against heat loss, and supports and protects organs. ADIPOSE TISSUE = FAT TISSUE.
Reticular connective tissue
fibers form a soft internal skeleton that supports other cell types including white blood cells, mast cells, and macrophages, found in the lymphoid organs
Dense regular connective tissue
Attaches muscles to bones or to muscles and even attaches bone to bone and can withstand a lot of force in one direction. These are in tendons and ligaments
Dense irregular connective tissue
Able to withstand tension exerted in many directions, these are found normall in joints and the digestive system
Elastic connective tissue
Allows recoil of tissues following stretching and maintaines pulsatile flow of blood through arteries, found in the walls of large arteries and within the vertebral column
Supports and reinforces, very resilient cushioning properties and can resist compression stress.. Found in the rib cage
Maintains the shape of a structure, found in the ear
tensile strength with the ability to absorb compressive shock, found in the intervertebral discs and discs of the knee
ALSO KNOWN AS BONE. Supports nad protects the body, provides levers for the muscles to act on and stores calcium and minerals for the body.
remember this is considered connective tissue, the fibers within blood are soluble protein molecules that dissolve.