Will Stephan Pass Bio 33?

Okay, kids...today,tissue is the issue.

There are two main types of tissues that we will discuss today (sorry muscle and nervous..you just don't rate!) These types are Epithelial and Connective.

Epithelial has you covered. Specifically, it covers your external body (epidermis),lines cavities and tubules, separates our insides from our outsides. The epithelium protects, absorbs, filters, excretes and secretes,and recieves the senses.
The two main types of epithelial tissue are:

1. Simple (just one layer)
2. Stratified (two or more layers)

For simple epithelia, we have four categories, named according to shape:

1. Squamous (think "squashed")
2. Cuboidal (cubelike)

3. Columnar (column-shaped)

4. Pseudostratified which LOOKS like more than one layer of cells, but it's just cells of all different heights with nuclei at various heights,also.


For stratified epithelia, it's pretty much just multi-layered versions of categories one through three, with the fourth type being Transitional epithetlium. It's a stratified squamous, but the cells are rounded. They can slide over each other to allow the organ to stretchhhhhh. The cells flatten out when the organ is full. It goes from 6 layers when empty to just three when it is full(perhaps after a drinking binge).

Stratified squamous
Stratified cuboidal
Transitional


Next up,is connective tissue. If epithelial tissue has you covered, connective tissue holds it all together. As its name implies,in connects body parts. The four main functions it has,though, are:

1)binding and supporting
2)protecting
3)insulating
4)transporting substances (in the case of blood)

The four main categories of connective tissue are:

1)connective tissue proper
2)cartilage
3)bone tissue
4)blood

All connective tissues develop from an embryonic tissue called mesenchyme and feature something called an extracelluar matrix, which is the nonliving material found between the cells of the tissue, which give it its strength. All connective tissue has the same three structural elements: ground substance,fibers, and cells.
Ground substance fills the space between cells and contains the fibers. It,in turn, is composed of tissue fluid, cell adhesion proteins(the glue that holds cells to matrix) and proteoglycans(the protein core).The ground substance holds fluids and acts like a sieve which lets nutrients go through between cells and blood capillaries.
Fibers provide support. The three types are:the strong collagen, the rubbery elastic, and the fine reticular.
Cells are a blast. Fibroblast for connective tissue proper, chondroblast for cartilage, osteoblast for bone, and hematopoietic stem for blood.All of these blasted cells make ground substabce and fibers for their matrix.
Connective tissue proper comes in two flavors: loose and dense.
Cartilage is tough and flexible, and has three varieties: hyaline,
elastic, and fibro.

Bone is rocklike and can support and protect like nobody's business.It also provides fat storage and blood cells synthesis.

Blood is the black sheep of the connective tissue family, neither connecting things nor supporting them(boo,hiss). Blood does the transporting for the cardiovascular system, and gets to stay in the family because it develops from the mesenchyme and consists of (blood) cells in a non-living matrix(blood plasma).

(all pics from the JayDoc Histoweb)
http://www.kumc.edu/instruction/medicine/anatomy/histoweb/index.htm