We start exploring tissues, which are collections of similar cell. A combination of tissues designed to perform a specific function or cell function is called an organ. Organs that work that together to perform specific activities often with the help of accessory structures, form what we call systems. Of course, all of those systems combine to make a living organism, the human body.
I. OVERVIEW A. Just as there are many different types of cells with various functions and responsibilities, tissues come in different shapes and sizes, again with the structure dependant on the function. B. TISSUE TYPES a. Tissue is a collection of similar cells that act together to perform a function. b. Example: “Brick Layering” c. FOUR TYPES OF TISSUES 1. Epithelial 2. Connective 3. Muscle 4. Nervous C. EPITHELIAL TISSUE a. Epithelial Tissue is layers of cells that form the epidermis of the skin as well as the surface layer of mucous and serous membranes.
• The cells in this form of tissue are packed tightly together, forming a sheet that usually has no blood vessels in it.
• Classified by their shaped and arrangement. o Squamous – flat or scale-like. o Cuboidal – cubed shaped. o Columnar – column-like. o Transitional – variably shaped.
If these cells are arranged in a single layer and are all the same type, we classify them as simple.
If they are arranged in several layers, we say they are stratified, and they are named by the type of cell that is on the outer layer (such as stratified columnar).
An exception to the rule is psuedostratified columnar epithelium, which looks stratified but is not.
• The function required of the cell dictates which type of cell formation is utilized
• Example: “Simple squamous cells are utilized in the lungs”
1. Membranes are sheet-like structures found throughout the body that perform special functions (aka thin soft pliable layer of tissue that can line a cavity or cover an organ or structure).
2. Epithelial membranes posses a layer of epithelial tissue and a bottom layer of a specialized connective tissue.
3. TYPES OF EPITHELIAL MEMBRANES o Cutaneous
Functions like a tarp placed over a boat.
The main organ of the integumentary system, commonly known as your skin.
Makes up approximately 16% of the total body weight.
Skin is your largest visible organ. o Serous
A two-layered membrane with a potential space between.
Composed of the parietal and visceral layers. o Parietal
Lines the wall of the cavities in which organs reside.
Produces serous fluid, which reduces friction between different tissues and organs. o Visceral
Wraps around the individual organs.
Also produces serous fluid, which reduces friction between different tissues and organs. o Mucous
Lines openings to the outside world, such as your digestive tract, respiratory system, urinary and reproductive tracts.
Called mucous membranes because they contain specialized cells that produce mucus.
Mucus can act as a lubricant like the oil in a car.
Mucous is an adjective that describes the type of membrane that produces mucus, the actual substance.
D. CONNECTIVE TISSUES a. Connective tissue is the most common tissue and is found throughout the body more than any other form.
• That is because it is found in organs, bones, nerves, muscles, membranes, and skin.
• Connective tissues job is to “hold thing together and provide structure and support.” o Areolar Tissue are fine, delicate webs of loosely connected tissue that hold organs together and help to hold other connective tissues together. o Adipose tissue, aka fat, is also known as connective tissue.
Connective tissue can also be more densely packed and form strong cord-like structures similar to wire cables on suspension bridges.
Tendons and ligaments are composed of dense connective tissue.