by Allyson Farmer
What is a tissue?
A tissue is a collection of specialized cells and cell products that perform a relatively limited number of functions.
What are the four types of tissues?
Epithelial, Connective, Muscle, and Neural (Nervous).
Epithelial tissues - are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.
Connective tissues - bind structures together, form a framework and support for organs and the body as a whole, store fat, transport substances, protect against disease, and help repair tissue damage. They occur throughout the body. Connective tissues are characterized by an abundance of intercellular matrix with relatively few cells. Their cells are able to reproduce but not as rapidly as epithelial cells. Most connective tissues have a good blood supply but some do not.
Muscle tissue- is composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts. The tissue is highly cellular and is well supplied with blood vessels. The cells are long and slender so they are sometimes called muscle fibers, and these are usually arranged in bundles or layers that are surrounded by connective tissue. Actin and myosin are contractile proteins in muscle tissue.
Neural tissue- is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning. To do all these things, cells in neural tissue need to be able to communicate with each other by way of electrical nerve impulses.
Epithelia- squamous, cuboidal, simple,pseudostratified, stratified, and columnar.
Connective- Connective tissue proper, Fluid connective tissues, and Supporting connective tissues.
Muscle- Cardiac muscle tissue, Skeletal muscle tissue, and Smooth muscle tissue
Neural- Unipolar neuron, Bipolar neuron, and Multipolar neuron.
Specializations of Epithelia
1. The movement of fluids over the epithelial surface, providing protection and lubrication.
2. The movement of fluids through the epithelium, to control permeability.
3.The production of secretions that provide physical protection or act as chemical messengers.
Where these tissues can be found
Epithelial- Outer layer of skin, lining of lungs, kidney tubules, and inner surfaces of the digestive system.
Connective- outer covering of blood vessels, skeleton, cartilage, tendons, ligaments, and around kidneys, hearts, and eyes.
Muscle- walls of the heart, walls of hollow visceral organs, and attached to the skeleton.
Neural- spinal cord, brain. eyes, ears, and peripheral nerves.