A tissue is...
is any of the distinct types of material of which animals or plants are made, consisting of specialized cells and their products.
Four Types of Tissues
- Connective tissue
- Muscle Tissue
- Nerve Tissue
~The cells are tightly packed, which allows epithelial tissue to function to form linings or coverings.
~Connective tissues perform a variety of functions including support and protection.
~Skeletal muscle is a voluntary type of muscle tissue that is used in the contraction of skeletal parts. Smooth muscle is found in the walls of internal organs and blood vessels. It is an involuntary type. The cardiac muscle is found only in the walls of the heart and is involuntary in nature.
~composed of specialized cells which not only receive stimuli but also conduct impulses to and from all parts of the body.
Classifcations of tissues
- Squamous – Cells are flat or shield-like.
- Cuboidal – The cells have the same height as width. They appear box-like. The nucleus is spherical and found in the center of the cell.
- Columnar – The cells are taller than wide. The nucleus is oval and tends to be found near the bottom of the cell. The apical surface of columnar epithelial cells often shows the presence of microvilli and cilia.
- Transitional epithelium – The appearance of transitional epithelial cells will vary with distension of the urinary organ which they line. When stretching is minimal, the cells appear full or balloon-like. When the organ is distended, the epithelium becomes flattened
Connective tissues are made up of many types of specialized cells.Connective tissues contain a large amount of non-living material referred to as the matrix (composed of ground substance and fibers). Typically, this material is manufactured and secreted by the cells of the specific connective tissues.
Muscle tissues color is a red or white color. It's appearance is Cardiac, Smooth, and Striated.
Nerve tissue conducts signals from body parts through the spinal cord to the brain. The brain also sends signals back to all body parts.
Specializations of Epithelial tissues
Several specializations of epithelial cells found on their free or exposed surface include the brush or striated border of the absorbing cells of the intestine and kidney, motile cilia of the pseudostratified epithelium of the respiratory system, and non-motile stereocilia of the pseudostratified epithelium lining the epididymis.
Where to find these 4 types of cells
Occurring in sheets of tightly packed cells. Covers the outside of the body,and lines organs and cavities of the body. In most cases the cells are held together by tight junctions. The cells are attached to a basal membrane.
Functions mainly to bind and support other tissues. They contain a sparse population of cells surrounded by a nonliving matrix. This matrix can be fibrous, liquid or jellylike.
Composed of long contractile cells. The cells are composed of long microfilaments made of the proteins actin and myosin. There are 3 types of muscle tissue: Striated or skeletal, cardiac, and visceral or smooth.
4. Nervous Tissue- Senses stimuli and sends signals from one part of the body to another. The cells are called neurons. The neuron consists of a cyton ( cell body), dendrites (many branches that carry impulses to the cyton), and an axon (long filament that carries impulses away from the cell).