Tissue - a group or mass of similar cells working together to perform certain common functions
There are 4 major types of tissue * Epithelial * Connective * Muscle * Nervous
1. Epithelial Tissue
- Found throughout the body, covers all body surfaces both inside and out.
- Main glandular tissue.
- Attached to underlying connective tissue by noncellular nonliving basement membrane.
- Usually has no vascular tissue - blood supply
- Cells reproduce rapidly (rapid healing).
- Cells tightly packed together Functions: Protection, secretion, absorption, excretion, sensory perception
Six Specific types of epithelial tissue - categorized based on the shape of the cells and the layers of cells. ( * We won't distinguish glandular epithelium because it is of the cuboidal or columnar type.)
A. SIMPLE SQUAMOUS - single layer (simple) of very thin, flattened cells (squamous). Function: diffusion and filtration. Found in air sacs of lungs, walls of capillaries.
B. SIMPLE CUBOIDAL - single layer, cube-shaped cells. Function: Secretion and absorption. Found: Lining of kidney tubules, ducts of glands, covering surface of ovaries
C. SIMPLE COLUMNAR - single layer, elongated cells with their nuclei in about the same position in each cell (usually near the basement membrane). Protection, secretion, absorption.
Found in the lining of digestive tract and uterous
- contains scatter goblet cells functioning in the secretion of mucus
- some columnar cells (involved in absorption) have tiny finger-like processes from their free surface called microvilli (increases surface area)
D. STRATIFIED SQUAMOUS - muli-layered, squamous cells. Thicker tisse.
Functions in protection. Found lining body cavities like the mouth and outer layer of skin
E. PSEUDOSTRATIFIED COLUMNAR - appear "stratified" but really a single layer with nuclei at various levels giving the appearance of layered cells. Usually ciliated (tiny, hair-like projections for sweeping materials along a surface). Contains goblet cells.
- Function: secretion and cilia-aided movement
- Location: lining air passages like the trachea and tubes of the reproductive system
F. TRANSITIONAL EPITHELIUM - thick, layered cuboidal cells. "Stretchable" tissue, also forms barrier to block diffusion. Found: lining of urinary bladder.
2. Connective Tissue
-Most abundant tissue in your body, found throughout
-Binds structures together
-Provides support, protection, framework, fills space, stores fat, produces blood cells, fights infection, and helps repair tissue.
-Composed of more scattered cells with abundant intercellular material ' matrix
-Made up of a ground substance (fluid, semi-solid) and fibers
-Most has a good blood supply
-Cells can reproduce
Three common types of cells:
1. mast cells (prevents blood clots)
2. macrophages (phagocytic) and
3. fibroblasts (most abundant, produce fibers)
Main types of fibers:
-collagenous fibers - thick, made of protein collagen, major structural protein in the body,…