Hole's Anatomy Ch 5 Tissues

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tissue
composed of several cells that work together to perform a common function. These cells are similar in structure.
histology
study of tissues
25
Approximate number of kinds of tissues that compose the body
4 primary types of tissues
1. epithelial tissue (protection) 2. connective tissue (support), 3. muscle tissue (movement) 4. nervous tissue (control)
organ
a collection of tissues that carry out a specialized function of the body
human development
begins with a single cell which is the fertilized egg. this cell rapidly divides, producing many identical smaller cells. The first tissues begin to appear when these cells organize into the three primary germ layers.
primary germ layers
cell layers that give rise to all body organs and systems. 1. ectoderm, 2. mesoderm, 3. endoderm
ectoderm
outermost layer. Develops into nervous tissue and the epidermis.
mesoderm
middle layer. develops into the dermis, muscle, bone and blood related organs (vessels, spleen)
endoderm
innermost layer. develops into the mucous membranes of the digestive and respiratory tracts as well as digestive glands and some urinary organs.
3
Most organs are derived from how many primary germ layers?
epithelial tissue
1. Covering and lining epithelium covers and lines every internal and external body surface. 2. Glandular epithelium forms glands.
5 functions of epithelial tissue
1. Protection, 2. absorption, 3. filtration, 4. excretion, 5. secretion
epithelial tissue: protection
keeps from physical and chemical injury, and from invasion by micro-organisms.
epithelial tissue: absorption
the taking in of nutrients for underlying tissues.
epithelial tissues: filtration
traps unwanted particles from reaching underlying tissues.
epithelial tissues: excretion
removal of wastes from underlying tissues
epithelial tissues: secretion
production and release of materials from glands
Characteristics shared by all types of epithelium
1. Composed of cells found close together (very little tissue fluid ound between them) 2. Cells fit tight together (held together by tight junctionsand desmosomes to form an uninterrupted layer of cells that lines nearly every external and internal body surface. 3. Always has ONE surface exposed to the exterior of the body or to the internal surface of a body cavity or organ. 4. basal surface 5. avascular, 6. well supplied with nerve fibers, 7.regenerate rapidly by mitosis.
apical surface
Free surface. 1. May be smooth and slick. 2. May have microvilli or cilia attahed.
mirovilli
fingerlike extensions of the plasma membrane; function to increase surface area.
cilia
hair'like extenson; function to move substances along cell surfaces.
lower surface/basal surface
attached to underlying tissues by a basement membrane. The basement membrane supports the epithelium and it separates epithelia tissue from connective tissue.
basal surface is compsed of what?
1. basal lamina, 2. reticula lamina
basal lamina
a thin, nonliving adhesive materal (mainly glycoprotein) produced and secreted by epithelial cells lying above it. Made by epithelial cells.
reticular lamina
an extracellular substance (containing fine collagen fibers) secreted by connective tissue cells (fibroblasts) below the basal lamina. Made by connective tissue cells.
avascular
without blood vessels. No blood supply. Epithelial tissue must recieve nutrients by diffusion from underlying connective tissues.
2 ways epithelium is classified
1. cell shape (shape of nucleus is important for identification purposes) , 2. number of layered
epithelium classification by shape:
1. squamous, 2. cuboidal, 3. columnar
squamous
flat, scale like cells. Nucleus is thin and flat.
cuboidal
box shaped. Nucleus is round and centrally located
columnar
Tall cells. Nucleus is oval and usually located near the base of the cell.
epithelium classified by number of cell layers
1. simple, 2. stratified, 3. pseudostratified
cell layers: simple
One cell layer. Common in locations where absorption and filtration take place. Ex. cappilaries; the very smallest of blood vessels.
cell layers: stratified
Many cell layers. Common in areas subject to abrasion. Where protection is important.
cell layers: pseudostratified
False cell laers. Composed of a single cell layer. All of the cells are columnar cells, and all sit on the basement membrane. However, not every cell reaches the apical surface.
4 classes of simple epithelium
1. simple squamous, 2. simple columnar, 3. simple cuboidal, 4. pseudostratified
4 classes of stratified epithelium
1. stratified squamous, 2. stratified cuboidal, 3. stratified columnar, 4. transitional ( a modified stratified squamous epithelium)
simple epithelial tissue
(single layer) Tissues in a single layer.
simple squamous
Very thin layer of cells. The most delicate type of epithelium. Function: filtration, diffurion, and absorption. 2 types: endothelium and mesothelium
endothelium
lines blood bessel walls, lymph vessels and the interior of the heart.
mesthelium
covers the viscera of the ventral cavity. Lines this cavity.
simple cuboidal
Single layer of cuboid (box) cells. May have microvilli on their apical surface, depending on location. Functions: absorption and excretion.
simple columnar
Single layer of tall cells. May have cilia or microvilli on their surface depending on ocation. In some areas of the body this tissue may have scagtered goblet cells. Functions: secretion and absorption.
goblet cells
single celled glands that function to secrete mucin.
pseudostratified
Single layer of cells with nuclei located at 2 or more distinct levels. This gives the tissue a layered look. All cells rest or sit on the basement membrane. However, all do not reach the exposed (or apical) surface. Cells at the apical surface may or may not have cilia. Depending on location, may contain goblet cells. Function: secretion and protection.
lumen
the inside of any tube
karatin
Water repellant protein as cells get close to the apical surface, the accumulate karatin and begin to die. These cells will be shed from the surface.
exfoliation
separation of dead cells from the apical surface. These cells are replaced by mitosis of cells in the basal layer.