Body tissues

Tissues: groups of cells closely associated that have a similar structure and perform a related function.
The tissues of the human body include four major types:-
1.Epithelial tissues.
2.Connective tissues.
3.Muscle tissues.
4.Nervous tissues.
1.Epithelial tissues :
Epithelium forms the coverings of surfaces of the body. As such, it serves many purposes, including protection, adsorption, excretion, secretion, filtration, and sensory reception.
Epithelium Characteristic
? Cells fit closely together
? Tissue layer always has one free surface
? The lower surface is bound by a basement membrane
? Avascular (have no blood supply)
? Regenerate easily if well nourished
Classification of Epithelium
? Number of cell layers
? Simple – one layer
? Stratified – more than one layer
? Shape of cells
? Squamous – flattened
? Cuboidal – cube-shaped
? Columnar – column-like
Simple Epithelium
a.Simple squamous :composed of single layer
of flattened cells with disc-shaped central nuclei.
Location
? Usually forms membranes,
? Lines ventral body cavities(serosae)
? Lines lungs and capillaries
? Kidney glomeruli
b.Simple cuboidal : composed of Single layer of cube-like cells
with large spherical centrale nuclei.
Location
? Common in glands and their ducts
? Forms walls of kidney tubules
? Covers the ovaries
c.Simple columnar: composed of tall cells,with round to oval nuclei .
Location
? Often includes goblet cells, which produce mucus
? Lines digestive tract
? Gallbladder .
d.pseudostratified : composed of Single layer, but some cells are shorter than others and Often looks like a double cell layer.
Location
? Nonciliated type in efferent ductules of epididymis .
? Ciliated in trachea and bronchi.
Stratified Epithelium
a.Stratified squamous : Cells at the free edge are flattened
Locations:
? Nonkeratinized type in
Esophagus and vagina.
? Keratinized in epidermis of skin .
b.Stratified cuboidal:composed of
2 or 3 layers of cuboidal cells.
Location :
Lining of larger ducts of
mammary glands ,sweets
glands ,salivary glands,and
pancreas .
c.Stratified columnar epithelium:found in vas deferens, part of the male urethra, parts of the pharynx (throat).
It?s function in protection and secretion
? d.Transitional epithelium: Can stretch,
and Shape of cells depends upon The amount of stretching.
Location
Lines organs of the urinary system
(bladder and urethra)