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.
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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).
It̕s 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)