BYMAYUR CHAKRABORTY

ASSISTANT PROFESSOR, BENGAL SCHOOL OF TECHNOLOGY,

HOOGHLY

a group of cells specialized to perform a a group of cells specialized to perform a particular functionparticular function

tissue = cells + extracellular matrixtissue = cells + extracellular matrix– nonliving portion of a tissue that supports cellsnonliving portion of a tissue that supports cells

There are 5 types of tissuesThere are 5 types of tissues– Epithelial tissues give protection, allow secretion Epithelial tissues give protection, allow secretion

and absorptionand absorption– Connective tissues support soft body parts and bind Connective tissues support soft body parts and bind

structures togetherstructures together– Muscle allow movementMuscle allow movement– nervous tissues conducts impulses used to help nervous tissues conducts impulses used to help

control and coordinate body activitiescontrol and coordinate body activities– Bone tissues forms structural unit of the bodyBone tissues forms structural unit of the body

Simple = one layer

Stratified = more than one layer

Pseudostratified = false layered (appears to be more than one

layer, but only one); ciliated = with cilia

Terms referring to the cell shapes Squamous = flat

Cuboidal = cube

Columnar = rectangular (column)

Transitional = ability to change shape

Stratified

Simple

Apical surface

Basal surface

Apical surface

Basal surface

Classification based on number of cell layers.

Squamous

Cuboidal

ColumnarClassification based on cell shape.

The following types of epithelial tissues are covered in this activity:

1. Simple squamous epithelial tissue (lungs)

2. Simple cuboidal epithelial tissue (kidneys)

3. Simple columnar epithelial tissue (small intestine)

4. Pseudostratified (ciliated) columnar epithelial tissue (trachea lining)

5. Stratified squamous epithelial tissue (mouth lining)

6. Stratified cuboidal epithelial tissue (salivary glands, sweat glands)

7. Stratified columnar epithelial tissue (male reproductive tract)

8 Transitional epithelial tissue (bladder)

a. The tissue may show a full bladder

b. The tissue may show an empty bladder

a single layer of a single layer of thin, flattened cellsthin, flattened cells– look like a fried egglook like a fried egg

easily damagedeasily damaged common at sites of common at sites of

filtration, diffusion, filtration, diffusion, osmosis; cover osmosis; cover surfacessurfaces

air sacs of the air sacs of the lungs, walls of lungs, walls of capillaries, linings capillaries, linings of blood and lymph of blood and lymph vesselsvessels

• Description: Single layer of

cubelike cells with large,

spherical central nuclei

Function: Secretion and

Absorption

single layer of cells single layer of cells that are longer than that are longer than they are widethey are wide– nucleus located near nucleus located near

basement mem.basement mem. ciliated or nonciliatedciliated or nonciliated some have microvillisome have microvilli goblet cells = goblet cells =

secrete mucussecrete mucus absorption, absorption,

secretion, protectionsecretion, protection linings of the uterus, linings of the uterus,

stomach, and stomach, and intestineintestine

• Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia.

• Function: Secretion, particularly of mucus; propulsion of mucus by ciliary action

Description: Thick membranecomposed of several cell layers;basal cells are cuboidal or

columnarand metabolically active; surfacecells are flattened (squamous);

in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers

Function: Protects underlying

tissues in areas subjected to abrasion

Stratified Stratified cuboidal cuboidal

epitheliumepithelium 2 or 3 layers of 2 or 3 layers of

cuboidal cellscuboidal cells protectionprotection linings of larger linings of larger

ducts of ducts of mammary glands, mammary glands, sweat glands, sweat glands, salivary glands, salivary glands, and pancreasand pancreas

Stratified Stratified columnar columnar

epitheliumepithelium protection and protection and

secretionsecretion vas deferens, vas deferens,

part of the male part of the male urethra, parts of urethra, parts of the pharynx the pharynx (throat)(throat)

Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamous like, depending on degree of organ stretch.

Function: Stretches readily and permits distension of urinary organ by contained urine

cells that are specialized to produce cells that are specialized to produce and secrete substances into ducts or and secrete substances into ducts or into body fluidsinto body fluids

gland = 1 or more cuboidal or gland = 1 or more cuboidal or columnar cellcolumnar cell

secretionsecretion salivary glands, sweat glands, salivary glands, sweat glands,

endocrine glandsendocrine glands

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