LEARNING OBJECTIVESLEARNING OBJECTIVES

DEFINE EPITHELIAMDEFINE EPITHELIAM TYPES OF EPITHELIAMTYPES OF EPITHELIAM DEFINE GLANDDEFINE GLAND NAME PARTS OF GLANDSNAME PARTS OF GLANDS CLASSIFY GLANDSCLASSIFY GLANDS

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Definition epithelium Definition epithelium Covering epitheliumCovering epithelium; covers the surface of ; covers the surface of

organsorgans ,line cavities, ,line cavities, Glandular ;Glandular ;form secretary parts of glandsform secretary parts of glands

Classification of Epithelial Classification of Epithelial TissuesTissues

Based on: *number of layers *shape of cells

Classification Classification of Epitheliaof Epithelia

The morphology of the cells may The morphology of the cells may be be

squamous (flat), squamous (flat), cuboidal, cuboidal, oror columnar columnar when viewed in when viewed in sections taken perpendicular to the sections taken perpendicular to the basement membrane. Stratified basement membrane. Stratified epithelia are classified by the epithelia are classified by the morphology of the cells in their morphology of the cells in their superficial layer onlysuperficial layer only. In addition . In addition to these two major classes of to these two major classes of epithelia, which are further epithelia, which are further identified by identified by cellular morphologycellular morphology, , there are two other distinct there are two other distinct types: types: pseudostratified pseudostratified and and transitionaltransitional

kidneys,lungs glands

GI tract

respiratory system

epidermis of skin

mouth, esophagus, vagina, anus

ducts of male reproductive system, interlobular ducts of liver; functions: protection and secretion)

ducts of sweat glands, salivary glands, mammary glands;function: protection

Relaxed, the outermost cells become bulbous

Distended, the uppermost cells are stretched into a squamous shape

GLANDSGLANDS

GLANDSGLANDS

A STRUCTURE CAPABLE OF A STRUCTURE CAPABLE OF SYNTHESIS,STORAGE AND RELEASE SYNTHESIS,STORAGE AND RELEASE OF CHEMICAL SUBSTANCES.OF CHEMICAL SUBSTANCES.

GlandsGlands

Glands arise during fetal life from covering Glands arise during fetal life from covering epithelia by means of epithelia by means of proliferation and proliferation and invasion invasion of the epithelial cells into the of the epithelial cells into the subjacent connective tissuesubjacent connective tissue, followed by , followed by further differentiation further differentiation

epithelial cells are the major component of epithelial cells are the major component of all the glands of the bodyall the glands of the body

According to duct systemAccording to duct system

ExocrineExocrine (Gr. (Gr. exo,exo, outside, + outside, + krinein,krinein, to to separate) separate)

glands retain their connection with the glands retain their connection with the surface epithelium from which they surface epithelium from which they originated. originated.

This connection is transformed into tubular This connection is transformed into tubular ducts lined with epithelial cells through ducts lined with epithelial cells through which the glandular secretions pass to which the glandular secretions pass to reach the surface. reach the surface.

EndocrineEndocrine glands (Gr. glands (Gr. endon,endon, within, + within, + krineinkrinein) are glands whose connection with ) are glands whose connection with the surface is the surface is lostlost during developmentduring development. . These glands are therefore These glands are therefore ductlessductless, and , and their secretions are picked up and their secretions are picked up and transported to their site of action by the transported to their site of action by the bloodstreambloodstream rather than by a duct rather than by a duct system. .system. .

Parts of glandParts of gland

Exocrine glands have Exocrine glands have a a secretory portionsecretory portion,, which contains the which contains the cells responsible for cells responsible for the secretory process, the secretory process, andand

ductsducts,, which which transport the transport the secretions.secretions.

Based on number of cellsBased on number of cells

Unicellular-goblet cellUnicellular-goblet cell Multicellular -Multicellular -

Classification of multicellular glandsClassification of multicellular glands

Based on branching of ductBased on branching of duct Simple glandsSimple glands have only one unbranched have only one unbranched

duct.duct. compound glandscompound glands have ducts that have ducts that

branch repeatedly.branch repeatedly.

Number of ducts

simple compound

simple glandssimple glands Simple tubularSimple tubular Simple coiled tubularSimple coiled tubular Simple branched tubularSimple branched tubular Simple branched acinarSimple branched acinar

Compound glandsCompound glands

compound branched tubular glandscompound branched tubular glands Compound tubulo-acinar glandsCompound tubulo-acinar glands Compound acinar glandsCompound acinar glands

Simple glands can have their secretory Simple glands can have their secretory portion in the form of portion in the form of a tubulea tubule, , a coiled a coiled tubuletubule, a , a branched tubulebranched tubule, or , or an acinusan acinus, in , in which the cells organize as spherical or which the cells organize as spherical or globular units.globular units.

Compound glands can be tubular, acinar, Compound glands can be tubular, acinar, or tubuloacinar or tubuloacinar

Example of an organ which is both Example of an organ which is both exocrine and endocrine isexocrine and endocrine is

LiverLiver UterusUterus OvaryOvary TestisTestis kidneykidney

Simple tubularSimple tubular

This type of gland has This type of gland has a a single, straight single, straight tubular lumen tubular lumen into into which the secretory which the secretory products are products are dischargeddischarged

Intestinal glandsIntestinal glands

Simple coiled Simple coiled tubulartubular

Consists of a Consists of a single tube single tube that is that is tightly coiled tightly coiled in in three three dimensionsdimensions; portions of the ; portions of the gland are thus seen in gland are thus seen in various planes of section. various planes of section.

Sweat glandsSweat glands

Simple branched tubularSimple branched tubular

Each gland consists Each gland consists of several of several tubular tubular secretory portionssecretory portions

wider diameterwider diameter

Mouth , tongue and Mouth , tongue and esophagusesophagus

Simple branched acinarSimple branched acinar

Each gland consists Each gland consists of several of several secretory acini secretory acini

TheyThey empty into a empty into a single single excretory ductexcretory duct

The excretory duct is formed The excretory duct is formed by the by the stratified epithelium stratified epithelium surrounding the hair shaft. surrounding the hair shaft.

the secretory product, the secretory product, sebumsebum, , accumulates within the accumulates within the secretory cells and is secretory cells and is discharged by degeneration of discharged by degeneration of the cells. the cells.

Sebacous glandsSebacous glands

compound branched tubular compound branched tubular glandsglands

The duct system is The duct system is branched, thus defining branched, thus defining the glands as compound the glands as compound glands and the secretory glands and the secretory portions have portions have a tubular a tubular form, form,

which which is branched and is branched and coiled.coiled.Salivary glands Salivary glands

Brunner's glands of the Brunner's glands of the duodenumduodenum, ,

Compound tubulo-acinar Compound tubulo-acinar glandsglands

Have three types of Have three types of secretory units; namely secretory units; namely branched tubularbranched tubular, , branched branched acinar acinar and and branched tubular branched tubular

The submandibular salivary The submandibular salivary gland . gland .

It contains two types of It contains two types of secretory cells, secretory cells, mucus-mucus-secreting cells and serous secreting cells and serous cells.cells.

Kidney and testisKidney and testis

Compound acinar glandsCompound acinar glands Those in which the secretory Those in which the secretory

units are acinar in form and units are acinar in form and drain into a branched duct drain into a branched duct system.system.

The lined by simple cuboidal The lined by simple cuboidal epitheliumepithelium..

Mammary glandsMammary glands pancreaspancreas

BASED ON SECRETIONSBASED ON SECRETIONS

MUCUS-MUCUS- SEROUSSEROUS MIXEDMIXED

Based on how the secretory Based on how the secretory products leave the cellproducts leave the cell

merocrinemerocrine (Gr. (Gr. meros,meros, part, + part, + krineinkrinein) In ) In merocrine glands merocrine glands (eg, the pancreas(eg, the pancreas), the ), the secretory granules leave the cell by exocytosis secretory granules leave the cell by exocytosis with no loss of other cellular material.with no loss of other cellular material.

holocrineholocrine (Gr. (Gr. holos,holos, whole, + whole, + krineinkrinein). In ). In holocrine glands (holocrine glands (eg, sebaceous glands), eg, sebaceous glands), the the product of secretion is shed with the whole cell—product of secretion is shed with the whole cell—a process that involves destruction of the a process that involves destruction of the secretion-filled cells.secretion-filled cells.

apocrineapocrine (Gr. (Gr. apo,apo, away from, + away from, + krineinkrinein) gland) gland—the secretory product is discharged together —the secretory product is discharged together with parts of the apical cytoplasm. with parts of the apical cytoplasm. sweat glandssweat glands

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