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Dr. Dina A. A. Hassan

Associate Professor

College of Pharmacy (Female Section)

Sattam Bin Abdulaziz University

Al kharj / Kingdom of Saudi Arabia

Email :- da.hassan@psau.edu.sa

Anatomy

PHL 212

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Anatomy

PHL 212

OBJECTIVES Upon completion of this lecture, students

should be able to:

Gain knowledge regarding different types of

epithelium and their functions.

Have a basic understanding of the microscopic

structure of various types of epithelial tissue.

Gain knowledge regarding the normal locations

of various epithelial tissue types.

Explain the relations between the different types

of epithelial tissue of the human body.

TISSUE

Tissue

Groups of closely associated cells that

are similar in structure and function are

called tissues

Four primary tissues types:

Epithelial (covering) tissue

Connective(support) tissue

Musclular (movement)tissue

Nervous (control) tissue

Chapter Outline

Epithelial Tissue

Connective Tissue

Nervous Tissue

Muscle Tissue

SECTION I

EPITHELIAL TISSUE

Epithelial Tissue

• Epithelial tissue is a sheet of cells with little

extracellular material lying in the space

between them.

• Epithelial tissue covers all the inner and

outer surfaces of the body including;

• Skin

• Viscera of the digestive and respiratory

system

• The lining of body cavities

• Linings of blood vessels

• Most glandular tissue

Special Characteristics of Epithelium

Special Characteristics of Epithelium

1) Cellularity : formed of sheets of cells

2) Polarity:

• All epithelia exhibit polarity where the cells near the

apical surface differ from those at the basal surface

• Apical surfaces can be smooth, most have microvilli,

and some have cilia

• The basal surface of epithelium is called the basal

lamina, which acts as a selective filter that determines

which molecules are allowed to enter the epithelium

• Deep to the basal lamina is a layer of reticular fibers

belonging to the underlying connective tissue

• Together the reticular fibers and the basal lamina form

the basement membrane

Special Characteristics of Epithelium

3) Supported by connective tissue

All epithelial tissue sheets rest upon and are supported by

connective tissue

4) Specialized connection (cell junctions) between epithelial cells.

5) Innervated but avascular

• Epithelial tissues are supplied with nerve cells

• Epithelial tissues contain no blood vessels

• Epithelial tissue receive nutrients by substances diffusing

from blood vessels in the underlying connective tissue

layers

6)Regeneration

• Epithelial cells have a high regenerative capacity

Types of Epithelial Tissue

(epithelium)

• Simple epithelium: formed of one layer

• Stratified epithelium: formed of more than one layer

Simple Epithelia cells are arranged in one layer that have the same shape

There are four major classes of simple epithelia

1- Simple squamous epithelium has flat epithelium.

eg: line blood vessels (endothelium) or serous membrane

( mesothelium)

Function: Thin and permeable for easy filtration or

diffusion.

2- Simple cuboidal epithelium has cubical epithelium

eg: thyroid gland.

Important functions are secretion and absorption

3-Simple columnar epithelium has tall shaped epithelium

e.g. Unciliated in the digestive tract

Ciliated in the respiratory passages

functions are secretion and absorption

4- Pseudostratified columnar epithelium : Single layer of cells

of differing heights BUT all of them rest on the basement

membrane. eg. trachea.

Simple Squamous Epithelium

Simple Cuboidal Epithelium

Types of Simple Columnar Epithelium

Ciliated simple columnar epithelium in

the respiratory passages

Non ciliated simple columnar epithelium

in the stomach mucosa

Pseudostratified Epithelium

Pseudostratified columnar ciliated

epithelium lining the human trachea

Stratified Epithelia

cells are arranged in more than one layer

According to the shape of the top epithelial layer , there are

also four major classes of stratified epithelia

Stratified squamous epithelium

Stratified cuboidal epithelium

Stratified columnar epithelium

Transitional epithelium (a modified stratified squamous

epithelium)

Stratified Squamous Epithelium

composed of several cell layers

Surface cells are flattened (squamous)

Types:

keratinized epithelium has surface layer of dead

cells (keratin ) e.g.: skin

Non keratinized epithelium lacks the layer of dead

cells .e.g. esophagus

Stratified Squamous Epithelium

Stratified squamous epithelium lining the esophagus

Keratinized stratified squamous epithelium lining the

skin

Stratified Cuboidal Epithelium

Stratified cuboidal forming a duct of parotid gland

Stratified Columnar Epithelium

Stratified columnar epithelium lining the male urethra

Transitional Epithelium

The cells vary in shape depending on the degree of

distension of the organ eg. Urinary bladder

Epithelial Surface Features

The apical, lateral and basal cell surfaces of epithelia

have special features

• Apical surfaces either smooth, have microvilli or have

cilia

• Lateral surfaces have cell junctions

• Basal surface has a basal lamina

Microvilli

Microvilli are fingerlike extension of the plasma

membrane of apical epithelial cells

Microvilli maximize the surface area across which small

molecules enter or leave cells .

Site & function: In the epithelial cells of the small

intestine to increase surface area for absorption.

Cilia & Flagellum

• a. Cilia are hair-like, highly motile extensions of the apical surface of epithelia cells

• Function: The cilia on an epithelium bend and move in coordinated waves. The waves push mucus or ovum over its surface .

• Site : Respiratory tract, digestive tract and ovary.

• Mucus

• Mucous is a viscid secretion that can trap and remove foreign particles and bacteria from internal body surfaces through movement of cilia.

• b. Flagellum

• Long isolated cilium

• Only found as sperm in human (site)

Cells junctions

• Cells junctions are characteristic of epithelia cells.

• Types of cell junction:

1 ) Tight junctions

2) Adherens junctions

3) Desmosomes

4) Gap junctions

Cell Junctions

PHL 212

• Tight junctions:

• So close

• It prevents molecules from passing through epithelial cells

• Adherens junctions:

• Transmembrane linker proteins

• Desmosomes:

• Filaments anchor to the opposite side

• Gap junctions:

• It is a spot-like junction

• Allow small molecules to move between cells

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Glandular Epithelia

• A glandular epithelium is a type of epithelium that make a

secretion

Secretion are aqueous (water-based) products

The protein product is made in rough ER, packed into secretory granules by Golgi apparatus, released from the cell by exocytosis

• Glands are classified on where they release their secretion:

• Endocrine (internal secretion through blood vessels)

• Exocrine (external secretion through ducts)

• Mixed gland do both. As ; liver, gonads, pancreas

• Exocrine glands are classified by number of cells:

• unicellular exocrine glands

• multicellular exocrine glands

Endocrine & Exocrine Glands

1- Endocrine glands

a. They deliver secretion directly (through blood vessels) into

the extracellular space.

b. They secrete only hormones

c. Pituitary, Thyroid, Parathyroid, Adrenal, Thymus are

e.g. of endocrine gland

2-Exocrine glands

a. They deliver secretion through a duct into a body surface or

into a body cavity

b. They secrete mucous, sweat, oil, saliva, bile, digestive

enzymes, and many other substances

c. mucus glands Sweet , sebaceous and salivary gland are

e.g. of exocrine glands

Goblet cells

It is the only unicellular exocrine gland found in columnar

epithelium cells lining the intestinal and respiratory tract

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Types of Exocrine Glands

Simple glands – un-branched duct

Compound glands - branched duct

Shape of gland

Acinar - secretory cells form dilated sac

Tubular – secretory cells form tubes

Tubuloacinar - both tube and sacs

PHL 212

classification of exocrine glands according to their

modes of secretion

Merocrine glands

(salivary, sweat,

pancreas)

Secret their products

by exocytosis and

gland is not altered

(fig. a)

Holocrine glands

(sebaceous oil glands)

The entire cell

ruptures releasing the

secretions (fig. b)

Apocrine glands

(mammary glands)

The apex of the

secretory cell pinches

off and release its

secretion (fig. c) (c)

Conclusion & summary

references

• Books:

Gray's Anatomy for Students: With STUDENT CONSULT Online Access by

Richard L. Drake, A. Wayne Vogl and Adam W. M. Mitchell

The Complete Human Body + DVD By; Elaine Marieb & Katja Hoehn

ISBN-10: 075666733X | ISBN-13: 978-0756667337 | Publication Date: August 16, 2010

• Websites:

www.PubMed.com

www.BiomedNetspacebmn.com

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