HUMAN TISSUES by: pr ,Dr, Sanaa El-Sherbiny

Cells are :The unit of structure of

living creatures

In 1665 Robert Hooke, observed thin

sections of cork with a simple

microscope of his own

making. He described his findings

as having the appearance

of cells in a jail.

Cells and Tissues

• Cytology or cell biology : the study of cells

• Histology : the micro-study of living tissues

and organs of all living creatures .

• Levels of Organization of human:

cells--tissue --organ---systems--body

• Types of organisms:

• Unicellular Organism:

consists of one cell as (bacteria ,amiba)

• Multicellular Organism:

consists of more than one cell ( plants and animals)

Human cell formed of 3 Main Parts

1) Nucleus – a spherical body often located near the center of the cell which contains the chromosomes that carry the genetic code of the cell and serves as the cell’s master control center.

2) Cytoplasm – the fluid medium for the many molecules and organelles the cell contains

3) Cell organelles: Membranous and

non-membranous cell organelles .

Tissue : definition

• Types of tissues

A group of connected, interdependent cells

that cooperate to perform

a specific function

1. Epithelial Tissue

2. Connective Tissue

3. Muscle Tissue

4. Nervous Tissue

Epithelial Tissues • General Features

1- Formed of one or more Cellular Layer

on a Basement Membrane.

2- Not Penetrated By Blood Vessels ,

get Blood supply from underlying connective tissue.

3- but nerve fibers ramify between cells.

4- Rapid Rate of Cell Regeneration.

5- Embriologically derived from

ectoderm, mesoderm or endoderm.

** Structural Classification According to number of layers and

Cell Shapes: 2 types :

simple and stratified.

**Functional Classification: 1-covering-epith.

2-glandular-epith.

3-neuro-epith.

Classifications of Epithelia

• Simple • stratified

Simple epithelium • One layer of cells on a basement membrane

• May be simple squamous, cubical or columnar

SIMPLE Squamous.epithelium

**structure: one layer of flat cells

on a basement membrane

**Sites – 1-THE Lung ALVEOLI

– 2- ENDOTHELIUM

LINING blood and

LYMPHATIC vessels.

– 3- lining of all serous

– Membranes as peritoneum

– And pleura.

WHICH 1

IS

YOURS…

1 or 2…?

1

2

simple cuboidal

epithelium

** formed of one layer of cubical cells on a basement membrane

– LINING THE FOLLICLES IN THE THYROID GLAND

– Medium sized ducts of glands

– Kidney tubules

Simple Columnar Epithelium one layer of columnar cells on a basemen

membrane

Figure 4.3c

simple columnar epithelium

types : 1- non modified ,lining ducts of glands

• 2-Modified:- absorptive Epithelium, lining

the , small intestine

- secretory Epithelium, lining the stomach.

- ciliated, Epithelium, lining the

uterus and fallopian tube

Microvilli

Pseudo-stratified Columnar

Epithelium

• One layer of overcrowded cells with

many levels of nuclei

Pseudostratified Ciliated Columnar Epithelium lining trachea and bronchi

Figure 4.3d

20

Stratified Epithelium

Stratified Squamous Keratinized

Epithelium ( st,sq,ker,epith)

** Function: Protection

** Locations:

epidermis

of

the skin

Stratified Squamous

Epithelium

• Many layers

• Basal one columnar

• Intermediate layers

• Polygonal in shape

• Upper layers are

• Squamous flat cells with

central oval nuclei

Stratified Squamous non-keratinized Epithelium

:found in* mouth cavity

*conjunctiva of the eye

Figure 4.3e

Transitional Epithelium

Figure 4.3h

TRANSITIONAL EPITH.

• many cell layers -

stretch

• cube-shaped and

elongated cells

• line urinary

bladder, ureters,

and part of urethra

Transitional Epithelium

• 6-8 layers in empty

bladder

• 2-3 layers in full one

• Basal layer columnar

on ill defined b.m

• Intermediate layers

polygonal

• Upper layer large

may be bi-nucleated

• Second layer flask

shaped

GLANDULAR EPITHELIUM

• T he cells are specialized for secretion

• According to number of cells we have:

• Unicellular glands ;

• as goblet cells

• Multicellular glands :

• as salivary glands.

1-ACCORDING TO

SECRETORY PASSAGES

• A-EXOCRIN GLANDS:

• Have duct system

• SUCH AS :salivary glands.

• -ENDOCRINE GLANDS:

• No ducts ,secrete directly into the blood

• SUCH AS:THE PITUITARY GLAND.

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Types of salivary glands

Major ♥ Submandibular

♥ Sublingual

♥ Parotid

Minor ♥ Buccal

♥ Labial

♥ Palatine

♥ Lingual

Second Year Section 4 2009/2010

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

The Main Salivary Glands

Figure 24.7a, b

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• 3 pairs that secrete into the oral cavity:

• parotid glands :produce a serous secretion containing large amounts of salivary amylase. Secretions are drained by a parotid duct at the level of the 2nd upper molar tooth

• sublingual glands:secrete a saliva that is predominantly mucus that acts as buffer and lubricant. Sublingual ducts open on both sides of the tongue root.

• submandibular glands produce a mixed serous and mucous secretion contains buffers, mucins glycoproteins and amylase.

Main Salivary glands

Function Secretion of saliva

Second Year Section 4 2009/2010

Structure

Second Year Section 4 2009/2010

• Connective tissue element Stroma

• Epithelial

• functioning elements

Parenchyma

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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

stroma

1- Capsule

2- Trabeculae

3- Reticular network

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•Parenchyma

1. Secretory part ( acini )

1.Transport system (branching ducts)

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What is the salivary acinus?

• It is the secretory part of salivary gland

Second Year Section 4 2009/2010

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Model of the gland: a bunch of grapes: berry= acinus

stalk of berry: intercalated duct

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Structure of salivary acinus:

• The salivary acinus is composed of a group of secretory cells that surround a central lumen leading to the duct system.

• The acinus is surrounded by a basement membrane.

• There are branching

• myoepithelial cells(basket cells)

• their contraction squeezes the

• secretions into the duct.

Second Year Section 4 2009/2010

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Classification

• According to the nature of secretion

• There are 3 types:

• Mucous

• Serous

• Muco-serous

Second Year Section 4 2009/2010

NEURO EPITHELIUM • THE EPITHELIAL CELLS ARE SPECIALIZED FOR

RECEPTION OF

• EXTERNAL STIMULI SUCH AS:

• RETINA OF THE EYE, OLFACTORY MUCOSA,

TASE BUDS and ORGAN OF CORTI .

• Neuroepithelium is formed of :

• Sensory cells &

• Supporting cells

• And stem basal

• cells

Taste buds

Olfactory epithelium and all neuro-

epithelium are formed of3 types of cells :

1-sensory cells 2-supporting cells

and 3-basal stem cells

Name this type of epithelium-------

Mention two sites for simple Squamous

Epithelium 1----------

2-------------

Figure 4.3a

This is --- ---- epithelium

Name this type of epithelium-------

Stratified

epithelium

This is ----- ----- ------ epithelium

it is found in -----------------------

This epithelium is --- ----- --------

-------- ------- with ------------ cells.

This is ------ ----- ----------------

its site is -----------------------

The arrow indicates ----- -------

This is ------ ----- -------------epithelium

its site is -----------------------------------

• Identify a tissue type

• 1. mucous gland

• 2. stratified columnar epithelium

• 3. stratified squamous epithelium

• 4. unicellular exocrine gland (goblet cell)

• Identify a tissue type

• 1. alveolar gland

• 2. mucous gland

• 3. simple columnar

epithelium

• 4. simple cuboidal

epithelium

• Identify a tissue type

• 1. mucous gland

• 2. serous gland

• 3. stratified columnar epithelium

• 4. pseudostratified

• 5. transitional epithelium

• Identify a tissue type

• 1. stratified cuboidal epithelium

• 2. stratified columnar epithelium

• 3. simple columnar epithelium

• 4. mucous acinus

• 5- simple columnar epithelium with goblet cells(absorptive )

• This is a histological section of:

• 1- Stratified squamous epithelium.

• 2- simple squamous epithelium.

• 3- simple cuboidal epithelium.

• 4- simple columnar epithelium.

• 5- stratified columnar epithelium.