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Know the definition of a tissue List the four types of basic tissues and their main functions Describe the classification of epithelium and know  the  functions and example locations  of  each type Understand the surface specializations of epithelial cells Describe the structural and functional classifications of glandular epithelium

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Tissues  are aggregates or groups of cells organized to perform one or more specific functions. Histology  is the study  of the  microscopic structure  and function of tissues and  organs. There are  4 types  of basic tissue that contribute to the formation of body organs and systems

TISSUE LEVEL
Smooth muscle tissue
Atoms
O
CHEMICAL LEVEL
Molecule
(DNA)
O CELLULAR
LEVEL
Smooth muscle cell
SYSTEM LEVEL
Esophagus
Liver
Stomach
Pancreas
Gallbladder
o
ORGAN
LEVEL
Serous
membrane
muscle
tissue layers
Stomach
Epithelial
tissue
Small intestine
Large intestine
O
ORGANISMAL LEVEL
Digestive system

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Epithelial Covers  body surfaces and lines hollow organs, body cavities, duct, and forms glands .

Connective Protects , supports, and binds organs and  other tissues Stores  energy as fat, provides immunity.

Muscular Generates  the physical force needed to make body structures move and generate body heat.

Nervous Detects  changes in body and responds  by generating  nerve impulses.

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Smooth
muscle tissue
Loose connective
tissue
Nervous
tissue
Blood
Stomach
Columnar
epithelium

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A  sheet-like covering of cells with one surface free (apical) and the other attached ( basal and lateral)  Creates a selective barrier between external environment and underlying connective tissue

The epithelium rests on a supporting extracellular layer called a  basement membrane .  Basement membrane is made of: Basal lamina : a dense filamentous sheet Reticular lamina : a semi-permeable  filter

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3 major functions: Selective  barrier that regulates the movement of materials in and out of the body  Secretory   surfaces that release products onto the free surface Protective  surfaces against the environment

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Surface epithelium  (Covering and lining) Covers the skin and internal organs Lines blood vessels, ducts and digestive and reparatory tracts Glandular epithelium Forms the secretory parts of the glands

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Based on the  number   of cell layers Simple  :  Single layer of cells that function in filtration, secretion, or absorption Stratified:   Two or more layers of cells that protect underlying tissues in areas of wear and tear Pseudostratified:  Appear to have multiple layers because cell nuclei at different levels

Arrangement
of layers
Simple
Pseudostratified
Stratified
Basement
membrane

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Based on the  shape  of cells Squamous Thin cells, arranged like floor tiles. Allows for rapid passage of substances Cuboidal like a cube (square).  Function for secretion or absorption Columnar   Like columns Function  for secretion or  absorption Transitional  Cell shape changes from flat to cuboidal Lining the urinary bladder

Basement
membrane
Squamous
Cuboidal
Columnar

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Simple squamous epithelium Simple cuboidal epithelium Simple columnar epithelium  ( ciliated and  nonciliated ) Pseudostratified columnar epithelium

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Single layer of flat cells Centrally located nucleus Location:  I t lines hollow structures. Heart & Blood vessels  (endothelium ) Alveoli of the lungs Lymphatic vessels It forms serous membranes such as  peritonium   (mesothelium) Functions Filtration and diffusion Secretion of serous membranes

Peritoneum
Nucleus Of simple
squamous cell
Cytoplasm
Plasma membrane
243X
Surfaæ view of simple squamous epithelium
Of mesothelial lining Of peritoneum

Simple squamous
cell
Basement membrane
Connective tissue
Simple squamous epithelium

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Single layer Cube-shaped Functions Secretion Absorption  Covering  Example locations K idney tubules  S mall ducts of glands Thyroid follicles Surface of ovary

0
Simple cell
Simple cuboidal epithelium
Basement
membrane
tissue

Nucleus of simple
cuboidal cell
Lumen
Of duct
Sinvle
ctmidal
epithelium
SEtional view Of simple epithelium
Of intralotNIar duct Of pancreas

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Cells have cilia on their apical side Function Move substances such as mucus by ciliary  action Example locations: Uterine tube Central canal of spinal cord

Cilia
Mucus in
goblet cell
Basement
Connective
tissue
Ciliated simple columnar epithelium

Cilia
Uterine
Lumen Of
uterine tube
Nucleus of
simple
columnar cell
Ciliated simple
columnar
epithelium
Connective
CD 500*
Sectional view Of ciliated sirnple columnar
epithenum Of uterine tube

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Single layer Rectangular in shape Have microvilli. Why? Example location: Most parts Gastrointestinal tract Gall bladder Function Secretion Absorption

Wcrovilli
intestine
Lumen of jejunum
Mucus in
goblet cell
Nucleus of
cell
Nucleus of
absorptive
Basement
Nonciliated
simple
columnar
epithelium
SEtional View 0' nonciliated sirnple colurnnar
epithelium Of lining Of jejunum Of small intestine

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Cells look stratified but they are not Not all cells reach apical surface Nuclei at different levels Ciliated Location R espiratory tract Male reproductive tract (vas deferens and epididymis) Functions Secretion and transport of mucus

Mucus in
goblet cell
ciliated columnar epithelium
Ciliated columnar cell
Cilia
Basement
membrane
Basal cell
Connective
tissue
Pseudostratified ciliated columnar
epithelium

Nucleus
Of ciüat«i
columnar cell
Nucleus Of
cen
Nucleus of
basal cell
Mucus in Cilia Lumen of
»let cell
Sectional view of pseudostratified ciliated columnar
epithelium ot trachea

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Many layers of cells Deeper cells are  cuboidal  or columnar The lost cells are replaced by division basal cells Location Skin ( keratinized ), contains protein keratin Mouth, oesophagus, vagina ( nonkeratinized )  Function Protection

Flattened
squamous
apical
membrane
Connective
Stratified squamous epithelium

Vagina
epithelium
Wional view of squamous epithelium ot vagina

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Stratified Cuboidal Locations  :ducts  of  glands, anorectal junction Functions  :Protection, transport

Stratified Columnar Locations  : large ducts of exocrine glands, anorectal junction Functions  : Protection, transport.

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Cells shape changes from squamous to cuboidal depending on stretch Cuboidal  when relaxed  Squamous  when stretched Function Allows distension of hollow  structures Found in  distensible  organs. Urinary bladder Ureter  Urethra

Urinary bladder
400*
Sectional view Of transitional epithelium Of urinary bladder in relaxed State
Lumen Of
urinary
b I acÆer
Nucleus of
Transitional

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The  surface of epithelial cells can be adapted to allow a specialized function. APICAL 	 Microvilli  are surface specializations to increase the  surface  area of  cells . 	 Cilia  are motile surface projections of cells involved in  transport . 	 BASAL 	 Basement membrane (2  laminae : Basal and Reticular). 	 Hemidemosomes BASOLATERAL 	 Junctional complexes (tight, adhering desmosomes, gap).

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acti n
junctional
co m plex
intermediate
filaments
tight
junction
adherens
junction
desmosome
gap
junction
hemidesmosome
seals neighboring cells together in an
epithelial, sheet to prevent leakage
of molecules between them
joins an actin bundlein one cell
to a similar bundle in a
neighboring cell
joins the intermediate filaments
in one cell to those ina neighbor
allows the passage of small
water-soluble ions and moleculæ
-anchors intermediate filaments
in a cell to the basal lamina
basal lamina

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Glandular Epithelium:    Endocrine Glands

Secretion of hormones that diffuse directly into the bloodstream Function: maintaining homeostasis

gland
follicle
view of endcx:rine gland (thyroid gland)
Hormone-prcxlucing
(epithelial) cell
Of horn-one
bllicle
Endocrine gland (thyroid gland)

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Secrete products into ducts that empty onto the surfaces of epithelium Secretions of the exocrine gland include mucus, sweat, oil, earwax, saliva, and digestive enzymes Examples of glands include  sudoriferous  (sweat) glands

cell 01
gland
View ot me portion
Exocrine gland
(9Neat

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Structural  Classification of  Exocrine  Glands

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Functional Classification of Exocrine Glands

Salivary
gland
Mammary
g larÉ
Sebaceous
(Oil gland)
Skin
(a) særetion
(b) Apcrrine særetion
(c) sention
Særetion
S Eretory
veside
Golgi complex
Pinched Off portion
Of cell is secretion
cell dies
and tEC0rnes
product
Cell division
replaces lost cell

http://higheredbcs.wiley.com/legacy/college/tortora/0470565101/hearthis_ill/pap13e_ch04_illustr_audio_mp3_am/simulations/figures/multicellular_exocrine_gland_classification.jpg

Merocrine: Secretory products released in  membrane-bound vesicles

Apocrine: Secretory products released in an envelop of plasma membrane and contain some of the cytoplasm

Holocrine: Secretory products accumulate in the cell, which dies by apoptosis. The debris discharged in lumen of the gland.