1. Tissue Types Overview Tissue Definitions Epithelial Tissue
Simple and Stratified
Connective Tissue
Characteristics
Bone, Cartilage, Dense
Connective, Loose Connective
Blood
Muscle Tissue
Skeletal, Cardiac, and Smooth
Nervous Tissue
Tissue Repair
Tissue Development and Aging

2. Body Tissues Cells are specialized for particular functions Tissues
Groups of cells with similar structure and function
Four primary types
Epithelium
Connective tissue
Muscle
Nervous tissue

3. Epithelial Tissues Found in different areas Body coverings
Body linings
Glandular tissue
Functions
Protection
Absorption
Filtration
Secretion

4. Epithelium Characteristics
Cells fit closely together
Tissue layer always has one free surface
The lower surface is bounded
by a basement membrane
Avascular (have no blood supply)
Regenerate easily if well nourished

5. Classification of Epithelium: Layering

6. Classification of Epithelium: Shape

7. Endothelium- the lining of lymphatic vessels, blood vessels, and heart
(a) Simple squamous epithelium
Description: Single layer of flattened
cells with disc-shaped central nuclei
and sparse cytoplasm; the simplest
of the epithelia.
Air sacs of
lung tissue
Function: Allows passage of
materials by diffusion and filtration
in sites where protection is not
important; secretes lubricating
substances in serosae.
Nuclei of
squamous
epithelial
cells
Location: Kidney glomeruli; air sacs
of lungs; lining of heart, blood
vessels, and lymphatic vessels; lining
of ventral body cavity (serosae).
Photomicrograph: Simple squamous epithelium
forming part of the alveolar (air sac) walls (125x).
Other important locations:
Endothelium- the lining of lymphatic vessels, blood vessels, and heart
Mesothelium- the epithelium of serous membranes in the ventral body cavity

8. (b) Simple cuboidal epithelium
Description: Single layer of
cubelike cells with large,
spherical central nuclei.
Simple
cuboidal
epithelial
cells
Function: Secretion and
absorption.
Basement
membrane
Location: Kidney tubules;
ducts and secretory portions
of small glands; ovary surface.
Connective
tissue
Photomicrograph: Simple cuboidal
epithelium in kidney tubules (430x).
Figure 4.3b

9. (c) Simple columnar epithelium
Description: Single layer of tall cells
with round to oval nuclei; some cells
bear cilia; layer may contain mucus-
secreting unicellular glands (goblet cells).
Simple
columnar
epithelial
cell
Function: Absorption; secretion of
mucus, enzymes, and other substances;
ciliated type propels mucus (or
reproductive cells) by ciliary action.
Location: Nonciliated type lines most of
the digestive tract (stomach to anal canal),
gallbladder, and excretory ducts of some
glands; ciliated variety lines small
bronchi, uterine tubes, and some regions
of the uterus.
Basement
membrane
Photomicrograph: Simple columnar epithelium
of the stomach mucosa (860X).
Figure 4.3c

10. (d) Pseudostratified columnar epithelium
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.
Cilia
Mucus of
mucous cell
Pseudo-
stratified
epithelial
layer
Function: Secretion, particularly of
mucus; propulsion of mucus by
ciliary action.
Location: Nonciliated type in male’s
sperm-carrying ducts and ducts of
large glands; ciliated variety lines
the trachea, most of the upper
respiratory tract.
Basement
membrane
Photomicrograph: Pseudostratified ciliated
columnar epithelium lining the human trachea (570x).
Trachea
Figure 4.3d

11. (e) Stratified squamous epithelium
Description: Thick membrane
composed of several cell layers;
basal cells are cuboidal or columnar
and metabolically active; surface
cells 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.
Stratified
squamous
epithelium
Function: Protects underlying
tissues in areas subjected to abrasion.
Nuclei
Location: Nonkeratinized type forms
the moist linings of the esophagus,
mouth, and vagina; keratinized variety
forms the epidermis of the skin, a dry
membrane.
Basement
membrane
Connective
tissue
Photomicrograph: Stratified squamous epithelium
lining the esophagus (285x).
Figure 4.3e

12. Stratified Epithelium, Other Types
Stratified cuboidal
Stratified columnar
Quite rare in body
Found in some sweat and mammary glands
Typically two cell layers thick
Limited distribution in body
Small amounts in pharynx, male urethra, and lining some glandular ducts
Also occurs at transition areas between two other types of epithelia
Mucous gland duct, tongue

13. (f) Transitional epithelium
Description: Resembles both
stratified squamous and stratified
cuboidal; basal cells cuboidal or
columnar; surface cells dome
shaped or squamouslike, depending
on degree of organ stretch.
Transitional
epithelium
Function: Stretches readily and
permits distension of urinary organ
by contained urine.
Location: Lines the ureters, urinary
bladder, and part of the urethra.
Basement
membrane
Connective
tissue
Photomicrograph: Transitional epithelium lining the urinary
bladder, relaxed state (360X); note the bulbous, or rounded,
appearance of the cells at the surface; these cells flatten and
become elongated when the bladder is filled with urine.
Figure 4.3f

14. Glandular Epithelium
Gland – one or more cells that secretes a particular product
Two major gland types
Endocrine gland
Ductless
Secretions are hormones
Exocrine gland
Empty through ducts to the epithelial surface
Include sweat and oil glands
Found as unicellular and multicellular types

15. Unicellular Exocrine Glands: Goblet Cell
The only important unicellular gland is the goblet cell
Microvilli
Secretory
vesicles
containing
mucin
Rough ER
Golgi
apparatus
Nucleus
(a)
(b)
Figure 4.4

16. Multicellular Exocrine Glands
Multicellular exocrine glands are composed of a duct and a secretory unit
Classified according to:
Duct type (simple or compound)
Structure of their secretory units (tubular, alveolar, or tubuloalveolar)

17. Compound duct structure
Simple duct structure
(duct does not branch)
Compound duct structure
(duct branches)
Tubular
secretory
structure
Simple tubular
Simple branched
tubular
Compound tubular
Example
Intestinal glands
Example
Stomach (gastric)
glands
Example
Duodenal glands of small intestine
Alveolar
secretory
structure
Simple
alveolar
Simple branched
alveolar
Compound alveolar
Compound
tubuloalveolar
Example
No important
example in humans
Example
Sebaceous (oil)
glands
Example
Mammary glands
Example
Salivary glands
Surface epithelium
Duct
Secretory epithelium
Figure 4.5

18. Modes of Secretion Merocrine
Products are secreted by exocytosis (e.g., pancreas, sweat and salivary glands)
Holocrine
Products are secreted by rupture of gland cells (e.g., sebaceous glands)

19. Tissue Types Overview Tissue Definitions Epithelial Tissue
Simple and Stratified
Connective Tissue
Characteristics
Bone, Cartilage, Dense
Connective, Loose Connective
Blood
Muscle Tissue
Skeletal, Cardiac, and Smooth
Nervous Tissue
Tissue Repair
Tissue Development and Aging

20. Connective Tissue Found everywhere in the body
Includes the most abundant and widely distributed tissues
Functions
Binds body tissues together
Supports the body
Provides protection

21. Connective Tissue Characteristics
Variations in blood supply
Some tissue types are well vascularized
Some have poor blood supply or are avascular
Extracellular matrix
Non-living material that surrounds living cells

22. Extracellular Matrix Two main elements
Ground substance - Gel like, high water content
Proteoglycans
Glycosaminoglycans (GAGs like hyaluronan), chondroitin sulfate as dietary supplement for osteoarthritis
Glycoproteins
Fibers
Produced by the cells
Three types
Collagen fibers
Elastic fibers
Reticular fibers
Reticular fibers

23. Table 4.1

24. Connective Tissue Types: Areolar
Areolar connective tissue
Generic organ packaging tissue, soaks up water

25. Connective Tissue Types: Bone
Bone (osseous tissue)
Has both an organic and a mineral component

26. Tissue Types Overview Tissue Definitions Epithelial Tissue
Simple and Stratified
Connective Tissue
Characteristics
Bone, Cartilage, Dense
Connective, Loose Connective
Blood
Muscle Tissue
Skeletal, Cardiac, and Smooth
Nervous Tissue
Tissue Repair
Tissue Development and Aging