An intro to tissues and the forms and functions of epithelial tissue, specifically.

1. TissueTissue

2.
Definition of tissue:
A mass of similar cells that,
together, perform a specific
function.

3. There are four basic types of tissue
in the human body:
1.Epithelial tissue
2.Connective tissue
3.Muscular tissue
4.Neural tissue

4.
Each of these types of tissue has
specific forms and functions.

5. Epithelial TissueEpithelial Tissue

6. Epithelial tissues form all of theEpithelial tissues form all of the
coveringscoverings andand liningslinings of the body.of the body.

7. Singular (one tissue) =Singular (one tissue) = epitheliumepithelium
Plural (two+ tissues) =Plural (two+ tissues) = epitheliaepithelia

8. Epithelia:Epithelia: FormForm

9. 1. Cells are closely bound together

10. 2. A free, or apical, surface is exposed to
open space (either the environment or a
cavity or passageway)
Free surface = apical surface

11. Example A:
The top layer of our
skin is epithelial
tissue.
The part of your skin
that you can touch is
its apical surface.

12. Example B:
This is a cross-section
of an artery (and
surrounding tissue).
Arteries and other
blood vessels are lined
with epithelial tissue.
The inner surface of
the artery is the apical
surface.

13. 3. Epithelia are attached to underlying
connective tissue by a basement
membrane.

14. 4. Epithelia are avascular. There are no
blood vessels.
without blood vessels = avascular

15. 5. Cells at the apical surface are
continually replaced or regenerated.
There is a very fast cell turnover on these
surfaces.

16. Epithelia:Epithelia: FunctionFunction

17. 1. Provide physical protection.
Epithelia protect underlying tissues from
pathogens, abrasion, dehydration, and
UV rays.

18. 2. Control permeability.
Permeable = having openings that let
things through.

19. 3. Provide sensation.
Sensation = physical feelings like hot,
cold, pain, etc.

20. 4.Produce specialized secretions.
Secretions = substances such as tears,
sweat, saliva, hormones, etc.
These secretions an be inside or outside the
body.

21. Why are apical epithelia being
continually replaced?
Think of of an epithelial apical surface
in the human body and describe why you
think it would need to be
constantly replaced.
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