simple epithelial tissues,

1. Simple Epithelial Tissue
M.Sc Hamid Al-Tameemi

2. Tissues
The approximately 200 distinctly different types of cells
composing the human body are arranged and
cooperatively organized into four basic tissues.
Groups of these tissues are assembled in various
organizational and
functional arrangements into organs, which carry out
functions of the body.

3. The body contain four basic tissues types
1- Epithelium tissues
2- Connective tissues
3- Muscular tissues
4- Nervous tissues

4. EPITHELIAL TISSUE
Epithelial tissue is present in two forms:
1- As sheets of contiguous cells (epithelia) that cover the
body on its external surface and line the body on its
internal surface,
2- As glands, which originate from invaginated epithelial
cells.

5. Epithelia are derived from all three embryonic germ
layers, although most of the epithelia are derived from
ectoderm and endoderm.

6. functions of Epithelial tissues
1_ Protection of underlying tissues of the body from
abrasion and injury
2_ Transcellular transport of molecules across epithelial
layers
3_ Secretion of mucus, hormones, enzymes, and so
forth, from various glands

7. 4_ Absorption of material from a lumen (e.g., intestinal tract
or certain kidney tubules) Control of movement of materials
between body compartments via selective permeability of
intercellular junctions between epithelial cells
5_ Detection of sensations via taste buds, retina of the eye,
and specialized hair cells in the ear.

8. Classification of Epithelial Membranes
Cell arrangement and morphology are the bases of
classification of epithelium.
Epithelial membranes are classified according to
1- number of cell layers between the basal lamina .
2- free surface and by the morphology of the epithelial
cells .

9. If the membrane is composed of a single layer of cells, it
is called simple epithelium; if it is composed of more
than one cell layer, it is called stratified epithelium .

11. Epithelium tissues
Epithelia can be divided into two main groups: covering
(or lining) epithelia and secretory (glandular) epithelia.

12. Covering or Lining Epithelia
Cells of covering epithelia are organized into one or more
layers that cover the external surface or line the cavities of an
organ. Such epithelia are classified according to the number
of cell layers and the cell morphology in the surface layer .
Simple epithelia contain one cell layer and stratified epithelia
contain two or more layers.
Based on cell shape, simple epithelia are classified as
squamous (thin cells), cuboidal (cell width and thickness
roughly similar) or columnar (cells taller than they are wide)

13. Types of Simple Epithelium
1-Simple Squamous Epithelium
2- Simple cuboidal Epithelium
3- Simple columnar Epithelium
4- Pseudo-stratified Epithelium

14. 1-Simple Squamous Epithelium

15. This tissue consists of thin flat, tile like polygonal or
hexagonal cells with a centrally located oval or spherical
nucleus. Each cell has irregular boundaries. The cells are
arranged like tiles on a floor, so, it is also known as
pavement epithelium.

16. Location - It lines the heart, alveoli, bowman’s capsule,
visceral and peritoneal lining of coelom.
Function - It helps in protection, filtration, absorption
and secretion.

17. 2-Simple Cuboidal Epithelium

18. This tissue consists of a single layer of cuboidal cells
with equal heights, width and spherical nucleus. The
cuboid epithelial cell covers the surface of the ovaries
and lines the inner surfaces of the cornea. This tissue
forms the kidney tubules and contains microvilli.

19. Location- It lies in the surface of ovaries, lens of eye and
inner surface of cornea, thyroid vesicles, salivary gland
and pancreatic ducts.
Function- It helps in protection, secretion, absorption
and excretion.

20. 3- Simple Columnar Epithelium

21. This tissue consists of tall and columnar cells with height
exceeding width. Nuclei are elongated and situated in
the basal part. This tissue also consists of goblet cells
which secrete mucus and protects the lining and
lubricates the passage.

22. Location- It lines the stomach, small and large
intestine, digestive glands, ureter, uterine wall and gall
bladder.
Function- This tissue helps in secretion excretion and
absorption.

23. 5- Pseudo-stratified Epithelium

24. This tissue consists of tall, elongated columnar cells.
Tips of columnar cells consists cilia. Between the
columnar cells, there are smaller cells which do not
possess the ciliated structure. Each cell contain oval
shaped nucleus.

25. Location - This tissue is found in lining of trachea,
bronchi, nasal chamber, etc.
Function - Mucus traps the bacteria and dust particles.