2 Epithelium and CT for 1st year mbbs.pdf

Here is a 3000-word description of epithelium:

*Introduction*

Epithelium is a type of tissue that forms the lining of various organs and glands in the human body. It is a crucial component of the body's structure and function, playing a vital role in protecting the body from external damage, regulating the exchange of substances, and facilitating the production of hormones and enzymes.

*Definition and Classification*

Epithelium is defined as a layer of cells that forms the lining of organs, glands, and other body surfaces. It is classified into several types based on its shape, function, and location in the body. The main types of epithelium are:

1. *Squamous epithelium*: This type of epithelium is composed of flat, plate-like cells that provide a smooth surface for the exchange of substances. Examples of squamous epithelium include the lining of the lungs, mouth, and vagina.
2. *Cuboidal epithelium*: This type of epithelium is composed of cube-shaped cells that provide a larger surface area for the exchange of substances. Examples of cuboidal epithelium include the lining of the kidneys and adrenal glands.
3. *Columnar epithelium*: This type of epithelium is composed of tall, column-like cells that provide a large surface area for the absorption and secretion of substances. Examples of columnar epithelium include the lining of the intestines and stomach.
4. *Pseudostratified epithelium*: This type of epithelium appears to be layered due to the varying heights of its cells. Examples of pseudostratified epithelium include the lining of the respiratory tract and urinary tract.
5. *Stratified epithelium*: This type of epithelium is composed of multiple layers of cells that provide a barrier against external damage. Examples of stratified epithelium include the lining of the skin and esophagus.

*Functions of Epithelium*

Epithelium performs several important functions in the body, including:

1. *Protection*: Epithelium provides a barrier against external damage, such as physical injury, pathogens, and toxins.
2. *Regulation of substance exchange*: Epithelium regulates the exchange of substances between the body and the external environment, such as the absorption of nutrients and the elimination of waste products.
3. *Production of hormones and enzymes*: Epithelium produces hormones and enzymes that help regulate various bodily functions, such as growth and development, metabolism, and immune response.
4. *Sensation*: Epithelium contains sensory receptors that allow us to perceive the world around us, such as touch, temperature, and pain.

*Locations of Epithelium*

Epithelium is found in various locations throughout the body, including:

1. *Skin*: The skin is the largest organ in the body and is covered by stratified epithelium.
2. *Respiratory tract*: The respiratory tract, including the lungs, trachea, and bronchi, is lined by pseudostratified epithelium.
3. *Gastrointestinal tract*: The gastrointestinal tract, including the mouth, eso

1. histology practical
For First year Medical students
Histology Department
2024
first part

2. EPITHELIUMLAB. (1)
1. Simple squamous epithelium(Bowman's capsule). X40
2. Simple columnar epithelium (gall bladder).x40
3.Simple cuboidalepithelium (renal tubule) x40
4.Keratinized stratified squamous epithelium( skin).x40.
5. Non keratinized stratified sqaumousepith.(soft
palate).X40
6. pseudostratified columnar ciliated epith. (trachea). X40
7.Transitional epithelium (urinary bladder) x40.

3. Simple SquamousEpithelium:
a-A single layer resting on a basement membrane.
b-The cells are spindle in shape.
c-Nuclei are flat & placed in the center.
X10
X40

4. Simple Columnar Epithelium:
a-A single layer resting on a basement membrane.
b-The cells are tall and column in shape.
c-Nuclei are oval and are found near the base of the cell.
X40
X10

5. Simple cuboidalepithelium:
a-A single layer resting on a basement membrane.
b-The cells are cubic in shape.
c-Nuclei are round & placed in the center.

6. Stratified squamouskeratinized epithelium:
a. Several layers of cells resting on a basement membrane.
b. The upper most cells are flat with flat nuclei.
c. The basal cells are columnar with basal oval nuclei.
d. The middle cells are polygonal with central round nuclei.
e. Contains keratin on superficial layer .

7. Stratified squamousnon-keratinized
epithelium:
a. Several layers of cells resting on a basement membarne.
b. The upper most cells are flat with flat nuclei.
c. The basal cells are columnar with basal oval nuclei.
d. The middle cells are polygonal with central round nuclei.
e. Have no keratin.

8. Pseudostratifiedcolumnar ciliated epithelium:
a. All cells rest on the basement membrane.
b. Its is formed of one layer of cells.
c. Not all cells reach to the surface.
d. Nuclei appear at different levels.

9. a-Several layers of cells rest on basement membrane.
b-Superficial cells are dome shaped.
C-Superficial cells may have two nuclei (binucleated).
Transitional epithelium

10. 1).Goblet cells (Jejunum)x40.
2). Serous acini(pancreas)x40
3).Mucous acini(sublingual gland)x40.
EPITHELIUMLAB. (2)

11. a. Flask shaped cells.
b. Unicellular gland.
c. Secretory granules fill the extensive apical pole of the cell..
d. Stained with (PAS +ve).
Goblet cell:

12. Serous acini:
a)Pyramidal shape cells.
b)Lumen is narrow
c)Multiple, rounded nuclei,close to the base
d)Apical cytoplasm is acidophilic (pink),basal cytoplasm
is basophilic (purple)

13. a)Lumen is wide.
b) Pyramidal cells.
c) flattened nuclei at the base of the cells
d) pale cytoplasm (foamy appearance)
Mucous acini:

14. Connective tissue lab 3
1-Loose areolarconnective tissue . x40
2-Dense regular connective tissue . X40
3. Dense irregular connective tissue. X40
4-Reticular connective tissue . X40
5-Elastic fibers (blood vesseles). X40

15. Loose (areolar) connective tissue:
a)A moderate amount of collagen, elastic, and reticular fibers appears
in this tissue.
b)Most numerous cells are fibroblasts and macrophages.
c)Sites: skin , peritoneal & pleural membranes .

16. Dense regular connective tissue:
a)Bundles of collagen fibers parallel to each other (all run in one
direction )
b)Rows of fibroblasts between bundles .
c)Sites: Tendon.

17. a)Collagen fibers are thick, short bundles run in different directions .
b)Fibroblast are seen with few blood vessels .
c) Stained pink with H&E, blue with Trichromedyes.
d) Site : Dermis of skin .
Dense irregular connective tissue:

18. reticular fibers:
a)Thin fibers branching & anastomosingforming a network.
b)Stain black by Silver impregnation .
c)Site: Support the liver and lymphoid tissues.
X10
X40

19. a)Thinner than collagen fiber .
b)short wavy fibers form continuous lamina.
c)Stained brown with orcein, violet withAldehydefuchsin.
d)Site : elastic artery.
Elastic Fibers:

20. Connective tissue lab4
1. Mucoidconnective tissue(umbilical cord). x40
2. Yellow adipose tissue. X40
3. Brown adipose tissue. X40

21. Mucoidconnective tissue (mucous c.t.)
a)Abundant matrix, homogenous, pale blue (jelly like) .
b)Cells mainly fibroblasts.
c)Fine collagen and elastic fibers.
X10
X40

22. Yellow adipose tissue:
a)Unilocularadipocyte,one large central droplet of yellow fat.
b)Round to polyhedral shaped cells.
c)Rim of cytoplasm (thesignet ring cell) .
d)Peripheral flat nucleus .

23. Brown adipose tissue:
a)Multilocularadipocyte,many small fat droplets.
b)Polygonal shaped cells.
c)Rounded central nucleus .