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Lecture 2

BIO210Y5 Lecture Notes - Lecture 2: Stratified Squamous Epithelium, Dense Irregular Connective Tissue, Stratum Corneum


Department
Biology
Course Code
BIO210Y5
Professor
Sanja Hinic- Frlog
Lecture
2

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LECTURE 2A – INTEGUMENT
Module 4.3
Epithelial Tissue: - includes the surface of your skin.
Exocrine glands
- secretes onto external surfaces or internal passageways
that connect to the exterior.
Endocrine glands
-
Secrete hormones into the interstitial fluid that then enters
the bloodstream.
Functions of Epithelial tissue
1. Provide physical protection
2. Control permeability – Regulation of any substance that enters or leaves the skin. Ex. calluses
3. Provide Sensation – sensory nerves extensively innervate most epithelia
4. Produce specialized secretions – Gland cells that are scattered among other cell types
The cells of epithelium share a number of basic features, it has an apical surface, which faces the exterior of the
body and a base which is attached to adjacent tissues.
Epithelial cells have 3 basic shapes: squamous, cuboidal, and columnar.
Epithelium with just one layer is called simple epithelium whereas a stratified epithelium contains several
layers.
Module 4.4
Epithelia lack blood vessels, and for this reason, they are said to be avascular. Epithelial cells must obtain
nutrients by diffusion or absorption across either the exposed or the attached epithelial surface. Cells forming the
deepest layer of an epithelium must remain firmly attached to underlying connective tissue because that’s how it
is nourished.
Module 5.1
Epidermis: consists of a stratified squamous epithelium.
Dermis: Consists of a papillary layer of areolar tissue and a reticular layer of dense irregular connective tissue.
Hypodermis (subcutaneous layer or artificial fascial): seperates the integument from the fascia around deeper organs.
Note that this tissue layer is not part of the integument.
Functions of the Integumentary System:
1. Protect underlying tissues and organs
2. Excrete salt, water, and organic waste by glands.
3. Maintain normal body temperature through either insulation or evaporative cooling
4. Produce melanin (protect against ultraviolet0, keratin (protects against abrasion and serves as water repellant)
5. Synthesize vitamin D3, Store lipids in adipocytes in dermis and adipose tissue in hypodermis.
Epithelia
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 
Glands
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