Appearance of stratified squamous epithelium location

appearance of stratified squamous epithelium
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Location:
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Lines the urinary bladder and parts of the ureters and urethra
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Function:
•
Allows urinary organs to stretch as they fill with wastes while
maintaining protective lining
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Transitional epithelium
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Glandular epithelium
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Glandular epithelium is responsible for secretion
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Accomplished through clusters of glandular cells that usually are deep to the
covering and lining epithelium
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A gland may consist of one or more cells that secrete substances into ducts (hollow
tubes) onto a surface, or directly into the bloodstream if no duct is present
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All glands are divided into two groups
• Endocrine glands
• Secrete substances called hormones into the interstitial fluid where they diffuse into the
blood stream
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These secretions have far reaching effects (discussed in chapter 18)
• Exocrine glands
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Secrete products into ducts that empty onto the surface of covering and lining
epithelium, such as the surface of the skin or into the lumen of the intestine
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The secretions have limited effect, and may even be harmful if they gained access to the
blood
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Note that some glands like the pancreas have both endocrine and exocrine
functions
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Endocrine glands
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Exocrine glands
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Classification of exocrine
glands
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Exocrine glands can be unicellular or multicellular
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Unicellular glands consist on one cell that secretes their products
directly onto the apical surface of a covering and lining
epithelium
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Most exocrine glands are multicellular glands, composed of many
cells arranged into distinctive microscopic structures
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Multicellular glands are divided based on two criteria
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Does the duct branch
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Simple glands do not branch
•
Compound glands have branching
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The shape of the secretory portion of the gland
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Tubular – secretory portion resembles a tube
•
Acinar- the secretory portion have a more rounded appearance
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Tubuloacinar – have both tubular and rounded secretory portions
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Simple exocrine glands
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Compound exocrine glands
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Functional classification of
exocrine glands
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Functional classification of exocrine glands is based on how
their secretions are released
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All forms begin with the endoplasmic reticulum and Golgi
forming intracellular secretory vesicles containing the product
•
Merocrine gland secretions are packaged by the Golgi and
released from the cell in secretory vesicles via exocytosis
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Most common form of gland
•
Apocrine gland secretions accumulate at the apical surface of the
secreting cell; that portion of the cell then pinches off, releasing
the secretion
•
Holocrine gland secretions accumulates secretory product in the
cytoplasm of the cell; when mature, the cell ruptures, releasing
the secretory product
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Merocrine
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Apocrine
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Holocrine
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Connective tissue
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One of the most abundant and widely distributed tissues in the body
•
Functions:
•
Binds, supports and strengthens other tissues
•
Compartmentalizes other tissues
•
Transport throughout the body