Introduction to Glandular Epithelia

Introduction to Glandular Epithelia

Author: Aaron Mullally

- know the definition of a gland and how it functions

- know the structural and functional differences between endocrine and exocrine glands

- understand the difference between a multicellular and unicellular gland

- know what the term alveolar means

- know that glands are derived from epithelial tissues of the body

This packet is an introduction into the specialized secreting structures of the body called glands. In this packet I discuss the origins of glands and how to differentiate between endocrine and exocrine glands.

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Endocrine vs. Exocrine Glands

 Exocrine glands

- synthesize and secrete watery or oily secretions

- involutions (inward folds) of epithelial tissues

- two functional parts: duct and acinus

- connect to body surfaces via ducts
- the acinus releases its secretions into the ducts which travel to other body surfaces
- the secretions travel very short distances
- some examples: sweat glands, mammary glands, pancreas, sebaceous glands, etc.

Endocrine glands
- ductless glands

- synthesize, store, and secrete chemical messages (hormones)

- release hormones into body fluids, which then diffuse into the bloodstream
- hormones travel long distances throughout the body to target tissues

There are also glands called mixed glands which have both exocrine and endocrine functions. The pancreas is a good example of this. The pancreas has a small duct called the pancreatic duct that is connected to the duodenum of the small intestine. The pancreas releases digestive enzymes and other secretions through this duct into the small intestine. The cells that produce pancreatic secretions are found in organized clusters called the islets of Langerhans. About 98% of the islet cells produce the various secretions that aid in digestion while the remaining 2% of the islet cells produce hormones. The hormone producing cells of the islets (alpha, beta, and delta cells) release hormones that aid our metabolism of carbohydrates and proteins.

Source: Self made

Glandular Epithelia Overview/Endocrine vs. Exocrine

In this video I highlight some new terminology you should know about this subject. Then I discuss the structural and functional differences between endocrine and exocrine glands.

Source: Self made

Introduction to Glandular Epithelia/Endocrine vs. Exocrine

Here are some slides introducing new terminology about glandular epithelia. I am also including the image from the presentation that compares and contrasts endocrine vs. exocrine glands.

Source: Self Made