Secretory Epithelia and Glands
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Questions and Answers

Which of the following is a primary function of secretory cells within epithelial tissue?

  • Synthesizing, storing, and releasing macromolecules (correct)
  • Facilitating rapid ion exchange across the epithelium
  • Contractile movement within the tissue
  • Providing structural support to adjacent tissues

In what specific epithelial types are scattered secretory cells (unicellular glands) commonly observed?

  • Pseudostratified, stratified columnar, and transitional epithelium.
  • Transitional, stratified squamous, and glandular epithelium.
  • Simple cuboidal, simple columnar, and pseudostratified epithelium. (correct)
  • Stratified cuboidal, transitional, and simple squamous epithelium.

How do exocrine glands form during the development of covering epithelia?

  • Migration of secretory cells from distant sites into the epithelium.
  • Differentiation of mesenchymal cells into secretory units.
  • Transformation of fibroblasts into glandular cells.
  • Proliferation of cells and their subsequent downgrowth into the adjacent connective tissue. (correct)

In exocrine glands, what is the primary role of the 'acinus' or 'secretory portion'?

<p>Synthesizing and secreting various substances. (D)</p> Signup and view all the answers

Which structural feature is used to classify exocrine glands?

<p>The arrangement and complexity of their duct system (B)</p> Signup and view all the answers

What is the key characteristic that distinguishes simple tubular exocrine glands from other types of exocrine glands?

<p>Elongated secretory portion with a typically short or absent duct (D)</p> Signup and view all the answers

How do compound glands differ from simple glands?

<p>Compound glands have ducts that branch extensively, with multiple secretory units converging into larger ducts. (B)</p> Signup and view all the answers

Which example represents a compound acinar exocrine gland?

<p>Salivary glands (C)</p> Signup and view all the answers

What is the key characteristic of holocrine secretion in exocrine glands?

<p>The disintegration of the entire secretory cell, which becomes part of the secretion. (B)</p> Signup and view all the answers

In which type of exocrine secretion is the cell unharmed and intact during the secretion process?

<p>Merocrine secretion (B)</p> Signup and view all the answers

How does apocrine secretion release products?

<p>By pinching off a portion of the apical part of the cell with secretory products inside. (B)</p> Signup and view all the answers

What is commonly secreted by mucous exocrine glands?

<p>Heavily glycosylated, hydrophilic proteins (mucins) (D)</p> Signup and view all the answers

Serous exocrine glands are characterized by the production and secretion of what?

<p>Proteins (D)</p> Signup and view all the answers

What is the primary function of myoepithelial cells associated with exocrine glands?

<p>To facilitate contraction and aid in the expulsion of secretory products (B)</p> Signup and view all the answers

Which trait distinguishes endocrine glands from exocrine glands?

<p>Endocrine glands release hormones into the bloodstream that affect distant target cells (A)</p> Signup and view all the answers

How do endocrine cells release proteins?

<p>By excreting content via exocytosis (B)</p> Signup and view all the answers

How are steroids released from endocrine cells?

<p>Steroids are released via diffusion through the cell membrane. (A)</p> Signup and view all the answers

Unlike exocrine glands, endocrine glands typically lack what?

<p>Myoepithelial cells (B)</p> Signup and view all the answers

What are the key processes generally involved in ion and water transport across epithelia?

<p>Selective transcellular and paracellular pathways, facilitated by membrane proteins and tight junctions (D)</p> Signup and view all the answers

What purpose do tight junctions serve in the mechanism of ion and water transport across epithelia?

<p>Act as selective barriers to regulate paracellular transport (B)</p> Signup and view all the answers

Regarding epithelial cell renewal, what characterizes a stable cell population?

<p>Little mitotic activity under normal conditions (C)</p> Signup and view all the answers

What triggers cell division in a stable cell population?

<p>Stimulation in response to injury. (D)</p> Signup and view all the answers

What role do adult stem cells play in epithelia renewal?

<p>They undergo mitotic activity to produce replacement cells. (D)</p> Signup and view all the answers

Exocrine glands that release their secretions via exocytosis are classified as:

<p>Merocrine (D)</p> Signup and view all the answers

Which type of gland is characterized by secretory units that consist of both acinar and tubular portions?

<p>Tubuloacinar (C)</p> Signup and view all the answers

Which of the following describes the process of transcytosis?

<p>Movement of molecules across the cell. (A)</p> Signup and view all the answers

What causes acne vulgaris?

<p>Excessive sebum and keratin production triggered by hormonal changes. (D)</p> Signup and view all the answers

What structural feature differentiates a branched tubular gland from a simple tubular gland?

<p>Branched tubular glands possess multiple secretory portions draining into a single duct. (C)</p> Signup and view all the answers

Which gland has sections of columnar epithelium?

<p>Submandibular gland (B)</p> Signup and view all the answers

What is the reason that the respiratory tract epithelium needs goblet cells?

<p>To secrete mucus. (A)</p> Signup and view all the answers

Which type of glands don't branch?

<p>Simple glands (A)</p> Signup and view all the answers

Where are glands found that have long secretory sections?

<p>Uterus and stomach (A)</p> Signup and view all the answers

Where are serous glands located?

<p>Salivary glands (D)</p> Signup and view all the answers

Which type of cell stimulates cell division when stimulated in response to injury?

<p>Stable cell population (A)</p> Signup and view all the answers

Which type of gland uses secretion for its mode of exocrine gland secretion?

<p>Merocrine (C)</p> Signup and view all the answers

If all of the acini produce heavily glycosylated, hydrophilic proteins for their secretion what type of gland are they?

<p>Mucous (C)</p> Signup and view all the answers

What structure does exocrine glands typically possess that endocrine glands don't have?

<p>Myoepithelial cells (B)</p> Signup and view all the answers

What function is synthesized by protein or steroid hormones?

<p>Hormone synthesis (B)</p> Signup and view all the answers

What cell population requires Mitotic activity?

<p>Adult stem cells (C)</p> Signup and view all the answers

What is the role of ducts in Exocrine glands?

<p>Secretion Product (D)</p> Signup and view all the answers

What distinguishes the functional characteristic of epithelial cells found in secretory epithelia from those in covering epithelia?

<p>Specialized ability to produce and secrete macromolecules. (A)</p> Signup and view all the answers

Why are goblet cells essential in the respiratory tract epithelium?

<p>To secrete mucus that traps pathogens and particles. (D)</p> Signup and view all the answers

During the development of exocrine glands from surface epithelia, what determines whether the gland remains connected to the surface via a duct?

<p>The persistence of the duct cells after initial proliferation. (B)</p> Signup and view all the answers

How does the presence of myoepithelial cells contribute to the function of certain exocrine glands?

<p>By contracting and aiding in the expulsion of secreted products. (D)</p> Signup and view all the answers

Which of the following is a critical step in the release of steroid hormones from endocrine cells?

<p>Diffusion of the steroid hormones across the cell membrane. (B)</p> Signup and view all the answers

In epithelia with a stable cell population, how do cells respond to injury to maintain tissue integrity?

<p>By increasing mitotic activity stimulated by injury-related signals. (D)</p> Signup and view all the answers

How do tight junctions contribute to the function of epithelial cells involved in ion and water transport?

<p>By preventing paracellular movement of ions and water, ensuring transcellular transport. (A)</p> Signup and view all the answers

What is the key role of adult stem cells in the renewal of epithelial tissues?

<p>To divide and differentiate, replacing damaged or aged cells. (B)</p> Signup and view all the answers

How can the excessive production of sebum and keratin, triggered by hormonal changes, contribute to the development of acne vulgaris?

<p>By blocking ducts in sebaceous glands and promoting bacterial growth. (D)</p> Signup and view all the answers

What structural features are critical in classifying exocrine glands?

<p>Cell shape, duct branching, and layering. (B)</p> Signup and view all the answers

Flashcards

Secretory Epithelia

Epithelial cells that produce and secrete macromolecules, either within epithelia or as specialized organs (glands).

Function of Secretory Cells

Synthesizing, storing, and releasing macromolecules, and secreting water and electrolytes.

Unicellular Gland: Goblet Cells

Scattered secretory cells that are unicellular glands commonly found in simple cuboidal, simple columnar, and pseudostratified epithelium.

Exocrine Glands

Glands that secrete substances into ducts which then lead to a specific location in the body.

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Simple Tubular Gland

Elongated secretory portion; duct usually short or absent, Found in mucous glands of colon and intestinal glands.

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Branched Tubular Gland

Several long secretory parts joining to drain into 1 duct, Found in glands in the uterus and stomach

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Coiled Tubular Gland

Secretory portion is very long and coiled. Sweat glands are an example.

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Acinar (or Alveolar) Gland:

Rounded, saclike secretory portion. Small mucous glands along the urethra are an example.

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Branched Acinar Gland

Multiple saclike secretory parts entering the same duct; Sebaceous glands of the skin are an example.

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Compound Tubular Gland:

Several elongated coiled secretory units and their ducts converge to form larger ducts; Submucosal mucous glands (of Brunner) in the duodenum.

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Compound Acinar (Alveolar) Gland:

Several saclike secretory units with small ducts converge at a larger duct. Exocrine pancreas is an example.

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Compound Tubuloacinar Gland

Ducts of both tubular and acinar secretory units converge at larger ducts. Salivary glands are an example.

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Merocrine Secretion

The cell remains unharmed and intact during the secretion process. Contents transfer from inside the cell to outside the cell via exocytosis. An example is sweat glands

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Holocrine Secretion

Disintegrating cells with contents becoming the secretion.

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Apocrine Secretion

Pinching off of apical portion of secretory cell is the secretion.

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Serous Glands

Glands that secrete proteins in secretions.

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Mucous Glands

Glands that secrete mucous in secretions.

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Seromucous or Mixed Glands

Glands that secrete both serous and mucous in secretions.

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Myoepithelial Cells

Contractile cells that surround glandular cells and help squeeze secretions out.

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Endocrine glands

Glands that secrete hormones directly into the bloodstream; they lack myoepithelial cells.

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Continuously renewing cell population

The most common type of epithelial cell renewal where population continuously replaces itself

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Stable Cell population

Epithelial renewal where cells have the same structural make up and only undergo mitosis based on outside signals, like injury

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Adult Stem Cells

Cells that have the ability to divide and self-maintain to replace other cells that have been damaged.

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Study Notes

Secretory Epithelia

  • Epithelial cells produce and secrete macromolecules.
  • These cells may be part of epithelia with other functions or form specialized organs called glands.

Function of Secretory Cells

  • Secretory cells synthesize, store, and release macromolecules.
  • They also secrete water and electrolytes.

Unicellular Gland: Goblet Cells

  • Scattered secretory cells, known as unicellular glands, are found in simple cuboidal, simple columnar, and pseudostratified epithelium.

Exocrine Glands

  • Exocrine glands are classified based on their structure and the manner and type of their secretions.

Simple Glands (Ducts Do Not Branch)

  • Simple tubular glands feature an elongated secretory portion and a short or absent duct:
    • Examples: Mucous glands of the colon and intestinal glands or crypts of Lieberkühn.
  • Branched tubular glands consist of several long secretory parts draining into one duct:
    • Examples: Glands in the uterus and stomach.
  • Coiled tubular glands have a very long, coiled secretory portion:
    • Examples: Sweat glands.
  • Acinar or Alveolar glands possess a rounded, saclike secretory portion:
    • Examples: Small mucous glands along the urethra.
  • Branched acinar glands have multiple saclike secretory parts entering the same duct:
    • Examples: Sebaceous glands of the skin.

Compound Glands (Ducts from Several Secretory Units Converge into Larger Ducts)

  • Tubular compound glands have several elongated coiled secretory units and their ducts merge to form larger ducts:
    • Examples: Submucosal mucous glands (of Brunner) in the duodenum.
  • Acinar (Alveolar) compound glands consist of several saclike secretory units with small ducts converging at a larger duct:
    • Examples: Exocrine pancreas.
  • Tubuloacinar compound glands feature both tubular and acinar secretory units which converge at larger ducts:
    • Examples: Salivary glands.

Mechanisms of Exocrine Gland Secretion

  • Merocrine glands secrete via exocytosis, where contents transfer from inside the cell to outside, leaving the cell unharmed.
  • Holocrine glands secretion involves disintegration of cells with contents becoming the secretion.
  • Apocrine glands secrete by pinching off of the apical portion of secretory cells.

Types of Secretions

  • Exocrine glands can be classified by the type of secretion they produce.
  • Mucous glands produce mucus.
  • Serous glands secrete a serous fluid.
  • Seromucous, or mixed glands, have both mucus and serous secreting units.

Myoepithelial Cells

  • Exocrine glands contain myoepithelial cells.

Endocrine Glands

  • Endocrine glands lack myoepithelial cells.
  • They specialize in steroid or protein hormone synthesis:
    • Proteins are released by exocytosis.
    • Steroids are released via diffusion through the cell membrane.

Epithelial Cell Renewal

  • Most epithelial cells exhibit a continuously renewing cell population.
  • Some epithelia, such as complex glands and the liver, have a stable cell population with little mitotic activity, only dividing when stimulated by injury.
  • Replacement cells in epithelia are produced by mitotic activity of self-maintaining adult stem cells.

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Description

This lesson covers secretory epithelia, their function in synthesizing and secreting macromolecules, and the classification of exocrine glands. It includes unicellular glands like goblet cells and various types of simple glands based on their structure and secretions. Examples of tubular, branched, and coiled tubular glands are provided.

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