Introduction to Epithelial Tissue

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Questions and Answers

What is a primary function of epithelial tissue?

  • Support
  • Movement
  • Secretion (correct)
  • Conducting nerve signals

What characteristic does epithelial tissue possess that allows it to fit closely together?

  • Continuous sheets (correct)
  • Presence of blood vessels
  • Vascularity
  • Interspersed organ structures

Which type of epithelial cell shape is described as 'cubes'?

  • Columniform
  • Squamous
  • Cuboidal (correct)
  • Columnar

Which of the following is NOT a function of epithelial tissue?

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

What feature describes the underside of epithelial cells?

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

Which type of epithelial tissue is best suited for filtration and absorption?

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

What type of epithelial tissue consists of multiple layers of cells?

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

How does epithelial tissue receive nourishment?

<p>Through connective tissue (A)</p> Signup and view all the answers

What does the term 'apical surface' refer to in epithelial tissue?

<p>The surface facing an open space (C)</p> Signup and view all the answers

Which is NOT a type of epithelial tissue based on cell shape?

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

What is the primary function of simple cuboidal epithelium?

<p>Filtration in kidneys (C)</p> Signup and view all the answers

Which type of epithelium is characterized by elongated cells with nuclei at the same level?

<p>Simple columnar epithelium (C)</p> Signup and view all the answers

Where is pseudostratified epithelium predominantly found?

<p>Respiratory linings (B)</p> Signup and view all the answers

What feature is unique to simple columnar epithelium that enhances its function?

<p>Microvilli on the apical surface (C)</p> Signup and view all the answers

What distinguishes stratified squamous epithelium from other types of epithelial tissue?

<p>It consists of many layers for protection. (D)</p> Signup and view all the answers

What is the main function of transitional epithelium?

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

Which glands release their secretions directly into the bloodstream?

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

Which of the following structures are associated with pseudostratified epithelium?

<p>Goblet cells and cilia (C)</p> Signup and view all the answers

Which location is primarily associated with simple cuboidal epithelium?

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

What is a characteristic of stratified cuboidal epithelium?

<p>Multiple layers of cuboidal cells (B)</p> Signup and view all the answers

Flashcards

Epithelial Tissue

Groups of similar cells forming continuous sheets that cover and line body surfaces and cavities.

Tissues

Groups of cells similar in structure and function.

Epithelial function-Protection

Epithelial tissues form a barrier protecting underlying tissues from pathogens and harm.

Epithelial function-Absorption

Epithelial tissues in the small intestines absorb nutrients into the bloodstream.

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Epithelial function-Filtration

Epithelial tissues in the kidneys filter wastes from blood plasma, maintaining body fluid balance.

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Epithelial function-Secretion

Epithelial tissues form glands that secrete substances like hormones, enzymes, and mucus.

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Simple Squamous Epithelium

Single layer of flattened cells, optimal for diffusion of substances like oxygen and carbon dioxide.

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Apical Surface

Top surface of epithelial cells bordering an open space (lumen).

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Basement Membrane

Layer under epithelial cells, anchoring them to connective tissue

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Avascularity

Epithelial tissues lack blood vessels; nutrients delivered from connective tissue.

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Simple Cuboidal Epithelium

Single layer of cube-shaped cells, involved in secretion, absorption, and filtration.

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Simple Columnar Epithelium

Single layer of elongated cells, specialized for absorption and secretion, often lined with microvilli and goblet cells.

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Pseudostratified Epithelium

Cells appear layered but all touch the basement membrane; involved in absorption, secretion and movement of mucus, often with cilia.

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Stratified Squamous Epithelium

Multiple layers of cells, primarily protective, often keratinized.

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Transitional Epithelium

Specialized for stretching, layers change shape as organ size changes (e.g., bladder).

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Endocrine Glands

Glands that secrete hormones directly into the bloodstream without ducts.

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Exocrine Glands

Glands that secrete their products into ducts that lead to an epithelial surface.

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Stratified Cubodial Epithelium

Multiple layers of cube-shaped cells, primarily protective, often found in ducts and glands.

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Basement Membrane

A thin layer that separates epithelium from underlying connective tissue.

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Cilia

Hair-like projections on epithelial cells that move mucus or fluids.

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Study Notes

Tissue Introduction & Epithelial Tissue

  • Human bodies develop from single to multicellular, cells specialize.
  • The body is an interdependent system, failure of even one group of cells can be catastrophic.
  • Cells become tissues, then organs.
  • Tissues are groups of cells with similar structure and function.

Types of Tissues

  • Epithelium: Coverings & linings of surfaces
  • Connective: Support (bone, ligaments, fat)
  • Muscle: Movement
  • Nervous: Control (brain, nerves, spinal cord)

Function of Epithelial Tissue

  • Protection: Skin protects from sunlight, bacteria, & physical damage.
  • Absorption: Lining of small intestine absorbs nutrients into blood.
  • Filtration: Lining of kidney tubules filters wastes from blood plasma.
  • Secretion: Glands produce perspiration, oil, digestive enzymes & mucus.

Characteristics of Epithelial Tissue

  • Forms continuous sheets (like tiles).
  • Apical Surface: Top surface of cells bordering an open space (lumen).
  • Basement Membrane: Underside of epithelial cells, anchoring them to connective tissue.
  • Avascular: Lacks blood vessels, nourished by connective tissue.
  • Regenerates quickly.

Classification of Epithelial Tissue

  • Cell Shape: Squamous (flattened like fish scales), Cuboidal (cubes), Columnar (columns)
  • Cell Layers: Simple (one layer), Stratified (many layers).
  • Naming is based on the cell type at the apical surface.

Simple Squamous Epithelium

  • Structure: Single layer of flattened cells.
  • Function: Absorption & filtration. Less protection due to single cell layer.
  • Location: Walls of capillaries, air sacs in lungs, and forms serous membranes in body cavities.

Simple Cuboidal Epithelium

  • Structure: Single layer of cube-shaped cells.
  • Function: Secretion & transportation in glands, filtration in kidneys.
  • Location: Glands and ducts (pancreas & salivary), kidney tubules, covers ovaries.

Simple Columnar Epithelium

  • Structure: Elongated layer of cells with nuclei at same level.
  • Function: Absorption, protection, secretion. Forms mucous membranes when open to body cavities.
  • Special Features: Microvilli (increase surface area & absorption), goblet cells (produce mucus).
  • Location: Linings of entire digestive tract.

Pseudostratified Epithelium

  • Structure: Irregularly shaped cells with nuclei at different levels—appear stratified, but all cells reach the basement membrane.
  • Function: Absorption & secretion. Goblet cells secrete mucus, cilia sweep mucus.
  • Location: Respiratory linings & reproductive tract.

Stratified Squamous Epithelium

  • Structure: Many layers, typically cuboidal or columnar at bottom with squamous at top.
  • Function: Protection. Keratin (protein) hardens & waterproofs skin.
  • Location: Skin (keratinized), mouth, & throat.

Transitional Epithelium

  • Structure: Many layers, specialized cells that change between stratified & simple forms based on tissue stretching. Cells at base are cuboidal or columnar; surface cells vary.
  • Function: Allows stretching (size change).
  • Location: Urinary bladder, ureters, & urethra.

Glands

  • Single or multiple cells producing & secreting products.
  • Secretion: Protein in aqueous solution (e.g., hormones, acids, oils).
    • Endocrine: No ducts, release secretions into blood vessels (e.g., hormones, thyroid, adrenal & pituitary).
    • Exocrine: Contain ducts, empty onto epithelial surface (e.g., sweat, oil, salivary, mammary).

Shapes of Exocrine Glands

  • Branching: Simple (unbranched duct) vs. Compound (branched).
  • Shape: Tubular (tube-like) vs. Alveolar (flask or sac-like). vs. Tubuloalveolar (both).

Modes of Secretion

  • Merocrine: Exocytosis, no gland alteration. (e.g., sweat & salivary glands)
  • Holocrine: Gland ruptures, releasing secretion and dead cells. (e.g., sebaceous oil glands)

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