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Questions and Answers
What type of gland is a goblet cell classified as?
What type of gland is a goblet cell classified as?
Which type of secretion is characteristic of serous glands?
Which type of secretion is characteristic of serous glands?
What distinguishes apocrine glands from other types of glands?
What distinguishes apocrine glands from other types of glands?
Which of the following is an example of a mixed gland?
Which of the following is an example of a mixed gland?
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How do holocrine glands release their secretions?
How do holocrine glands release their secretions?
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What is the primary function of simple squamous epithelium?
What is the primary function of simple squamous epithelium?
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Which type of epithelium is characterized by a single layer of cube-shaped cells?
Which type of epithelium is characterized by a single layer of cube-shaped cells?
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What is a distinguishing feature of simple columnar epithelium?
What is a distinguishing feature of simple columnar epithelium?
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Which of the following statements is true regarding transitional epithelium?
Which of the following statements is true regarding transitional epithelium?
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In which locations can simple squamous epithelium be typically found?
In which locations can simple squamous epithelium be typically found?
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Which of the following describes the arrangement of epithelial cells?
Which of the following describes the arrangement of epithelial cells?
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What characterizes the basal surface of epithelial cells?
What characterizes the basal surface of epithelial cells?
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What is true about the vascularity of epithelial tissues?
What is true about the vascularity of epithelial tissues?
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Which of the following pairs the classification of epithelial tissues correctly?
Which of the following pairs the classification of epithelial tissues correctly?
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What is the relationship between the shape of the cells and the naming of epithelial tissues?
What is the relationship between the shape of the cells and the naming of epithelial tissues?
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What is a defining characteristic of pseudostratified columnar epithelium?
What is a defining characteristic of pseudostratified columnar epithelium?
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What type of stratified squamous epithelium has dead cells filled with keratin?
What type of stratified squamous epithelium has dead cells filled with keratin?
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Which statement is true regarding the function of stratified epithelia?
Which statement is true regarding the function of stratified epithelia?
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What is the primary function of glandular epithelia?
What is the primary function of glandular epithelia?
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Which type of gland secretes hormones directly into the bloodstream?
Which type of gland secretes hormones directly into the bloodstream?
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What are the two main portions of a gland?
What are the two main portions of a gland?
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What type of epithelium lines large ducts of glands?
What type of epithelium lines large ducts of glands?
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What happens to the surface cells of transitional epithelium when the organ is expanded?
What happens to the surface cells of transitional epithelium when the organ is expanded?
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What are the two main types of epithelial tissue?
What are the two main types of epithelial tissue?
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Which germ layer gives rise to the epidermis of the skin and the cornea?
Which germ layer gives rise to the epidermis of the skin and the cornea?
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Which function is NOT typically associated with epithelial tissue?
Which function is NOT typically associated with epithelial tissue?
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Which of the following is a specialization found in the respiratory epithelium?
Which of the following is a specialization found in the respiratory epithelium?
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Endocrine glands are characterized by which of the following features?
Endocrine glands are characterized by which of the following features?
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Which of the following epithelial function helps protect against dehydration?
Which of the following epithelial function helps protect against dehydration?
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What is the primary function of microvilli in epithelial cells?
What is the primary function of microvilli in epithelial cells?
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Which type of epithelium lines the serous cavities of the body?
Which type of epithelium lines the serous cavities of the body?
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Study Notes
Tissues
- Tissues are groups of cells organized to perform one or more functions.
- The cell is the basic structural unit of the body.
- In multicellular organisms, tissues are responsible for maintaining body functions due to the collaborative efforts of their individual cells.
Four Basic Tissue Types
- Epithelium (90% of tumors)
- Connective tissue
- Muscular tissue
- Nervous tissue
Epithelial Tissue
- Covers body surfaces, lines body cavities, and forms glands.
- Two main types:
- Covering and lining: Covers outer body surfaces (skin), inner body surfaces (lumen of hollow organs - intestines), and cavities (peritoneal, pericardial, pleural), blood vessels, ducts, and tubules. They separate the underlying connective tissue from the environment of internal cavities.
- Glandular: Forms glands.
Origin and Distribution of Epithelium
- Ectoderm: Epidermis of skin, cornea epithelium, oral cavity, sebaceous and mammary glands, anterior pituitary
- Endoderm: Alimentary tract, liver, pancreas, gastric glands, intestinal, Endocrine glands (lose connection to surface)
- Mesoderm: Endothelium (lining of blood vessels), Mesothelium (lining serous cavities)
Epithelia Specialized for Functions
- Absorption (intestine)
- Secretion (pancreas)
- Transport (eye, endothelium in vessels)
- Excretion (kidney)
- Protection (against mechanical damage and dehydration)
- Sensory reception (pain, taste, smell)
- Contraction (myoepithelium)
Surface Specializations of Epithelia
- Microvilli: Intestinal absorptive cells
- Cilia: Respiratory epithelium
- Basal lamina: All epithelium
- Intercellular canaliculus: Hepatocytes
- Secretory canaliculus: Gastric parietal cells
- Flagella
Characteristics of Epithelial Tissue
- No extracellular substance between cells
- Cells are tightly attached to each other by special junctions.
- Basal surface attached to an underlying basement membrane (extracellular protein-polysaccharide-rich layer).
- Polarity: Two surfaces—apical (outer) and basal (inner).
Epithelial Tissues and Basement Membrane
- Epithelial cells have an apical surface (free surface) and a basal surface that contacts the basement membrane.
- The basement membrane is a layer made of connective tissue that lies under the epithelium.
Additional Characteristics of Epithelial Tissue
- Avascular: No blood vessels; nourished by diffusion.
- Frequently mitotically active: Capable of dividing quickly.
Morphological Classification of Epithelial Tissues
- Classification based on the number of cell layers and shape of surface cells.
- Simple: One cell layer thick.
- Stratified: Two or more cell layers thick.
- Shape of Surface Cells:
- Squamous: Flat cells
- Cuboidal: Cube-shaped cells
- Columnar: Tall, column-shaped cells
Epithelia: Histological Identification
- Simple squamous: Single layer of flat cells; lines blood vessels, organs.
- Simple cuboidal: Single layer of cube-shaped cells; lines kidney tubules, liver cells, etc.
- Simple columnar: Single layer of tall, thin cells; lines intestine, etc.
- Stratified squamous: Multiple layers of cells; outer layers flat; covers skin, gums.
Simple Squamous Epithelium
- Single layer of flat cells, very thin.
- Lines blood vessels (endothelium), closed body cavities (mesothelium), alveoli in the lungs.
- Function: Controls diffusion, osmosis, and filtration.
Mesothelium and Endothelium
- Mesothelium: Lines closed body cavities.
- Endothelium: Lines blood vessels
Simple Cuboidal Epithelium
- Single layer of cube-shaped cells.
- Lines tubules and ducts
Simple Columnar Epithelium
- Single layer of tall, thin columnar cells.
- Lines stomach, intestine; Often has microvilli (finger-like projections) for absorption.
Pseudostratified Columnar Epithelium
- Appears layered but all cells contact basement membrane, not all reach free surface.
- Nuclei at varying depths.
Stratified Squamous Epithelium
- Several cell layers thick
- Two types:
- Keratinized: Outer layers of dead cells filled with keratin; skin
- Nonkeratinized: Moist, living cells at apical surface; cornea
Stratified Cuboidal Epithelium
- Surface cells are cuboidal
- Lines sweat gland ducts
Stratified Columnar Epithelium
- Surface cells are columnar;
- Lines large ducts of glands
Transitional Epithelium
- Multilayered; surface cells vary in shape, round to flat when stretched.
- Lines hollow organs of urinary tract.
Glandular Epithelia
- Secretion is the primary function.
- Secretion is a cyclical process with 4 phases:
- Diffusion of metabolites into cells
- Proper synthesis
- Release of substances from cells
- Cell restoration
Mechanisms of Glandular Secretion
- Merocrine: Secretion released via exocytosis; cells remain intact
- Apocrine: Secretion released with a portion of the cytoplasm; cells remain intact.
- Holocrine: Entire cell disintegrates to release secretions.
Gland Parts
- Parenchyma: Secretory cells
- Stroma: Connective tissue framework
Gland Types
- Exocrine: Secretes through ducts onto a surface or into a cavity
- Unicellular (e.g., goblet cells)
- Multicellular (e.g., salivary, sweat)
- Classified by secretion type: mucous, serous, mixed
- Classified by structure: tubular, alveolar (acinar), tubuloalveolar
- Endocrine: Secretes hormones into blood.
Functions of Epithelial Tissue
- Transport across the epithelium
- Protection of underlying tissues
- Secretion and excretion of various substances
- Communication (e.g. hormones, nerve signaling, etc)
- Absorption / passage of substances across.
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Description
Test your knowledge on the various types of epithelial tissues and their characteristics with this quiz. Questions cover gland types, secretion methods, and tissue arrangements. Perfect for students studying histology or anatomy.
