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Questions and Answers
Which type of epithelium is specialized for the sense of taste?
Which type of epithelium is specialized for the sense of taste?
What is the primary function of the cells in taste buds?
What is the primary function of the cells in taste buds?
What shape do the cells of the taste buds primarily have?
What shape do the cells of the taste buds primarily have?
Which type of junction forms a tight seal between adjacent epithelial cells?
Which type of junction forms a tight seal between adjacent epithelial cells?
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What is the main role of the supporting cells in the taste buds?
What is the main role of the supporting cells in the taste buds?
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Which of the following describes the structure of tight junctions?
Which of the following describes the structure of tight junctions?
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What type of binding material is associated with adherens junctions?
What type of binding material is associated with adherens junctions?
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Which of the following best describes the shape of taste bud cells?
Which of the following best describes the shape of taste bud cells?
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What is the primary function of adherens junctions in epithelial cells?
What is the primary function of adherens junctions in epithelial cells?
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What structural component is present within desmosomes that loops back into the cytoplasm?
What structural component is present within desmosomes that loops back into the cytoplasm?
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Which type of cellular connection allows for the direct passage of ions between adjacent cells?
Which type of cellular connection allows for the direct passage of ions between adjacent cells?
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What is a characteristic of the two cell membranes in gap junctions?
What is a characteristic of the two cell membranes in gap junctions?
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Which structure helps to increase the surface area for absorption in epithelial cells?
Which structure helps to increase the surface area for absorption in epithelial cells?
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Where are stereocilia primarily found?
Where are stereocilia primarily found?
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What defines epithelial cells as 'polarized'?
What defines epithelial cells as 'polarized'?
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What is the role of cilia in epithelial tissue?
What is the role of cilia in epithelial tissue?
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Which structure is responsible for transmitting taste sensations through interaction with dissolved tastants?
Which structure is responsible for transmitting taste sensations through interaction with dissolved tastants?
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What type of stem cells exist in taste buds that contribute to the regeneration of sensory cells?
What type of stem cells exist in taste buds that contribute to the regeneration of sensory cells?
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What is the primary difference between zonula occludens and fascia occludens in terms of their junctions?
What is the primary difference between zonula occludens and fascia occludens in terms of their junctions?
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Which intercellular junction involves cadherin and actin filaments as part of its structure?
Which intercellular junction involves cadherin and actin filaments as part of its structure?
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What is the approximate intercellular space width associated with adherens junctions?
What is the approximate intercellular space width associated with adherens junctions?
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Which type of epithelial cells are involved in the reception of auditory stimuli?
Which type of epithelial cells are involved in the reception of auditory stimuli?
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In terms of volumetric measurements, which structure's shapes do the cells in taste buds exhibit?
In terms of volumetric measurements, which structure's shapes do the cells in taste buds exhibit?
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What role does the opening called the taste pore play in the function of taste buds?
What role does the opening called the taste pore play in the function of taste buds?
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What is the primary structural component that makes up adherens junctions?
What is the primary structural component that makes up adherens junctions?
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Which feature distinguishes gap junctions from other types of junctions?
Which feature distinguishes gap junctions from other types of junctions?
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How do tonofilaments contribute to the function of desmosomes?
How do tonofilaments contribute to the function of desmosomes?
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Which epithelial surface adaptation is specifically involved in increasing the absorption surface area?
Which epithelial surface adaptation is specifically involved in increasing the absorption surface area?
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What is a distinct characteristic of polarized epithelial cells?
What is a distinct characteristic of polarized epithelial cells?
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Which type of cells primarily utilize gap junctions for intercellular communication during contraction?
Which type of cells primarily utilize gap junctions for intercellular communication during contraction?
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What connects the base of epithelial cells to the basement membrane?
What connects the base of epithelial cells to the basement membrane?
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Which of the following is a function of cilia in epithelial tissues?
Which of the following is a function of cilia in epithelial tissues?
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Study Notes
Epithelial Cells for Sensory Reception
- Epithelial cells specialize in receiving external sensory stimuli.
- Olfactory Epithelium: Responsible for the sense of smell.
- Retina: Contains rods and cones, responsible for vision.
- Organ of Corti: Located in the inner ear, essential for hearing.
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Taste Buds: Onion-shaped structures containing specialized cells for taste perception:
- Sensory Cells: Tall cells with microvilli projecting through a taste pore.
- Supporting Cells: Provide support for sensory cells.
- Basal Cells: Act as stem cells, replenishing other cell types.
Cell Junctions: Connecting Epithelial Cells
-
Occludens (Tight) Junctions: Membranes of adjacent cells fuse, forming a tight seal that prevents flow between intercellular and luminal fluids.
- Zonula Occludens: Forms a complete seal around the cell.
- Fascia Occludens: Creates a patchy seal.
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Adherens Junctions: Adjacent membranes are bound by intercellular binding material.
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Desmosomes: Spot-like junctions that provide strong adhesion between cells. These junctions consist of:
- Intercellular space filled with binding substance.
- Two cell membranes.
- Electron dense plaques on the cytoplasm.
- Tonofilaments (intermediate filaments) that attach to the plaques.
- Hemidesmosomes: Connect the base of epithelial cells to the basement membrane.
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Desmosomes: Spot-like junctions that provide strong adhesion between cells. These junctions consist of:
-
Gap Junctions: Allow for direct communication between the cytoplasm of adjacent cells through hydrophilic channels.
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Function:
- Allow passage of ions between cells.
- Facilitate conduction of electrical signals like muscle contractions.
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Function:
Modifications of the Epithelial Cell Surface
- Epithelial cells are polarized, meaning they have distinct apical, basal, and lateral surfaces.
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Microvilli: Short, finger-like projections, increasing surface area for absorption. Found in:
- Intestines
- Proximal convoluted tubules of kidneys.
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Stereocilia: Long, non-motile microvilli. Found in:
- Epididymis.
- Inner ear receptors for hearing and equilibrium.
- Cilia: Hair-like projections that move in coordinated waves.
- Flagella: Long and whip-like, used for movement.
Epithelium & Sensory Reception
- Epithelial cells are specialized for reception of external sensory stimuli.
- Olfactory Epithelium: responsible for the sense of smell.
- Retina: contains light-sensitive cells, rods and cones, that detect light for vision.
- Organ of Corti: located in the inner ear, responsible for hearing.
-
Taste Buds: onion-shaped structures that contain taste receptor cells for the sense of taste.
- Each taste bud contains 50-100 cells.
- Taste Receptor Cells: tall with an oval nucleus, microvilli project through the taste pore, and are surrounded by sensory nerve axons.
- Supporting Cells: tall & support the sensory cells.
- Basal Cells: pyramidal, located between the taste and supporting cells, and function as stem cells, dividing to produce other cell types.
Cell Junctions
- Structures that join adjacent cells, creating pathways for communication and providing structure.
-
Occludens (Tight) Junctions: fuse the outer surfaces of adjacent cell membranes, forming a seal between intercellular and luminal fluids.
- Zonula Occludens: a complete band of fusion that encircles the cell.
- Fascia Occludens: a patchy fusion of adjacent cell membranes.
-
Adherens Junctions: join adjacent cell membranes by intercellular binding material.
- The intercellular space is filled with an electron-dense binding substance (cadherin).
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Desmosomes: a type of spot adhesion junction.
- Hemidesmosomes: half desmosomes, join the base of epithelial cells to the basement membrane.
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Gap Junctions: link the cytoplasm of adjacent cells.
- Cell membranes are separated by approximately 2nm.
- Cylindrical protein structures form hydrophilic channels that directly link the cytoplasm of adjacent cells.
Epithelial Cell Structures
- Epithelial cells have apical, basal, and lateral surfaces, each with specific modifications for function.
-
Microvilli: short, finger-like projections that increase surface area for absorption.
- Found in the intestines and proximal convoluted tubules of the kidneys.
-
Stereocilia: long and non-motile microvilli, involved in absorption.
- Found in the epididymis.
-
Cilia: motile hair-like structures that aid in movement.
- Found in the respiratory tract and fallopian tubes.
-
Flagella: long, whip-like structures involved in movement.
- Found in sperm cells.
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