Questions and Answers
What are the functions of cell connections? (Select all that apply)
What are the three types of cell connections?
Desmosomes, Tight junctions, Gap junctions
What are desmosomes?
Disk-shaped regions of cell membrane that adhere cells under stress
What is the function of hemidesmosomes?
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What do tight junctions do?
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What are gap junctions?
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What is an adhesion belt?
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What are intercalated disks?
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Study Notes
Cell Connections
- Located on lateral and basal surfaces of cells, cell connections are essential for maintaining tissue structure and function.
- Perform three main functions: creating a permeability barrier, binding cells together, and facilitating intercellular communication.
- Major types include desmosomes, tight junctions, and gap junctions.
Desmosomes
- Disk-shaped regions of the cell membrane, primarily found in areas exposed to mechanical stress.
- Composed of adhesive glycoproteins that anchor cells together.
- Intermediate filaments extend into the cytoplasm, providing additional support and stability.
Hemidesmosomes
- Serve as half-desmosomes that anchor epithelial cells to the basement membrane.
- Crucial for maintaining the structural integrity of epithelial tissue.
Tight Junctions
- Form impermeable barriers, holding cells tightly together and preventing the passage of substances between them.
- Consist of two types:
- Zonula adherens: Provides a weak adhesive holding adjacent cells together, primarily in simple epithelium.
- Zonula occludens: Acts as a permeability barrier utilizing carrier proteins, found in tissues like the stomach and urinary bladder where it prevents leakage.
Gap Junctions
- Composed of protein channels called connexons that enable direct intercellular communication.
- Facilitate the passage of ions and small molecules, essential for coordinating the activity of cardiac and smooth muscle.
- Play a role in synchronizing ciliary movement in certain epithelial types.
Adhesion Belt
- A layer of glycoproteins located beneath tight junctions that acts as a weak adhesive to hold adjacent cells together.
- Provides less mechanical strength compared to desmosomes, but contributes to tissue cohesion.
Intercalated Disks
- Specialized connections that contain gap junctions, uniquely found between cardiac muscle cells.
- Enable rapid communication and coordination of contractions in cardiac tissue, crucial for heart function.
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Description
Test your knowledge on cell connections, including desmosomes, tight junctions, and hemidesmosomes. This quiz covers their functions, structures, and importance in tissue integrity. Explore how these connections contribute to cellular communication and permeability.
