The statements below all pertain to cellular junctions. Select the terms from the drop-downs to accurately complete the sentences. 1. Epithelial cells of the (Click to select) are held together by (Click to select) junctions, which prevent lumenal contents from leaking between cells. 2. Cells of the (Click to select) can contract without chemical synapses because of (Click to select) junctions. 3. Because of (Click to select) , adjacent cells can resist being pulled apart. 4. Epithelial cells can resist being pulled away from their (Click to select) because of (Click to select)
The Correct Answer and Explanation is:
Here is the correctly completed version of the statements:
- Epithelial cells of the small intestine are held together by tight junctions, which prevent lumenal contents from leaking between cells.
- Cells of the heart can contract without chemical synapses because of gap junctions.
- Because of desmosomes, adjacent cells can resist being pulled apart.
- Epithelial cells can resist being pulled away from their basement membrane because of hemidesmosomes.
Explanation
Cells in the body often need to work closely together, and this is especially true in tissues like epithelium and cardiac muscle. Various specialized structures, called cellular junctions, ensure that cells maintain physical contact, communicate, and stay anchored where they are needed. The four main types relevant to this context are tight junctions, gap junctions, desmosomes, and hemidesmosomes.
Tight junctions are found at the top, or apical, side of epithelial cells such as those in the small intestine. They form a seal that blocks the movement of substances between cells, making sure that nutrients or toxins in the intestinal lumen do not leak into the tissues below.
Gap junctions are found in tissues that require quick and coordinated communication, like the heart. These junctions form channels between neighboring cells that allow ions and small molecules to pass directly from one cell to another. This enables the heart cells to contract together without needing chemical synapses.
Desmosomes act like molecular rivets. They connect the cytoskeletons of adjacent cells and provide strength to tissues under mechanical stress, such as skin and cardiac muscle. This is how cells resist being pulled apart.
Hemidesmosomes are similar in structure to desmosomes, but instead of connecting two cells, they anchor cells to the basement membrane, which is a sheet of extracellular material that supports epithelial tissue. This anchoring keeps the epithelial layer stable and prevents it from detaching under stress.
Each of these junctions plays a unique role in maintaining the integrity, communication, and function of tissues in the human body.
