The myocardium (cardiac muscle tissue) undergoes a significant amount of mechanical stress due to its contractions. You would expect to see relatively large numbers of which of the following embedded within their plasma membrane?
transport proteins
glycolipids
tight junctions
desmosomes
The Correct Answer is D
A. Transport proteins: Transport proteins are essential for moving ions, nutrients, and other molecules across the plasma membrane. While they play an important role in cardiac muscle function, they do not address mechanical stress caused by repeated contractions.
B. Glycolipids: Glycolipids contribute to cell recognition, signaling, and stability of the cell membrane. However, they are not structural elements that resist the pulling forces and stress cardiac muscle cells experience during contraction.
C. Tight junctions: Tight junctions create a seal between adjacent cells to prevent leakage of extracellular fluid. In cardiac muscle, their role is less about mechanical strength and more about maintaining selective permeability, so they do not counteract contractile stress effectively.
D. Desmosomes: Desmosomes are strong anchoring junctions that mechanically bind cardiac muscle cells together. They provide structural integrity and prevent separation during forceful contractions, making them the key feature that resists mechanical stress in the myocardium.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Left upper quadrant: The spleen is located in the left upper quadrant of the abdominopelvic cavity, tucked under the diaphragm and lateral to the stomach. It plays a role in filtering blood, recycling red blood cells, and supporting the immune system.
B. Left lower quadrant: The left lower quadrant primarily contains parts of the descending colon, sigmoid colon, and some reproductive organs. The spleen is not located in this region.
C. Right upper quadrant: The right upper quadrant contains the liver, gallbladder, part of the pancreas, and portions of the small intestine, but not the spleen.
D. Right lower quadrant: The right lower quadrant houses structures such as the appendix, cecum, and portions of the small intestine.
Correct Answer is C
Explanation
A. Pinocytosis: Pinocytosis is a form of endocytosis where the cell engulfs extracellular fluid and dissolved solutes. This process requires energy in the form of ATP to allow vesicle formation and internalization, so it is restricted by ATP availability.
B. Exocytosis: Exocytosis involves vesicles fusing with the plasma membrane to release substances outside the cell. The vesicle movement and membrane fusion are energy-dependent processes, making ATP essential for this mechanism.
C. Osmosis: Osmosis is the passive movement of water molecules across a selectively permeable membrane, driven by concentration gradients. Since it does not require cellular energy, it is not restricted by ATP levels and can occur even when ATP is depleted.
D. Phagocytosis: Phagocytosis is the engulfment of large particles or pathogens by the cell. This process requires ATP to reorganize the cytoskeleton and form phagosomes, so limited ATP availability would restrict its function.
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