뒤로Anatomy & Physiology: Cell Membranes, Cytoskeleton, and Transport Mechanisms
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Saturated fatty acid tails make the membrane less permeable due to tight packing, while unsaturated tails increase permeability by creating kinks that prevent tight packing.
The cytoskeleton provides structural support, enables cell movement, facilitates intracellular transport, and organizes the cell's components.
Common membrane specializations include cilia for movement, microvilli for absorption, and folds to increase surface area.
Tight junctions seal cells together, desmosomes provide mechanical strength, and gap junctions allow communication between cells.
Passive transport moves substances down their concentration gradient without energy input.
Active transport moves substances against their concentration gradient using cellular energy, usually ATP.
Diffusion is the movement of molecules from an area of higher concentration to lower concentration until equilibrium is reached.
Examples include simple diffusion, facilitated diffusion via carrier proteins, and osmosis for water.
Examples include the sodium-potassium pump and endocytosis and exocytosis processes.
Cilia move fluid, mucus, or cells over their surface, aiding in processes like respiratory tract cleaning.
Microvilli increase the surface area of the plasma membrane to enhance absorption.
Tight junctions prevent leakage of extracellular fluid between cells, maintaining distinct compartments.
Desmosomes anchor cells together, providing mechanical stability in tissues under stress.
Gap junctions allow direct chemical and electrical communication between adjacent cells.
Unsaturated fatty acids increase membrane fluidity by preventing tight packing of phospholipids.
Saturated fatty acids decrease membrane fluidity by allowing phospholipids to pack tightly.
Simple diffusion occurs directly through the membrane, while facilitated diffusion requires carrier or channel proteins.
Osmosis is the passive diffusion of water across a selectively permeable membrane.
Active transport uses ATP as the energy source to move substances against their gradient.
The sodium-potassium pump maintains cell potential by moving 3 Na+ out and 2 K+ into the cell using ATP.