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Cell Transport Processes in Anatomy & Physiology

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Terms in this set (21)

  • What is passive transport across the cell membrane?
    Movement of molecules from high to low concentration without energy input, including simple diffusion, facilitated diffusion, and osmosis.
  • Define simple diffusion.
    Movement of nonpolar lipid-soluble substances directly through the phospholipid bilayer down their concentration gradient without energy.
  • What types of molecules typically move by simple diffusion?
    Oxygen, carbon dioxide, steroid hormones, fatty acids, and small amounts of water.
  • Describe carrier-mediated facilitated diffusion.
    Transport of specific polar molecules like sugars and amino acids by transmembrane proteins that change shape to move molecules down their concentration gradient without energy.
  • What is channel-mediated facilitated diffusion?
    Movement of ions or molecules through water-filled protein channels down their concentration gradient without energy.
  • What are the two types of channels in channel-mediated facilitated diffusion?
    Leakage channels (always open) and gated channels (controlled by chemical or electrical signals).
  • Explain osmosis in cell transport.
    Movement of water through a selectively permeable membrane from low solute (high water) concentration to high solute (low water) concentration.
  • How does water cross the plasma membrane during osmosis?
    Through the lipid bilayer and specific water channels called aquaporins.
  • What is osmolarity?
    The total concentration of all solute particles in a solution, expressed in osmoles per liter (osmol/L).
  • Define tonicity and its types.
    Ability of a solution to change cell water volume: isotonic (no change), hypertonic (cell shrinks), hypotonic (cell swells).
  • What is active transport?
    Energy-requiring process that moves solutes against their concentration gradient using ATP.
  • Describe primary active transport.
    Direct use of ATP hydrolysis by transport proteins (pumps) to move ions like Na+ and K+ across the membrane.
  • What is the sodium-potassium pump?
    A primary active transport pump that moves 3 Na+ out and 2 K+ into the cell using ATP.
  • Explain secondary active transport.
    Uses energy stored in ion gradients created by primary active transport to move multiple substances via cotransport proteins.
  • Differentiate symporters and antiporters in secondary active transport.
    Symporters move two substances in the same direction; antiporters move one substance in while moving another out.
  • What is vesicular transport?
    Active transport moving large substances or amounts across membranes inside vesicles, requiring ATP.
  • Name the two main types of vesicular transport.
    Endocytosis (into cell) and exocytosis (out of cell).
  • Describe phagocytosis.
    Endocytosis where the cell engulfs large particles by forming pseudopods, creating a phagosome that fuses with lysosomes.
  • What is pinocytosis?
    Non-specific endocytosis where the cell ingests extracellular fluid and dissolved solutes in tiny vesicles.
  • Explain receptor-mediated endocytosis.
    Selective endocytosis where substances bind to specific receptors, triggering vesicle formation to ingest and concentrate substances.
  • What occurs during exocytosis?
    Vesicles fuse with the plasma membrane to eject substances like hormones, neurotransmitters, mucus, or wastes from the cell.