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Anatomy & Physiology: Cell Membrane Transport and Cell-Environment Interactions

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Terms in this set (20)

  • What are the two major active membrane transport processes?
    Active transport and vesicular transport, both requiring ATP to move solutes across the plasma membrane.
  • What is the role of carrier proteins in active transport?
    Carrier proteins bind specifically and reversibly with substances, moving solutes against their concentration gradient using energy from ATP.
  • What is the difference between antiporters and symporters?
    Antiporters transport one substance into the cell while moving another out; symporters transport two substances in the same direction.
  • What distinguishes primary active transport from secondary active transport?
    Primary active transport uses energy directly from ATP hydrolysis; secondary active transport uses energy stored in ionic gradients created by primary active transport.
  • How does the sodium-potassium pump function?
    It pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell against their concentration gradients using ATP, maintaining electrochemical gradients.
  • Why are leakage channels important in cells?
    Leakage channels allow Na+ to leak into the cell and K+ to leak out, traveling down their concentration gradients, which the Na+-K+ pump counteracts.
  • What is secondary active transport and how does it work?
    It uses the ion gradient created by primary active transport to drive the transport of other solutes, often with Na+ dragging molecules like glucose into the cell.
  • What are the three types of endocytosis?
    Phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (selective uptake via receptors).
  • Describe phagocytosis.
    The cell engulfs large particles by forming pseudopods that surround the particle, creating a phagosome that fuses with lysosomes for digestion.
  • What is pinocytosis?
    A nonspecific process where the plasma membrane infolds to bring extracellular fluid and dissolved solutes into the cell in vesicles.
  • How does receptor-mediated endocytosis differ from other types?
    It involves specific receptors binding substances, concentrating them in clathrin-coated vesicles for selective uptake.
  • What is exocytosis and what triggers it?
    Exocytosis ejects material from the cell via secretory vesicles, usually triggered by cell-surface signals or changes in membrane voltage.
  • What is resting membrane potential (RMP)?
    The electrical potential energy from separation of oppositely charged particles across the plasma membrane, typically between –50 to –100 mV.
  • How does K+ contribute to the resting membrane potential?
    K+ diffuses out through leakage channels, leaving behind negatively charged proteins, creating a negative charge inside the cell that balances K+ movement.
  • Why does Na+ have less influence on RMP than K+?
    Because the membrane is more permeable to K+ than Na+, so K+ primarily sets the RMP despite Na+ being attracted inside.
  • How does the Na+-K+ pump maintain electrochemical gradients?
    By continuously pumping 3 Na+ out and 2 K+ in, it balances ion diffusion and maintains the steady state of RMP.
  • What are cell adhesion molecules (CAMs) and their functions?
    Sticky glycoproteins on cell surfaces that anchor cells, assist movement, attract WBCs, regulate junctions, and transmit signals for migration and specialization.
  • What roles do plasma membrane receptors play?
    They bind chemical signals for contact and chemical signaling, triggering enzyme activation or ion channel opening to change cellular activity.
  • How do G protein–linked receptors work?
    They activate G proteins that relay signals inside the cell, affecting ion channels, enzymes, or releasing second messengers like cyclic AMP.
  • What is the glycocalyx and its function?
    A sugar coating on the cell surface made of glycolipids and glycoproteins that acts as a biological marker for cell recognition and immune response.