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Membrane Dynamics and Transport in Anatomy & Physiology Ch.5

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Terms in this set (20)

  • What is osmolarity?

    Osmolarity describes the total number of solute particles in a solution, affecting water movement across membranes.

  • Define osmotic pressure.

    Osmotic pressure is the pressure required to stop water movement by osmosis across a membrane.

  • What is tonicity and its types?

    Tonicity describes how a solution affects cell volume: isotonic (no volume change), hypotonic (cell swells), hypertonic (cell shrinks).

  • What is the difference between molarity and osmolarity?

    Molarity is moles of solute per liter; osmolarity counts total solute particles, including dissociated ions.

  • What creates chemical driving forces for membrane transport?

    A concentration gradient causes molecules to move from high to low concentration, driving passive transport.

  • What is membrane potential and its role in transport?

    Membrane potential is the electrical charge difference across a membrane, influencing ion movement by electrical driving forces.

  • Define electrochemical driving force.

    The electrochemical driving force combines chemical concentration and electrical forces to determine ion movement direction.

  • Difference between passive and active transport?

    Passive transport moves substances down their gradient without energy; active transport moves substances against their gradient using energy.

  • List the seven properties of diffusion.

    Diffusion is passive, moves molecules from high to low concentration, reaches equilibrium, is faster over short distances, increases with temperature, decreases with molecular size, and occurs across membranes or open systems.

  • What factors affect the rate of simple diffusion across membranes?

    Rate depends on molecule lipid solubility, membrane surface area, concentration gradient, and membrane thickness.

  • What are the four major functions of membrane proteins?

    Membrane proteins function as structural proteins, enzymes, receptors, and transport proteins.

  • Compare channel proteins and carrier proteins.

    Channels form open pores for ions or water; carriers bind and change shape to transport specific molecules.

  • What are gated and open channels?

    Gated channels open or close in response to signals; open channels are usually always open.

  • Explain facilitated diffusion.

    Facilitated diffusion uses carrier proteins to move molecules down their concentration gradient without energy.

  • What limits the rate of carrier-mediated transport?

    Transport rate saturates because carriers have a limited number and binding sites, causing a maximum flux.

  • Describe primary active transport.

    Primary active transport uses ATP hydrolysis to move substances against their gradient, e.g., Na+/K+ pump.

  • What is secondary active transport?

    Secondary active transport uses energy from an ion moving down its gradient to transport another substance against its gradient.

  • Name two factors affecting the rate of active transport.

    Rate depends on the number of pumps and the transport rate of individual pumps.

  • Define endocytosis and its types.

    Endocytosis forms vesicles to bring substances into cells; types include pinocytosis, receptor-mediated, and phagocytosis.

  • What is exocytosis?

    Exocytosis releases large molecules from cells by vesicle fusion with the membrane, opposite of endocytosis.