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Anatomy & Physiology: Cell Structure and Membrane Transport (Lecture 4)

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Terms in this set (20)

  • What are the three basic parts of a generalized human cell?
    Plasma membrane (flexible outer boundary), cytoplasm (intracellular fluid with organelles), and nucleus (DNA-containing control center).
  • What is the function of the plasma membrane?
    Acts as an active barrier separating intracellular fluid from extracellular fluid and controls what enters and leaves the cell.
  • What is the composition of the plasma membrane lipid bilayer?
    75% phospholipids (polar hydrophilic heads and nonpolar hydrophobic tails), 5% glycolipids, and 20% cholesterol for stability.
  • What roles do membrane proteins play?
    They allow cell communication, act as transport proteins, enzymes, receptors, and help in cell adhesion and shape.
  • What is the glycocalyx and its function?
    A sugar coating on the cell surface made of glycoproteins and glycolipids that serves as biological markers for cell recognition.
  • Name the three types of cell junctions and their functions.
    Tight junctions: impermeable seals; Desmosomes: anchoring junctions providing strength; Gap junctions: communicating junctions allowing molecule passage.
  • What is simple diffusion?
    Passive movement of lipid-soluble, nonpolar molecules directly through the phospholipid bilayer down their concentration gradient.
  • How does facilitated diffusion differ from simple diffusion?
    Facilitated diffusion uses carrier or channel proteins to transport hydrophilic or larger molecules down their concentration gradient.
  • What is osmosis?
    Diffusion of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration.
  • What factors influence the speed of diffusion?
    Concentration gradient, molecular size (smaller diffuses faster), and temperature (higher temperature increases diffusion rate).
  • Define tonicity and its types.
    Isotonic: no volume change; Hypertonic: cell shrinks; Hypotonic: cell swells and may burst.
  • What is primary active transport?
    Transport of solutes against their concentration gradient using energy directly from ATP hydrolysis.
  • Describe the sodium-potassium pump function.
    Pumps 3 Na+ out and 2 K+ into the cell against their gradients using ATP, maintaining electrochemical gradients essential for nerve and muscle function.
  • What is secondary active transport?
    Uses energy stored in ionic gradients created by primary active transport to move other solutes against their gradients.
  • What is vesicular transport?
    Movement of large particles or fluids across the membrane in vesicles, including endocytosis, exocytosis, transcytosis, and vesicular trafficking.
  • What are the three types of endocytosis?
    Phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (selective uptake using receptors).
  • How do tight junctions function in tissues?
    They form impermeable seals around cells to prevent molecules from passing between cells.
  • What is the role of desmosomes?
    They act like molecular 'velcro' to anchor cells together and provide resistance to mechanical stress.
  • How do gap junctions facilitate cell communication?
    They form channels allowing ions and small molecules to pass directly between adjacent cells, enabling rapid electrical signaling.
  • What is the role of membrane carbohydrates?
    They form the glycocalyx, which helps in cell recognition and immune system identification of self versus non-self.