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Anatomy & Physiology CH. 3: Cells and Membranes

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이 집합의 용어 (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 plasma membrane primarily composed of?
    A lipid bilayer made of 75% phospholipids, 5% glycolipids, and 20% cholesterol, forming a flexible, fluid mosaic structure.
  • What is the function of phospholipid heads and tails in the membrane?
    Phosphate heads are polar and hydrophilic (water-loving), while fatty acid tails are nonpolar and hydrophobic (water-hating), creating a bilayer.
  • What roles do membrane proteins play?
    They enable transport, intercellular joining, signal transduction, attachment to cytoskeleton and matrix, enzymatic activity, and cell recognition.
  • What is the glycocalyx and its function?
    A sugar coating of carbohydrates on the cell surface that acts as a biological marker for cell recognition and immune system identification.
  • What are the three main types of cell junctions?
    Tight junctions (impermeable barriers), desmosomes (anchoring junctions), and gap junctions (channels for communication).
  • Where are tight junctions commonly found and what is their function?
    Found in the lining of the digestive tract, they prevent substances from passing between cells by forming an impermeable seal.
  • How do desmosomes function and where are they found?
    They use cadherin proteins to anchor cells together like molecular Velcro, found in skin and cardiac tissue to resist mechanical stress.
  • What is the role of gap junctions and where are they important?
    They form protein tunnels allowing ions and small molecules to pass quickly, important in cardiac and muscle tissue for electrical coupling.
  • What is the difference between passive and active membrane transport?
    Passive transport requires no energy and moves substances down their concentration gradient; active transport requires ATP and moves substances against the gradient.
  • What are the three types of passive membrane transport?
    Simple diffusion, facilitated diffusion, and osmosis, all moving substances from high to low concentration.
  • What substances typically move by simple diffusion?
    Nonpolar, lipid-soluble substances like oxygen, carbon dioxide, steroid hormones, and fatty acids diffuse directly through the lipid bilayer.
  • What is facilitated diffusion and its two major types?
    Movement of substances via protein carriers or channels down their concentration gradient; includes carrier-mediated and channel-mediated diffusion.
  • What is osmosis and how does it relate to solute concentration?
    Osmosis is the diffusion of water across a membrane from low solute (high water) to high solute (low water) concentration.
  • What is the glycocalyx's role in cancer cell immune evasion?
    Rapid changes in the glycocalyx can prevent the immune system from recognizing mutated cancer cells, allowing them to replicate.
  • What are extracellular fluids and examples?
    Fluids outside cells including interstitial fluid, blood plasma, and cerebrospinal fluid that surround and support cells.
  • What is the extracellular matrix?
    A substance outside cells that acts as glue to hold cells together in tissues.
  • What are the two types of membrane proteins?
    Integral proteins embedded in the membrane and peripheral proteins attached to the membrane surface.
  • How do channel-mediated facilitated diffusion channels differ?
    Channels can be leakage channels (always open) or gated channels (controlled by chemical or electrical signals).
  • Why can't pure water be used directly for IV fluids?
    Pure water is hypotonic and can cause red blood cells to swell and burst due to osmotic imbalance.