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Anatomy & Physiology: Membrane Dynamics and Cell Communication

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Termini in questo insieme (28)

  • Define homeostasis and equilibrium

    Homeostasis is the maintenance of a stable internal environment. Equilibrium is a state where there is no net change, often implying balance in chemical or electrical gradients.

  • Main fluid compartments of the body

    Two main types: Intracellular fluid (ICF) and Extracellular fluid (ECF). ECF is divided into plasma and interstitial fluid.

  • Difference between osmotic equilibrium, chemical disequilibrium, and electrical disequilibrium

    Osmotic equilibrium: equal water concentration across compartments.
    Chemical disequilibrium: different solute concentrations.
    Electrical disequilibrium: unequal charge distribution across membranes.

  • Why is the body electrically neutral despite electrical disequilibrium?

    The body is overall electrically neutral because positive and negative charges balance out globally, but local differences across membranes create electrical disequilibrium.

  • Define osmosis and osmotic pressure

    Osmosis is the movement of water across a semipermeable membrane from low to high solute concentration.
    Osmotic pressure is the pressure required to stop osmosis.

  • Difference between molarity and osmolarity

    Molarity measures moles of solute per liter of solution.
    Osmolarity measures total solute particles per liter, more relevant for physiological effects.

  • Define tonicity and differences between isotonic, hypertonic, and hypotonic solutions

    Tonicity describes a solution's effect on cell volume.
    Isotonic: no volume change.
    Hypertonic: cell shrinks.
    Hypotonic: cell swells.

  • Define bulk flow and give examples

    Bulk flow is the movement of fluid driven by pressure gradients, e.g., blood flow in vessels or air flow in lungs.

  • Selective permeability of cell membranes

    Cell membranes allow some molecules to pass while restricting others, based on size, charge, and lipid solubility.

  • Lipophobic vs lipophilic molecules and membrane transport

    Lipophilic molecules dissolve in lipids and cross membranes easily (e.g., O2).
    Lipophobic molecules do not dissolve in lipids and require transport proteins (e.g., ions).

  • Differences between active and passive transport

    Active transport requires energy to move molecules against gradients.
    Passive transport moves molecules down gradients without energy.

  • Define diffusion and factors affecting its rate

    Diffusion is movement of molecules from high to low concentration.
    Rate affected by temperature, surface area, membrane thickness, molecule size, and concentration gradient.

  • Simple diffusion vs facilitated diffusion

    Simple diffusion is direct passage through membrane.
    Facilitated diffusion uses transport proteins to move molecules down gradients.

  • Four main functional classifications of membrane proteins

    Channels, carriers, receptors, and enzymes.

  • Differences between channel and carrier transport proteins

    Channels allow rapid passage of ions.
    Carriers bind and change shape to transport molecules, slower than channels.

  • Three types of gated ion channels

    Voltage-gated, ligand-gated, and mechanically gated channels open or close in response to stimuli.

  • Three types of carrier proteins

    Uniport (one molecule), symport (two molecules same direction), antiport (two molecules opposite directions).

  • Primary vs secondary active transport

    Primary active transport uses ATP directly.
    Secondary active transport uses energy from ion gradients created by primary transport.

  • Properties of carrier proteins similar to enzymes

    Specificity (bind specific molecules), competition (molecules compete for binding), saturation (limited transport rate).

  • Three vesicular transport mechanisms

    Endocytosis, exocytosis, and transcytosis; all move large molecules or particles via vesicles.

  • Apical vs basolateral sides of epithelial cells

    Apical side faces lumen.
    Basolateral side faces basement membrane and blood supply.

  • Absorption vs secretion; transcellular vs paracellular transport

    Absorption moves substances into the body.
    Secretion moves substances out.
    Transcellular transport crosses cells.
    Paracellular transport passes between cells.

  • Junctions that inhibit paracellular transport

    Tight junctions seal spaces between epithelial cells to prevent paracellular movement.

  • Two basic types of physiological signals

    Electrical signals (e.g., nerve impulses) and chemical signals (e.g., hormones).

  • Two types of cell-to-cell signaling by distance

    Local signaling (short distance, e.g., paracrine) and long-distance signaling (e.g., endocrine).

  • Four basic methods of cell-to-cell communication

    Gap junctions, contact-dependent signals, paracrine/autocrine signaling, and long-distance electrical/chemical signaling.

  • Differences between neurotransmitters, neuromodulators, and neurohormones

    Neurotransmitters act quickly at synapses.
    Neuromodulators modulate neuron activity.
    Neurohormones travel in blood for longer-lasting effects.

  • Common features of signal pathways

    Involve first messenger, receptor, second messenger cascade, protein targets, and cellular responses.