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Anatomy & Physiology: Homeostasis, Cell Structure, Membrane Transport, and Electrical Potentials

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Terms in this set (22)

  • What is homeostasis?

    Homeostasis is the ability to detect change, activate mechanisms that oppose it, and maintain relatively stable internal conditions.

  • What is negative feedback in homeostasis?

    Negative feedback is a mechanism that reverses a change to maintain dynamic equilibrium around a set point, such as body temperature regulation.

  • Name the three components of a negative feedback loop.

    1. Receptor senses change.
    2. Integrating center processes information.
    3. Effector carries out corrective action.

  • What is positive feedback?

    Positive feedback amplifies a change, leading to greater change in the same direction, such as oxytocin release during childbirth.

  • List the levels of biological organization from simplest to most complex.

    Atom → Molecule → Macromolecule → Organelle → Cell → Tissue → Organ → Organ system → Organism

  • What is the function of the nucleus in a cell?

    The nucleus contains the cell's DNA and controls cellular activities.

  • Describe the role of the mitochondria.

    Mitochondria are the powerhouse of the cell, converting nutrients into ATP (energy).

  • What is the plasma membrane composed of?

    The plasma membrane is a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails inward, making it selectively permeable.

  • What does 'selectively permeable' mean regarding the plasma membrane?

    It means the membrane allows some substances to pass while blocking others, controlling entry and exit of molecules.

  • Name four types of membrane proteins and their functions.

    1. Receptors bind chemicals to communicate.
    2. Enzymes catalyze reactions.
    3. Channels allow solutes/water passage.
    4. Cell identity markers identify cells.

  • What is simple diffusion?

    Movement of particles from high to low concentration down their concentration gradient without energy use.

  • What factors affect the rate of simple diffusion?

    Temperature, molecular weight, steepness of concentration gradient, membrane surface area, and membrane permeability.

  • Define osmosis.

    Osmosis is the net flow of water across a selectively permeable membrane from low to high solute concentration.

  • What is facilitated diffusion?

    Carrier-mediated transport of solutes down their concentration gradient without energy, using membrane proteins.

  • What distinguishes active transport from facilitated diffusion?

    Active transport moves solutes against their concentration gradient and requires ATP, unlike facilitated diffusion.

  • Explain the sodium-potassium pump function.

    The pump moves 3 Na+ ions out and 2 K+ ions into the cell using ATP, maintaining ion gradients essential for cell function.

  • What is resting membrane potential (RMP)?

    RMP is the electrical potential difference across the plasma membrane at rest, typically around −70 mV in neurons.

  • Why is the inside of a resting cell membrane negatively charged?

    Because of unequal ion distribution: more K+ inside, more Na+ outside, and negatively charged proteins inside.

  • What are gated channels and their types?

    Channels that open or close in response to stimuli: voltage-gated, ligand-gated, mechanically-gated, and leak channels.

  • How does filtration differ from diffusion?

    Filtration uses physical pressure to force fluid through a membrane, while diffusion is movement down a concentration gradient.

  • What is the role of membrane receptors in cell communication?

    Membrane receptors bind specific chemicals, triggering intracellular signaling cascades (second messengers) to alter cell activity.

  • What is the significance of the phospholipid bilayer's amphipathic nature?

    It has hydrophilic heads and hydrophobic tails, allowing formation of a stable membrane that controls substance passage.