Homeostasis and Cell Membrane Transport
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Questions and Answers

What type of energy is required for active transport?

  • No energy required (correct)
  • Kinetic energy
  • Potential energy
  • Chemical energy
  • Which of the following is NOT a factor that affects the rate of diffusion according to Fick's law?

  • Surface area
  • Membrane thickness
  • Temperature of extracellular fluid (correct)
  • Concentration gradient
  • How does changing the composition of the lipid layer affect membrane permeability?

  • It only increases permeability.
  • It has no effect on permeability.
  • It can increase or decrease permeability. (correct)
  • It only decreases permeability.
  • According to Fick's law, what is the relationship between membrane thickness and the rate of diffusion?

    <p>Reversibly proportional</p> Signup and view all the answers

    What does increased surface area do to the rate of diffusion?

    <p>Increases the rate</p> Signup and view all the answers

    Which component is NOT considered while evaluating membrane permeability?

    <p>Chemical nature of protein</p> Signup and view all the answers

    What role does kinetic energy play in active transport?

    <p>It provides the energy for molecular movement.</p> Signup and view all the answers

    In increasing membrane permeability, which factor is primarily affected?

    <p>Lipid composition</p> Signup and view all the answers

    What symptoms were observed in the 9-month-old boy that indicate dehydration?

    <p>Increased respiratory rate and diminished skin turgor</p> Signup and view all the answers

    What electrolyte imbalances were indicated in the 86-year-old man?

    <p>Hypernatremia and hyperchloremia</p> Signup and view all the answers

    Which transport mechanism allows macromolecules to enter cells through engulfing?

    <p>Phagocytosis</p> Signup and view all the answers

    What is a primary function of the cell membrane?

    <p>Regulating the entry and exit of substances</p> Signup and view all the answers

    What condition was indicative of the 9-month-old boy's state during his treatment?

    <p>Severe dehydration requiring immediate surgical intervention</p> Signup and view all the answers

    What is the primary function of channel proteins in facilitated diffusion?

    <p>To provide corridors for specific molecules to cross the membrane</p> Signup and view all the answers

    Which of the following substances can typically undergo facilitated diffusion?

    <p>Glucose</p> Signup and view all the answers

    What occurs when facilitated diffusion reaches Vmax or Tmax?

    <p>Rate of diffusion stabilizes at the maximum rate</p> Signup and view all the answers

    What is a key characteristic of carrier proteins in facilitated diffusion?

    <p>They undergo shape changes to transport solutes</p> Signup and view all the answers

    In primary active transport, how is energy utilized?

    <p>By hydrolyzing ATP to transport substances against their gradients</p> Signup and view all the answers

    What role does the Na+-K+ ATPase pump play in cellular function?

    <p>It creates an electrical potential across the cell membrane</p> Signup and view all the answers

    Which statement is true about facilitated diffusion?

    <p>It involves specific transport proteins based on solute type</p> Signup and view all the answers

    What defines the term 'chemical specificity' in the context of facilitated diffusion?

    <p>The preferential transport of certain molecules, like glucose and amino acids</p> Signup and view all the answers

    What is the primary function of the Ca2+ ATPase in relation to cell volume?

    <p>To maintain a low cytosolic Ca2+ concentration</p> Signup and view all the answers

    Which scenario describes secondary active transport?

    <p>Transport that relies on the diffusion gradient for Na+</p> Signup and view all the answers

    Which type of secondary active transport involves solutes moving in the same direction as Na+ ions?

    <p>Co-transport (symport)</p> Signup and view all the answers

    Where is H+ ATPase primarily found, according to the content provided?

    <p>In parietal cells of gastric glands</p> Signup and view all the answers

    What happens to secondary active transport processes when Na+/K+ ATPase is inhibited?

    <p>They are diminished due to a reduced Na+ gradient</p> Signup and view all the answers

    What energy source indirectly powers secondary active transport?

    <p>Concentration gradient of Na+ ions</p> Signup and view all the answers

    Which of the following is NOT a type of secondary active transport?

    <p>Facilitated transport</p> Signup and view all the answers

    The process in which a solute moves against its concentration gradient in the opposite direction to Na+ is referred to as what?

    <p>Antiport</p> Signup and view all the answers

    What is the main purpose of endocytosis in a cell?

    <p>To capture substances from outside the cell</p> Signup and view all the answers

    Which type of endocytosis is specifically associated with the ingestion of large particles?

    <p>Phagocytosis</p> Signup and view all the answers

    What initiates the invagination in receptor-mediated endocytosis?

    <p>The clustering of receptors in coated pits</p> Signup and view all the answers

    Which mechanism describes the movement of ions and water through the junctions between epithelial cells?

    <p>Paracellular transport</p> Signup and view all the answers

    What is required for both endocytosis and exocytosis to occur?

    <p>Energy and calcium ions</p> Signup and view all the answers

    Which of the following correctly describes solvent drag?

    <p>Osmosis causing solutes to be reabsorbed along with water</p> Signup and view all the answers

    Which process involves vesicles fusing with the plasma membrane to release contents?

    <p>Exocytosis</p> Signup and view all the answers

    What type of particles does pinocytosis primarily concern?

    <p>Fluids and small particles</p> Signup and view all the answers

    Study Notes

    Homeostasis and Cell Membrane Transport

    • Homeostasis refers to the body's ability to maintain stable internal conditions despite external changes.

    Medical Case Studies

    • A 9-month-old boy presented with diarrhea, vomiting, fever, tachycardia, and a sunken fontanel; treated with intravenous glucose saline.
    • An 86-year-old man showed symptoms of lethargy, confusion, dry mouth, and sunken eyes; diagnosed with hypernatremia and hyperchloremia; treated with 5% glucose in saline.

    Cell Membrane Functions

    • Primary functions include selective permeability and regulation of substance movement.

    Membrane Transport Mechanisms

    • Endocytosis and Exocytosis: Active processes for transporting macromolecules.
      • Endocytosis includes phagocytosis (large particles) and pinocytosis (fluids).
      • Exocytosis involves vesicles merging with the plasma membrane to release contents.

    Transport Types

    • Passive Transport: No ATP required; relies on kinetic energy.
    • Facilitated Diffusion: Assisted by transport proteins, including:
      • Channel Proteins: Provide corridors for specific molecules.
      • Carrier Proteins: Undergo shape changes to transport substances like glucose and amino acids.

    Fick’s Law of Diffusion

    • Diffusion rate is influenced by:
      • Surface area
      • Concentration gradient
      • Membrane permeability
      • Membrane thickness

    Active Transport

    • Primary Active Transport: Requires ATP; substances move against concentration gradients.
      • Example: Na+/K+ ATPase pump (3 Na+ out, 2 K+ in).
    • Secondary Active Transport: Dependent on diffusion gradient from primary transport.
      • Can be symport (same direction with Na+) or antiport (opposite direction).

    Other Membrane Transport Mechanisms

    • Paracellular Transport: Movement between cells (e.g., in kidney tubules).
    • Solvent Drag: Water reabsorption in osmosis carries solutes.

    Receptor-Mediated Endocytosis

    • Involves receptors clustering in coated pits to engulf specific ligands; requires energy and extracellular calcium.

    Exocytosis

    • Active process for releasing substances like hormones and neurotransmitters; requires energy and calcium.

    Summary of Transport Protein Actions

    • Channel Proteins: Allow specific ions/molecules to cross.
    • Carrier Proteins: Change shape to facilitate transport, involving saturation kinetics.
    • Hormonal Regulation: Insulin enhances facilitated diffusion of glucose via GLUT4.

    Important Considerations

    • Changes in lipid layer composition impact membrane permeability.
    • ATPase involvement in Ca2+ and H+ pumps regulates cytoplasmic concentrations.

    These notes cover key concepts related to homeostasis and mechanisms of cell membrane transport, essential for understanding physiological processes in medical contexts.

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    Explore the intricate processes of homeostasis and cell membrane transport in this quiz. Delve into various mechanisms that regulate these vital biological functions. Perfect for students studying advanced biology concepts.

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