Biology Chapter on Osmosis and Osmotic Pressure
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Questions and Answers

What is a key characteristic of active transport mechanisms?

  • They operate from higher to lower concentration.
  • They facilitate the passive movement of water.
  • They require energy to move substances against a gradient. (correct)
  • They do not require carrier molecules.

    • In primary active transport, the energy derives directly from which source?

  • Light energy from the environment
  • The breakdown of ATP (correct)
  • Stored ionic concentrations
  • Temperature differences across the membrane

    • What process uses the electrochemical gradient established by primary active transport?

  • Osmosis
  • Facilitated diffusion
  • Endocytosis
  • Secondary active transport (correct)

    • Which example is NOT associated with primary active transport?

    <p>Osmotic balance via aquaporins</p> Signup and view all the answers

    What is the general function of carrier proteins in the context of active transport?

    <p>To undergo conformational changes for transport</p> Signup and view all the answers

    What is the primary fluid found within all body cells?

    <p>Intracellular fluid</p> Signup and view all the answers

    Which of the following fluids surrounds the cells and serves as an exchange medium?

    <p>Interstitial fluid</p> Signup and view all the answers

    How many liters of plasma are there in a body with 70 kg total body water?

    <p>3.5 L</p> Signup and view all the answers

    What significant charge characterizes the proteins found in intracellular fluid?

    <p>Negative charge</p> Signup and view all the answers

    What is the role of homeostasis in the body?

    <p>To maintain a stable internal environment</p> Signup and view all the answers

    Which component of extracellular fluid is responsible for the transport of nutrients and waste products?

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

    What is the main ion found in high concentration within intracellular fluid?

    <p>K+</p> Signup and view all the answers

    What distinguishes extracellular fluid from intracellular fluid?

    <p>Exists outside the cells</p> Signup and view all the answers

    Which process is primarily responsible for maintaining osmotic balance in the body?

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

    What is the main factor contributing to the high fluid levels in the intracellular space compared to extracellular fluid?

    <p>Greater potassium concentration</p> Signup and view all the answers

    Which type of transport mechanism requires a special membrane protein?

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

    What is the primary characteristic that distinguishes active transport from passive transport mechanisms?

    <p>Requirement for energy</p> Signup and view all the answers

    What is the approximate resting membrane potential of a cell?

    <p>-70 mV</p> Signup and view all the answers

    Which transport mechanism moves substances in the same direction as sodium ions?

    <p>Co-transporters</p> Signup and view all the answers

    What is a common feature of facilitated diffusion?

    <p>Utilizes channel or carrier proteins</p> Signup and view all the answers

    What is NOT a property of passive transport mechanisms?

    <p>Requires energy</p> Signup and view all the answers

    Which physiological process relies on changes in resting potential for signaling?

    <p>Neuronal signaling</p> Signup and view all the answers

    How does active transport typically move substances?

    <p>Against a concentration gradient</p> Signup and view all the answers

    What defines amphipathic molecules?

    <p>Contains both hydrophilic and hydrophobic regions</p> Signup and view all the answers

    What process is essential for maintaining osmotic balance in cells?

    <p>Active transport of ions</p> Signup and view all the answers

    What is the primary direction of water movement during osmosis?

    <p>From regions of lower solute concentration to regions of higher solute concentration</p> Signup and view all the answers

    What occurs to a cell in a hypotonic solution?

    <p>The cell will swell as water enters</p> Signup and view all the answers

    What is the osmotic pressure of human cells equivalent to?

    <p>0.9% NaCl solution</p> Signup and view all the answers

    What happens to cells in a hypertonic solution?

    <p>Cells lose water and shrink</p> Signup and view all the answers

    Why is an isotonic NaCl solution preferred over an isoosmotic solution of penetrating solutes like urea for restoring blood volume?

    <p>Because isotonic NaCl does not penetrate cells, maintaining osmotic balance</p> Signup and view all the answers

    In which scenario would osmosis not occur?

    <p>When the osmotic pressure is equal on both sides of a membrane</p> Signup and view all the answers

    What is the effect of an isotonic environment on a cell?

    <p>No net movement of water occurs into or out of the cell</p> Signup and view all the answers

    What is the primary goal of homeostasis?

    <p>To ensure survival and function of all cells</p> Signup and view all the answers

    What role does osmosis play at the tissue level?

    <p>It allows for water movement across epithelial cells</p> Signup and view all the answers

    Which factor is NOT homeostatically regulated?

    <p>Atmospheric pressure</p> Signup and view all the answers

    Which component of the homeostatic control mechanism is responsible for monitoring internal conditions?

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

    What is the function of the effector in the homeostatic control mechanisms?

    <p>To elicit responses that change internal conditions</p> Signup and view all the answers

    Homeostasis relies primarily on which type of feedback mechanism?

    <p>Negative Feedback loops</p> Signup and view all the answers

    What happens when there is a failure to compensate for homeostatic imbalances?

    <p>Illness and potentially death can occur</p> Signup and view all the answers

    Which of the following best describes the relationship between homeostasis and the external environment?

    <p>Homeostasis allows for dynamic changes despite external variations</p> Signup and view all the answers

    Which of the following is an example of a factor that homeostasis regulates?

    <p>Nutrient concentration</p> Signup and view all the answers

    In the context of homeostasis, what does the term 'set point' refer to?

    <p>The optimal value that internal conditions aim to maintain</p> Signup and view all the answers

    What might be a physiological consequence of failing to regulate body temperature?

    <p>Potential for hypothermia or hyperthermia</p> Signup and view all the answers

    Study Notes

    Osmosis

    • Movement of water through a selectively permeable membrane from regions of higher concentration to regions of lower concentration.
    • Water moves from high concentration of water to lower concentration of water (and from lower concentration of solutes to higher concentration of solutes).
    • Important at cellular level, causing cells to shrink or swell.
    • Important at tissue level, osmosis occurs through epithelial cells in the GIT and renal system. It also occurs through capillary walls.

    Osmotic Pressure

    • The osmotic pressure inside human cells is equal to the concentration of a 0.9% solution of sodium chloride (99.1 g water + 0.9 g NaCl).
    • 0.9% NaCl solution is called “normal or physiologic saline”.
    • Hypotonic: OP in extracellular fluid is less than OP intracellular fluid, causing water to enter the cell.
    • Hypertonic: OP in extracellular fluid is greater than OP intracellular fluid, causing the cell to lose water.
    • Isotonic: OP in extracellular fluid is equal to OP intracellular fluid, resulting in hydrostatic equilibrium.

    Active Transport

    • Carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration.
    • Examples: glucose, amino acids, sodium ions, potassium, calcium, and Hydrogen ions.
    • It is carrier-mediated and requires energy to move “uphill” against an electrical or pressure gradient.

    Primary Active Transport

    • Energy comes directly from the breakdown of ATP or some other high-energy phosphate compound.
    • Examples:
      • Na+/K+ pump found in all cells.
      • Ca++ active transport in cell membrane and inside the cell.
      • Active transport of H+ found in gastric glands of the stomach and distal and collecting tubules of the kidney.
      • H+/K+ pump (proton pump at the stomach).

    Secondary Active Transport

    • Energy is derived secondarily from energy stored in the form of ionic concentration differences between the two sides of the membrane, created by primary active transport.
    • Examples:
      • Na+/glucose co-transport.
      • Na+/amino acid co-transport.

    Body Fluids

    • Extracellular fluid (ECF): fluid environment in which the cells live (fluid outside the cells), containing ions, O2, nutrients, and waste products.
      • Includes:
        • Plasma (inside blood cells)
        • Interstitial fluid (around the cells)
    • Intracellular fluid (ICF): fluid contained within all body cells, high in K+ and low in Na+. It contains protein with a negative charge.
    • ICF:ECF ratio: 2:1, meaning that ICF accounts for 2/3 and ECF for 1/3 of total body water.

    Homeostasis

    • Maintenance of a relatively constant/stable internal environment (extracellular fluids).
    • Maintaining a dynamic steady state in the internal environment.
    • The internal environment remains relatively constant despite changes in the external environment.
    • Stable does not mean rigid, values can vary within a narrow limit (normal physiological range).
    • Essential for survival and function of all cells.

    Factors Homeostatically Regulated

    • Concentration of nutrients (e.g., glucose, O2, CO2, and waste products).
    • Concentration of water, salt, and other electrolytes.
    • pH.
    • Blood volume and pressure.
    • Body temperature.

    Homeostatic Control Mechanisms

    • Three components:
      • Receptor: provides information about the stimuli.
      • Control Center: tells what a particular value should be (called the set point).
      • Effector: elicits responses that change conditions in the internal environment.

    Negative Feedback Loops

    • Sensor: monitors internal conditions, detects changes.
    • Integrating Center (Controller): receives and integrates information.
    • Effector: responds to changes, activity of effectors results in return of the condition to normal levels.

    Movements Into and Out of the Cell

    Property Simple Diffusion Facilitated Diffusion Active Transport
    Requires special membrane protein No Yes Yes
    Highly selective No Yes Yes
    Uphill transport No No Yes
    Requires energy No No Yes

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    Description

    Explore the fundamental concepts of osmosis and osmotic pressure in this quiz. Understand how water movement influences cellular behavior and the impact of different saline solutions on human cells. Test your knowledge of hypotonic, hypertonic, and isotonic environments.

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