Homeostasis Overview in Physiology
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Questions and Answers

Which transport mechanism directly utilizes ATP hydrolysis to move solutes against their electrochemical gradient?

  • Facilitated diffusion
  • Carrier mediated diffusion
  • Secondary active transport
  • Pumps (correct)

    • In which direction does endocytosis primarily transport substances?

  • Across the cell membrane via channel proteins
  • From intracellular fluid to extracellular fluid
  • From an area of high concentration to an area of low concentration
  • From extracellular fluid to intracellular fluid (correct)

    • Which type of transport is characterized by the movement of multiple solutes in the same direction across a cell membrane?

  • Symport (correct)
  • Simple diffusion
  • Uniport
  • Antiport

    • Which of the following best describes the relative concentration of Na+ inside a typical cell compared to its extracellular environment?

    <p>Na+ concentration is lower inside the cell. (A)</p> Signup and view all the answers

    What does it mean when an ion reaches its equilibrium potential?

    <p>The electrical gradient and concentration gradient for the ion are equal and opposite. (D)</p> Signup and view all the answers

    What primarily separates the intracellular fluid (ICF) from the extracellular fluid (ECF)?

    <p>The cell membrane (D)</p> Signup and view all the answers

    Which of the following cellular processes is directly affected by the differences in ion concentration across the cell membrane?

    <p>Electrical activity in the nervous system (D)</p> Signup and view all the answers

    Which property of the cell membrane allows for the establishment of different solute concentrations between the intracellular and extracellular environments?

    <p>Its selective permeability (A)</p> Signup and view all the answers

    What type of movement describes the random thermal motion of particles in a liquid?

    <p>Brownian motion (B)</p> Signup and view all the answers

    According to the information, what is the relationship between the speed of a particle and its size during diffusion in a liquid?

    <p>Speed is inversely related to size (A)</p> Signup and view all the answers

    Which transport mechanism is characterized by its ability to move small, uncharged solutes directly through the phospholipid bilayer?

    <p>Simple diffusion (D)</p> Signup and view all the answers

    Which of the following pathways through the membrane is always open and non-selective?

    <p>Pores (B)</p> Signup and view all the answers

    What primarily controls the opening and closing of gated channels in a cell membrane?

    <p>Voltage, ligands, or secondary messenger receptors (A)</p> Signup and view all the answers

    What is the primary role of negative feedback in maintaining homeostasis?

    <p>To maintain a dynamic equilibrium by counteracting deviations from the set point. (B)</p> Signup and view all the answers

    Which component of a negative feedback loop detects changes in the controlled variable?

    <p>The receptor (sensor) (A)</p> Signup and view all the answers

    Which of the following is an example of an effector mechanism in a homeostatic control system?

    <p>Urine concentration (C)</p> Signup and view all the answers

    What type of communication does the nervous system primarily use for rapid information transfer in maintaining homeostasis?

    <p>Electrical (C)</p> Signup and view all the answers

    What is the likely outcome if a disturbance in homeostasis goes beyond what negative feedback mechanisms can correct?

    <p>It may lead to illness and/or death. (A)</p> Signup and view all the answers

    In the context of homeostasis, what is the 'set point'?

    <p>The ideal or target value for a controlled variable. (A)</p> Signup and view all the answers

    How do changes in extracellular fluid (ECF) composition affect intracellular fluid (ICF)?

    <p>Changes in ECF directly affect ICF composition. (C)</p> Signup and view all the answers

    What is the difference between a controlled variable and an effector mechanism?

    <p>A controlled variable is what is being maintained at a specific level, and an effector mechanism adjusts physiological processes. (D)</p> Signup and view all the answers

    What effect does hypokalemia have on muscle function?

    <p>Causes muscle weakness (D)</p> Signup and view all the answers

    Which of the following correctly describes osmosis?

    <p>Movement of water from higher to lower solvent activity (A), Movement of water from lower to higher osmolarity (B)</p> Signup and view all the answers

    What is the primary determinant of tonicity?

    <p>Osmolarity of the solution (C)</p> Signup and view all the answers

    How do isotonic solutions affect cells?

    <p>Have no net movement of water (A)</p> Signup and view all the answers

    What is the definition of osmolarity?

    <p>Measure of total number of osmole particles per volume (A)</p> Signup and view all the answers

    What effect does hyperkalemia typically have?

    <p>Increases cardiac arrhythmias (C)</p> Signup and view all the answers

    What effect does an increase in extracellular osmolarity have on cells?

    <p>Causes cell shrinkage or crenation (D)</p> Signup and view all the answers

    Which of the following is a property of a solvent that is affected by added solute?

    <p>Colligative properties (C)</p> Signup and view all the answers

    What factor is critical for determining the actual osmotic pressure in biological systems?

    <p>Properties of the separating membrane (A)</p> Signup and view all the answers

    What is the role of NaKATPase in the Gibbs-Donnan effect?

    <p>It counteracts ion imbalances by exchanging sodium and potassium (C)</p> Signup and view all the answers

    Which of the following describes the difference between osmolarity and tonicity?

    <p>Osmolarity reference to solute composition, tonicity relates to cell volume effects (A)</p> Signup and view all the answers

    What is the characteristic of hypotonic solutions?

    <p>They result in net movement of water into the cell (D)</p> Signup and view all the answers

    What happens to solvent activity when osmolarity increases?

    <p>Solvent activity decreases (B)</p> Signup and view all the answers

    What is the implication of ECF being isotonic to ICF?

    <p>Cell volume will remain stable (C)</p> Signup and view all the answers

    Flashcards

    Homeostasis

    The process of maintaining a stable internal environment.

    Dynamic Equilibrium

    Variable changes but are continually corrected within narrow limits.

    Negative Feedback

    A mechanism that helps maintain homeostasis by counteracting changes.

    Controlled Variable

    The factor in a body that is regulated to maintain homeostasis.

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    Effector Mechanism

    The structure that carries out a response to restore balance.

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    Receptor (Sensor)

    Detects changes in the controlled variable and sends signals to the processor.

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    Set Point

    The ideal value for a controlled variable that the body strives to maintain.

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    Disturbance in Homeostasis

    An event that disrupts the stable internal environment, potentially leading to illness or death.

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    Types of Transporters

    Carrier proteins that transport solutes across membranes.

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    Active Transport

    Movement of substances against their concentration gradient using energy (ATP).

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    Exocytosis

    Process of exporting substances from inside to outside the cell.

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    Endocytosis

    Process of taking substances into the cell from the extracellular fluid.

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    Electrochemical Gradient

    Combined effect of charge and concentration gradients on ion movement.

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    Intracellular Fluid (ICF)

    Fluid within cells, separated from the extracellular fluid by the cell membrane.

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    Extracellular Fluid (ECF)

    Fluid outside of cells, encompassing the interstitial fluid and blood plasma.

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    Diffusion

    Movement of solutes from an area of high concentration to an area of low concentration.

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    Cell Membrane

    A lipid bilayer that separates the intra- and extracellular environments.

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    Transporters vs. Channel Proteins

    Transporters actively move solutes across membranes; channels allow passive movement.

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    Pores

    Always-open pathways in membranes allowing passive diffusion of molecules.

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    Gated Channels

    Channel proteins that can open or close in response to signals.

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    Hypokalemia

    Low extracellular potassium concentration causing muscle weakness and cardiac arrhythmias.

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    Hyperkalemia

    High extracellular potassium concentration leading to cardiac arrhythmias.

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    Membrane Permeability

    Varies with size, charge, and lipid solubility of solutes.

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    Transport Proteins

    Integral proteins facilitating solute transport across membranes.

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    Osmosis

    Water movement from higher to lower solvent activity across a membrane.

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    Osmolarity

    Measure of solute concentration in a solution (osmoles per volume).

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    Osmotic Pressure

    Pressure needed to stop osmosis, influenced by membrane characteristics.

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    Isotonic Solution

    No net water movement; cell volume remains unchanged.

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    Hypotonic Solution

    Higher water influx causing cell volume to increase (potential lysis).

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    Hypertonic Solution

    Higher solute concentration leading to water exiting cells (crenation).

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    Tonicity

    Effect of a solution on cell volume, based on osmolarity and permeability.

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    Gibbs-Donnan Effect

    Ionic distribution influenced by protein charges, counteracted by NaKATPase.

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    NaKATPase Function

    Transports 2 K+ in and 3 Na+ out, helping maintain ion balance.

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    ECF Homeostasis

    Maintenance of constant osmotic pressure in extracellular fluid.

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    Study Notes

    Homeostasis Overview

    • Physiology is the study of the mechanisms of living things and how the body responds to stimuli.
    • Homeostasis is maintaining a stable internal environment in the body.
    • Dynamic equilibrium describes the body's internal environment, fluctuating but constantly corrected within a limited range.
    • Negative feedback is the mechanism for regulating homeostasis.
    • Key components of a negative feedback loop are controlled variables, receptors/sensors, Integrating centers, and effectors.
    • Controlled variables are the aspects of the body that are regulated (e.g., body temperature).
    • Receptors detect changes in the controlled variable.
    • Integrating centers process the information and determine the appropriate response.
    • Effectors carry out the necessary action to restore the controlled variable to its set point (e.g., sweating to lower body temperature).
    • Positive feedback mechanisms amplify a response, unlike the tendency of negatie feedback loops towards stability.
    • Homeostasis can be disrupted, potentially leading to health problems or death

    Disturbances in Homeostasis

    • Disturbances in homeostasis can lead to illness or death.
    • Examples include heat stroke and conditions like diabetes.

    Intra- and Extracellular Environment

    • The cell membrane separates the intracellular fluid (ICF) from the extracellular fluid (ECF).
    • Cell membranes allow the separation of body fluid compartments by controlling the movement of substances across the cell membrane.

    Properties of Cell Membranes

    • The lipid bilayer is selectively permeable, allowing some substances to pass through but not others.
    • Transport proteins (channels, carriers) facilitate the passage of substances across the membrane.
    • Diffusion, osmosis, and active transport are examples of processes that may happen across the membrane.

    Movement of Solutes Across Membranes

    • Diffuison can be through the lipid bilayer, or through channels and carriers.
    • Pore, channels, and carriers are pathways for specific molecules across the membrane.
    • Pumps like the Na+/K+ pump use energy to move substances against their concentration gradients.

    Pumps (Specialized Pathway)

    • Active transport mechanisms move substances using energy (like ATP).
    • Examples like the Na+/K+ pump are crucial for maintaining cellular function.

    Exocytosis and Endocytosis

    • Exocytosis: Intracellular to extracellular flow of molecules (e.g., hormone release).
    • Endocytosis: Extracellular to intracellular flow of molecules (e.g., phagocytosis, pinocytosis).

    Composition of Fluid and Solutes Across Cell Membranes

    • Relative concentrations of electrolytes (ions) like Na+, K+, Cl−, and proteins differ between intracellular and extracellular fluids.
    • These differences are important for cellular function and nerve impulses

    Electrochemical Gradient

    • The electrochemical gradient is the driving force for passive transport.
    • The gradient is related to both concentration and electrical differences.
    • An imbalance in extracellular potassium or sodium can have major effects on excitable cells.

    Water Transport and Distribution in the Body

    • Water movement between body compartments is crucial for maintaining homeostasis.
    • Osmosis, affecting fluid movement, is dependent on the concentration of dissolved substances in the compartment.
    • Osmolarity is the concentration of osmotically active particles per unit volume, while tonicity describes the effect of a solution on cell volume based on it osmolarity.
    • Tonicity is the relationship between the osmolarity of two solutions and impacts cell shape and volume

    Gibbs-Donnan Effect

    • This phenomenon arises from the unequal distribution of charged molecules across cell membranes.
    • Imbalances in this effect disrupt osmotic equilibrium.

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    Physiology PDF - Homeostasis & Cell Membranes

    Description

    Explore the concepts of homeostasis and how the body maintains a stable internal environment. Understand the roles of negative and positive feedback mechanisms, as well as the key components involved in regulating controlled variables. This quiz will enhance your knowledge of physiological responses to stimuli.

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