BIO WEEK 10 LECTURE 2

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odun osh

Cards (111)

  • Homeostasis

    The ability of an organism or system to maintain a stable internal environment despite changes in the external environment
  • Homeostatic control systems

    1. Sensor detects changes in internal environment
    2. Integrator receives input from sensor and determines appropriate response
    3. Effector carries out response
  • Homeostatic control systems

    • A set of processes that work together to maintain the internal environment of an organism within a narrow range of values known as the set point
    • Operate through feedback mechanisms that can detect changes in the internal environment and then trigger responses to counteract those changes
  • Negative feedback

    A process that plays a crucial role in maintaining homeostasis by counteracting any deviations from the desired set point
  • Negative feedback

    1. Detecting changes in the internal environment
    2. Triggering responses that oppose those changes
    3. Bringing the system back to its desired set point
  • Negative feedback mechanisms

    • Shivering to raise body temperature
    • Sweating, increased blood flow to skin, increased respiration to lower body temperature
  • Homeostasis

    A regulatory mechanism that maintains stability and prevents deviations from a desired set point
  • If the system deviates too far from the set point
    Negative feedback will activate to bring it back into balance
  • Negative feedback occurs at the organism level, organ level, and cellular level
  • Negative feedback is a critical component of homeostasis as it helps maintain stability and prevent excessive fluctuations in the internal environment
  • Negative feedback example

    1. Sensor activated (blood vessels)
    2. Integrator activated (brain)
    3. Hormones and nerves from brain travel to effector (kidney, heart, blood vessels)
    4. Response raises blood pressure back to normal
  • Negative feedback

    A process that plays a crucial role in maintaining homeostasis by counteracting any deviations from the desired set point
  • Negative feedback

    1. Detecting changes in the internal environment
    2. Triggering responses that oppose those changes
    3. Bringing the system back to its desired set point
  • Negative feedback mechanisms

    • Shivering to raise body temperature
    • Sweating, increased blood flow to skin, increased respiration to lower body temperature
  • Homeostasis

    A regulatory mechanism that maintains stability and prevents deviations from a desired set point
  • If the system deviates too far from the set point
    Negative feedback will activate to bring it back into balance
  • Negative feedback occurs at the organism level, organ level, and cellular level
  • Negative feedback is a critical component of homeostasis as it helps maintain stability and prevent excessive fluctuations in the internal environment
  • Negative feedback example

    1. Sensor activated (blood vessels)
    2. Integrator activated (brain)
    3. Hormones and nerves from brain travel to effector (kidney, heart, blood vessels)
    4. Response raises blood pressure back to normal
  • Negative feedback

    1. Removal of the stimulus to the sensor
    2. Turns off any additional signals
  • Positive feedback

    • Moves the system away from a homeostatic set point
    • Reinforces and amplifies deviations from the normal range of a physiological variable, rather than counteracting it
  • Positive feedback is less common than negative feedback in homeostatic control systems
  • Processes that use positive feedback

    • Need to proceed rapidly and reach a threshold before stopping abruptly
    • Are not intended to maintain steady state conditions but rather to produce an all or nothing type of response
  • Example of positive feedback in homeostatic control systems

    • Blood clotting
    • Platelets adhere to the site of injury and release chemicals that attract more platelets
    • The growing plug releases more chemicals that attract more platelets, amplifying the clotting process until the injury is sealed off
  • Negative feedback is the predominant mechanism for maintaining homeostasis
  • Feed forward regulation

    • A mechanism by which homeostatic control systems can anticipate changes in internal or external environments and adjust their responses before these changes actually occur
    • Allows the system to prepare itself for an impending change and minimize the impact of that change on the internal environment
  • Feed forward regulation

    1. The control system receives information from the environment or other parts of the body that suggests some change is imminent
    2. The system then generates a response that prepares the body for this change, even before the change has actually occurred
    3. The anticipatory response can reduce the magnitude of the change to help maintain homeostasis
  • Example of feed forward regulation

    • Anticipatory salivary production when an animal sees or smells food
  • Regulation of body temperature during exercise
    1. Body temperature begins to rise
    2. Brain anticipates change
    3. Initiates sweat production
    4. Increases blood flow to skin
    5. Dissipates heat generated by exercise
    6. Prevents large increases in body temperature
  • Feed forward regulation

    Can help to predict or anticipate changes in advance to prevent gross level deviations
  • Feed forward regulation can be learned
  • Homeostatic processes

    1. Changes at local level allow cells to communicate using chemical signals
    2. Longer distance communication through hormones produced in endocrine system and secreted into blood
  • Solute movement

    Important aspect of homeostasis, which is the process by which living organisms maintain a stable internal environment despite changes in external conditions
  • Diffusion

    1. Passive movement of molecules or ions from an area of high concentration to an area of low concentration
    2. No ATP hydrolysis required
    3. Important for exchange of gases, movement of nutrients and waste products
  • Active transport

    1. Movement of molecules or ions against their concentration gradient, from low to high concentration, using energy from ATP hydrolysis
    2. Important for maintaining concentration gradients of ions, movement of glucose and amino acids
  • Osmosis

    Passive movement of water molecules across a selectively permeable membrane
  • Osmosis

    Movement of water from an area of low solute concentration to an area of high solute concentration
  • Osmosis

    • Important for the regulation of water balance in cells and in the body as a whole
    • Rate of diffusion depends on temperature, area/surface of the barrier
  • The surface is important for diffusion as well as the relative discrepancy in concentration between two locations
  • J

    Diffusion rate