1. Define homeostasis
    a state of body equilibrium or stable internal environment
  2. what two systems maintain homeostasis in the body
    the endocrine and the nervous systems
  3. what are feedback loops
    mechanisms used to maintain homeostasis in the body
  4. Explain a negative feedback loop
    • 1.stimulus changes e.g. rise in BP
    • 2. the receptor (sensor) detects a disturbance
    • 3. information is sent along the efferent pathway to the control center
    • 4. information is sent along the afferant pathway to the effector
    • 5. effector opposes disturbance
    • 6. homeostatic equilibrium is restored
  5. Define a negative feedback loop
    causes the variable to change in the direction oppisite to that of the stimulus. returns system back to it's ideal value
  6. give 3 eg's of negavtive feedback loops within the body
    • 1. body temperature control
    • 2. blood pressure control
    • 3. Blood PH levels
  7. Define a positve feedback loop
    the response or result enhances the original stimulus so that the output is enhanced.an external event is required to break the feedback loop e.g. childbirth
  8. Explain a positive feedback loop
    • 1. the receptor (sensor) detects disturbance
    • 2. information is sent to the control center along the efferent pathway
    • 3.information is sent to the effector along the afferent pathway
    • 4.the effector reinforces the disturbance
  9. Explain the positive feedback loop involved in the clotting of blood
    • 1. break or tear in vessel wall initiates feedback cycle
    • 2. clotting occurs as platelets adhere to site and release chemicals
    • 3. released chemicals attract more platelets
    • 4. clotting proceeds; newly forming clot grows
    • 5. feedback cycle ends after clot seals break
  10. what are 4 main points of homeostatic disturbance
    • 1.cause of most disease
    • 2. can lead to disease or death
    • 3. may temporarily alter homeostatic equilibrium
    • 4. early life disturbances can persist later in life
  11. list 3 positive feedback cycles that occur in the body
    • 1. the realease of oxytocin when a stretch in the urterine wall muscle is detected during childbirth
    • 2. the realease of chemicals and platelets to attract more platelets during blood clotting
    • 3. a surge in prolactin during lactation, the infants suckling encourages milk production
  12. optimal body temp
  13. optimal blood PH
  14. Optimal heart rate
    60-70 BPM
  15. Optimal respiratory rate
    20 Breaths/min
Card Set
Module 1: homeostatis