Chapter 6: Homeostasis Martin Caon Examination Questions and Answers in Basic Anatomy and Physiology Third Edition

Martin Caon Examination Questions and Answers in Basic Anatomy and Physiology Third Edition Chapter 6: Homeostasis 1. Choose one answer below that completes the sentence so that it makes a true statement. Positive feedback: a. Is the way the body maintains homeostasis b. Is a response that opposes a stimulus c. Is a response that maintains a dynamic state of equilibrium d. Is a response that enhances a stimulus Answer is D: “Positive” feedback will reinforce the stimulus, making it greater or more insistent. 2. The hypothalamus and core thermoreceptors notice if body temperature is too low. The hypothalamus signals smooth muscle in blood vessels to vasoconstrict and skeletal muscle to shiver. This activity causes body temperature to rise, which is again noticed by hypothalamus and core thermoreceptors, so the hypothalamus turns off these heat gain mechanisms. In this scenario, which of the following statements is correct? a. The scenario describes positive feedback in action. b. The core thermoreceptors are the effector organs. c. The hypothalamus is the control centre. d. Skeletal muscle is the efferent pathway to the effector organ. Answer is C: The hypothalamus interprets the sensory input and determines the response. Choice A is wrong as this is a negative feedback. The effector organs are the skeletal muscles (which are not a “pathway”). 3. The human body’s ability to maintain a relatively constant internal temperature is an example of what? a. Respiratory heat loss b. Homeostasis c. Vasodilation and evaporative heat loss d. Positive feedback Answer is B: Homeostasis is derived from words that mean remaining similar and standing still and refers to physiological conditions remaining more or less the same. 4. Some of the body’s homeostatic responses rely on “negative feedback”. Which of the following happens in negative feedback? a. The body ignores changes in a physiological variable that are directed towards the set point for that variable. b. The body ignores changes in a physiological variable that are directed away from the set point for that variable c. The body’s response acts to oppose the change in the physiological variable. d. The body’s response acts to enhance the change in the physiological variable Answer is C: “Negative” refers to the response being in the opposite direction to the stimulus. Thus if a variable is increasing, then the body’s response is to produce a change that causes the variable to decrease. The body does not “ignore” stimuli. 5. In homeostasis, what is it that produces the response that moves the physiological variable back towards the middle of its healthy range? a. The effector b. The receptor c. The integrating centre d. The efferent pathway Answer is A: The effector produces the effect that it is directed to by the integrating centre. That direction is passed along the efferent (or outgoing) pathway. 6. The “afferent pathway” in the description of a feedback loop in homeostasis, refers to the: a. Circulating blood b. Pathway from the integrating centre to the effector c. Outgoing signal d. Path taken by the signal produced by a stimulus Answer is D: The afferent signal is incoming from the receptor to the integrating centre. It may be via the blood, but may be via a nerve. 7. Homeostasis usually returns the body to a healthy state after stressful stimuli by: a. Negative feedback b. Positive feedback c. Means of the immune system d. Means of the nervous system Answer is A: Negative feedback is far more common in maintaining homeostasis than is positive feedback. 8. What does the word “homeostasis” refer to? a. The steps leading to repair of a blood vessel and the coagulation of blood b. The maintenance of internal body conditions within narrow limits c. The controlled response that opposes the influence that caused it d. The production of blood cells in active bone marrow Answer is B: This is the best definition. Choice C refers to negative feedback only. 9. How does homeostasis return the body to a healthy state after stressful stimuli? By producing a: a. Responses that oppose the stress b. Learned behaviour c. Reflex action d. Buffering mechanism Answer is A: Refers to negative feedback. Positive feedback is also possible (but rare), nevertheless choice A is the best answer. 10. What causes the body to maintain a relatively constant internal environment? a. Positive feedback b. Homeostasis c. Reflexes d. pH buffers Answer is B: Homeostasis matches the definition in the question. 11. Homeostasis relies on feedback to achieve its aims. “Negative” feedback refers to which situation below? The body’s response: a. Travels from the effector to the integrating centre via the afferent pathway b. Opposes the stressful stimulus c. Is to decrease the set point d. Enhances the stressful stimulus Answer is B: “Negative” refers to the opposing nature of the response. 12. The term “homeostasis” is described by which one of the following statements? The body’s ability to: a. Respond to a stimulus or stress in such a way as to enhance the stress b. Maintain a relatively constant internal temperature c. Respond to a stimulus or stress in such a way as to reduce the stress d. Maintain a relatively constant internal environment