Question #07: Physiology of Metabolism, Food intake AND Energy Balance The question for this week is as follows: The neuroendocrine control of food intake AND thyroid function involves neurotransmitters / neuropeptides as inputs and outputs to an integrator located in the PVN (paraventricular nucleus of the hypothalamus, a main integrator center). From a conceptual view of cell connectivity and function, describe a possible circuitry consisting of neuronal and endocrine signals to and from the PVN integrator, operating during a typical Thanksgiving day, an hypermetabolic AND thermogenic condition. Your answer must follow the outline shown in the introduction (sub-questions a, b, c, d, see above). Please notice that in this question the structure is defined as the PVN integrator in relation to food intake AND thyroid involvement. You should define a function associated to the PVN in relation to this hypermetabolic condition (hint: TRH cell bodies are located in the PVN). Hint: think on âthe circleâ. This question is an attempt to make you navigate through two circles. The answer will be achieved if you are able to transform these two circle into one. Itâs a good exercise and summary.
The four sub-questions to be used in answering most recitation questions are:
a) Name the structure and the function on which your overall answer will be based? Be as specific as you can in delimiting the boundaries of your example (the most important part of your answer, since the following b, c, & d sub-questions are based on your answer to this first sub-question, a). Please notice that only 1 item is required (in your answer it should be labeled as âaâ). This answer should look like: âa.- My structure (S) is â¦. and its function (F) is â¦â. In same cases a second sentence might be needed.
b) Why do you think that your structure and your function are related? Support your contention based on 3 lines of evidence based on the chemistry, physics, anatomy, or physiology involved in your example. Please notice that 3 items are required (answers should be labeled as âb1, b2, and b3â). One of this answers might look like: âb1.- If I do this experiment and measure this variable using this technique, this result will suggest that my S/F is correctâ. Please notice that MY question does not ask you to tell me what happens since this can be copy from any source, but it asked how do you know that your S/F relationship is true.
c) Which are the levels of organization involved in your example (c1)? Cite events occurring at its main level of organization (c2) and indicate how they relate to the whole body level (c3). Please notice that 3 items are required (thus, answers should be labeled as âc1, c2, and c3â). These answers should look as follows: âc1.- molecularâ or any level of organization involved in your âaâ answer (S/F); âc2.- the first event is; the next even is; the middle event is; the next event is; the last event isâ. Five events distributed equidistant from each other is a good summary for the story line of the your S/F named in your âaâ answer. Finally, âc3.- at a whole individual level my S/F described in âaâ plays this roleâ.
d) Which are the main feedback mechanisms involved in your example (cite at least two) (d1)? Expand on one of them (d2) and name 2 absolute requirement for that feedback to work (d3). Please notice that 3 items are required (answers should be labeled as âd1, d2, and d3â). These answers should look as follows: âd1.- an increase in this negative feedback ligand must decrease this variable under controlâ. This is how you NAME a negative feedback. For d1 you need to name two negative feedbacks; âd2.- the first event is; the next even is; the middle event is; the next event is; the last event isâ. Five events distributed equidistant from each other is a good summary for the most important negative feedback story line involved as a control of the your S/F named in your âaâ answer, that you named in d1; âd3.- this two components are absolutely necessary for the negative feedback described in d2 to be operational.
