Biomedical Engineering - Bioengineering of Physiological Control Systems

Full exam

Surname Fist name mark of this test final mark Reg. No. Biomedical Engineering MSc Program Politecnico di Milano Bioengineering of the Physiological Control Systems -Prof. G. Baselli June 10th, 2022 (Summer session 1" call) - 10 questions max. score 30/30 Duration 90 min. No material apart these sheets Any answer scores 3/30. Laude upon quality Attention: questions under the same number (e.g., la, lb, ..) are connected Attention: severely wrong answers score a penalty of -1/30 /3 la Define the concept of "milieu intérieur" Literal translation (in English or Italian) What are the living units immersed in the milieu intérieur? Who was the physiologist introducing this concept by the end of the 19th century? How did he name the optimal condition of the milieu intérieur? ... /31b Why is it assumed that this concept implies control feedbacks on larger physiological scales? Explain how the ultimate goal of optimal milieu intérieur condition can be related to the intrinsic working point of larger scale control loops. ******* 2 e Provide a single example of a physiological control system that ultimately contributes to keep one ot the milieu intérieur chemical/physical variables to its optimal level. No formulas. Just mention the involved organs, reflexes, and control actions. 3 /3 2a Given a system of n ordinary diferential equations (ODEs) i = f(x, u) define the equilibrium condition for u = Uss = constant: How many solutions (number of equilibrium points) can be found in case of a non-linear system? How many solutions can be found in the case of a linear system * = Ax +Bu? I) If A is . . then I)If A is not.... ... then /3 2b Given a non-linear system à = fx,u) and an equilibrium point Xss, Uss, write the equations to derive the linearized system 8i = Aôx + Bôu, with ôx = * -Xss, ou =u-Uss A B Changing the equilibrium point, are A and B changed? (Yes/No) Why? Cognome Nome 3 What important property about the dynamics around the equilibrium point can be derived considering the linearized system? Which matrix is involved? What indexes derived from the matrix are considered?... What rules do apply? 1) 1). ). /3 3a Saul et al. estimated the frequency response (FR) from the parasympathetic outflow (vagus) to the heart rate (HR) and from the sympathetic outflow to the HR. This was done non-invasively in humans by means of a physiological action known to excite both the vagal and the sympathetic fibres. What activity was used? What signal of time was used to quantify such activity? . How was the activity changed by volunteers compared the spontaneous one? Why the above change was applied to permit a reliable FR estimate? *****'*** '*** Equation of the FR estimate: G (w) = /3 3b Since the chosen input was exciting both the vagal and the sympathetic fibres, the researchers had to repeat the experiments in two conditions: a) prevalent vagal activity; b) prevalent sympathetic activity. a) Prevalent vagal activity. How was this obtained? b) Prevalent sympathetic activity. How was this obtained? /3 3e Draw the (prevalently) vagal and the sympathetic FRs (amplitude and phase spectra) amplitude a) vagal b) sympathetic phase a) vagal b) sympathetic Highlight the main differences:. .. '''* Provide the physiological explanation:. 10 /3 Draw the scheme of an open-loop parametric system with the deterministic part G (w) and the 4 stochastic part H (w) to be identified by a prediction error model (PEM). Define and describe the asymptotic properties of the deterministic part estimate Gy (o) Consistency (concept only).. Accuracy (concept).. Equation Bias (concept only)..