Physiologie | EPFL Graph Search

La physiologie (du grec φύσις, phusis, la nature, et λόγος, logos, l'étude, la science) étudie le rôle, le fonctionnement et l'organisation mécanique, physique et biochimique des organismes vivants et de leurs composants (organes, tissus, cellules et organites cellulaires). La physiologie étudie également les interactions entre un organisme vivant et son environnement. Dans l'ensemble des disciplines biologiques, en définissant schématiquement des niveaux d'organisation, la physiologie est une discipline voisine de l'histologie, de la morphologie et de l'anatomie. La physiologie regroupe des processus qu'elle étudie en grandes fonctions qui sont :

les fonctions de nutrition ;
la fonction de reproduction ;
les fonctions de relation : la locomotion et les fonctions sensorielles (voir les articles détaillés dans la liste ci-dessous).

Le terme physiologie a aussi été utilisé au par les écrivains réalistes pour qualifier de petites études de mœurs de personnage typiques comme les

Evaluation and extension of an automated system to diagnose the health of premature babies

Camille Joggi

Premature babies are not fully equipped to deal with the outside world. Their immature bodies make them highly at risk to a large number of physiological complications. Therefore, while they are still immature, premature babies are taken care of in neonatology intensive care units, where they are kept in a controlled and protective environment. In these units, the babies' vital parameters, such as their heart rate and temperature, are tightly monitored. The devices used to record this data are fitted with alarms that are triggered automatically when something wrong is detected. However, the alarm systems currently used are often unable to discriminate between real physiological problems and artefacts that should be ignored (e.g. when a measurement device drops-out). As a result, these systems produce a high rate of false alarms, where the alarm is triggered when nothing is clinically wrong. The can have unwanted consequences: first, it creates a noisy environment, which may disturb the babies; second, it can lead to the alarm being ignored when there is actually something wrong. In order to address this problem, my host laboratory has constructed a system that can automatically infer the state of health of premature babies in neonatology units, based on their recorded physiological data. The new system is designed to be able to deal with artefactual changes in the measurements, hopefully resulting in a reduced number of false alarms. In this thesis, I describe my contribution to this project, which is twofold. The first part deals with the problem of evaluating the performance of the system. To do this, I developed an online feedback process, where clinicians could provide information about the true clinical interpretation of the physiological data, which could be compared to the output of the system. The feedbacks provided by the clinicians were then analysed to investigate how the system could be improved. The second part of my thesis was motivated be early feedbacks from the clinicians, which indicated that the system was unable to deal with changes in the humidity measurements that occurred when the incubator door was opened and closed. To address this, I extended the current system, so that it was able to account for these changes, thereby increasing its capability to detect "true" physiological problems during the period after the incubator door is closed.

2011

Genetic, metabolic, and molecular insights into the diverse outcomes of diet-induced obesity in mouse

Alexis Maximilien Bachmann

Overweight and obesity are increasingly common public health issues worldwide, leading to a wide range of diseases from metabolic syndrome to steatohepatitis and cardiovascular diseases. While the increase in the prevalence of obesity is partly attributable to changes in lifestyle (i.e. increased sedentarity and changes in eating behaviour), the metabolic and clinical impacts of these obesogenic conditions varies between sexes and genetic backgrounds. The conception of personalised treatments of obesity and its complications require a thorough understanding of the diversity of responses to environmental stimuli such as high-fat diet intake. In this thesis, by analysing nine genetically diverse mouse strains, we show that much like humans, mice respond to high-fat diet in a genetic- and sex-dependent manner. Physiological and molecular responses to high-fat diet are associated with the expression of genes involved in immunity and mitochondrial function. Finally, we find that mitochondrial function and mitochondrial supercomplex assembly may explain part of the diversity of physiological responses. By exploring the complex interactions between genetics and metabolic phenotypes via gene expression and molecular traits, we shed light on the importance of genetic background and sex in determining metabolic outcomes. In addition to providing the community with an extensive resource for optimizing future experiments, this work serves as an exemplary design for more generalizable translational studies.

EPFL2021

Arterial in vitro remodeling

Gabriela Montorzi Thorell

Vascular remodeling is defined as any enduring change in the size and composition of an adult blood vessel, allowing adaptation or repair. The vascular remodeling response has been shown to depend on a variety of endogenous and environmental factors. Physiological remodeling is a tightly regulated process that mainly occurs in response to long-term changes in hemodynamic conditions. The adaptation to these hemodynamic changes implies the production of mediators that influence structure as well as function. A loss of regulation in the adaptive response underlies the pathogenesis of major cardiovascular diseases, including hypertension, atherosclerosis, restenosis and arterial aneurismal dilatation. Specialized enzymes called matrix metalloproteinases (MMPs) have been shown to have a predominant participation in the reorganization of the vessel structure, through the degradation of the extracellular matrix scaffold. The aim of this thesis is to gain insight in the biological and mechanical processes taking place in the vascular wall as an adaptive response to different biomechanical stimuli such as blood pressure and blood flow. This work proposes a new model for the study of vascular remodeling where physical factors acting on the arterial wall can be dissociated and analyzed, individually, in relation to the biological response. The results are presented in form of an introduction, three scientific papers and a conclusion section. The investigation has been designed around three different approaches: adaptation of a non-uniform artery to an in vitro environment, vascular adaptation to steady and pulsatile pressure and vascular adaptation to unidirectional and oscillatory flow. The adaptive response to each one of the variables chosen has been analyzed through biological and biomechanical remodeling indicators of the arterial wall. The introduction is an overview of the biological and biomechanical characteristics of arterial wall in relation to the remodeling process. The contribution of vascular smooth muscle cells and extracellular matrix to physiological and pathological arterial remodeling is discussed. Paper I assesses the relative remodeling of a non-axisymmetric artery in relation to its environment. The study considers the native circumferential asymmetry of the porcine right common carotid, which results from the non-homogenous mechanical and hemodynamic native environment. The adaptive response of the artery to an in vitro perfusion environment is analyzed. The study shows that in vitro perfusion leads, through remodeling, to a circumferentially uniform scleroprotein distribution and to a change in arterial compliance. This study emphasizes the link between structural changes, the biomechanical response and the enzymatic implication in the adaptive response. In paper II we investigate the role of continuous and cyclic stretch, produced by steady or pulsatile pressure acting on the arterial wall, on the remodeling response. The study shows that exposure to continuous and cyclic stretch differentially affects the relative scleroprotein content and leads to a change in arterial wall stiffness. The adaptive outcome is studied through an integrative approach taking into consideration the geometrical and structural adaptation, the biomechanical behavior and the enzymatic agents implicated in extracellular matrix turnover. Paper III analyzes the influence of different flow patterns on the arterial adaptive response. We investigate the differential effects of oscillatory flow, mimicking a plaque-prone hemodynamic environment, and unidirectional flow, to mimicking a physiologically protective (plaquefree) environment. The effect of these hemodynamic forces on the remodeling response are characterized through the study of endothelial and smooth muscle cell function as well as through assessment of agents influencing extracellular matrix turnover. The conclusions section presents a synthesis of the results and contribution of this thesis and proposes perspectives for future studies.

EPFL2004