Education
Homeostasis
Homeostasis plays a pervasive role in shaping the form and function of all biological molecules and organisms
Students should be able to explain and apply core concepts of underlying homeostasis, including the need for biological balance, linked steady state processes, quantification of homeostasis, the organization of chemical processes, and control mechanisms.
The learning goals below are categorized as introductory A, intermediate B and upper C.
1. Biological need for homeostasis
Biological homeostasis is the ability to maintain relative stability and function as changes occur in the internal or external environment. Organisms are viable under a relatively narrow set of conditions. As such, there is a need to tightly regulate the concentrations of metabolites and small molecules at the cellular level to ensure survival. To optimize resource use and to maintain conditions, the organism may sacrifice efficiency for robustness. Breakdown of homeostatic regulation can contribute to the cause or progression of disease or lead to cell death.
Associated learning goals
- Students should be able to describe why maintenance of homeostasis is advantageous to an organism. A
- Students should be able to define homeostasis in a biochemical context to both scientifically trained and lay audiences. B
- Students should be able to describe how homeostatic pathways and mechanisms have been conserved throughout evolution. B
- Students should be able to appraise the costs and benefits of different homeostatic mechanisms to an organism. C
- Students should be able to relate different environmental factors necessitating homeostasis to a specific adaptation. C
2. Link steady state processes and homeostasis
A system that is in a steady state remains constant over time, but that constant state requires continual work. A system in a steady state has a higher level of energy than its surroundings. Biochemical systems maintain homeostasis via regulation of gene expression, metabolic flux and energy transformation but are never at equilibrium.
Associated learning goals
- Students should be able to explain that a system at chemical equilibrium (or just equilibrium) is stable over time, but no energy or work is required to maintain that condition. A
- Students should be able to apply the principles of kinetics to describe flux through biochemical pathways. A
- Students should be able to discuss a metabolic pathway in terms of equilibrium and Le Chatelier’s principle. A
- Students should be able to relate the laws of thermodynamics to homeostasis and explain how the cell or organism maintains homeostasis. B
- Students should be able to model how perturbations to the steady state can result in changes to the homeostatic state. C
- Students should be able to propose how resources stored in the homeostatic state can be utilized in times of need. C
3. Quantifying homeostasis
Multiple reactions with intricate networks of activators and inhibitors are involved in biological homeostasis. Modifications of such networks can lead to activation of previously latent metabolic pathways or even to unpredicted interactions between components of these networks. These pathways and networks can be mathematically modeled and correlated with metabolomics data and kinetic and thermodynamic parameters of individual components to quantify the effects of changing conditions related to either normal or disease states.