Fluid shear stress

Definition

Fluid shear stress is the force per unit area exerted by a fluid as it flows over a surface, which affects the mechanical environment of cells within bioreactors. This type of stress can influence cellular behaviors such as proliferation, differentiation, and extracellular matrix production. In regenerative medicine, understanding fluid shear stress is crucial because it can help optimize the design of bioreactors for tissue engineering applications.

5 Must Know Facts For Your Next Test

1. Fluid shear stress is typically measured in pascals (Pa) and is calculated using the formula: shear stress = viscosity × shear rate.
2. In bioreactors, controlled levels of fluid shear stress can be used to enhance cell growth and function, mimicking the natural mechanical environment of tissues.
3. High levels of shear stress may lead to cell damage or apoptosis, while optimal levels promote healthy cell behavior and tissue development.
4. Different cell types respond uniquely to fluid shear stress; for instance, endothelial cells may adapt to higher shear rates due to their location in blood vessels.
5. Adjusting the geometry of bioreactors can modify fluid flow patterns and shear stress distribution, allowing for tailored conditions that support specific regenerative medicine applications.

Review Questions

• How does fluid shear stress influence cellular behavior in bioreactors?
  • Fluid shear stress significantly influences cellular behavior by affecting processes like cell proliferation, differentiation, and extracellular matrix production. When cells experience appropriate levels of shear stress, they can mimic their natural environment more closely, leading to enhanced growth and function. Conversely, excessive shear stress can cause cell damage or even death, highlighting the need for careful control in bioreactor designs.
• What role does viscosity play in the context of fluid shear stress within bioreactors?
  • Viscosity is a critical factor in determining fluid shear stress because it affects how easily a fluid flows over surfaces within a bioreactor. Higher viscosity fluids will transmit shear stress differently than lower viscosity fluids, leading to variations in how cells experience mechanical forces. Understanding the interplay between viscosity and shear stress helps in optimizing bioreactor conditions for specific cell types or tissue engineering goals.
• Evaluate the impact of turbulence on fluid shear stress and its implications for tissue engineering applications.
  • Turbulence can greatly increase fluid shear stress levels, leading to unpredictable mechanical environments for cells in bioreactors. While some level of turbulence might enhance mixing and nutrient distribution, excessive turbulence can cause cellular injury and disrupt normal physiological responses. Evaluating how turbulence interacts with shear stress allows researchers to design more effective bioreactor systems that minimize negative effects on cell viability while promoting optimal tissue development.

Related terms

Viscosity: A measure of a fluid's resistance to flow, which impacts how shear stress is transmitted through the fluid.

Turbulence: The chaotic, irregular flow pattern of fluids that can lead to increased shear stress and altered cellular responses.

Bioreactor: A controlled environment where biological reactions take place, often using mechanical and biochemical stimuli to cultivate cells or tissues.