MolCell-Lecture28Notes - How does a cell interact with its...

This preview shows page 1 - 3 out of 10 pages.

Lecture notes – last week 1How does a cell interact with its environment? Feilim Mac Gabhann, Molecules and Cells, Fall 2013We must go beyond thinking of the cell as an isolated entity and begin to view cells in the context of the human body. What is the cell's environment? What does a cell interact with? How does it interact with and sense other cells, molecules and forces? How do the activities inside the cell – DNA replication, transcription, protein synthesis, signaling, molecular motors – come together to cause multicellular behaviors?
Alberts 4thEd, Figure 22-22 A. CELLS OF THE VASCULAR SYSTEMEndothelial cellsform the lining of the entire circulatory (vascular) system including the heart and all blood vessels – arteries, veins and capillaries. Their apical side faces the lumen of the blood vessel (i.e. is in contact with the bloodstream) while their basal side is in contact with the basal lamina component of the basement membrane. Beyond the basement membrane, endothelial cells are surrounded by smooth muscle cells (in arteries and veins) or pericytes (in capillaries). Endothelial cells typically align and elongate in the direction of blood flow, as shown below in response to shear stress– a : Izumo et al. JAMA. 1999. Make sure you understand and can define all words in bold italics
Lecture notes – last week 2Fluid shear stressis the stress that is applied parallel to the face of a material, e.g. by the flowing blood, and shear stress is characterized as the viscosity, μ, of the fluid times the velocity gradient of the fluid perpendicular to the direction of shear, dv/dyThis is one example of cells sensing forces. Endothelial cells sensing this blood flow-caused force physically change their shape, which causes rearrangement of proteins and protein complexes within the cell and in its membrane. These rearrangements can activate/deactivate signaling networks leading to changes in cell behaviors. For example, increased shear stress on endothelial cells due to a rise in blood pressure results in increased production of nitric oxide, which is a potent vasodilatorVasodilators act on vascular smooth muscle cells, causing smooth muscle relaxation and widening of the blood vessel (which leads to a reduction in shear stress). In this way a mechanical signal sensed by one cell is converted to a chemical signal that is in turn sensed by another cell, leading to a coordinated multicellular tissue behavior. Water and Solute Transport Across the Endothelium. Endothelial cells form the barrierbetween the bloodstream and the rest of the body and thus control movement of cells, proteins and other materials (gases, drugs) from the blood to tissues throughout the body. The endothelium also regulates the fluid
.
.

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture