Cells need to intake things like nutrients, water, and oxygen, and they need to be able to export things like metabolic products and waste materials. No matter which direction the material is moving in, it needs to cross the cell membrane at some point.
The lymphatic system includes areas of high concentrations of APCs, T and B cells.
<h3>What is the lymphatic system?</h3>
The lymphatic system is a branch of the circulatory system which consists of a system of organs , tissues, cells and vessels known as lymphatic vessels, which help transport the fluid, lymph around the body.
The lymphatic system contains high concentration of immune cells.
Therefore, the lymphatic system includes areas of high concentrations of APCs, T and B cells.
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External stimulus. The rain is something out of your control while you're waiting. Rain is not something you are doing nor is it a response to you waiting for the bus.