![]() The signal is transmitted through the cell membrane, and each new protein is activated in turn. The growth factor binds the receptor proteins outside the cell, drawing the receptor ends together. (04:25) Now we'll watch the action again from our position in the cell's cytoplasm. While active – as shown by the yellow flashes of light – the ends of the receptor interact with the messenger proteins. (03:46) Beneath the cell membrane, you see the grey receptor ends surrounded by pink fibers – these structures help to give the cell its shape – and a range of messenger proteins that will carry the signal through the cytoplasm. You'll see this better from inside the cell. This change in the protein conducts the signal through the membrane and into the cell's interior – the cytoplasm. The binding of the growth factor causes the receptor to change shape. ![]() A second receptor protein joins in, making the growth factor fit like a key in a lock. When the growth factor from the platelet (shown in purple and blue) encounters a matching receptor, it binds to it. The gray structures sticking out of the cell membrane are receptors for incoming signals. (02:45) Fibroblasts, like all your cells, have a fluid, outer membrane that regulates the flow of molecules in and out. To see how a growth factor from a platelet signals a nearby fibroblast cell, we need to swoop in close to the rippling fibroblast surface. When activated, platelets release a stream of protein messengers, called growth factors, to stimulate cell growth and tissue repair. The smaller dark cell fragments between the fibroblasts are platelets. ![]() Early in the healing process, fibroblasts multiply and produce proteins that help to repair the damage. The flat, light-colored cells are fibroblasts. Many different types of cells are involved in tissue repair. Moments after an injury, these blood cells and cell fragments start to form a mesh-like clot. Blood cells are flowing out of the broken blood vessel ahead. (01:20) Now we've arrived at the wound site. They communicate using their own language of chemical signals. ![]() ![]() If you are hurt, your cells work together to repair the damage. We're following blood cells as they're propelled through a blood vessel toward the boy's injured knee. (00:55) Your body is an incredible living system made up of billions of cells. OW.Are you Ok? Yeah, I think I just fell over a root. ![]()
0 Comments
Leave a Reply. |