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Microbiology

Learn the toughest concepts covered in Microbiology with step-by-step video tutorials and practice problems by world-class tutors.

19. Innate Immunity

Cell Communication: Surface Receptors & Adhesion Molecules

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concept

Cell Surface Receptors

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in this video we're going to begin our lesson on cell communication by focusing on surface receptors and adhesion molecules. And so cell surfaces contain many types of receptor proteins as well as many types of adhesive molecules. And these receptor proteins and adhesive molecules are important for communication during an infection. And so these receptor proteins and adhesive molecules allow cells of the immune system to signal an infection and to migrate to the infected location within the body. Now first we're going to focus on cell surface receptors and then later we'll focus on adhesive molecules. And so cell surface receptors or just surface receptors again are proteins on the cell surface and they are specifically going to allow the cell to sense and respond two external signals or environmental signals. Now the surface receptor protein is going to span the entire cytoplasmic membrane and uh it is going to connect the outside of the cell to the inside of the cell, allowing the cell to uh respond to external signals on the outside. Now each specific surface receptor is going to have a specific molecule that it will bind to. So surface receptors do not respond to all molecules. They only respond to very specific molecules. And these molecules we refer to as a lai Gan. So a lie again is going to be a molecule that binds to a surface receptor and the login when it binds to a surface receptor it can elicit a response inside of the cell allowing the cell to respond to the external signal. Now cells are actually capable of altering the number and types of receptor of surface receptors that they have and this allows the cells to change the response rates and response sensitivity to a certain ligand. And so notice down below and this image we're showing you our map of the lesson on the scanning systems of innate immunity which again serve as security cameras and were specifically focusing on cell communication and the surface receptors here in this video. And so notice we're here, we're showing you the cell surface receptors and so notice that on the left hand side we're showing you a signaling cell that's creating some kind of signal and this signal that's being released. We can refer to this as the ligand here in this case. And so the signal or this Ligon is going to be able to bind to these uh receptor proteins. So these cell surface receptors are here in purple and this is the recipient cell. And so only cells that have the specific cell receptor can respond to the specific ligand. And so this recipient cell over here has the specific cell surface receptors that are going to allow to detect the ligand. And so the binding of the Ligon to the cell surface receptor will trigger a cascade of events causing one uh substance to lead to another to lead to another ultimately uh will lead to some kind of cellular response allowing the recipient cell to respond to external signals. And so this is how cell communication can occur. And again, this is very, very important for immunity. And so this year concludes our brief introduction to the cell surface receptors that are important for cell communication. And again, later in our next lesson video, we'll get to talk more about the adhesion molecules, so I'll see you all in our next video.
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Problem

Which of the following is likely to be a response by a receptor protein to an approaching signal molecule?

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Problem

Which of the following statements about cell surface receptors is incorrect?

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concept

Adhesion Molecules

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in this video, we're going to talk about adhesion molecules and their role and cell communication. And so adhesion molecules, as their name implies, are going to be cell surface proteins involved in adhering or binding to other cells. Now this adhesion is going to be very, very important because it allows immune system cells to bind to adhesion molecules of endothelial cells that are lining the blood vessels, which allows these immune system cells to enter into the tissues that are infected with microbes. Now, these adhesion molecules can also be used by cells to attach to other cells and directly deliver uh signaling molecules to the cell that they are binding to. And so, if we take a look at our image down below, over here on the left hand side, notice that we're showing you our map of the lesson on the scanning systems of innate immunity which serve as security cameras to detect signs of microbes. And we're focusing specifically on cell communication and adhesion molecules here in this video. And notice here we're showing you adhesion molecules and how they are important in cellular immunity. And so notice that here, we're showing you our blood vessels. And uh if a site is going to be infected in the tissues, then what can happen is the cells that line the blood vessels, uh the endothelial cells can create adhesion molecules and that's what we're seeing here is adhesion molecules. And so notice that these adhesion molecules that are created by these particular cells lining the blood vessels, allow for uh cells of the immune system to bind and what you can see here is a binding event where adhesion molecules on the immune cells combined to adhesion molecules on the endothelial cells lining the blood vessels. And this binding event can slow down these immune system cells and allow these immune system cells to migrate from the blood into the tissues. And that migration of these immune system cells into the tissues allows them to attack and generate immune responses to the microbial infection or the bacterial infection here in this case. And so adhesion molecules are very important for cell communication and allowing cells to migrate to an area of infection. And so this year concludes our brief lesson on adhesion molecules and their role in cell communication. And we'll be able to apply these concepts as we move forward. And then also we'll be able to talk about cytokines as we move forward as well. So, I'll see you all in our next video.
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Problem

Why are adhesion molecules considered a form of cell communication in immune responses?

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Problem

If the endothelial cells of the blood vessels in the body did not possess adhesion molecules, which of the following would occur?

a) The immune cells which respond to infection or injury would not be able to leave the blood stream.

b) The immune cells would not be able to detect where the infection is in the body.

c) The immune cells would not be able to phagocytose the infecting microbes and damaged tissue.

d) The blood vessels would adhere to the immune cells allowing them entry to infected regions of the body.

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