in this video we're going to continue discussing the plasma membrane but particularly uh we're concentrating on the functions of proteins within the plasma membrane so there are many many functions and we're not going to be able to discuss all of them but we're going to concentrate on some of the functions that we're going to see through different topics in the ap1 and 82. so the first function what we're going to write down here is receptors a lot of proteins are going to be used for communication and usually those receptors are very specific to the chemicals that attach to them so for example um [Music] if we talk about hormones hormones can affect change within the cell by attaching two receptors on the surface and a lot of times those receptors are proteins so that can initiate certain changes within the cell which means the cell is able to communicate in response to um certain changes in the outside environment so uh there is an example here um there are multiple examples where uh you know that we have hormone static imbalances that affect receptors one of them is a disease called diabetes mellitus and in a type of diabetes mellitus we have receptors that are not responding to insulin right so there is no attachment um that can happen between the insulin and the receptor and as a result of that we're not able to use glucose for fuel purposes there is another condition but similar to that called anthrogen insensitivity syndrome and an endogenous insensitivity syndrome the testosterone receptor is defective so testosterone cannot have an effect on the cell so those receptors are really important in how the cell respond and communicate to the outside environment function number two proteins are going to form a lot of infracellular junctions so two inter cellular junctions and what that means is that when we have two cells next to each other proteins in their membranes will be able to form certain connections right so a lot of times we refer to it as intercellular connections but we're going to talk more about different types of junctions a little bit later that keeps cells together um either from external forces so they don't disintegrate um their junctions that allow cells to communicate with each other and so forth function number three proteins act as channels that's particularly true of these transmembrane proteins so um channels um because they're proteins and we know the proteins have ability to change their three-dimensional shape right they do nature they lose their conformation and as they change their shape they are allowing solutes to ever enter the cell or exit the cell right so there are different types of channels and we talk about channels a lot in anatomy so uh we're going to introduce the groups here and then we're going to come back to them in later topics so group of channels called ungated and that means they are constantly open since these channels are also specific very much like receptors that means if this channel is ungated the solutes that pass through the channel can pass in or out of a cell at any given time right so we have constantly open channels for potassium or sodium we're going to come back and talk more about them but that means the potassium and sodium can pass through the plasma membrane all the time because those channels do not have the ability to close the second group is represented by gated channels um and let's see if you think about the name it kind of makes sense that they have a gate which means they can open and close so can open or close and um the solutes can only pass when channels are open right so when they are open solutes pass when they are closed no passing so all these gated channels too are of special importance to us so we write them here one group is called ligand gated and ligand-gated means that these channels are going to open in response to chemicals right so um they are normally closed but if we have the chemical that fits like a key in the lower kind of analogy then those ligand-gated channels will open and solutes would be able to pass through so when we discuss muscle contraction we're going to talk about sodium ligand-gated channels okay the second group is called voltage-gated and again voltage-gated channels stay closed unless we have a change in charge across the plasma map right so we're going to talk a lot about this voltage across the plasma membrane called the resting membrane potential when we do have changes in voltage these channels are going to open and we're going to talk about sodium and potassium voltage-gated channels a little bit later and then lastly proteins connect as carriers i'm going to put number four here and if you think about carriers think they can help solutes pass from one side to another um right some of those carriers can do it without the use of energy but some of those carriers are actually going to require atp and if they require atp then carriers are called pumps so we have a very important sodium oxide pump in the body which we are going to discuss later in the semester but the word pump tells us it's an active transport mechanism which means we are going to require energy and we are usually going against the concentration gradient so in this video we took a more detailed look at proteins within the plasma membrane and we mentioned um four functions of proteins here we have way more so proteins have lots and lots of importance for the functioning of a cell but we concentrated on receptors intercellular junctions which we're going to discuss later in more details channels and carriers