hello in this video I'm going to talk about adrenergic receptors these are also called adrenal receptors and they are the protein receptors that mediate the effects of epinephrine which is also called adrenaline and norepinephrine which is also called noradrenaline so we're talking about the hormone receptors or the neurotransmitter receptors that are on the surface of cells that are activated by the release of epinephrine or norepinephrine so adrenergic receptors are classified as alpha or beta and then there are multiple types of each so I'm going to go through those differences which of the two chemicals activate them and what the effects are so first are the alpha receptors there are alpha 1 and Alpha 2 receptors they are both activated by norepinephrine and epinephrine Alpha 1 receptors are primarily located in smooth muscle cells of blood vessels and the urinary tract so when they are activated they induce constriction um Alpha two receptors are a little bit more complicated less is known about them um but in the central nervous system they inhibit the release of more norepinephrine so norepinephrine acts on them to inhibit the release of more norepinephrine on the peripheral nervous system the function is not very well understood but these receptors are found in the pancreas veins adipose tissue gastrointestinal sphincters salivary glands and other places activation results in decreased arterial blood pressure so if you think about the systemic effects of norepinephrine is to increase blood pressure it makes sense that if in certain places the norepinephrine is inhibiting for the release of more norepinephrine that it would have the opposite effect and it will cause the decrease of blood pressure okay then we have three types of beta receptors and so on this slide I included a lot of the terminology that is commonly used to describe the locations and functions of these receptors and I will walk you through what they all mean so beta 1 receptors are also activated by both norepinephrine and epinephrine they're primarily found in the heart but they are located in a few other places throughout the body so in the heart they cause increased cardiac chronotropic effects and inotropic effects so um here what we mean by chronotropic is that it increases heart rate chronotropic doesn't imply increase it means a change in heart rate but um when the beta 1 receptors are activated it does cause increased chronotropic effects meaning increased heart rate similar to inotropic effects that means force or power and in this case it's increased so essentially we're saying that it increases the forcefulness of contraction of the heart beta 2 receptors are not activated by norepinephrine only by epinephrine these are found throughout the body but especially in the lungs and the bronchial smooth muscle cells in the lungs so when these are activated they have the effect to dilate blood vessels and bronchioles that is why epinephrine is effective in treating asthma and anaphylaxis is it because it does cause the bronchii to kind of react relax and and open up bronchi bronchioles depending on the level um it also causes the muscles in the uterus bladder and gastrointestinal tract to relax it decreases platelet aggregation which is part of our blood clotting so it decreases blood clotting and it also increases glycogenolysis meaning the breakdown of glycogen into glucose so it's helping to um sort of move our it's helping to put more usable energy into our circulation to fuel our fight or flight so glycogen is the stored form of glucose and we want to mobilize our resources so that we can use that glucose to fuel our activity uh now I found this picture that you see here uh that I thought was very clever it put um B1 because we have one heart so our B1 receptors are primarily in the heart B2 we have two lungs and those receptors are found abundantly in the lungs I thought that was a clever way to help you remember where those are located again they're located in other places but those are the primary locations and their primary functions then beta 3 receptors are only activated by epinephrine they're found in both white and brown adipose tissue and the increased fat oxidation energy expenditure and Insulin mediated glucose uptake so again we're working on mobilizing our resources providing energy to our cells to fuel our fight or flight so by breaking down the fat stored in our adipose tissue and improving our ability to utilize that energy to support activity in fight or flight all all right well thank you so much for watching this video and I hope you have a great day