Alright. So here we're going to briefly revisit our map of the lesson on biosignalling pathways, which is down below right here. And of course, we know that we've been exploring this map by following the leftmost branches first. And already in our previous lesson videos, we've covered g-coupled protein receptors or GPCRs, and we've talked about all of these different branches in our previous lesson videos. And we've also talked about the receptor tyrosine kinases or RTKs. And we've covered the insulin and insulin receptor and talked about 2 different insulin RTK signaling pathways, one on glucose metabolism that included PI3K, PIP3, PKB, and PDK1, and another insulin RTK signaling pathway that was as a growth factor that included both the RAS pathway and the MAPK pathway. The RAS pathway, which included GRB2, SOS, and RAS, and the MAPK pathway, which included RAF1, MEK, and ERK. And we also discussed in our previous lesson videos a variation of an RTK, which was the JAK-STAT signaling pathway. And so now that we've covered all of the GPCRs and all of the RTKs that we're going to cover here in our course, we can finally move on to the final branch of our bio signaling map, which is over here, and we're going to discuss lipid hormone signaling. So let's get started with that. So here we're going to begin our introduction to lipid hormone signaling. And so recall from our previous lesson videos that hormones are really just defined as signaling molecules that are going to be released by a cell or gland that can travel and affect distant cells in other areas of the body. Now moving forward in our course, we're mainly going to talk about 2 main types of hormones, paracrine hormones and endocrine hormones. Now paracrine hormones are going to travel short distances, and only affect cells that are nearby in the vicinity of the synthesis of the paracrine hormone. Whereas, endocrine hormones, on the other hand, are released into the bloodstream, and we know that our bloodstream pretty much extends to all of the cells in our body. And so once endocrine hormones are released into the bloodstream, they could pretty much travel through the bloodstream long distances to their target cell. And so if we take a look at our image down below, notice that we're going to distinguish between, the top half of the image and the bottom half of the the image. And so the top half is showing us the paracrine hormones, and again the paracrine hormones are going to travel short distances, whereas the bottom half of the image down below is showing us the endocrine hormones, which again are going to travel long distances and affect target cells at a greater distance in different areas of the body. And so paracrine hormones, again, they travel short distances and only affect nearby cells in the area of their synthesis. And so notice over here on the left, we're showing you a signaling cell that's creating this green paracrine hormone here, and it's binding to the receptors on this specific target cell. And so the target cell is expressing the correct receptor to respond to the signals that the signaling cell is creating. This is going to elicit a bio signaling pathway in the target cell that leads to a cell response. But really the main difference here is paracrine hormones are traveling short distances here, affecting a neighboring target cell. Now if we take a look at the endocrine hormone down below the bottom half, again, it's going to travel long distances, and this is because the signaling cell that's creating the endocrine hormone is going to be, is going to be secreting the endocrine hormone into the bloodstream. And, of course, once it's in the bloodstream, it can diffuse long, long distances to completely different areas of the body and affect target cells in different areas of the body. And so here we have a target cell that's expressing the correct receptor here to respond to the endocrine hormone, and that's going to elicit a bio signalling pathway in the target cell that leads to a cell response. But, again, the main difference here is paracrine hormones travel short distances, whereas endocrine hormones travel long distances because they are secreted into the bloodstream. And so this here concludes our introduction to hormones, specifically paracrine and endocrine hormones. And as we move along in our course, we'll be able to talk more and more about lipid hormone signaling. And so I'll see you guys in our next video.
Lipid Hormone Signaling: Study with Video Lessons, Practice Problems & Examples
Created using AIBiosignaling pathways involve various hormones, primarily categorized as paracrine and endocrine. Paracrine hormones act locally, affecting nearby cells, while endocrine hormones travel long distances through the bloodstream to reach target cells. Lipid hormones, such as steroids derived from cholesterol, can diffuse through plasma membranes and bind to intracellular receptors, influencing metabolic responses and gene expression. In contrast, non-lipid hormones bind to extracellular receptors, necessitating signal transduction for their effects. Understanding these mechanisms is crucial for grasping cellular communication and response.
Lipid Hormone Signaling
Video transcript
What is the major difference between paracrine and endocrine signaling?
Upon secretion, a chemical messenger (hormone) binds its receptors on other cells that were nearby. The hormone was secreted in such low concentration that it did not have any effect on distant cells, even though those distant cells had the appropriate receptors. We would best classify this hormone as a(n):
Lipid Hormone Signaling
Video transcript
So here in this video, we're going to continue to talk about lipid hormone signaling. More specifically, we're going to focus on how lipid hormones are capable of diffusing straight through the plasma membrane. Now what's important to note is that most hormones are either proteins such as insulin, amino acid derivatives such as epinephrine, or steroids such as estrogen. And so recall that way back in some of our previous lesson videos, we actually did cover steroid hormones when we talked about lipids, and so we know that these steroid hormones are really just defined as these hydrophobic molecules that are derived from cholesterol. Now the hydrophobic nature of these lipid steroid hormones is really really important because this allows lipid hormones to commonly bind to intracellular receptors. And these intracellular receptors are going to be found on the inside of cells, either in the cytoplasm or in the nucleus. And this is very, very different from the non-lipid hormones that we talked about in our previous lesson videos, because non-lipid hormones don't really have this hydrophobic nature, and so they are going to bind exclusively to extracellular portions of receptors in the plasma membrane. And so if we take a look at our image down below, notice that the non-lipid hormones that we talked about in our previous lesson videos, such as Epinephrine and Insulin, are going to bind specifically to the extracellular portions of receptors that are embedded in the cell's plasma membrane. But the non-lipid hormones are not capable of diffusing directly through the plasma membrane or into the nuclear membrane. And again, that's because the nature of non-lipid hormones is not really hydrophobic enough to allow them to diffuse directly through plasma membranes. However, when it comes to lipid hormones on the other hand such as estrogen, notice that they are capable of diffusing directly through the plasma membrane to have a direct effect on the metabolic response, or they could diffuse through the plasma membrane and through the nuclear membrane to have a direct effect on gene expression responses. Whereas again, the non-lipid hormones have to bind to the extracellular portions and they have to go through signal transduction in order to have their effect on metabolic response or gene expression. And so, notice that some lipid hormones, can also have the capability of binding to extracellular portions of receptors as well, and they can also lead to signal transduction in some cases as well that leads to metabolic responses or gene expression responses. But, you can see how lipid hormones can be diverse. They can bind to extracellular portions. They can diffuse directly through the plasma membrane, or they can diffuse through the plasma membrane and through the nuclear membrane. And so a scientist or a researcher needs to be really, really aware of the type of hormone that they're working with. Because if they're working with non-lipid hormones, then they know for sure that they're going to bind to extracellular portions of receptors. But if they're working with lipid hormones, then they need to be aware that lipid hormones are capable of either binding to extracellular portions of receptors, but they're also capable of diffusing directly through plasma membranes and nuclear membranes as well to have a more direct effect on metabolic response and gene expression responses. And so this here concludes our lesson on how lipid hormones have the ability to diffuse through plasma membranes unlike non-lipid hormones. And so we'll be able to get some practice applying these concepts as we move forward in our course, so I'll see you guys in our next video.
The main difference between hormones that have intracellular receptors and those that have cell membrane receptors is that the former tend to be _______:
a) Larger.
b) Charged.
c) Amino acid derivatives.
d) Proteins.
e) Hydrophobic.
Here’s what students ask on this topic:
What are the main differences between paracrine and endocrine hormones?
Paracrine hormones act locally, affecting nearby cells in the vicinity of their synthesis. They travel short distances and bind to receptors on neighboring target cells. In contrast, endocrine hormones are released into the bloodstream, allowing them to travel long distances to reach target cells in different areas of the body. This distinction is crucial for understanding how different hormones coordinate various physiological processes. Paracrine signaling is typically involved in localized responses, while endocrine signaling can regulate functions throughout the entire organism.
Created using AIHow do lipid hormones differ from non-lipid hormones in their mechanism of action?
Lipid hormones, such as steroids derived from cholesterol, are hydrophobic and can diffuse directly through the plasma membrane. They often bind to intracellular receptors located in the cytoplasm or nucleus, directly influencing metabolic responses and gene expression. Non-lipid hormones, like proteins and amino acid derivatives, are hydrophilic and cannot pass through the plasma membrane. Instead, they bind to extracellular receptors, initiating a signal transduction pathway to exert their effects. This fundamental difference in mechanism highlights the diverse ways hormones can regulate cellular functions.
Created using AIWhy can lipid hormones diffuse through the plasma membrane while non-lipid hormones cannot?
Lipid hormones are hydrophobic molecules, allowing them to easily diffuse through the lipid bilayer of the plasma membrane. This property enables them to enter cells and interact with intracellular receptors. Non-lipid hormones, on the other hand, are hydrophilic and cannot penetrate the hydrophobic core of the plasma membrane. Therefore, they must bind to extracellular receptors to initiate a signal transduction cascade that transmits the signal into the cell. This difference in permeability is due to the distinct chemical nature of lipid versus non-lipid hormones.
Created using AIWhat roles do intracellular receptors play in lipid hormone signaling?
Intracellular receptors are crucial for lipid hormone signaling. These receptors are located either in the cytoplasm or the nucleus of target cells. When lipid hormones, such as steroids, diffuse through the plasma membrane, they bind to these intracellular receptors. This binding often results in the hormone-receptor complex translocating to the nucleus, where it can directly influence gene expression by acting as a transcription factor. This mechanism allows lipid hormones to exert a direct and potent effect on cellular functions, including metabolism and growth.
Created using AIHow do paracrine and endocrine hormones contribute to biosignaling pathways?
Paracrine and endocrine hormones are integral to biosignaling pathways. Paracrine hormones act locally, affecting nearby cells and facilitating rapid, localized responses. This is essential for processes like inflammation and tissue repair. Endocrine hormones, released into the bloodstream, can travel throughout the body to regulate distant target cells. This long-range signaling is vital for maintaining homeostasis, growth, and development. Together, these hormones ensure that cells can communicate effectively, coordinating complex physiological processes across different scales and distances within the organism.
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