Okay, so cells signal to other cells. There are organisms like bacteria that are individual cells, but we of course are not. We are made of trillions of cells that all have to go through regulatory process and work together to actually carry out functions as tissues and organs and whole organisms. So regulatory signals, environmental signals, such as outside of our bodies or even outside of our cells, we're constantly receiving signals. We're going to get signals to different types of cells, we're going to do things like repair, right? We repair cells on a physiological level, if we cut our cells or have a torn muscle, but on a cellular level as well. We're going to have up and down regulation certain cells might need more or less of some proteins or some enzymes. You might change your function like take on a new practice such as yoga and all of a sudden need more energy or more glucose to certain types of tissues. And there's also a lot of signaling we're going to see that happens between cells. So we are constantly going through cell signaling processes that you probably haven't even imagined happening yet. One of the classic examples of cell signaling is between two neurons. So this example on the side you looking at is a synapse between two different neurons in the brain that are communicating. And we have a different looking cell, because it's a neuron, so it has an elongated structure. And what you are looking at is one set up between two cells and they are passing in this case a neurotransmitter. So what's happening is one cell got excited, it released a neurotransmitter into what's called a synaptic cleft and the other cell is going to pick up that signal. And if we can imagine how many cells we have in our brain and in other types of tissue, this kind of communication is happening all the time. So what we want to do is promote healthy signalling and healthy pathways where we're promoting good structure, good signaling path leads, and promoting overall cell health. So one of the most important parts of implementing a new practice whether it be yoga, constant exercise, healthy positive thinking, mindfulness, meditation, is that cells are constantly turning over. So they are repairing themselves if they're damaged, but a large majority of our cells are also going to be creating new cells every second, every day, every year. Such as skin cells, right, skin cells is the easiest cells for us to imagine turning over because you probably can imagine if you rub your skin really hard, you'll see actual dead skin cells move away. It's estimated that we lose about nine pounds per year of skin cells and there's about 22 billion per night made. And when we start to calculate all of this together with all of our cells, what this means is sometime next year you will wake up and you will be in a 95% new body. Which means if you want that new body to be optimal health and feel different, there's a lot of things we can do over time to start to promote healthier cell development. So cells are changing at a very, very, very fast rate and the cumulative effects of this is very profound. And this is an amazing metaphor for the cumulative effects of a daily yoga practice. Understanding how much is going into cell signaling, how much energy, and time, and behavior, and action is going into every cell. When we think of this, the level of the trillions and then over time of a year, we can see how profound of an impact daily life style changes to promote health and wellness on a cellular level can really have an impact. What this means is that when we put all of this together, we are younger than we think we are, right? Every day, every month, every year we get an opportunity to promote new cell growth that's healthy and will basically have us living in an even healthier body. These are some figures of average time it takes for cells to turn over. So for example, stomach cells on average are turning over every two to nine days, lungs without damage around eight days. We mentioned earlier that red blood cells are going to last about three to four months. And things like skin cells are constantly happening. So one to every 30 days. Some cells, such as certain cardiac cells, cells of the nervous system, they don't actually turn over. So when we talk about nervous system health and cardiac health, of course, promoting optimal health for those systems is crucial since they are not actually going to divide and create new cells. All of this work that our cells are going to be doing, interacting with each other to create systems and carry out optimal health is going to take a ton of energy. And the really interesting thing and amazing thing about our bodies is they are a great example of all types of energy that is going to be taking place. So for example we have mechanical energy, right? Proteins are going to be moving within a cell across different types of actual protein networks. We have enzyme shapes that are going to be changing, we have electrical energy, so central nervous system and actually all parts of our nervous system are going to be reacting with charged ions as a signaling component. So we have electricity happening all the time. Not to mention ions in our blood and in our cells that are going to be part of facilitating chemical reactions, because they're charged like sodium, and chlorine, and potassium, and calcium, they're also considered electrical energy. We also of course have chemical energy. This is mostly in the form of stored bonds such as in glucose or glycogen, but it's also going to be in transmitting signals. So when we talk about neurotransmitters in the brain, that's a great example of chemical energy. So we have all different types of energy that are going to be coming together to form the basis of life and help ourselves carry out all of their reactions. Cells, of course, as you've noticed, are not an island, right? They are not acting in our bodies just in and of themselves. They are actually completely surrounded by what's called an extracellular matrix or ECM. And the extracellular matrix is going to help all of the cells interact with the environment and then other cells. So the extracellular matrix is going to be unique to different types of cells and unique to different types of tissues. It's usually going to be made of proteins and carbohydrates and lipids that are all going to facilitate certain reactions that go from outside of the cell environment to inside of the cell environment. And this can include the micro environment, but on a larger scale, it's also important to realize that our cells and our bodies are constantly getting feedback. So this feedback can do things like signal the cell to have certain proteins, it can regulate regeneration, it regulates gene control through transcription factors. Its studies have shown and we have a paper linked, where there's actually suppressing cancer's genes that are carried out by the extracellular matrix. It can itself be used to regrow tissue. So it's not just a scaffold or it's not just a protective barrier, but it's actually a very dynamic aspect of cell health where it's helping to signal proper growth and optimal environment and tissue health. Outside of the extracellular matrix, we have cells that are going to be interacting with other cells. So they are going to relay messages. We saw a figure before, there's a lot of figures in the text book about this where neurons are going to be interacting with other neurons to carry out a signal. They're going to interact for overall function. They're going to signal action through development of proteins or enzymes, through degradation of toxic material, they're going to signal about the environment. So we're actually going to have receiving internal signals that are going to tell different behavior of cells what's happening, what's needed. And this kind of cell to cell interaction is going to be constant. Because we have this constant signaling pathway that's occurring throughout all of our cells and all of our tissue, it means it's susceptible. And it's susceptible to things like toxins, but it's also susceptible to things like stress. And we all know stress in many, many forms. And so there are cell stress and certain cell stresses would be things like toxins from the environment, alcohol, nicotine, UV light, byproducts in processed foods, and sort of the list can kind of go on. One really important component of cell stress are reactive oxygen species, which are an example of free radicals. And free radicals means that they are a volatile free electron that can interact with different components of your cell and cause a damage. In general, when we talk about free radicals and reactive oxygen species, they're a byproduct of cell metabolism and creating energy. What happens is, if the cell is stressed, it's old, it's carrying out too many functions, there's been toxins like UV light, there's been toxins in food, it can actually start to accumulate too many free radicals. And these can really start to damage things like membranes, they can damage DNA, and it can cause mutations. And it can overall start to reduce the health of the cell. So what does this mean, right, for us? It means that we want to keep both our cell stress, and therefore our physiological overall stress at a minimum. Our cells hopefully at this point, we realize, are already working really hard through signalling, through protein development, through cell respiration, through homeostasis, that we really need to give them minimal more things to be stressed about. And life can get really stressful and probably everybody has experienced some level of stress in their life. So what does stress do, right? There's a list and the list is probably different for everybody, but in general, we have an increase in cortisol, we have a decrease in immunity, we have increase in things like ulcers, we have an increase in mutation, we have decrease in overall nutrient absorption, we can be tired or erratic in mood. I know nobody at home has ever experienced any of these, but the list definitely goes on. So what we want to do about all of this stress is we want to minimize it. And we want to minimize it because our cells are already working hard enough. So part of mindfulness and part of this yoga practice is hopefully to start to engage you in a lifestyle that will start to reduce stress and increase optimal cell health, and therefore overall physiological health. When we talk about cell health, we're talking about all the homeostatic activity we've already discussed. We're talking about being able to absorb all of the vitamins and cofactors that are necessarily to carry out proper digestion and therefore proper protein development. We want to decrease both molecular stress in terms of toxins, UV light, free radical increases. And we also want to start to create the healthiest proteins, the healthiest functioning of our cells, and the cell signalling. One of the best things to do in order to promote overall cell health and the course of the next year is repetition of healthy choices. And this goes with not only yoga and mindfulness, but eating healthy, by decreasing unhealthy thoughts of stress, by increasing the consistency of our sleep patterns and our positive thinking. So overall cell health and overall body health is really going to start at this molecular level and start to be incorporated on a daily basis for the next year. So because we want to start to promote the healthiest optimal lifestyle that we can starting in a cell level and moving up through a physiological level. Knowing how much work our cells are going to do and how much constant turnover is happening, we have this amazing opportunity to start to make a change in our overall cell health starting now. And that means implementing things like mindfulness, meditation, and yoga. So in this next part of this module, we're going to start to do our yoga postures and our yoga practice, and start to really to build over this entire course, a practice that will be doable at home, feasible to be repeated, and hopefully start to make a big physiological change over time.
