An Essential Guide to Your Body and Brain Episode 07 | Life Cycle and The Aging Brain

This is the last episode of our series, An Essential Guide to Your Body and Brain and in it, we will talk about the body’s life cycle and we will finish the series talking about the aging brain. 

Get the transcript of this episode on https://englishpluspodcast.com/an-essential-guide-to-your-body-and-brain-episode-07-life-cycle-and-the-aging-brain/

Transcript

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Every human body starts with a meeting of two cells, a sperm cell and an egg cell and develops from that union. Almost immediately, hundreds of other kinds of cells arise, each suited to a particular task, and yet all made up of the same basic parts, dividing, specializing, proliferating and dying, the cells follow instructions encoded into their DNA to become the magnificently coordinated colony, that is the human body. The adult body contains trillions of cells, each with its own life cycle all are born from the Division of pre existing cells, most will grow, divide and eventually die to be replaced by new cells. In some tissues such as those of the skin this cycle runs almost continuously. In yet other tissues such as those of the heart, mature cells cannot divide and damage to the organ is repaired with scar tissue. The processes that control cell birth, death and specialization are still not well understood. And solving these mysteries is a major goal of biologists today. These questions are key to understanding just how the body grows and ages and how its greatest enemies such as cancer can be defeated. interested to learn more, of course you are because today is our last episode of an Essential Guide to your body and brain. And in today's episode, we're going to talk both about the body and the brain about the body. We're going to talk about the life cycle, which I just gave you an introduction to and about the brain, we're going to talk about the aging brain. So we're going to start talking about the life cycle that's coming next. Don't go anywhere. This is your host, Danny and this is a new episode from English plus podcast. Now before we start, let me remind you that you can find the transcript of this episode on the website English plus podcast.com. And while you're on the website, you will find a lot of other interesting and fun learning opportunities that you can find not only about the body and brain, but about a lot of other things, English plus other things. Remember, we're English plus. So we talk about English. And we talk about a lot of other things. So you can check all these learning opportunities out on the website. And if you want to unlock everything, especially now that we're starting our premium series next week premium episodes, we're going to have vocabulary and speaking series, we're going to have business English series, a very special series that talks about the history of classical music with a lot of beautiful music to listen to my premium fiction series in which you will be able to listen to exclusive novel series. And there's also the immortal book series that is coming back as a premium series only available to my Patrons on Patreon. So there's never been a better time to become a patron. And by doing that you will be supporting our show and helping us continue. But also you will get a lot of benefits and premium content available exclusively to you as patrons. So what are you waiting for, take your learning in a fun way to the next level with English plus and take this link to my Patreon page, the one you can find in the show notes and become a patron today enjoy all the benefits and support the show so that we can go on and become better and better. And with that being said, let's not waste any more time and let's talk about the life cycle. Let's start with the Body Talk about the life cycle. And of course, since we're talking about the life cycle, we're going to start talking about the beginnings. That's coming next. Don't go anywhere. I'll be right back. We're gonna start talking about the beginnings and of course the human reproductive system. The human reproductive system that drives the process of life giving it is essential to human existence. Now superficially, the reproductive system is a series of tubes, ducts, glands, and organs. But underlying it all is a delicate chemical dance, a pulsation of hormones and neuro chemicals. In reproduction. Both the man and the woman have important parts to play. The man's main biological function is to supply sperm, the cells that combined with a woman's egg when conception occurs. For that reason, the male reproductive anatomy is relatively simple and centered on the production storage and delivery of sperm. Before the 18th century, physicians viewed females as incomplete males early physicians saw that females had a womb with a shape on top not unlike a scrotum, but with the testes represented in the woman's ovaries lying outside the womb, the womb opened into a tubular canal, something like a penis turned inside out. Thus the notion of sexual difference put forth by the second century Greek physician Galen prevailed for many years, females must be males who because of the lack of vital heat retain their reproductive structures inside their bodies. While those of true males were located outside, of course, we're just talking about the old notion which is completely wrong. Of course, modern scientists have come to understand that the female reproductive system is far more complex than its male counterpart, females after all, must create and store eggs for fertilization, provide an environment where those eggs can develop and thrive and house and nurture a growing fetus much more complex. And if you didn't think the idea I gave you about the old notion physicians had about the woman's reproductive system. Weird enough. Let me tell you about something else. Did you know that ancient physicians believed that the womb could detach and move around inside a woman's body? Well, they did. But of course, that comes down not only to the lack of science, but to the prejudice we had back then. And most of the physician or almost all the physicians back then, just like anything else in ancient societies were men. So consider the source. But of course, modern science dissipated all these ridiculous ideas that we have in the past, and when maybe there are still more ridiculous ideas that science needs to defy and eventually destroy. So we talked about the beginnings we talked about the reproductive system, the male and female, and we got to the point when we talk about fertilization, and that's exactly what we're going to talk about next. So don't go anywhere. I'll be right back. Remember, we're talking about the life cycle, which starts from a sperm and an egg, and then comes fertilization. So don't go anywhere, I'll be right back. For the human egg, the literal journey towards fertilization begins when the egg pops out of an ovary and drifts into the nearby fallopian tube. As it moves down the fallopian tube, propelled by hair like cilia in the tubes lining, the egg is chaperoned by a cloud of encircling smaller cells called the corona radiator. So that was about the female part. But what about the male part? Well, it's kind of race to the finish thing. Some 250 million sperm are furiously swimming up the reproductive tract consisting of little more than tails plus head filled with 23 chromosomes. The sperm die by the millions as they traverse the uterus, only a few 100 will survive to meet the egg, the first to arrive won't even get to fertilize it. Instead. As they begin to batter the outside of the egg. They release enzymes that disperse the corona radiator and gradually expose it surface. Finally, one sperm penetrates the eggs outer covering the Zona Pellucida, or the area Pellucida. And the egg internalizes it. As soon as this event happens, calcium ions from within the egg flood the cell, and its charge changes from negative to positive repelling all other sperm, and then the nuclei of the internalized sperm and the main body of the egg, each containing 23 chromosomes, then merge, the egg cell is now fertilized almost immediately, its chromosomes duplicate and the cell divides by mitosis, creating two identical daughter cells. This tiny entity is called a zygote. It's amazing, isn't it? I mean, of course, we're only scratching the surface of what really happens. But it is remember, it's an essential guide to your body and brain. And what we need to understand is just what's happening within our bodies, and our brains are not so deep level. But I hope that I'm encouraging you to dig deeper and search for more information. If I get you to do that, then I have reached my goal to encourage you to learn even more. So we're still talking about the life cycle folks. And we talked about how it all starts with what with a sperm and an egg, of course, and how fertilization happens. Let's talk next about the first eight weeks of the life of a human being. That's coming next. Don't go anywhere, I'll be right back. In its first three weeks of development, the speck size bowl of cells now in embryo implants in the uterus and develops three layers, the endoderm, the mesoderm, and the ectoderm. From these three layers will arise all the structures of the human body in a process called Organic Genesis. Now exactly how this process is controlled is still one of the mysteries of biology. So how does the embryo moves from embryo to feed us? Now we do know that the embryo develops at a furious pace. Some of the mesodermal cells collect into an enclosed pipe which is called the neutral tube, the top end of this tube will become the brain and the rest the spinal cord. Cells nearby move around the embryo to become eventually such diverse features as sensory nerves bones of the face and connective tissue. Blood vessels form and link up throughout the embryo and a primitive heart tube arises from the mesoderm and starts to beat. During the fourth week, the embryo grows into an irregular cylinder with a recognizable head and tail, part of its yolk sac now merges with the embryos midsection to form a primitive gut, eyes and ears begin to appear on the head while upper and lower limb buds form eventually to be transformed into arms and legs. From the fifth through the eighth week after fertilization, almost all remaining structures and organs such as the bones, the liver and the lungs begin to appear. At the end of the eighth week, the embryo is about 1.2 inches or three centimeters long and ready to move into the next stage of its life as a fetus. Incredible, isn't it? I mean, I was fascinated when I researched this to prepare for the episode. It is a world of wonders what happens every day. And what we see every day, we unfortunately take for granted. These are miracles happening all around us. And all I'm saying is that sometimes we look but we don't see. And I'm getting philosophical. Now I know. But we look at those things around us. And we just take them for granted. We don't see them while people see those little things that are happening around you. Because they're not little, they're huge. And most of them are still mysteries that we don't understand. So maybe you will understand them one day, maybe one of you who's listening to me right now we'll come up with a solution or we'll discover something that nobody knew about before. But let's continue the lifecycle. And next we're going to talk about becoming a baby. That's coming next. Don't go anywhere. I'll be right back. We talked about what happened in the first eight weeks. So let's continue with week nine. At nine weeks, the foundations of all of a fetuses major organ systems have been laid down from that time on its body begins a campaign of growth, development and consolidation. By 27 weeks a baby born prematurely has a reasonable chance for survival. Though with a high risk of complications I will have to say at 38 weeks, the fetus is considered full term bones fully developed eyes open and lungs ready for air. Throughout this period of growth the fetus is immersed in amniotic fluid it survives because of remarkable adaptations of its cardiovascular system. The blood that flows through a fetus his body picks up its oxygen and nutrients from the mother's blood by way of the umbilical cord, which is attached to the placenta and contains two arteries and veins. blood circulates through the fetal heart and body but largely bypasses the lungs and liver by using the blood vessels as shunts around these organs. Just enough blood flows through the lungs and liver to keep them alive and growing. And now we come to the magical moment of birth. Nine are a remarkable feat of biological engineering, all of these shunts will shut off instantly at birth. As it is exiting the mother's body, the baby no longer receives oxygen from the mother's placenta rising level of carbon dioxide in its blood signals respiratory centers in its brain to jumpstart the process of breathing. The baby takes its very first breath. With the lungs working the baby's cardiovascular system must also kick in the foramen ovale Lee which is an opening between the atria of the fetal heart closes, sending blood to the lungs, blood vessels that bypass the lungs and liver close off as do the umbilical arteries. In a matter of moments, the body switches from liquid to air. How does that happen? I have absolutely no idea. I mean, it just happens instantly. We can do that with all the technologies we have so far. Maybe in science fiction, they talk about this and we can breathe and fluid and stuff like that. But we're still not there. But look at a woman's womb look at this magical place where all these things happen. And the baby switches just like that in a matter of seconds from liquid to air with no scientists around no big machines, just a woman's womb, the most sophisticated factory of life. Well, of course, we talked about miracles, but of course we will have to talk about what can go wrong as well. And here I'm going to talk about misplaced pregnancies. ectopic pregnancies occur when an embryo implants outside the uterus, usually in the fallopian tube. Although they are rare they can cause rupture and internal bleeding and are a medical emergency. The mother may have a mild pain or bleeding or no symptoms at all. ectopic pregnancies are typically found when a woman's blood tests positive for pregnancy. But a sonogram shows nothing in the uterus. Such pregnancies are not viable, and they either resolve themselves or require surgical removal. In rare cases, a fertilized embryo will implant within the abdomen with the placenta attaching to local organs and drawing on their blood supply. Occasionally, a baby has lived to be delivered in these cases. But in general, the pregnancies are too dangerous to continue when they are misplaced, just like I told you. So of course, miracles happen, but sometimes things go wrong. And thankfully, we know these things by now and we can handle them without risking the mother's life. But in the past, they didn't know about these things. And a lot of women died just because of misplaced pregnancies. So we've talked about the miracle of birth. Next, we're going to continue talking about the life cycle and we're going to talk about inheritance that's coming next. Don't go anywhere. I'll be right back. In a February day, in 1953, two scientists, an American biologist and a British physicist walked into a pub called the eagle in Cambridge, England and cheerfully announced that they had found the secret of life. This was not the usual Guinness fueled boast. The two had in fact deciphered the double helix structure of DNA, the molecule that shapes all living things. Since the 19th century, scientists had known that a cell's nucleus held a long organic molecule called deoxyribonucleic acid since the 1940s. They had suspected that this molecule played a part in transmitting genetic information. Watson Crick and their colleague Rosalind Franklin figured out just how that worked. The DNA molecule is built like a ladder. The sides are chains of sugars called deoxy ribose that alternate with phosphate groups for bases attached to the sugars pair up each pair forming a rung, adding in links to thymine and guanine links to Saito sin, the DNA molecule twists around itself in a spiral called a double helix. So what about chromosomes then? Well, within the nucleus of almost every cell are 46 of these spiraling molecules in 23 matched pairs, which make up to 46 human chromosomes. The basic unit of each chromosome is a nucleotide formed of a sugar, a phosphate group and a base a piece of the side of a ladder attached to half a rung. Genes are simply groups of nucleotides and the order of the nucleotides in the gene. For example, att GCCA dictates the genes purpose, the average gene consists of 3000 nucleotides, but some genes have more than a million. I know, you must have been scratching your head as I was scratching mine, I'll be honest with you, it doesn't mean that I really understand every single word I was saying. And I tried to make it as simple as possible. But it is very, very complicated. And although yes, these gentlemen claimed that they had found the secret of life, which they did, obviously, we still have a lot to discover and to understand. So maybe this is something for the Bright Minds among us, but it's definitely worth looking into. So I'm sorry about this bit. That was kind of complicated. But anyway, that's part of life, those genes, chromosomes DNA, it's very complicated. I know and we're not done. We're going to talk a little more about genes. So please bear with me, and that's what we're going to do next. So don't go anywhere, I'll be right back. an organism's complete set of DNA called its genome contains about 20,500 genes. A large portion of DNA seems to consist of repetitive strands of non coding nucleotides. Some of these give rise to ribonucleic acid, which is RNA, or they help serve other genetic functions. Others might be extinct genes whose traits were discarded in the course of evolution, or they might be strands whose meaning has not yet been deciphered. So what do genes do exactly? These moleculer snippets loom large in the popular imagination, they are depicted as dictators of everything from criminal behavior to cold sores. Yet a gene is nothing more than a set of instructions for making a particular protein in a cell, a genes molecule or code the sequence of a T, C and G nucleotides that give it its identity. spells out the order in which amino acids are the building blocks of proteins must be strung together. The gene doesn't even transmit the instructions. That job which falls to RNA consists of two steps transcription when information from the gene is copied onto a strand of RNA, and translation, when the information in the RNA is used to make the protein in the cells ribosomes, still, protein production is an extraordinarily powerful job. In controlling proteins. genes control the growth and workings of every cell in the body. They also dictate the growth, specialization and development of every cell in a human embryo. So we talked about genes. Next we're going to talk about genetic partners. So don't go anywhere, I'll be right back. The genes on each of the paired chromosomes in every cell code for the same proteins and the same traits. This redundancy provides critical backup for the cell. If one gene is damaged, the matching gene on the link chromosome will usually pick up the slack of the match genes which are called alleles aren't always identical. However, if they do code for the same form of a trait, they are called homozygous. If they code for two different versions, they are called heterozygous. Sometimes one heterozygous allele suppresses the expression of its partner. Such an allele is called dominant while its partner is called recessive. So what about those inherited traits? Now a few traits are expressed by one gene, almost all traits result from several genes working in tandem. Some traits are expressed by multiple allele forms in which two can be codominant, such as the A B blood type. Some alleles are incompletely dominant, such as those that can cause sickle cell anemia. Nor are dominant traits necessarily more common or desirable than recessive ones, Huntington's disease and polydactyly, which means extra fingers or toes are caused by dominant genes, while normal vision and normal cartilage formation are found on recessive genes. In the game of heredity, two chromosomes stand out from the rest the X and Y sex chromosomes. The Y chromosome contains the genes that determine maleness, every man's sex chromosomes are an X and Y set, while every woman's are xx xx, the X chromosome is much larger and richer in genetic information. It contains about 900 genes versus 50, or 60. On the y most characteristics on the X chromosome will be expressed in men because they are not countered by matching genes on the Y. And again, we're talking about miracles. We're talking about things that are complicated, difficult to understand, I know but what can go wrong? What about inheriting illness, genetic disorders can be linked to a single damaged gene to entire misplaced chromosomes or too many genes working together. Those linked to a single gene say haemophilia are the easiest to track down. But most disorders are probably caused by the complex and difficult to trace interaction of multiple genes and the outside environment. In recent years, geneticists have begun to pinpoint the location of some genetic diseases. The neurological disorder Huntington's disease, for instance, is caused by excessive repetitions of the nucleotide triplets C, a G on chromosome 455 to 65% of women baring a mutated BRCA one gene, which is in its healthy form produces tumor suppressing proteins will develop breast cancer by age 70. Now, by understanding more and more of these things, and maybe we will have a safe way of altering the work of these genes or maybe inhibiting their work, we might discover a way to nip cancer in the bud before it even appears. But of course, it is, I have to say, very complicated, and maybe it will still take some years to get there. But we're getting there closer we're getting close every day. The more we understand about our own DNA, about our own genetic inheritance, and all that the more problems we may solve in the future. And now let's talk about powerful dividers that we have within our bodies. That's coming next. Don't go anywhere, I'll be right back. Almost every stage in human life in almost every part of the human body cells are locked into a specific shape and function. Only stem cells are different. These are the blank slates of human biology, genetic cells with the potential to develop into a great variety of others. In theory, stem cells could be used to repair damaged tissues to test new drugs and to research birth defects. Now what about The types of stem cells or stem cells are found in a range of locations, and some seem to have more potential than others. embryonic stem cells used in laboratory cultures are derived from blasts to sites created in an in vitro fertilization clinic and scheduled to be discarded with the ability to transform into any kind of cell in the body except those that develop a fetus. embryonic stem cells are called pluripotent adult stem cells are scattered in minute quantities in some adult tissues, including bone marrow, skin, brain, livers, skeletal muscle, blood vessels, and cornea. With the right stimulus, adult stem cells can develop into a limited range of cells related to the tissue in which they are found. In general, stem cells remain difficult to obtain to culture and to put to use without harming the patient. Even so, they remain one of the most exciting pathways to new therapies and new medicines in the near future. And here, let me tell you about some cutting edge biotechnology and that is about creating multipurpose cells. Now the use of embryonic stem cells raises ethical issues, while the use of adult stem cells limits applications. In 2006, scientists found a third path induced pluripotent stem cells or IPS C's. Using viruses as delivery vehicles, the researchers introduced four key proteins into the nuclei of mouse cells. These transcription factors change the cell's genetic programming and forced them to return to an embryonic stem cell state in 2007. The same process was successful in adult cells. The advantages are obvious. If scientists can use any adult cell to create lines of pluripotent stem cells, they might be able to produce an unlimited supply of powerful cells, researchers are now proceeding to study the process more carefully, and to ensure that it can be employed safely in human therapies. Well, the ability to do that is just mind blowing. But I guess we still need a few more years to get there. But these things are being researched nowadays. And I'm not so sure if they got to the stage of starting human trials. But definitely, it's going to be there soon. And now continuing with the lifecycle, of course, we get to the later stages of life, maturity and getting old, and we'll talk about maturity next. So don't go anywhere. I'll be right back. Aging is an ongoing process of growth and maturation. It starts in infancy and encompasses the healthy development of a child into a young adult as well as the journey from young adulthood into maturity. When most people think of the grimmer aspects of aging, they're actually contemplating citizens, which is the process by which the body gradually breaks down and becomes unable to function properly leading eventually to death. So what about normal aging? Now even this form of aging needs some clarification to most of us senescence is synonymous with disease and impairment, hearing loss, arthritis, osteoporosis, heart disease, dementia, and so forth. And it's true that old ages typically marked by increasing illness and disability. But these are still disorders, not examples of normal body functioning at any age. Usual aging may include these disorders, but normal aging does not old age style. Aging. senescence is a set of cellular changes that occurs to the body over time in adulthood. As the body ages it cells work less effectively. Eventually, cells stop dividing and die. As a result, tissues shrink, and organs don't function as well as they once did. But of course, with this comes the question why do we age aging ranks with sleep as one of the fundamental mysteries of human biology? What causes the body to slow down its cells to stop dividing and its organs to fall prey to increasing illness and disability? No one has a definitive answer to these questions. But theories can be grouped into the gradual damage over time camp and the genetic programming camp. And if you listen to my great mystery series, we talked about just that. But of course, here again, we're talking again about it because it's relevant to our topic today. But if you want to learn more about those mysteries, you can check out my great mystery series. And you can find it of course here in the podcast or on the website, because every single episode is right there on the website. You can go there, search for whatever you want, and you will find them and very soon I will make it even a lot easier for you to find the things you're looking for by organizing them into topics but that will take some time to organize. But anyway, the question I'm talking about right now was definitely there In my great mystery series, so if you want to check it out, please go ahead. But don't go there yet, because we're not done in today's episode. Today's episode is a little bit long I know but it is worth it because we're talking about this last stage in the body and yet to come the brain so back to our question, why do we age I said that there are two theories are actually two camps the gradual damage over time camp and the genetic programming camp, or the first group of theories holds that the body ages because of wear and tear that accumulates in the tissues over the years, waste products build up in cells backup systems fail, repair mechanisms gradually break down and the body simply wears out like an old car. But the second group of theory says that aging is driven by our genes by an internal moleculer clock set to a particular timetable for each species support for this theory comes from animal studies, scientists have been able to cause an increased lifespan in some animals by altering just one gene. Biologists point out that from an evolutionary point of view, the effects of natural selection greatly decline after reproductive age, evolution favors genes that are beneficial early in life, putting the body's resources into reproduction, and leaving fewer available for long term maintenance. But of course, that doesn't mean that we have a definitive answer to the question. Why do we age because we don't know exactly we have theories? We don't know exactly why do we age we know how we age and not to the last detail, but we almost know everything about how we age but why we age is the big question, the big mystery. So that's about maturity and why we age next we're going to talk about the limits of division don't go anywhere, I'll be right back. The process of aging begins in the body smallest units, the cells how and why cells age is a subject of debate, though a few mechanisms are becoming clear. In the early 1960s. Biologist Leonard Hayflick discovered that cultured cells would divide only an average of 50 times before they stopped a number that has become known as the Hayflick limit. with the exceptions of stem cells and cancer cells. This limit applies to all human tissues, though cells from older people divide fewer times. So what makes cells slow down and die. An interesting finding is the discovery of the role of telomeres. Telomeres are stretches of DNA that cap the ends of chromosomes protecting chromosomes from damage and keeping them from fusing with other chromosomes. Researchers found that each time a cell divides about 50 to 100 of the telomeres nucleotides are lopped off. When the telomere reaches a minimum length a cell division stops altogether. This finding was bolstered by the discovery of telomerase, which is an enzyme in immortal cells, such as stem cells that repairs telomeres after each division, the enzyme does not affect non dividing cells, such as those in the brain and heart tissues. And in cells that do divide. Telomerase may promote cancer. Amazing, isn't it? But again, we still have a lot to learn about these things. But let's talk now about some cutting edge. I'm about fitness and DNA. Biology is not destiny, even when telomeres are involved. And that is what research is studying the relationship between telomere length and the environmental factors say people with stressful lives are found to have telomeres that are shorter than average. On the other hand, a small study conducted by Dean Ornish at the University of California San Francisco showed that people who adopted healthier lifestyles such as those including moderate exercise, a plant based diet and stress reducing regimens experienced on average, a 10% increase in telomeres, more research is needed to confirm the findings. But the studies appeared to be another break in the wall of evidence in favor of staying lean, fit and mellow. So fitness does help even your DNA. Well, I know that this is not like 100% proven yet, but it makes sense. So just think of healthier lifestyles, people that will help you on many different levels. But anyway, we have one more thing to talk about the life cycle. And that has to do with the changes that happen in old age that's coming next. Don't go anywhere. I'll be right back. Aging affects almost all of the body systems senses the digestive organs, the cardiovascular system, the immune system, the bones and the muscles. Interestingly, the central nervous system which is the brain and spinal cord is among those least affected by age. In most tissues, the decline in function is not drastic, only in situations of stress or disease. Does it become clear that the Older body has trouble coping, changes to bones and muscle affect an older person's daily life perhaps more than anything else between the ages of 30 and 60. Bone density decreases in both men and women muscles also change over time between the ages of 30 and 75. About half the body's muscle mass disappears while the amount of fat doubles. And what about breath and blood? Oh, the heart, blood vessels and lungs are durable structures built for a long lifetime. The fact that so many older people develop heart and lung problems has less to do with the aging process than with lifestyle factors such as smoking, obesity, and lack of exercise, the systems do change a bit with time, the valves and walls of the heart become thicker and stiffer, which makes the heart work harder to pump blood artery walls also thicken and stiffen which can contribute to high blood pressure. lung tissues also lose some elasticity as the body grows old, perhaps more significant, the lungs immune system begins to break down with age, because they pull in airborne organisms lungs become particularly vulnerable to infections. And that's why we say diseases like COVID, for example, is more dangerous for older people because of these reasons. And with that, we've talked about the life cycle. And next since we're talking about maturity and aging, we're going to finish with talking about the aging brain. So don't go anywhere. That's going to be next, I'll be right back. So now that we have talked about the body, and what happens in maturity and old age, let's focus on what happens to the brain, especially the aging brain, and we'll talk about the senses first the changing senses. As we age, our senses become less acute through changes in the sense organs themselves, as well as changes in the brain. minimum levels of stimulation, called thresholds are required before the brain perceives a sensation. With age. These thresholds rise requiring greater stimulation before sensations register. In addition, aging brains suffer a decline in working memory, making them more prone to distraction. That's why driving especially in heavy traffic becomes more difficult with age, not about the vision and hearing. Now the eyes and ears suffer the most dramatic ravages. Nearly everyone older than 55 needs corrective lenses at least part of the time. Some studies have found that impaired vision in the elderly is linked to mental decline. why that's so isn't clear. But logic suggests the lack of clear vision for reading and performing eye hand coordination would limit the ability to do brain strengthening exercises. Ears also suffer abuses through age with the ability to hear high pitched sounds the first function to disappear. But unfortunately, that was considered a disease of old age only, which is the loss of hearing in high pitch registers. And now it's appearing in younger patients and all that thanks to the noisy world we live in. People lose their hearing in specially this high pitched hearing very early in life and not in a natural way at all. So we talked about the senses what about memory and learning that's coming next. Don't go anywhere, I'll be right back. For centuries, observers have known that people process information more slowly as they age but as a trade off for their decline in speed, the elderly tend to consider problems more carefully and then offer well reasoned responses. One area concretely affected by age is memory. Recalling facts and autobiographical data may be clouded by anxiety, depression, and other negative states which are more common among the elderly than young people. Nevertheless, when controlling for these variables, it becomes clear that aging weakens memory. Normal degradation of memories occurs both for events of the recent past and those long ago. Furthermore, the elderly lose a degree of working memory, which is the mental desktop that allows them to hold and manipulate information for a few seconds. PET scans of elderly brains reveal how they differ in memory tasks from younger brains. both young and old brains activate the hippocampal regions in both hemispheres to begin the process of encoding memories. However, during the experiments aimed at testing the recognition of a set of 32 faces the elderly showed lower levels of activation in the hippocampus than more useful brains and elderly brain may attempt to force the recall of uncertain information by calling on the frontal lobes to assist in memory, but PET scan As revealed older brains have more trouble activating these lobes, particularly in the left hemisphere. Even so minor problems with memory are not a cause for concern until they become serious enough to interfere with daily life. So what about coping with impairments? That's coming next. So don't go anywhere. I'll be right back, we still have a couple of things to talk about the brain, and then it will be the end of the series. But don't go just yet. Stay tuned. I'll be right back. Today's scientists know that dementia and strokes are not normal parts of the aging process. Dementia from the Latin for apart and mine describes a variety of symptoms that stem from as many as 50 disorders of the brain. All these disorders involve neuron destruction. Physicians diagnose dementia if two or more brain functions typically including memory and language skills are significantly impaired. But of course, dementia is not the only problem we have strokes as well. Unlike dementia as stroke occurs in an instant, the ancient Greek physician Hippocrates described stroke as blesser, meaning to be thunderstruck. A stroke occurs when a blood clot or broken artery cuts off the flow of blood to the brain. Without oxygen rich blood brain cells die taking with them the cognitive and motor functions they make possible. But we have different types of strokes we have the thrombotic strokes which occur when an artery serving the brain closes through the buildup of fatty deposits on its inner walls. And there are the embolic strokes which occur when a fatty clot forms elsewhere in the body, such as in the walls of the heart and flows through open arteries until it lodges like a dam in a blood vessel of the brain. Together these two accounts for 80% of strokes. hemorrhagic strokes occur when an artery ruptures in the brain, usually as a result of high blood pressure. Although strokes happen in the brain, they affect the whole body. They are one of the leading causes of death and disability among older people. But the brain has remarkable abilities to recover even from stroke damage. With therapy. Most people recover some or all physical functions, especially if they receive treatment within the first three hours. And now says we're talking about impairments and coping with impairments of course, we will have to talk about Alzheimer's disease. And Alzheimer's disease is the most common form of dementia targeting the portions of the brain that are crucial to remembering, thinking and reasoning. It is marked by an accumulation of plaques and tangles in the brain dense bundles of fibers formed by a molecule called Tau inside the neurons alter plaques and tangles from orderly patterns of neural connections to chaotic twists and turns. Outside the afflicted cells live fatty globs of plaque, the accumulation of plaques and tangles makes neurons shrink and disappear. Drugs are now available to treat progressive dementia, including Alzheimer's disease. But for now, they only offer relief from the disease, not a reversal of the disease. But hopefully, we will get there very soon. Because definitely Alzheimer's disease is one of the most painful diseases. It's not like the physical pain, but it is the emotional pain, especially at its first stages. When patients realize that they are starting to have it, it's very difficult. So hopefully, we'll get very soon to figuring out a way to reverse this disease and to control its spread in the brain. And now we are left with one more topic to talk about that has to do with the aging brain. And here we're talking about new directions that's coming next. So don't go anywhere. You've listened to all the episodes, there's just one little bit of information. And then we are done with this episode and the entire series of an Essential Guide to your body and brain. Stay tuned, I'll be right back. In the fetal brain unspecialized stem cells grow into hundreds of particular kinds of neurons, each appropriate to its location and function. Until 1998. scientists believed the adult brain contained no stem cells and that no neurons could form after early childhood. However, the discovery that year of stem cells in the hippocampus and the subsequent recognition of stem cells in the olfactory bulb and code eight nucleus touched off a frenzy of speculation about ways they might be induced to create replacement neurons for damaged parts of the brain. Research is now focusing on finding the right chemical stimuli to turn a laboratory dish of stem cells into mature nerve cells. And there's also what we call the precursor cells. Another thread of research aims to prompt precursor cells already in the brain to migrate to damaged areas and change into the necessary replacements. Jeffery mapless, of Children's Hospital in Boston has induced the birth of neurons in mature mice brains, cells that move toward areas of cortical damage and developed into mature neurons that acted just like those already there. With more research, doctors hope to be able to induce the body's most complex organ to heal itself. So who knows, we might get there very soon, or it might take some time. But this is definitely one of the most exciting areas of brain research that we have nowadays. So with that, also, we come to the end of today's episode and the end of our series and Essential Guide to your body and brain. If you're listening to this series. For the first time, we have more episodes, just go search for the episodes on my website, or here in the podcast itself, and make sure you get them all because there's a world of knowledge in the series. And I just included the essential things you need to know about your body and brain. Before you try to understand what's happening around you in the world. Start with yourself. First, that's the most important person that you need to know about and what better to start with than your own body and brain. And that's what an Essential Guide to your body and brain is all about. So I would like to thank you very much for listening to this episode and to listening to the entire series. And of course, listening to other episodes from English plus, and of course, with one series ends, another begins. And next week, we're going to have a new series, and we're going to focus on something very exciting. And that has to do with the brain as well. And we're going to talk about brain myths. I hope that you learned a lot from the series and I hope that you enjoy the other series as well. Don't forget that you can find the transcript of this episode on my website. The link is in the show notes. And of course while you're there, just explore the many learning opportunities you can find on English plus podcast, especially if you decide to become a patron because a lot is coming your way starting from next week. Now a lot is coming your way already. There is a lot of extra things you get as a patron and they're right there on the website. But there's a lot more coming starting from next week we have a whole set of premium episodes that I will make regularly on a weekly basis and that will be available only to my Patrons on Patreon. The link is also in the description. So what are you waiting for? Take your learning in a fun way to the next level with English plus podcast especially if you become a patron on Patreon. With that being said, I would like to thank you very much for listening to another episode from English plus, this is your host Danny I will see you next time.