ডিমেনশিয়া (Dementia): Dementia is a term used to describe a range of symptoms associated with a decline in cognitive function, affecting memory, thinking, and social abilities severely enough to interfere with daily life. It is caused by physical changes in the brain,
such as the buildup of abnormal proteins or damage to brain cells, and includes various types, with Alzheimer's disease being the most common cause. Symptoms are progressive, starting slowly and worsening over time, and may include memory loss, difficulty performing regular tasks, and changes in thinking skills. Importantly, dementia is not a normal part of aging, as many people live into their 90s without any signs of it. Early recognition of symptoms is crucial for management and support.
মস্তিষ্ক নয়, ডিমেনশিয়া শুরু হয় পা থেকে!
বিশ্বজুড়ে বয়স্ক মানুষের অক্ষমতা ও নির্ভরশীলতার প্রধান কারণ হিসেবে ডিমেনশিয়া এখন এক ভয়াবহ বাস্তবতা। ২০২১ সালের হিসাব অনুযায়ী, বিশ্বে প্রায় ৫ কোটি ৭০ লাখ মানুষ এই রোগে আক্রান্ত ছিলেন, এবং প্রতিবছর নতুন করে আরও প্রায় ১ কোটি মানুষ এতে ভোগেন। অধিকাংশ মানুষই মনে করেন, মস্তিষ্ক সচল রাখাই ডিমেনশিয়া প্রতিরোধের মূল চাবিকাঠি। কিন্তু ভারতের অল ইন্ডিয়া ইনস্টিটিউট অব মেডিকেল সায়েন্সেস (এইমস) প্রশিক্ষিত স্নায়ুশল্য বিশেষজ্ঞ ডা. অরুণ এল. নাইক জানালেন চমকপ্রদ তথ্য—ডিমেনশিয়ার সূত্রপাত নাকি মস্তিষ্কে নয়, পা থেকেই!
ডিমেনশিয়া কী?
ডিমেনশিয়া কোনো একক রোগ নয়; এটি স্মৃতি, চিন্তাশক্তি ও দৈনন্দিন কাজের সক্ষমতাকে ধীরে ধীরে ক্ষয় করে এমন একাধিক স্নায়ুরোগের সামষ্টিক নাম। বয়স বাড়ার সঙ্গে সঙ্গে এটি আরও জটিল হয়ে ওঠে এবং জীবনের মান নষ্ট করে দেয়। তবে সময়মতো নির্ণয়, যত্নশীল পরিচর্যা, জীবনযাপনে পরিবর্তন ও চিকিৎসার মাধ্যমে রোগীর অবস্থা অনেকটাই নিয়ন্ত্রণে রাখা সম্ভব।
ডিমেনশিয়া শুরু হয় পা থেকে। ডা. নাইক এক ভিডিও বার্তায় বলেন, “আপনি কি জানেন, ডিমেনশিয়া আসলে শুরু হয় আপনার পা থেকে? শারীরিক নিষ্ক্রিয়তা পায়ের পেশিকে দুর্বল করে, যার ফলে স্যারকোপেনিয়া বা পেশি ক্ষয়ের ঝুঁকি বাড়ে। এখানেই শুরু হয় বিপদ। গবেষণায় দেখা গেছে, দুর্বল পায়ের কারণে জ্ঞানগত ক্ষমতা দ্রুত হ্রাস পায় এবং ডিমেনশিয়ার ঝুঁকি বেড়ে যায়।” তিনি ব্যাখ্যা করেন, শরীরের সক্রিয় পেশি এমন রাসায়নিক উৎপাদন করে যা মস্তিষ্ককে সচল রাখে। এই
রাসায়নিকগুলোর নাম ব্রেইন-ডিরাইভড নিউরোট্রফিক ফ্যাক্টর (BDNF), যা মস্তিষ্কের স্মৃতিনির্ভর অংশ হিপোক্যাম্পাসে সংযোগ বৃদ্ধি করে। শক্তিশালী পা শুধু ভারসাম্য বজায় রাখে না, বয়স বাড়লেও পড়ে যাওয়ার আশঙ্কা কমায়। “৬৫ বছরের পর পড়ে যাওয়াই সবচেয়ে বিপজ্জনক,” বলেন ডা. নাইক।
তিনি ২০২০ সালের Neurology সাময়িকীতে প্রকাশিত এক গবেষণার উদাহরণ দেন, যেখানে দেখা গেছে, যাদের হাঁটার গতি কম, তাদের মস্তিষ্কের আকারও ছোট এবং জ্ঞানীয় ক্ষমতা হ্রাসের ঝুঁকি বেশি। “হাঁটা শুধু শরীরচর্চা নয়, এটি পুরো মস্তিষ্কের এক অনুশীলন,” যোগ করেন তিনি।
কীভাবে হাঁটা মস্তিষ্ককে সুরক্ষিত রাখে?
হাঁটা এমন এক সহজ ব্যায়াম যা শরীর ও মস্তিষ্ক দুটিকেই সক্রিয় রাখে। ডা. নাইক বলেন, “প্রতিটি পদক্ষেপের সঙ্গে যুক্ত থাকে মস্তিষ্কের ফ্রন্টাল লোব, সেরিবেলাম, স্পাইনাল কর্ড ও স্নায়ু প্রতিক্রিয়ার সমন্বয়।” হাঁটা রক্তসঞ্চালন বাড়ায়, যা মস্তিষ্কে অক্সিজেন ও গ্লুকোজ সরবরাহ করে এবং টক্সিন দূর করে।
তিনি আরও বলেন, “হাঁটার ধরনে বা ভারসাম্যে পরিবর্তন দেখা গেলে সেটি মস্তিষ্কের আগাম সতর্ক সংকেত। এটি প্রায়ই স্মৃতি সমস্যার বছরখানেক আগেই দেখা দেয়।”
হাঁটা নিউরোপ্লাস্টিসিটির এক জীবন্ত উদাহরণও বটে। “হাঁটার সময় শরীরে BDNF সক্রিয় হয়, যা নিউরনগুলোর সংযোগ শক্তিশালী করে,” বলেন ডা. নাইক।
ডিমেনশিয়া প্রতিরোধের উপায়য়?
ডা. নাইক কয়েকটি সহজ অভ্যাসের পরামর্শ দিয়েছেন, যা নিয়মিত চর্চা করলে মস্তিষ্কের কর্মক্ষমতা বজায় থাকে এবং ডিমেনশিয়ার ঝুঁকি অনেক কমে যায়।
*প্রতিদিন অন্তত ৩০ মিনিট দ্রুত হাঁটুন।
*ভারসাম্য রক্ষার ব্যায়াম যেমন এক পায়ে দাঁড়ানো বা সরলরেখায় হাঁটার অভ্যাস করুন।
*হাঁটার সময় কথা বলা বা হালকা মানসিক কাজ করুন—এটি মস্তিষ্কের সমন্বয় ক্ষমতা বাড়ায়।
*নিয়মিত পায়ের পেশির ব্যায়াম করুন, এটি মস্তিষ্কের জন্য একপ্রকার ‘বিমা’।
*দীর্ঘ সময় বসে থাকা পরিহার করুন; প্রতি ঘণ্টায় কিছুটা নড়াচড়া করুন।
তিনি বলেন, “যখন আপনার পা ধীরে ধীরে কাজ হারায়, তখন মস্তিষ্কও তার পথ অনুসরণ করে। আপনার হাঁটার গতি বজায় রাখুন, তাহলেই সুরক্ষিত থাকবে মস্তিষ্ক।”
ডা. নাইক আরও পরামর্শ দেন, পেশির গঠন রক্ষায় প্রোটিনসমৃদ্ধ খাদ্য গ্রহণ করা জরুরি। তার মতে, কখনোই দেরি হয়ে যায় না। “গবেষণায় দেখা গেছে, ষাট বছর বয়সেও হাঁটা ও ব্যায়াম শুরু করলে ডিমেনশিয়ার ঝুঁকি অনেক কমে যায়। মনে রাখবেন, শক্ত পা মানেই তীক্ষ্ণ মস্তিষ্ক। স্যারকোপেনিয়া মাথা পর্যন্ত পৌঁছানোর আগেই সচেতন হোন—চল্লিশের কোঠা থেকেই শুরু করুন।”
সর্বোপরি, সক্রিয় থাকা শুধু চলাফেরার বিষয় নয়; এটি মস্তিষ্ককে তরুণ রাখার সবচেয়ে কার্যকর উপায়। নিয়মিত হাঁটা, ব্যায়াম ও সুষম খাদ্য—এই তিন অভ্যাসই হতে পারে বার্ধক্যের ডিমেনশিয়ার বিরুদ্ধে সবচেয়ে শক্তিশালী প্রতিরোধ।
However, the materials they produce are not alive!
All men can do is examine the living creatures on earth, in all sizes and shapes and wherever they live, and find what they have in common. Then we can say that these common qualities make up life.
Let’s find out what these qualities are. All living things must be able to grow. They grow up to a fairly definite size and shape. A kitten becomes a cat; an acron becomes an oak tree. For some living things, it takes a short time to grow to full size; a redwood tree may take thousands of years. But all living things grow.
Living things are able to adapt to their environment. Man can do this better than any other creature because of his brain. But plants can do this only to a limited extent.
Living things can also respond to stimuli. This means if something outside of themselves affects them, they can react. When you smell food, you respond, and flowers grow towards the light.
This does not define life, but it does describe the characteristics that must be present for something to be considered "alive".
So, we can tell if an object is alive by considering the following four signs:
Ans. We all understand that we must breathe. But why do all living plants and animals need to breathe? The reason is very simple. By breathing, we take in air that contains oxygen. Without this gas, no life would exist.
When we exhale, the air changes. As it made its way through our system, some of the oxygen was used up, while the amounts of carbon dioxide and water were increased.
Nature constantly supplies our bodies with oxygen for breathing. In fact, from year to year, there is little change in the amounts of oxygen and carbon dioxide found in the air. This is because the carbon dioxide we breathe out into the air is taken in by plants. They breathe out oxygen, which we need.
Internal breathing is the opposite of external breathing. The oxygen taken from the air in the lungs is carried to the tissues of the body by the red red cells in the blood. In the tissues this oxygen burns certain food products, making them available for use by the body. The blood takes away the waste products, including water and carbon dioxide. These are returned in the blood to the lungs for exhaling.
Since an exchange of gases (oxygen and carbon dioxide) takes place both in the lungs and in the tissues, a large surface is needed to make this possible. The lining of the lungs of an adult, for example, is equal to a space of about 3 square metres. This is larger than the ceiling space of one floor of an average house! Much of this area is kept in reserve, since we might need 8 or 10 times as much oxygen during work as we need at rest. If we need more oxygen, we breathe more deeply or more quickly.
Different creatures breathe at different rates, depending of the oxygen they need.
A newborn baby breathes about once a second, but at the age of 15, breathing is about twenty times a minute. An elephant breathes 10 times a minute; a dog, 25 times a minute.
Ans. As most of us know, the heart is a pump. It drives the blood through the body, thus making our lives possible.
But what an amazing pump it is! With each beat of the heart, it sends out about one hundred cubic centimetres of blood. In the course of a day this amounts to about 10,000 litresof blood that are pumped through the blood vessels. In an average lifetime, a heart pumps approximately 250,000,000 litres of blood!
Each human heartbeat lasts about eight-tenths of a second. The heart beats about one hundred thousand times a day and rests an equal number of times between beats. So it rests for about six hours per day.
What we call the "beat" of the heart is a contraction and relaxation. During the contraction, blood is pumped out; during the relaxation, new blood enters. However, this doesn't occur in a straightforward manner, as when you open and close your fist. The contraction occurs in a wave that starts at the bottom of the heart and moves up towards the top.
What keeps the heart beating? Does this impulse to contract and relax come from somewhere else? Is it self-starting? It is one of the most fascinating questions in biology, and much about it still remains a mystery. Allow me to tell you about an intriguing experiment that has been known for hundreds of years.
Suppose you take a chicken egg and incubate it for about twenty-six years. Now you open it and, with a magnifying glass, study those cells in the egg from which the chick's heart will later develop. You will see those cells beating! Even before those cells have become a heart, they are already beating.
Now, suppose you remove this mass of cells and allow them to grow in a medium. If you cut the growing heart into six pieces, each piece continues to contract for some time! What is the explanation? We don't know. All we can conclude is that the heart has a tendency to contract automatically. And one of the secrets of life – why it keeps beating—remains a riddle.
Ans. Every new organism, whether it is a plant, fish, animal, or human, resembles its parents—and yet it differs from them. For example, children may look like one parent or the other, but usually they have some features of each parent. Parents pass down certain traits to their children, which the children "inherit". Heredity is the study of how offspring resemble their parents.
The unit of heredity is called the "gene". Genes are largely molecules found in the nuclei of both sperm cells and egg cells. Within the nucleus of each cell are long, thin strands or threads. They are called "chromosomes", and they carry the genes.
Since chromosomes form pairs, their genes are also paired. The chromosomes of a cell contain hundreds of thousands of pairs of genes. Each gene pair controls one or more aspects of the organism, such as hair colour, nose shape, body size, and so on.
There are many "laws" of heredity, which means that the process takes place in certain ways. For example, every trait that is inherited depends on a single "factor," and each factor behaves independently. Because a certain trait is inherited from the parents, it doesn't mean that any other trait will also necessarily be inherited. In other words, the factors, or genes, have no relationship to one another.
Some genes carry traits that are "dominant", and others carry traits that are "recessive". For example, the gene for curly hair seems to be dominant over the gene for straight hair. When both parents have curly hair, their children are typically curly-haired too.If both parents carry a recessive gene for straight hair, some of their children can inherit straight hair.
Scientists have studied such human traits as the colour of eyes, hair, and skin so that they usually can tell how they will be inherited by people whose family history is known for several generations.
Ans. Storing information is remembering, and remembering closely linked to learning.
Psychologists have tried to explain how people remember and why they forget many of the things they learn. No one has yet has yet found all the answers. It is believed, according to one theory, that when a person learns something, a physical change of some kind takes place. A trace, or pattern, is left in the brain. And it is believed that memories, or the traces memory may leave in the brain, or simply fade away in the course of time.
The way you feel about a particular experience may also determine whether you remember or forget it. In general, people tend to forget things that are unpleasant or upsetting and recall pleasant experiences.
Brains can learn different kinds of tasks. Better-developed brains can learn more complicated tasks. In the simplest brains, learning is very crude. Humans show the greatest learning abilities.
But how and where does the brain store the information that we call memory? As we said, scientists are not yet able to fully explain it. In the human brain, areas of the cortex appear to be involved. The cortex is the twisted, wrinkled, and knotted surface of the largest part of the brain (the cerebrum).
When these areas are excited by weak electrical currents, a person "relives" past experiences. These stimuli prompt the brain to recreate past experiences stored within it. It is a well-known fact that damage to certain areas of the brain can result in memory loss.
But are these places in the brain where the information is stored? We don't know. Nor are we aware of how the information is stored. Some scientists think that storing information is a chemical process---the individual nerve cells have chemically-coded information within them. Other scientists believe that memory is the result of some permanent change in the structure of the nerve. So memory is still a mystery.
Ans. Do you know anyone afraid of heights or someone afraid of small spaces? Some people are afraid of large crowds or being touched by others. This type of behavior is known as a "phonic reaction", and the individual is said to have a "phobia".
Is something "wrong" with such people? Are they "sick" in some way? No, but it might be fair to say they are going through some emotional distress. Something has profoundly upset them, either recently or at some time in the past. And such a person is trying to deal with this emotional disturbance—it can be "emotional pain"—just as you would try to deal with physical pain.
We all react to emotional upset. We cry, we blush, and we might break out in a sweat. But some people, who feel this stress more strongly, or whose power of resistance is weaker, try to deal with this emotional pain in an unnatural, unusual way. This kind of reaction is sometimes referred to as "neurotic."
One such way of reacting is to develop a phobia, which is an unreasonable fear of a specific thing, such as a fear of high places or closed-in places. An interesting aspect of a phobia is that the object or situation causing fear is often something a person can typically avoid. After all, nobody forces people to climb to high places or get into closed places. And as long as a person can avoid these things, he feels fine. He doesn't have what is called "anxiety".
But why should a particular person have a fear of high places, to take an example? The truth is, he is really afraid of something else, or perhaps felt afraid of something else when he was a child. It might have been his father whom he loved and feared at the same time. He didn't want to admit he was afraid of his father, or he submitted a fear of high places, which is a symbol of his father, and substituted a fear of high places, he can avoid facing the fact that he is afraid of his father. All of this seems very complicated, doesn't it? But then, human beings and their behaviors are indeed a highly complex subject!
Ans. If this question had an answer, such as a formula that could be learned, every comedian would know it! But laughter is a complicated thing, and the best explanations of it are still only duties.
We know, of course, that laughter is an expression of many feelings and that laughter is found only among human beings. But psychologists are still studying two basic questions about laughter: What makes people laugh, and what is the function or purpose of laughter?
When you try to think of what makes people laugh, or what people consider funny, you catch yourself thinking in the way a psychologist or philosopher might. You become concerned with people's reaction to other people in all kinds of institutions---for example, why people laugh when they see awkwardness or some kind of weakness or imperfection in another person.
Another explanation of laughter is that it depends on our suddenly seeing some incongruity; that is, things that don't normally or naturally go together. A big fat man wearing a tiny hat, or a very short man dancing with a big, tall woman, are examples of this. However, this theory doesn't explain many of the other reasons for laughter that are related to the comic, humorous, and so on.
From the physical point of view, laughter is good for us. It's good for our lungs, and it's an outlet for some extra energy. Laughter also has a great social value. We usually laugh as members of a group. According to this theory, laughter is used by social groups as a way of communicating about the behaviour of people and then conforming to our standards.
Ans. Fun is defined by the Oxford English Dictionaryas "light-hearted pleasure, enjoyment, or amusement; boisterous joviality or merrymaking; entertainment". The word fun is associated with sports, entertainment, etc.
Ans. A comic is a form of storytelling that uses images to convey ideas, often paired with text or other visual elements. It usually appears as a series of image panels. Textual tools like speech bubbles, captions, and sound effects are commonly used to enhance the narrative. … See more
Ans. What is the first word a baby says? We all know the answer---"Mama!" That seems like quite an easy thing to accomplish, doesn’t it? But it's a very complicated process indeed. Not only does it require many steps of development, but you realize that no other creature on earth is capable of accomplishing this.
Let's go through the process step by step. When a baby is born, his brain is like an unwritten page. There is nothing there. The areas in the brain that receive sense impressions haven't received any. The baby's eyes are open, but the nerves between the eyes and the brain are not yet developed, so the brain doesn't register anything.
After one or two months, these nerves are developed, and now the baby "sees" its mother. As a result of seeing the same object again and again, the visual memory centre in the brain develops. The infant's impressions of the mother register in this centre as memories. So now the child "recognizes" the mother.
As soon as the mother realizes this has happened, she keeps pointing to herself and saying "Mama" at the same time. At first, the child can't hear, but gradually the nerves develop and the baby "hears" the sound "Mama". Through repetition, the child forms a memory image of the sound. The baby now remembers and "understands" the word "Mama".
Now the mother has to teach the child to speak. By repeating, the word "Mama" over and over, she makes this happen: A connection is made in the brain between the image of the mother in the visual centre and the sound of "Mama" in the hearing centre. This is called an association. Now the child not only recognizes Mama's face, but also thinks of the sound "Mama" when he sees the mother. He "identifies" her. The child now begins to intimate the mother. He forms the word without saying it at first. After trying to say the word many times, the baby can make the vocal muscles move when it sees the mother. Finally, he can say "Mama". And, of course. the proud mother says, "My baby is talking already!"
Ans. The kind of voice you have depends chiefly on your vocal cords are made of elastic fibres. You might compare them to the very best violin strings.
The vocal cords can be made tense or slack. In fact, your vocal cords can be in any of about 170 different positions. When a column of air (which you push upward) strikes the vocal cords, they begin to vibrate. This vibration produces sound waves.
বাগধারা, যা বাগ্বিধি নামেও পরিচিত, হলো কথার বিশেষ রীতি। এটি ভাষার এমন শব্দ বা শব্দসমষ্টি, যা আভিধানিক অর্থের বাইরে গিয়ে বিশেষ ভাব প্রকাশ করে। উদাহরণস্বরূপ, ‘আদার ব্যাপারী’ বলতে সামান্য ব্যক্তিকে বোঝানো হয়। বাংলাসহ বিশ্বের প্রায় সব ভাষাতেই বাগধারার ব্যবহার দেখা যায়। এটি ভাষাকে সমৃদ্ধ করে, শ্রুতিমধুরতা আনে এবং অর্থ প্রকাশের ক্ষমতা বাড়ায়। বাগধারা রচনার সৌন্দর্য ও সাবলীলতা বৃদ্ধি করে এবং শব্দের গভীরে লুকানো ভাব প্রকাশে সাহায্য করে।
This image represents the evolutionary history of humankind, showing six different species of the Homo genus that once coexisted on Earth — a powerful reminder of our shared origins and survival through time.
History Behind the Image:
Millions of years ago, humanity was not a single species. The Earth was home to six distinct human species, each adapted to its environment, with its own tools, culture, and intelligence.
Known as the “handy man”, they were among the first to use stone tools. Living in Africa, Homo habilis marked the beginning of human technological development.
The only surviving species — us. With advanced language, creativity, and adaptability, Homo sapiens spread across the world, shaping civilisations and the modern era.
The Legacy: Though the others vanished, they live on in us — through shared DNA and the evolutionary steps that made us who we are. This image is more than a timeline; it’s a portrait of survival, intelligence, and unity — a reminder that our ancestors once walked side by side.
Bengali incorporates foreign words from various languages, including Arabic, Persian, Portuguese, and English. These words have been adopted either unchanged or with modifications. Wikipedia articles in Bengali often present foreign words in three different forms, with the most accessible Bengali form being used for the article title and the first mention of the word. This reflects the significant influence of different languages on the Bengali vocabulary.
নিচের যুক্তবর্ণের তালিকাটি বাংলা সঠিকভাবে লিখতে সহায়ক হতে পারে। এখানে বাংলায় ব্যবহৃত ২৮৫টি যুক্তবর্ণ দেওয়া হয়েছে। এর বাইরে কোন যুক্তবর্ণ সম্ভবত বাংলায় প্রচলিত নয়।
ক্ক = ক + ক; যেমন- আক্কেল, টেক্কা
ক্ট = ক + ট; যেমন- ডক্টর
(মন্তব্য: এই যুক্তাক্ষরটি মূলত ইংরেজি/ বিদেশী কৃতঋণ শব্দে ব্যবহৃত)
ঈশ্বরচন্দ্র বিদ্যাসাগরের বর্ণপরিচয় (প্রথম ভাগ ও দ্বিতীয় ভাগ) অনলাইনে বিনামূল্যে পড়া ও ডাউনলোড করার সুযোগ আছে। এটি বাংলা ভাষার অন্যতম প্রাথমিক পাঠ্যপুস্তক, যা প্রথম প্রকাশিত হয়েছিল ১৮৫৫ সালে এবং আজও সমানভাবে জনপ্রিয়।
আপনি চাইলে নিচের উৎসগুলো থেকে দেখতে বা ডাউনলোড করতে পারবেনঃ
– এখানে পুরো বইটি একত্রে রাখা আছে, পড়া ও ডাউনলোড দুটোই সম্ভব।
– অনলাইনে উল্টিয়ে-পড়ার মতো ফ্লিপবুক আকারে পাওয়া যাবে।
বইটির ইতিহাস ও গুরুত্ব সম্পর্কে জানতে চাইলে পড়তে পারেন।
If you want to create your own blog, you can seek our advice and assistance.
