Internal medicine on Instagram: “MRI scan of a patient with primary central nervous system lymphoma A nodular enhancing lesion produces moderate mass effect on the frontal…”
“MRI scan of a patient with primary central nervous system lymphoma A nodular enhancing lesion produces moderate mass effect on the frontal horn of the…”
about 6 years ago
The Gut-Brain page describes the interrelationships between hormonal signals from the gut and neuroendocrine signals from the brain in the control of appetite and feeding behavior.
almost 6 years ago
Professor Fink describes the organization of the Nervous System. Check-out professor fink's web-site or additional resources in Biology, Anatomy, Physiology ...
almost 6 years ago
Central nervous system, spinal and cranial nerves or ...let's get brainy on this page "The central nervous system (CNS) consists of the brain and the spinal cord, while the spinal nerves and cranial nerves are part of the peripheral nervous system (PNS)"
over 5 years ago
The specialized nodal and conducting cells of the heart are responsible for heartbeat. These specialized nodal and conducting cells tend to contract weakly because they contain very few contractile cells (myofibrils). What makes these cells unique is that they can easily generate an action potential (electrical impulse that causes the heart to beat) without the assistance of neurotransmitters or any nervous system input like any regular neurons. Along with these special properties of self-excitability, these cells can also rapidly conduct impulses to atrial and ventricular muscles. This explains why after death, the heart continues pumping because of the nodal and conducting cells; this is because the nodal and conducting cells are not hooked up with any neurotransmitters. Therefore, these specialized cells provide a self-excitatory system for the heart to generate impulses and a transmission system for rapid conduction of impulses in the heart.
over 5 years ago
This question is about the somatic nervous system (SNS). I read that this the SNS part of the peripheral nervous system (PNS) and that it controls skeletal muscle. It is therefore thought to be voluntary. In contrast, the autonomic nervous system controls smooth muscle, under involuntary control. What I'm wondering is if reflex arcs (or reflexes) are controlled by the autonomic nervous system, why is it making use of skeletal muscle? Take the example of the reaction of moving your hand away when it is placed on something hot. These motor commands come from the autonomic nervous system but control the arm muscles that are normally controlled consciously. In other words things normally controlled voluntarily. The response was activated by the ANS, and was therefore automatic, but the muscles supplied by these motor commands were skeletal muscles? Can someone explain this (contradition) or perhaps correct my wrong thinking?
over 7 years ago
The reference given when answering the question about the increase in permeability of sodium ions during hypocalcemia is satisfactory but "does hypocalcemia not reduce the release of neurotransmitters at a chemical synapse" Will it not affect the speed and efficiency of conduction of impulse. Therefore how will it cause tetany?" Reference Increased Permeability of the Sodium Channels When There Is a Deficit of Calcium Ions. The concentration of calcium ions in the extracellular fluid also has a profound effect on the voltage level at which the sodium channels become activated. When there is a deficit of calcium ions, the sodium channels become activated (opened) by very little increase of the membrane potential from its normal, very negative level. Therefore, the nerve fiber becomes highly excitable, sometimes discharging repetitively without provocation rather than remaining in the resting state. In fact, the calcium ion concentration needs to fall only 50 per cent below normal before spontaneous discharge occurs in some peripheral nerves, often causing muscle “tetany.”This is sometimes lethal because of tetanic contraction of the respiratory muscles. The probable way in which calcium ions affect the sodium channels is as follows:These ions appear to bind to the exterior surfaces of the sodium channel protein molecule. The positive charges of these calcium ions in turn alter the electrical state of the channel protein itself, in this way altering the voltage level required to open the sodium gate. From: Guyton, Arthur C. Textbook of medical physiology / Arthur C. Guyton, John E. Hall.—11th ed.
about 7 years ago
Many know that engaging in regular physical activity and exercise will tremendously improve one’s health and overall well-being. This goes the same, if not tenfold, for individuals suffering with diabetes. However, before rushing in a high intensity or physically straining physical régime, consult with your diabetes care provider. Make sure to discuss your plans take note of any precautions that may be needed to be made prior or during these activities. It will be interesting to know that individuals with type 2 diabetes who do participate in some exercise (even at work) reduce their risk for heart disease. Remember that a physical examination that focuses on the signs and symptoms of diseases affecting the heart and blood vessels, eyes, feet, nervous system, and kidneys must be made in advance before any extensive work out plan takes into action. Any strenuous strength training or high-impact exercise is generally not recommended for people with uncontrolled diabetes. Such strain caused by these exercises can weaken blood vessels in the eyes of patients who suffer from the common diabetic complication known as retinopathy. High-impact exercise can also injure blood vessels in the feet. In fact, diabetes can contribute to foot problems in several ways: diabetic neuropathy; which is a nerve disorder that causes numbing and pain in the hands, legs and feet as well as damage to internal organs; also poor circulation to the feet is another problem that can be associated due to diabetes. Keeping this in mind it is imperative to keeping your feet healthy, investing in some great therapeutic footwear like these can be a great step in moving toward healthy feet! One thing is for sure, physical activity can increase the health in anyone’s life. Always make sure to take care of your body and take the extra precautions needed in order to maintain proper health.
about 7 years ago
Can you imagine being able to search for locations in the human body in the same way you can on Google Maps? This thinking lead Programmer Rich Stoner to create this amazing video of a 21st Century Map of the Brain which was our most popular tweet last week. A 21st Century Map of the Brain http://t.co/tkojzJBW55 via @brianglanz #openscience— Meducation (@Meducation) October 18, 2013 Rich writes in his blog - “Now we can quickly search Google Maps for a location, ask what is nearby, and even see what it looks like using StreetView. Now, imagine if something like that existed for the human brain: an interactive environment to search, visualize, and explore layers upon layers of neuroanatomy. This is the dream of cortical cartographers (also known as neuroanatomists). 10 years ago, one of the largest brain mapping initiatives was founded by Paul Allen with a single goal: to build a 21st Century Map of the Brain.” Click here to read more. The mapping of the brain is a working progress and therefore not 100% accurate. Even so the video gives us an insight into the innovate ways we will be able to interact with science in the future. You can follow Meducation on twitter to see more tweets like this at twitter.com/meducation.
over 6 years ago
Great people make mistakes. Unfortunately, medicine is a subject where mistakes are not tolerated. Doctors are supposed to be infallible; or, at least, that is the present dogma. Medical students regularly fall victim to expecting too much of themselves, but this is perhaps not a bad trait when enlisting as a doctor. If it weren’t for mistakes in our understanding, then we wouldn’t progress. Studying a BSc in Anatomy has exposed me to the real world of science – where the negative is just as important as the positive. What isn’t there is just as important as what is. If you look into the history of Anatomy, it truly is a comedy of errors. So, here are three top mistakes by three incredibly influential figures who still managed to be remembered for the right reasons. 3. A Fiery Stare Culprit: Alcmaeon of Croton Go back far enough and you’ll bump into someone called Alcmaeon. Around the 5th century, he was one of the first dissectors – but not an anatomist. Alcmaeon was concerned with human intellect and was desperately searching for the seat of the soul. He made a number of major errors - quite understandable for his time! Alcmaeon insisted that sleep occurs when the blood vessels filled and we wake when they empty. Perhaps the most outrageous today is the fact that he insisted the eyes contained water both fire and water… Don’t be quick to mock. Alcmaeon identified the optic tract, the brain as the seat of the mind (along with Herophilus) and the Eustachian tubes. 2. Heart to Heart Culprit: Claudius Galen Legend has it that Galen’s father had a dream in which an angel/deity visited him and told him that his son would be a great physician. That would have to make for a pretty impressive opening line in a personal statement by today’s standards. Galen was highly influential on modern day medicine and his treatise of Anatomy and healing lasted for over a thousand years. Many of Galen’s mistakes were due to his dissections of animals rather than humans. Unfortunately, dissection was banned in Galen’s day and where his job as physician to the gladiators provided some nice exposed viscera to study, it did not allow him to develop a solid foundation. Galen’s biggest mistake lay in the circulation. He was convinced that blood flowed in a back and forth, ebb-like motion between the chambers of the heart and that it was burnt by muscle for fuel. Many years later, great physician William Harvey proposed our modern understanding of circulation. 1. The Da Vinci Code Culprit: Leonardo Da Vinci If you had chance to see the Royal Collection’s latest exhibition then you were in for a treat. It showcased the somewhat overlooked anatomical sketches of Leonardo Da Vinci. A man renowned for his intelligence and creativity, Da Vinci also turns out to be a pretty impressive anatomist. In his sketches he produces some of the most advanced 3D representations of the human skeleton, muscles and various organs. One theory of his is, however, perplexing. In his sketches is a diagram of the spinal cord……linked to penis. That’s right, Da Vinci was convinced the two were connected (no sexist comments please) and that semen production occurred inside the brain and spinal cord, being stored and released at will. He can be forgiven for the fact that he remarkably corrected himself some years later. His contributions to human physiology are astounding for their time including identification of a ‘hierarchal’ nervous system, the concept of equal ‘inheritence’ and identification of the retina as a ‘light sensing organ’. The list of errors is endless. However, they’re not really errors. They’re signposts that people were thinking. All great people fail, otherwise they wouldn’t be great.
over 6 years ago
So you're sitting in a bus when you see a baby smile sunnily and gurgle at his mother. Your automatic response? You smile too. You're jogging in the park, when you see a guy trip over his shoelaces and fall while running. Your knee jerk reaction? You wince. Even though you're completely fine and unscathed yourself. Or, to give a more dramatic example; you're watching Titanic for the umpteenth time and as you witness Jack and Rose's final moments together, you automatically reach for a tissue and wipe your tears in whole hearted sympathy ( and maybe blow your nose loudly, if you're an unattractive crier like yours truly). And here the question arises- why? Why do we experience the above mentioned responses to situations that have nothing to do with us directly? As mere passive observers, what makes us respond at gut level to someone else's happiness or pain, delight or excitement, disgust or fear? In other words, where is this instinctive response to other people's feelings and actions that we call empathy coming from? Science believes it may have discovered the answer- mirror neurons. In the early 1990s, a group of scientists (I won't bore you with the details of who, when and where) were performing experiments on a bunch of macaque monkeys, using electrodes attached to their brains. Quite by accident, it was discovered that when the monkey saw a scientist holding up a peanut, it fired off the same motor neurons in its brain that would fire when the monkey held up a peanut itself. And that wasn't all. Interestingly, they also found that these motor neurons were very specific in their actions. A mirror neuron that fired when the monkey grasped a peanut would also fire only when the experimenter grasped a peanut, while a neuron that fired when the monkey put a peanut in its mouth would also fire only when the experimenter put a peanut in his own mouth. These motor neurons came to be dubbed as 'mirror neurons'. It was a small leap from monkeys to humans. And with the discovery of a similar, if not identical mirror neuron system in humans, the studies, hypotheses and theories continue to build. The strange thing is that mirror neurons seem specially designed to respond to actions with clear goals- whether these actions reach us through sight, sound, smell etc, it doesn't matter. A quick example- the same mirror neurons will fire when we hop on one leg, see someone hopping, hear someone hopping or hear or read the word 'hop'. But they will NOT respond to meaningless gestures, random or pointless sounds etc. Instead they may well be understanding the intentions behind the related action. This has led to a very important hypothesis- the 'action understanding' ability of mirror neurons. Before the discovery of mirror neurons, scientists believed our ability to understand each other, to interpret and respond to another's feeling or actions was the result of a logical thought process and deduction. However, if this 'action understanding' hypothesis is proved right, then it would mean that we respond to each other by feeling, instead of thinking. For instance, if someone smiles at you, it automatically fires up your mirror neurons for smiling. They 'understand the action' and induce the same sensation within you that is associated with smiling. You don't have to think about what the other person intends by this gesture. Your smile flows thoughtlessly and effortlessly in return. Which brings us to yet another important curve- if mirror neurons are helping us to decode facial expressions and actions, then it stands to reason that those gifted people who are better at such complex social interpretations must be having a more active mirror neuron system.(Imagine your mom's strained smile coupled with the glint in her eye after you've just thrown a temper tantrum in front of a roomful of people...it promises dire retribution my friends. Trust me.) Then does this mean that people suffering from disorders such as autism (where social interactions are difficult) have a dysfunctional or less than perfect mirror neuron system in some way? Some scientists believe it to be so. They call it the 'broken mirror hypothesis', where they claim that malfunctioning mirror neurons may be responsible for an autistic individual's inability to understand the intention behind other people's gestures or expressions. Such people may be able to correctly identify an emotion on someone's face, but they wouldn't understand it's significance. From observing other people, they don't know what it feels like to be sad, angry, surprised or scared. However, the jury is still out on this one folks. The broken mirror hypothesis has been questioned by others who are still skeptical about the very existence of these wonder neurons, or just how it is that these neurons alone suffered such a developmental hit when the rest of the autistic brain is working just dandy? Other scientists argue that while mirror neurons may help your brain to understand a concept, they may not necessarily ENCODE that concept. For instance, babies understand the meaning behind many actions without having the motor ability to perform them. If this is true, then an autistic person's mirror neurons are perfectly fine...they were just never responsible for his lack of empathy in the first place. Slightly confused? Curious to find out more about these wunderkinds of the human brain? Join the club. Whether you're an passionate believer in these little fellas with their seemingly magical properties or still skeptical, let me add to your growing interest with one parting shot- since imitation appears to be the primary function of mirror neurons, they might well be partly responsible for our cultural evolution! How, you ask? Well, since culture is passed down from one generation to another through sharing, observation followed by imitation, these neurons are at the forefront of our lifelong learning from those around us. Research has found that mirror neurons kick in at birth, with infants just a few minutes old sticking their tongues out at adults doing the same thing. So do these mirror neurons embody our humanity? Are they responsible for our ability to put ourselves in another person's shoes, to empathize and communicate our fellow human beings? That has yet to be determined. But after decades of research, one thing is for sure-these strange cells haven't yet ceased to amaze and we definitely haven't seen the last of them. To quote Alice in Wonderland, the tale keeps getting "curiouser and curiouser"!
about 6 years ago