Medical Quirks!

Arms Akimbo

2008-10-18T16:13:00.006+08:00

Following a straining jog or run, we tend to rest with our arms akimbo (hands on hips, with elbows facing outwards), as seen in this picture.

How does this help?

After the exercise, our body would be desperate to breathe as much as it possibly can. Standing this way actually causes a muscle in our chest to pull on our rib cage and lift it up.

As seen in the diagram, the pectoralis major muscle is attached to our clavicle (collar bone), sternum (breast bone), and to our humerus (bone of arm). Try to picture the humerus (arm) being pulled outwards and upwards. The pectoralis major muscle then creates a slight lift in our rib cage by pulling on the sternum, creating more space in our chest cavity. Our lungs can expand more fully, allowing us to breathe easier.

Effect on knuckle cracking on the joints

2008-10-11T22:20:00.003+08:00

I greatly detest knuckle cracking, and get rather annoyed when people crack many knuckles one after another, which probably stems from a mindset that it will give you spoiled joints in time. Perhaps, it came from my personal experience where I had accidentally cracked joints and experienced pain (my pain threshold is extremely low).

From the understanding of the basis through which the sound is produced, then there will technically be no damage caused by the cracking. The sound produced has nothing to do with snapping or friction, and after all, the gas forced out would eventually redissolve.

However, there are tendons, ligaments and other structures that lie adjacent to your joints. Perhaps in serial crackers, these may be overstretched and damaged in some form. Still, many have claimed to have cracked their knuckles over many years, but have not experienced any repercussions.

The lack of research on this topic leaves it much open to debate. For now, knuckle cracking could be considered 'innocent until proven guilty'.

Cracking of fingers

2008-10-10T22:29:00.005+08:00

Welcome back to the former NeuroChowzy blog, now known as Mediquirks. I decided to restart this blog whilst in medical school because of the exorbitant amount of interesting information we are taught in medical school. This blog will still retain its former purpose of being a layman medical blog, as well as a portal for questions. My former posts are still available for viewing and you can be a follower of this blog, by clicking on "Followers" section on the right.

Please do welcome a fellow contributor to this blog, my girlfriend Grace, who also is in the NUS Medical School.

Today's topic is one which is close to the heart of many, especially guys. It is concerned with the "cracking" of fingers. Ever pulled your finger forwards, away from your palm before? Or bent your finger and "cracked" your knuckle? You might have heard a distinct crack sound which can't be reproduced for a few minutes after that. This is why:

The joints which you normally "crack" are formed by connective tissues and ligaments which hold the two bones at the joint together in a capsule. There is fluid in the capsule, known as synovial fluid. When the bones are pulled apart, the capsule holding the both bones stretches, creating a vacuum in the capsule. Gases do not dissolve as rapidly and bubbles form in the capsule. When the bones are pulled far away from each other, the pressure drops so low that the bubbles burst, causes a "crack" sound.

It takes some time for these gases to redissolve into the joint fluids, so in the meantime, you will not be able to crack your knuckles or joints again in the same way.

Interesting eh?

In response to Xinhui's question

2006-08-20T14:59:00.006+08:00

I hope this answers your question cause I was quite confused when I read the question.

Firstly, there are two major structural differences between the neuroanatomy of males and females. The first of which is is the hypothalamus. Males and females differ in the preoptic area and the Suprachiasmatic Nucleus of it; the former controlling mating cycles and the latter controlling circadian rhythms and reproductive cycles. (Will not be elaborating on this in the post). When you referred to the brain stem linking the left and right hemispheres of the brain being thicker in females, I assume you are referring to the corpus callosum? That is the only bridge which connects both the left and right hemispheres of the brain. The corpus callosum is an independent structure, not a part of the brainstem (which only includes the medulla oblongata, pons, midbrain, thalamus and hypothalamus)

There have been conflicting studies on the differences between the gender dimorphism of the corpus callosum. However, researchers have agreed upon some of these differences. In the sagittal plane, the rostrum of the corpus callosum of the males is slightly larger than that of the females, while the rostral body, the isthmus and the splenium were somewhat larger in the females. In the coronal plane, the area of the male corpus callosum tended to be larger than that of the female.

However, the statistical differences in all males and females do not differ significantly to warrant a theoretical structual difference in the corpus callosum. Females however, do have a slightly thicker corpus callosum.

A thicker corpus callosum would mean that is more white matter (consisting of nerve fibres and axon projections). This would allow for a greater amount of coordination between activities that happen in both hemispheres of the brain. Because of the thinner corpus callosum, it is harder for both sides of the brain to work together in males and on the converse, it explains the ability for females to multitask.

If you do want more information, please do not hesitate to tell me. Or you could search for it using the keywords: Corpus Callosum, Dimorphism.

Useful references:

Dubb A, Gur R, Avants B, Gee J. "Characterization of sexual dimorphism in the human corpus callosum."

Brain Degeneration

2006-06-21T13:08:00.001+08:00

This post is specially for all the Ventures who went for the Malaysian Expedition and had one form of brain degeneration or other. Let me introduce to you to a Protista. Pronounce with me: Toxoplasma gondii.

Statistics show that half the world's population is infected with T. gondii. The protista originates from the guts of cats and is excreted in its urine. Just a breeze of wind is enough to transport hundreds of T. gondii into the respiratory and GI tract of the unsuspecting homosapien. And it is from there when the Brain Degeneration begins.

T. gondii, unlike most protista, is specific. It targets only one organelle.

It targets the Astrocytes. (Really cool name if you think about it). Astrocytes are extremely important in the brain. Without the Astrocytes, the neurons will die. This is because of the important functions an astrocyte carries out. Astrocytes structure the brain, provide neurons with metabolic support, supplying the neurons with glucose. Astrocytes also have more complicated functions, which I will not explain in this entry. (An interesting function is vasomodulation and its role in the blood-brain barrier).

So without an astrocyte, the neurons will have a lack of nutrients and be destroyed. After that, everything is simple. Neurons die, deteriorating brain functions... Bingo. Brain degeneration.

But do not worry. It can be cured by Haloperidol, an antipsychotic.

Pictures taken from:
www-ermm.cbcu.cam.ac.uk/01002216h.htm
www.physoc.org/publications/.../article.asp?ARTICLE_ID=95

The Venture Rash

2006-06-20T16:43:00.001+08:00

This is called The Venture Rash.

Almost half the Ventures came down with this rash during the expedition and were unable to complete it due to the pain and itchiness. Though the etiology was unknown, they went for an antihistamine jab... although I felt that it was quite a rash decision.

Interesting

2006-06-11T21:50:00.000+08:00

Last year I mentioned about Pyrexia being a positive feedback symptom and cyclooxygenase being inhibited with the use of Paracetamol.

What really intrigues me is my current condition. I'm having a fever of about 38.6 degrees Celsius. An in-ear thermometer was used to measure my temperature. I was feeling bored (troubling neurological disease) and thus I inserted the thermometer into my other ear and took my temperature again.

Left ear: 38.6 degrees Celsius
Right ear: 37.9 degrees Celsius

I did this a few times and the results were the same! Interesting huh?
Does anyone know why?

Sensitive Women

2006-06-10T11:46:00.001+08:00

Biologically speaking, I emphasize Biologically (in case some people do want to kill me because of my statement), women are more sensitive as compared to the other gender of homosapiens.

The average woman has 34 nerve endings per one centimetre square of facial skin, while the average man has only 17; half of what a woman actually has. Thus, women feel more pain when subjected to "painful" stimuli.

Thinking about it the other way... I just labelled men as insensitive.
Which is also biologically true.

Picture taken from: http://pixelhead.typepad.com/weblog/images/nerveendings.jpg

Clubbing

2006-05-17T20:53:00.000+08:00

No! Not those with party and drinks, but rather that which is on your fingers.
Your fingers club too, if you didn't know.

A picture of digital clubbing, taken from http://www.mja.com.au/public/issues/181_05_060904/col10367_fm-1.jpg.

If you see anyone you know who has hands like those, or even hands which mildly looks like the one displayed, you should ask the person to see a doctor immediately. This is because the symptom of clubbing is almost universally, very bad.

Most lung diseases, heart diseases, liver diseases and even hyperthyroidism have clubbing as its symptoms.

Although the etiology of clubbing as a symptom of these diseases is unknown, scientists hypothesized that because these diseases cause the blood vessels in the fingers to vasodilate, nailbed tissues undergo hypertrophy and thus causes clubbing.

Please don't die?!

2006-05-05T23:01:00.000+08:00

When your brain thinks that your body is dying, it sends out a signal to your muscles telling it to contract suddenly in an effort to wake your body up.

This is called a myoclonic jerk.

It normally happens when your heart rate and breathing slows down quicker than normal. Thus, the brain inteprets it as signal that the body is dying and the myoclonic jerk causes your body to have a "defibrillated" effect. Myoclonic jerks can happen in any part of the body. Most oftenly, the hands and feet.

Myoclonic jerks may also originate from lesions in the cortex and the spinal cord.

So, if you get a myoclonic jerk, 3 things. You might want to thank your lucky stars that your body prevented you from dying. Secondly, you might want to question your brain's intelligence if you knew that you were not dying. Thirdly, you might have to worry because you may have a brain problem.

Meiosis

2006-05-03T20:35:00.000+08:00

Dear people, before I answer your questions, I think I have to clear a topic which I am super confused. Not confused by how it occurs, but rather by the technicalities and quantity.

The topic is Meiosis.

In response to John

2006-04-17T00:11:00.000+08:00

Hey, why is it then that I get high, or feel less lethargic after eating sugar-rich apples? Why do I feel more energetic only if my coffee has loads of sugar, but still feel sleepy when I drink it black?

Doesn't taking sugar before a race enhance performance? Carbo-loading and all that? If people feel high when they are energetic, and sugar gives energy, doesnt that mean sugar makes people high?

-jloh

To John:

Disclaimer:
Though I am confident of the facts that are listed in this blog entry, I am uncertain if this is the real cause of what you are experiencing. I am only going to hypothesize and not try to give a definitive answer to each of your questions.

Definitions:
High - A sudden change in mood, delirious or hyperactive arousal of some sort.
More energetic - An increase in alertness and capability of mental activity.

1) Apples and lethargy
It is a fact that apples help to increase mental alertness. Chemicals found in the apple regulate and prevent the buildup of serotonin, another neurotransmitter. Serotonin is a “sleep-inducing” chemical which causes drowsiness. This would be the most probable cause of feeling less lethargic after eating apples. Another hypothesis would also be that apples contain a huge amount of zinc. Zinc is an integral part in many enzymes, one of which is carbonic anhydrase, present in high concentrations in red-blood cells. It is responsible for the rapid combination of carbon dioxide and water in the blood as well as the release of carbon dioxide from the blood into the alveoli to be exhaled. As such, a faster decrease in the amount of carbon dioxide would result in a faster increase of the amount of oxygen in the blood, thus causing mental alertness. Apples do not cause a fast increase in blood sugar levels, but however regulates the blood sugar levels through slow digestion and through chemicals like isoleucine, leucine.

2) Coffee with Sugar
As a coffee drinker myself, I believe that coffee with sugar does also give me that extra perk. However, I feel that coffee with a lot of sugar would not cause someone to get high but rather to be more energetic. Sucrose, table sugar, is easily hydrolysed in the stomach and is easily assimilated. As such, the brain has an excess of energy to perform its routine functions. However though the brain has an excess of energy, hyperactivity nor arousal does not happen because dopamine is not excessively released and production of serotonin is not reduced. ATP can be formed readily and thus the brain works fast, causing mental alertness. But in no way does the brain register a sharp increase in released neurotransmitters nor other excitement related symptoms.

3) Carbo-loading and Energy
Yes it is no doubt that taking sugar in the form of sucrose before races does enhance performance. More glucose is available for aerobic and anaerobic respiration to be converted into energy. After consuming the supplements, an athele does not feel high. However the "high" is not caused by the intake of excess sugar, but instead is caused by the exercise itself. During an exercise or a race, many hormones are produced. It is the endorphines, adrenaline, enkephalins and catecholamines produced. These hormones cause the high and the excitement after an exercise.

_________________________

In conclusion:
Your bodily enzymes can be more efficient in energy production after you drink a cup of sugar loaded coffee because more glucose is available. However, after you exercise, you feel "high" because of hormones produced. Think about it. The feeling that you get after exercise greatly differs from the feeling you get after drinking sugar loaded coffee. Think deeper. Your adrenal glands do not pump out adrenaline when you drink coffee with lots of sugar. Endorphines are not produced when you suck a sweet.

Interestingly, though its 1 am in the morning, I have come up with what I will call Chow's hypothesis. A neurological "high" is caused and defined by an increase in hormonal production causing a change in neurological behaviour. An increase in energy levels / decrease in lethargy is caused and defined by an increase in enzymatic function, liberating energy from glucose thus causing a change in mental alertness. =)

Hope this answers your question.

Aphrodisiac

2006-04-16T21:49:00.000+08:00

It has to be Kink who asks about Aphrodisiacs. Nothing wrong with that, just a little amusing.

Before I introduce you to the accomplice of Aphrodisiacs, let me introduce you to a fascinating component of the human brain, called the brain stem. I will not go into details of what the brain stem actually is; or not in this entry at least. At the core of the brain stem, between the myelencephalon and the metencephalon (known unofficially as the medulla oblongata and midbrain respectively), lies the reticular activating system, which is the centre for arousal in animals. So, aphrodisiacs must be able to stimulate the system. How does it do so?

Dopamine.

As said in Biology, Concepts and Connections, Dopamine is a Neurotransmitter. What it does not say is that Dopamine, more often than not, is responsible for the after effects of aphrodisiacs. What happens when aphrodisiacs are consumed is that there is an increase of secretion / release of Dopamine from the Schwann knobs. This causes an increase in activity in that particular part of the brain, in this case the reticular activating system. This also stimulates the hypothalamus which in turn causes the "pleasure feeling" to be turned on in the hypothalamus. (As to how this happens, you can leave a question asking me to explain it to you).

Also, Dopamine is also a pre-cursor to to epinephrine (adrenaline). An increase in the secretion of Dopamine would lead to more adrenaline produced and thus, tachycardia, hypertension and symptoms associated with excitement gets manifested.

To sum everything up, Aphrodisiacs --> Increase in Dopamine production --> Stimulation of the Hypothalamus (Pleasure centre), Reticular activating system / Increase in adrenaline production.

Aren't we getting all excited?

John, will answer your really interesting question soon.

Wang, wanna contribute to the sports medicine section if I start one?

Pohboi, will do something on caffeine for my next post.

Sugar HIGH

2006-04-15T16:39:00.000+08:00

Simply put it, there is no phenomenon called a sugar high. Sugar, as proven by Neurologists does not cause any increase in activity in the frontal lobes nor basal ganglia or any part of the brain for that matter.

Experiments conducted by scientists proved that there is no such thing as a sugar high, but rather, people now do get high because of the Placebo effect or perception of sugar as a cause of hyperactivity.
(For those who do not know, the Placebo effect is one thing that medical scientists always write down in their errors in clinical trials)

But then again, when people eat chocolates, they do get high. Sugar High? No. Endorphins rather.

Hypoglycemic conditions with regard to the brain

2005-09-20T21:39:00.000+08:00

To Kink:

You are right to a small extent. Anorexic people and people who starve themselves to lose weight to maintain their figure (i.e supermodels) may damage the brain, regardless whether it is white or gray matter which is degenerated.

When the body is under nourished, it has a lack of carbohydrates and thus has a low source of glucose. When this happens, cells, tissues and organs in the body feed back to the brain that more glucose is needed. The brain itself also runs only on pure glucose and thus also determines more glucose is needed. However, there is no source of glucose found in the body from carbohydrates and thus other methods must be employed quickly to obtain glucose to prevent the body from suffering a neurogenic shock.

An important process to note is the process of gluconeogenesis. Gluconeogenesis refers to the production of glucose by the liver from other substances beside carbohydrates, thus referring to proteins and fats.

Muscle tissue and triglycerides (fats) are broken down to obtain glucose. Triglycerides are broken down into glycerol through lipolysis. Non-esterified fatty acids mix with the glycerol to form glucose and toxic ketone bodies. These ketone bodies, produced in the process of ketoacidosis, are toxic to the body and can lead to major organ failure.

The proteins in muscles are broken down through proteolysis to form pyruvate. Glycogen stored in the muscles is also broken down through glycogenolysis to form lactate. Together with alanine absorbed assimilation, lactate, pyruvate and alanine combine to form glucose. Thus we can see, glucose can be obtained from muscle and fat cells, however detrimental it might be.

Muscle and fat cells all over the body may be broken down for this purpose. However, the muscles and fat cells broken down are mostly cells which do not constitute any major organ in the body. It would be dangerous and suicidal if the body breaks down the proteins making up the heart just to supply glucose to the brain. In extreme cases of hypoglycemia (low blood glucose level), the brain would then be forced to shut down organs of the body, beginning with the least important. The brain’s fatty deposits may also be broken down. (N.B Brain is composed of 66% triglycerides). When the body cannot overcome the lack of glucose, it will fall into neurogenic shock, triggering sudden hypotension and stopping all organ activity.

Thus, in my opinion, it is likely that the person may suffer from ketone poisoning and muscle degeneration, but very unlikely that the brain would degenerate with starvation.

2005-09-20T21:35:00.000+08:00

Gluconeogenesis from triglycerides and proteins.

Neurotic Enzyme that regulates weight?

2005-09-19T22:11:00.000+08:00

"According to the 'Wall Street Journal', researchers at Harvard have found an enzyme in the brain that regulates obesity. They said if it wasn't for our brains, we would all be thin. That's why supermodels are so skinny. No brain, no gain." -Jay Leno

The first part is true. The second part, a whole load of guano.

Well, in this blog entry I will prove that indeed there is an enzyme in the brain regulating obesity. However, I do not belief that Harvard researchers said in their paper that enzymatic regulation of weight results in supermodels being skinny. It is an apparent bias and is utter defamation to view supermodels in that light.

Scientists have found an enzyme in the hypothalamus of the brain called AMP-Kinase (AMPK) which complements leptin (a hormone that is produced by fat cells). Leptin inhibits the production of AMP-Kinase. Thus we can say that the more adipose tissues a person has, the more leptin produced which results in lower levels of AMP-Kinase. This will allow the body to cut down on the production of fatty acids and detrimental substances leading to obesity. The levels of AMP-Kinase are directly proportionate to the obesity of the human. As can be seen from the chart below, an increase in the amount of AMP-Kinase would bring about fatty acid synthesis, cholesterol synthesis, fatty acid synthesis, lipolysis and many other detrimental effects to the body which may in turn cause atherosclerosis or angina.

However, it is important to note that obesity means that the AMP-Kinase is immune to the effect of leptin. Thus, regardless of the amount of leptin produced, AMP-Kinase will still be produced and thus, obesity and weight gain sets in. AMP-Kinase immunity to leptin may be genetic in nature, thus some people are “born fat”.

Regarding supermodels, the amount of gray matter, or rather intelligence of their brain is not in any way linked to the production of AMP-Kinase thus completely refuting Jay Leno’s groundless claim. But a conclusion that supermodels’ AMP-Kinase are not leptin resistant can be drawn.

2005-09-19T21:23:00.000+08:00

The effects of AMPK activation. Arrows indicate positive effects, T lines indicate inhibitory effects.

2005-09-19T00:12:00.000+08:00

An MRI of a dyslexic brain. As can be seen from the MRI, there are areas (colour coded orange) of the brain of a dyslexic person which have a lower density of gray matter as compared to a normal person. This is the cause of dyslexia.

Dyslexic?

2005-09-18T23:54:00.001+08:00

In response to Mr Tay Wenbin's question.

Dyslexia

Dyslexia is a neurological, genetic based disease affecting 5% of the population. The cause of dyslexia is genetic based which means mutations in germ line (sex cells) can cause an offspring to have dyslexia. Dyslexic people have compromised reading and writing abilities and intelligence which is significantly lower than which would be predicted by his general level of intelligence. This is because of decreasing amounts of gray matter in the parietal and temporal lobe (please refer to above image). In layman terms, the amount of gray matter in the brain is directly proportionate to the intelligence of a human.

There are many characteristics of Dyslexia. Some of which are silent characteristics, which means that they are not shown outwardly. Some of these characteristics are reading and writing disabilities and complaining of dizziness, headaches or stomach aches while reading. This entry will not go into the further symptoms of dyslexia.

Dyslexic people tend to look at words as pictures and thus are slower in comprehending.

Treatment of dyslexia is based mainly on phonological training, which involves breaking down and rearranging sounds to produce different words.

As of my knowledge, dyslexic people are born dyslexic from birth. No non-dyslexic turns can turn dyslexic at any point of his/ her life.

I hope this answers your question. If you have any feedback, please tag on my tagboard.

2005-09-18T23:54:00.000+08:00

When a normal reader hears rapid sounds, the language-critical left frontal cortex lights up (left). When a dyslexic hears rapid sounds, no brain activity is recorded there and it remains dark.(Credit: Elise Temple/PNAS)

2005-09-18T23:48:00.000+08:00

Dyslexia affects mainly the left temporal lobe and the occipital lobe, specifically the temporopareitooccipital juntion (where the Parietal, Occipital and Temporal lobes meet)

Pyrexia

2005-09-18T01:36:00.000+08:00

I shall deviate from Neurology to talk about something that many of my friends are suffering from now.

Pyrexia (common name: Fever)

Fever is a common term to describe a medical symptom in which a human's internal body temperature rises to temperatures above normal. Fever is not a neurological disease, but can be brought about by one. Fever is brought about by pathogens (biological agent which can cause disease to its host). It is a postive feedback mechanism which opposes the homeostatic negative feedback thermal regulatory mechanism. As with any positive feedback mechanism, fever aims to achieve a normal body condition by raising the internal body temperature to denature enzymes which enable the pathogen to work, indirectly killing the pathogen itself. Thus fever cannot be labelled as a disease, but rather as a symptom and as the body's defense mechanism towards pathogens.

As mentioned above, Fever is caused by infections and thus is not termed a disease. However, there are drugs to stop the development of fever. These drugs are called antipyretics. Acetaminophen or Paracetamol (Panadol) are examples of it. These drugs inhibit the production of the cyclooxygenase enzyme responsible for inducing the increase in body temperature.

However, antipyretics only suppress the fever and stops the positive feedback mechanism. They do not inhibit the source of it. Thus, a patient who is immunodeficient may be on antipyretics alone for months without antibiotics and die. Antibiotics must be prescribed together with the antipyretics so as to minimize the fever and to eliminate the source of infection which results in the fever. Thus it is absolutely necessary to see a doctor to obtain antibiotics when fever arises. However, a patient may recover totally without the use of antibiotics as the body's immune system will produce its own antibodies to combat the infection, but the time for recovery would be significantly longer.

2005-09-18T00:54:00.000+08:00

Interesting. The bottle-nose dolphin's brain is bigger than a human's, has more lobes and folds. Does it mean it's smarter than a human?

BrainFreeze

2005-09-15T21:59:00.000+08:00

Brain Freeze is a term used to describe a headache or a throbbing pain felt after consuming cold beverages or foods such as ice-creams. The chances of this happening is increased as rate of consumption is increased.

The scientific term for Brain Freeze is Temporal Neurocranial Vasodilation.

When cold food touches the roof of the mouth, or anywhere near the Parotid gland, the Sphenopalatine Ganglia nerves there are triggered. They send a signal to the brain that it is in a very cold environment. Homeostatic functions are induced. Negative feedback causes the blood vessels in the brain to vasodilate and swell for about 30 seconds to provide the brain with the necessary heat. The swell presses against the cranial nerves, inducing pain.

A simple cure to it would be to move your tongue to the roof of your mouth when you suffer from Neurocranial Vasodilation. This would cause greater warmth to the Sphenopalatine Ganglia nerves and thus, they will not send impulses for vessels in the brain to vasodilate.

2005-09-15T21:58:00.000+08:00

Neurocranial vasodilation, depending on intensity of cold, affects the whole brain.

2005-09-14T20:35:00.000+08:00

A picture of the human brain. Please note the two main cortexes are not labelled in the diagram. (Primary Motor Cortex, Primary Somatosensory Cortex)

Opening of NeuroChowzy

2005-09-14T20:17:00.000+08:00

Hello everyone. Welcome to the opening of NeuroChowzy. A little blog which updates on Neurological advances and development. I will be bringing you ideas and interesting facts on the human brain. Feel free to comment, tag on the tagboard. Hope this site will be one of much interest to you guys!