Tag: medicine

Posted in Psychology & Medicine

Viscera: Heart

Posted on by Jinavie

(Learn more about the organs of the human bodies in other posts in the Viscera series here: https://jineralknowledge.com/tag/viscera/?order=asc)

Out of the numerous organs found in the human body, the heart is perhaps the most well-known. This is probably because since the dawn of time, man has put his hand on his chest and felt the rhythmic pounding of his heart – a reminder that he is alive. The function of the heart is to pump oxygenated blood from the lungs to the rest of the body via the circuit of blood vessels (vascular system).

The heart relies on electricity to pump blood in a rhythmic, autonomous way. Because of this property, a heart will beat on its own even if you took it out of the human body. Every muscle in the human body requires an electrical impulse for it to contract. This is also the case in the heart, but unlike the skeletal muscle in other parts of the body which receive their impulses from the brain and spinal cord, the heart has its own source of electricity.

The heart has a small group of pacemaker cells in the right atrium called the sinoatrial node, which always fires electrical impulses at a set rate and rhythm (sinus rhythm). The SA node will do this without any instruction from the brain. The impulse from the SA node spreads throughout the atria of the heart, causing the atrial muscles to contract simultaneously to squeeze blood into the ventricles. The impulses then reach the atrioventricular node, which filters the signals and sends a stream of electricity through a wiring system known as the Purkinje fibres. These fibres act like a high-speed internet cables running down the centre of the heart, sending rapid signals through out the ventricles to induce a strong, cooridnated contraction in both ventricles. This causes blood to be forcefully squeezed out through the two outlet vessels of the heart: the pulmonary artery (to the lungs) and the aorta (to the rest of the body).

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Although the SA node is completely autonomous, it can be controlled using hormones, nerve signals and medications. For example, adrenaline will speed up the rate the heart beats at while massaging the carotid arteries in the neck will slow the heart down.

One thing people wonder about is what the doctors listen to when they put a stethoscope to a patient’s chest. Everyone knows the heart makes a rhythmic “lub dub” sound as it beats away, but what information could that give away? A doctor can gain much information about the heart from a cardiac examination by taking the pulse and blood pressure, but listening to the heart (auscultation) may reveal a medical sign known as a murmur. A murmur is any added sound other than the normal “lub dub” sound of the heart. For example, a heart with aortic stenosis may give the sound “shhhhhhh” as if it was giving off static. This sound is produced when blood flow in the heart is turbulent and not smooth. This may be for a number of reasons but the most common reason is because the valves of the heart are not functioning properly. For example, the valve between the left atrium and left ventricle may be leaky (mitral regurgitation) or the valve at the start of the aorta may be stiff and narrowed (aortic stenosis).

By carefully listening to the sound the heart makes, an experienced doctor may pick up on such structural abnormalities even without the use of fancy medical imaging technologies.

Posted in Psychology & Medicine

Agonal Breathing

Posted on by Jinavie

When a person is on the verge of death, they may show a very strange pattern of breathing. They will begin gasping for breath, take deep laboured breaths, begin to make strange noises and possibly have some muscle jerks (which may look like a seizure). The breathing makes it look as if the person is taking a deep breath and sighing, while gasping every now and then irregularly. This is called agonal breathing and it is most likely caused by an oxygen-starved brain sending weak signals to try kick up the respiratory drive for more oxygen.

Agonal breathing is not uncommon in cases of cardiac arrest. It is important to note that agonal breathing is not an efficient form of breathing and thus it cannot be said that the victim is “breathing” when this occurs. Because it looks like the patient is taking deep breaths, bystanders may be fooled into thinking that they have been resuscitated and have begun breathing again. But this is not the case and the patient is still clinically dead. Ergo, one should not stop CPR even if the patient begins taking deep breaths and sighs. The presence of agonal breaths usually indicate a better outcome for the patient.

(Link to video examples of what agonal breathing looks like: http://emsbasics.com/2011/04/21/what-it-looks-like-agonal-respirations/)

Posted in Psychology & Medicine

Placebo Effect

Posted on by Jinavie

A strange phenomenon found in medicine is the placebo effect, where a patient’s symptoms improve after being given a completely inert substance (like a sugar pill) under the guise of a medication. The placebo effect is not only limited to pills, but any procedure that is intended for a therapeutic purpose (but does not have any actual therapeutic value). It is believed that the placebo effect is a strong component in many forms of alternative medicine such as homeopathy and faith healing. The placebo effect has been proven to be effective in improving or even curing the symptoms of some diseases such as allergies, asthma, headaches, abdominal pains and even severe illnesses such as heart attacks and cancer. Placebos are particularly effective for psychological symptoms.

There has been much research to determine how the placebo effect works. The leading theories so far are that placebos act to relieve anxiety and condition the patient into a more positive mindset, reducing stress and boosting the body’s natural healing process. This would also explain why placebos are effective in pain relief as perceived pain is amplified by negative emotions. Cognitive dissonance may also play a role, where the patient’s mind believes that since it is receiving treatment, it must be getting “better”, producing a beneficial psychosomatic reaction. Essentially, fooling the mind to believe and expect that it will get better makes the patient actually feel better.

Research into the placebo effect has also revealed some bizarre characteristics of the effect. For example, it has been found that the placebo effect is stronger if there are more pills, the pill is larger, branded or generally looks fancier. Even colour plays a role, with blue pills acting better as depressants (“downers”) and red pills acting better as stimulants (“uppers”). Telling a patient that a placebo will have a certain effect boosts that effect. Human factors such as the doctor’s credibility and confidence or the patient’s expectations and culture are known to drastically change the efficacy of a placebo. What is weirder is that studies have shown that telling a patient that they are being prescribed a placebo will not affect its efficacy, as long as they are told that “it could help them”.

The placebo effect is a great example of how much influence our mind, beliefs and expectations have on our health and our lives. The more positive thoughts and beliefs we have, the healthier we become. The more negative we are, the less effective treatments become. In fact, the same pill that gives people the placebo effect can be used to increase pain and symptoms if it is described in a certain way. This is known as the nocebo effect – the opposite of the placebo effect.

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Posted in Science & Nature

Alligator

Posted on by Jinavie

What is the best or easiest way to protect yourself from an alligator attack? Obvious answers aside (such as avoiding them), it is to use something like an elastic band or a rope to tie their snout shut. Alligators have the strongest bite in the natural world – clocking in at about 2125 pounds of force (about 966kg). The sheer force of the bite is enough to crush the victim and kill them instantly. Even if the victim survives, there is a serious risk of being left with a permanent disability or die from an infected wound.

Although the force of the bite is incredible thanks to its extremely strong jaw muscles, alligators do not have nearly enough the same strength when opening their jaws. This means that a simple elastic band is enough to keep their jaws shut, leaving the alligator helpless and giving you a chance to run before its friends come to find you.

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Posted in History & Literature

Rod Of Asclepius

Posted on by Jinavie

There are many symbols that represent the field of medicine such as a red cross or a stethoscope. However, one of the most famous symbols representing medicine and healthcare is the rod of Asclepius. This symbol is used in the logos of numerous medical associations and army medical corps. Those who do know of the rod may describe it as a staff with two wings and two snakes intertwining on it, but this is a common misconception. That symbol is called the caduceus and is actually the symbol of Hermes – the Greek god of messengers, merchants, markets, the high roads, gamblers and thieves. The misconception is very common and many medical associations use the caduceus as their symbol instead of the correct Rod of Asclepius.

The Caduceus

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The actual rod of Asclepius is much simpler looking, as it is simply a stick with one serpent intertwining it. The reason that it is associated with medicine and healthcare is that it was wielded by the Greek god Asclepius – the god of medicine and healing. Asclepius was the son of Apollo and had a particular interest in the human body and the healing of ailments. The ancient Greeks often referred to Asclepius in the field of medicine. In fact, the famous Hippocratic Oath originally began with the line “I swear by Apollo the Physician and by Asclepius and by Hygieia and Panacea and by all the gods…” (Apollo was the god of many things and medicine was one of his minor domains).

The rod of Asclepius

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So why does the rod of Asclepius have a serpent wrapped around it? In Greek mythology, it is said that Asclepius commanded many non-venomous snakes which he used in healing rituals. The snakes would crawl around the temple, living freely among the physicians and patients. A certain species of snake called the Aesculapian snake is considered to be the model for this story. The reason why the Greeks chose the snake as the animal of healing may be because snakes shed their skin periodically – symbolising rebirth and fertility. 

Another possible root of the symbol may be the traditional treatment for a certain parasitic infection. The Guinea worm (Dracunculus medinensis) is a parasite that lives under the skin, digging itself out through a painful blister when mature. As the blisters burn, the patient immerses the area in cold water to soothe it. The worm detects the change in temperature and releases its larva, completing its life cycle. The traditional treatment was to slowly pull the worm out of the skin, entwine it around a stick and leave it for a period of hours to weeks until it would be completely removed. The Greeks may have taken this image (of the worm wrapped around a stick) and applied it to the rod of Asclepius.

Posted in Psychology & Medicine

Urine

Posted on by Jinavie

Despite the implied disgusting nature (especially smell) of urine, it is one of the most important types of “samples” used in medicine for diagnostic purposes. Like blood, urine can tell a lot about a person’s health and whether they have a certain disease or not.

One of the earliest recorded uses of urine as a medical test was for the detection of diabetes mellitus. People noticed that the urine of a diabetic would often smell quite sweet, and also taste sweet (it is uncertain how they came to test urine this way). This is because a diabetic has too much glucose (sugar) in their blood, causing it to spill over into the urine as the kidneys become saturated. In fact, the words diabetes mellitus stand for “passing through” (referring to the symptom of frequent urination) and “honey-sweet”. A completely unrelated disease called diabetes insipidus also causes frequent urination, but the urine does not taste sweet, hence “insipidus” (tasteless). This type of etymology is also seen in countries like Korea, China and Japan, where the word 당뇨(糖尿) literally stands for “sugar urine”. Although we no longer taste urine, it is still used to gauge the severity of diabetes by measuring the amount of protein in the urine (due to kidney damage).

There are many other tests one can do with urine to check for certain diseases. The chemical composition of urine tells us about the hydration status of a person, while giving away clues to diseases that cause electrolyte imbalance. It also gives some indication of how well the kidneys can do their job of concentrating urine. Certain markers such as white blood cells and bacteria in the urine can indicate a urinary tract infection. Antibodies in the urine can point towards a certain type of bacteria as the cause of a patient’s pneumonia, or whether a woman is pregnant (βhCG). Looking for proteins or sediments in the urine can be diagnostic of certain kidney diseases such as glomerulonephritis. Even rare diseases such as phaeochromocytomas can be diagnosed from the level of catecholamines in the urine (this is slightly too complex for our scopes).

A more interesting part of urinalysis is looking at the colour of the urine. Urine is usually a yellow colour, ranging in darkness depending on the concentration of urine. But when there are other things in the urine, the colour changes. Reddish urine suggests blood (which is not an indicator of kidney failure as TV shows say), which can be caused by trauma, UTIs, kidney stones or some other disease. Brown urine could be due to muscle breakdown somewhere in the body. Urine can appear very dark if the person has an illness called obstructive jaundice. Eating beetroots can cause your urine to turn bright red, while medications can change your urine colour from anywhere from red to orange to green. Murky or cloudy urine (with an offensive smell) may suggest a UTI.

Perhaps the most interesting urine colour known in medicine is purple. This unique colour is produced in a rare genetic disease called acute intermittent porphyria. If urine is collected from a patient suffering an attack of AIP (causes crippling abdominal pain) then left in the sun or under a UV light, it will turn purple due to certain proteins. Because of this, urine collected to test for AIP is wrapped in tinfoil before sending to the lab (where the chemicals are measured) to limit light exposure.

(Also read the article on how different colours of skin can be of diagnostic importance: http://jinavie.tumblr.com/post/32313894252/skin-colour)

Posted in Psychology & Medicine

Phineas Gage

Posted on by Jinavie

On September 13, 1848, a 25-year-old foreman named Phineas P. Gage was working on a railroad with his work team. In an unfortunate turn of events, as he was using a tamping iron (large iron rod with a pointed end, measuring 3 feet 7 inches in length and 1.25 inches in diameter) to pack gunpowder into a hole, the powder detonated. The forceful explosion drove the metal pole skyward through Gage’s left cheek, ripped into his brain and exited through his skull, landing dozens of metres away. His workmates rushed to Gage’s assistance (who they presumed to be dead at the time of the accident), and to their surprise, found that he was still alive.

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In fact, Phineas Gage spoke within a few minutes of the incident, walked without assistance and returned to his lodging in town without much difficulty – albeit with two gaping holes in his head, oozing blood and brain everywhere. He was immediately seen by a physician who remarked at his survival. In fact, it is reported that he was well enough to say: “Here is business enough for you” to the doctor. Another physician named Dr John Harlow took over the case, tended to the wound, fixed up the hole and recorded that he had no immediate neurological, cognitive or life-threatening symptoms.

By November, he was stable and strong enough to return to his home, along with the rod that nearly killed him. His family and friends welcomed him back and did not notice anything other than the scar left by the rod and the fact that his left eye was closed. But this was when things started to get interesting.

Over the following few months, Gage’s friends found him “no longer Gage”, stating that he was behaving very differently to the man who he was before the accident. Dr Harlow wrote that the balance between his “intellectual faculties and animal propensities” had seemingly been destroyed. Gage became more aggressive, inattentive, unable to keep a job, verbally abusive and sexually disinhibited. He would frequently swear using the most offensive profanities and would be as sexually suggestive as a March hare. How did the iron rod cause such a dramatic change in Gage’s personality?

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Phineas Gage would go on to be one of the most famous patient case histories in the history of modern medicine. His case was the first to suggest some sort of link between the brain and personalities. Neurologists noted that the trauma and subsequent infection destroyed much of Gage’s left frontal lobe – the part of the brain that we now attribute to a person’s logical thinking, personality and executive functions. It is in essence the “seat of the mind”. Ergo, Gage’s loss of one of his frontal lobes meant that his control of bodily functions, movement and other important brain functions like memory were undisturbed, while his “higher thinking” was essentially destroyed (he was essentially lobotomised). This explains Dr Harlow’s observation of his “animal propensities”.

Thanks to this case, a great discussion was sparked and the idea that different parts of the brain govern different aspects of the mind was conceived. We are now able to localise almost exactly where the language area is, what part controls movement and how a certain piece of the brain converts short-term memory into long-term memory.

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Posted in Science & Nature

Banana Equivalent Dose

Posted on by Jinavie

No form of energy has been more feared or creatively explored in science fiction (e.g. Godzilla) as radiation, yet the layman tends to know little about the actual properties and effects of radiation. The word “radiation” is commonly associated with things like Chernobyl, mutation and cancer. However, most people only know that radiation is “bad” while not knowing exactly how and why it is dangerous. Radiation is essentially high-frequency light which can deliver a large dose of energy (just like how microwaves cook food and sunlight can burn paper when focussed through a magnifying glass). When this high-dose of energy passes through living organisms, it damages the DNA in cells, potentially causing irreparable damage. This can lead to mutation and disruption of cell division (which can lead to cancer) or cell death (which is why radiation is ironically used to kill cancer cells).

The more technical question is “how much” radiation is harmful. For example, how much more dangerous was the Chernobyl incident compared to an x-ray? Like many other things in science, radiation is measured using an internationally universal unit called the Sievert (Sv). The radiation received from standing next to the Chernobyl reactor core after meltdown was 50Sv, while a chest x-ray is 20μSv (1000μSv = 1mSv, 1000mSv = 1Sv). Therefore, the Chernobyl incident could be considered to be as strong as 2.5 million chest x-rays. Although there is great variation, it is considered that a dose of 400mSv can cause symptoms of radiation poisoning, while 4~8Sv of radiation will lead to certain death.

Fascinatingly, radiation is not an uncommon thing. Radiation is all around us, with an average person receiving about 10μSv of background radiation per day just by living on Earth. Ergo, two days of walking around gives you the same amount of radiation as a single chest x-ray. A CT scan gives out a significantly greater dose of radiation at about 7mSv (approximately 350 x-rays or a year’s worth of background radiation).

However, the Sievert is a unit that is difficult to understand. Thus, some scientists devised a clever, humorous equivalent unit called the banana equivalent dose (BED). Bananas contain a certain amount of radioactive isotopes (radioactive potassium), making them technically radioactive. A banana contains 0.1μSv of radiation. Ergo, a chest x-ray is the equivalent to eating 200 bananas, a CT scan is 70000 bananas, while the Chernobyl incident gave people nearby a dose of roughly 500 million bananas.

The banana equivalent dose is a rather useful (and hilarious) way of comparing the danger of radiation from different sources. The next time you go to hospital for an x-ray, just picture 200 bananas being shot through your chest.

Posted in Psychology & Medicine

Skin Colour

Posted on by Jinavie

The world is full of people of all creed and races and it is a common fact that people from certain races have different skin colours to people from other races. But other than the range of normal skin colours, there are certain skin colours that can occur with specific medical conditions.

The most common reason for a change in skin colour is a suntan, which damages the skin and causes darkening of the skin (hyperpigmentation). However, some diseases are also known to cause hyperpigmentation, such as Addison’s disease or haemochromatosis.

The converse is lightening of the skin (hypopigmentation) and can happen with diseases such as leprosy, vitiligo or albinism. Alternatively, people can look pale when they are anaemic or extremely frightened, triggering a sympathetic nervous response, shutting down blood circulation to the face and extremities.

It is common to see red skin with flushing, sunburns, skin infections or numerous dermatological conditions such as rashes. Occasionally, these rashes may be associated with serious diseases such as lupus or Crohn’s disease.

Cyanosis (literally “blueness” in Latin) causes the skin to bluish-purple and it is due to the lack of oxygen in the blood. This could be caused by any number of reasons that causes hypoxia. For example, babies can be born with a heart defect that causes mixing of oxygenated and deoxygenated blood, leading to something called “blue baby syndrome”.

Liver dysfunction can present as jaundice, which is yellowing of skin and the white of the eyes due to a build-up of bilirubin.

Some stranger skin changes can be caused by certain chemicals. Carrots contain beta-carotene (which gives carrots their orange colour) and excess consumption can cause carotenosis (or carotenodermia), a yellowing of the skin. Eating too many tomatoes causes a similar condition called lycopenodermia, which presents as reddened skin (lycopene gives tomatoes their red colour). A combination of the two produces a distinctively orange colour. Both conditions are harmless and disappear after reducing the amount of carrots and tomatoes eaten.

Even stranger still is a condition called argyria, which can be caused by exposure to silver, either through medications especially alternative medicine), mining or contamination of the water supply. Silver causes skin to turn a deep blue colour and the pigmentation is irreversible. Similarly, copper can turn skin green and gold can turn skin grey.

Posted in Psychology & Medicine

Tetrachromacy

Posted on by Jinavie

They say that human imagination is infinite and limitless. But consider this: can you imagine a colour outside of the visible spectrum? Most likely, you are incapable of thinking of a new colour that cannot be mapped on a standard colour chart. Interestingly, a small proportion of people can see and understand colours beyond the range that the majority of us can see.

The physiology of vision is rather complex, but essentially boils down to the retina (inside lining of the eyeball) acting as a film for the image that you see. Cells known as photoreceptors convert the visual image into electrical signals that are transmitted to the occipital lobe of the brain via the optic nerve. There are two types of photoreceptors: rod cells, which sense movement, and cone cells, which sense colour and provide sharp images (visual acuity). Human beings typically see colour by combining three primary colours: red, green and blue (known as the RGB system). There are cone cells for each primary colour. The brain processes the signals sent by each cone cells and figures out what “colour” you are seeing. Therefore, you can only perceive colours made from a combination of red, green and blue. It is easy to visualise this by playing with colour palettes on computer programs such as Photoshop.

In recent years, it has been speculated that a certain percentage of women have an extra type of cone cell that senses a different wavelength of light. Ergo, they can theoretically sense a greater range of colours compared to someone who has three types of cone cells. This condition is called tetrachromacy (“four colours”). Tetrachromacy is the opposite to colour blindness, which is caused by a deficiency or fault in one or two types of cone cells. To these people, the average person (a trichromat) will appear “colour blind”.

According to one estimate, as many as 12% of women are tetrachromats. Although there are many theoretical barriers to true tetrachromacy, there have been several documented cases of women who perceive colour in much more depth.

The ability to see an extra primary colour is more significant than just a 25% increase in the person’s colour range. An average person can see about 1 million different hues (shades of colours), while a true tetrachromat can see 100 million hues – a hundred-fold increase in the range of colours they can see. One can only wonder what kind of amazing sights a tetrachromat sees when she gazes upon a field of flowers or even a rainbow. Unfortunately, even if a tetrachromat tried to explain the colours she saw to us, we would not be able to grasp the colours as our minds would be incapable of visualising the colours, much like how describing the colour red to a blind person is impossible.

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