Tag: medicine

Posted in Psychology & Medicine

Process Of Elimination

Posted on by Jinavie

“How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?” ~ Sherlock Holmes

If there is not enough evidence to come to a conclusion of what is the truth, start by removing the possibilities that cannot be true. If you hack away these impossible answers one by one, you will ultimately end up with the truth. This method is highly useful in a multiple-choice type exam, where you cross off the false answers until only one remains (or take an educational guess from whatever remains). In medicine, a process of elimination can be used to narrow down a differential diagnosis, or to reach a diagnosis of exclusion – that is, a diagnosis that cannot be proven to be true but seems to be the only one that fits since all other diagnoses do not. 

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Posted in Psychology & Medicine

Hypothermia

Posted on by Jinavie

A person’s body temperature is always maintained between 36.5~37.5°C. This is because enzymes, which are crucial in all physiological reactions in the body, work most efficiently at this temperature. As physiology is essentially a series of chemical reactions, it is heavily dependent on temperature. If the temperature falls, chemical reactions occur slower and vice versa. When body temperature falls below 35°C, metabolism becomes too slow and it poses a risk to the person’s health. This is known as hypothermia.

How does hypothermia affect the body? Hypothermia is categorised into three classes depending on the severity.

  • Mild hypothermia (32~35°C) leads to the slowing of bodily functions, tremors and difficulty in walking. The patient’s speech is impeded and other neurological symptoms such as decreased judgement skills and confusion start to appear. Also, blood pressure, pulse and breathing rate rise.
  • Moderate hypothermia (28~32°C) causes paralysis of muscles and extreme fatigue (they may complain of being sleepy). As blood (carrying heat) is rerouted to major organs, the skin (especially lips and extremities) become white or purple and very cold. Neurological symptoms worsen with amnesia, memory loss, severe confusion and delusion beginning to show. As sustained hypothermia leads to the tremors stopping, one should not take the lack of tremors as a good sign. Heart rate becomes irregular and arrhythmia may occur.
  • Severe hypothermia (20~28°C) leads to chemical reactions becoming so slowed that physiological functions that support life decline dramatically. Heart rate, blood pressure and breathing all lower to dangerous levels and the heart and lungs may stop functioning. As the patient’s major organs begin to shut down, they enter a state of unconsciousness and eventually, clinical death.

As you can see, hypothermia is a highly dangerous situation that can kill. There are some other fascinating facts about hypothermia.

20~50% of hypothermia death cases are associated with paradoxical undressing. This is a strange phenomenon where the person begins to take off their clothes due to confusion and a lack of judgement from the hypothermia. One theory suggests it is related to the cold damaging the hypothalamus (which controls body temperature), causing the brain to think that the body temperature is rising. Whatever the reason, it is extremely dangerous as it worsens the hypothermia.

As explained above, severe hypothermia leads to death. But interestingly, hypothermia also protects organs. This is why organs for transplanting are transported in ice. Similarly, there are examples of people who “died” from hypothermia recovering with no brain damage. Because of this, medical professionals traditionally say: “they’re not dead until they’re warm and dead”. In fact, if there is something wrong with the patient’s circulation and there is risk of damage to their organs (such as in surgery), sometimes the patient’s body temperature is forced down with ice water injections and cooling blankets, known as protective hypothermia.

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Posted in Psychology & Medicine

Spinach

Posted on by Jinavie

Spinach is a vegetable that is excellent for your health as it is rich in nutrients such as vitamins and minerals. If you ask someone the first two things that come to mind regarding spinach, they will most likely reply Popeye and iron. Popeye is a cartoon that began airing in the 1930’s and every child knows that the man gains superhuman powers from eating a can of spinach. In fact, after Popeye began airing, US consumption of spinach grew 33%. Most people believe that Popeye gains powers due to spinach having a high iron content. Thus, adults always tell children that if they want to be as strong as Popeye, they must eat their spinach.

Unfortunately, eating spinach does not make you as strong as Popeye. In fact, it is not even related to iron either. Firstly, the reason why Popeye eats spinach was because the producers wanted to advertise the high vitamin A content in spinach. Furthermore, spinach does not have a high iron content. The spinach iron myth originated from a German scientist named Emil von Wolff. In 1870, von Wolff was analysing the nutrition contents of different foods when he, from severe fatigue, accidentally misplaced a decimal point while recording the iron content of spinach. This led to spinach being known to have ten times the amount iron it actually has (to the level of red meat).

One problem with this is that this story is not true either. There are no detailed records of von Wolff’s experiments and no one knows if he misplaced a decimal point or not. The myth most likely originates from a 1980 article in The British Medical Journal that first brought up the story. Does that mean spinach is actually is a good source of iron? Wrong. Vegetarians often claim that spinach has iron levels close to red meat, but there is something about iron that they do not know. Many plants have a high iron content (it is found in chlorophyll which is used for photosynthesis), but this is mostly non-heme iron. There are two types of iron the human body can absorb: heme and non-heme. Heme iron can be used directly after absorption whereas non-heme iron needs to be metabolised by the liver to be usable. This takes a long time and is inefficient meaning it is far more effective to eat foods rich in heme iron. Plant iron is all non-heme iron while 40% of iron in red meat is heme iron, meaning it is a much better source of iron. Furthermore, spinach has a high oxalate content, which is an iron absorption inhibiting agent, making what little usable iron it has unabsorbable. 

In short, it is true that spinach has “iron” but as we cannot absorb it or use it, it practically has no iron content. But if you tell this to your parents and refuse to eat spinach, you may get into a lot of trouble.

Posted in Psychology & Medicine

Clubbing

Posted on by Jinavie

Among the thousands of signs and symptoms in the field of medicine, there is one that every doctor and medical student knows since the development of medicine. Clubbing is an easily noticeable sign in a patient’s fingers that can have wide implications on their health.

Clubbing is essentially when the angle (gap) between the fingernail bed and finger disappears. The formal definition is much more complicated, such as “the loss of the normal <165° angle, or Lovibond angle between the nailbed and the fold”, but for all intents and purposes the simple definition is sufficient.

To see if a patient has clubbing, the physician carefully studies the fingers against light. There are a few ways to check for clubbing but the most popular methods are holding the fingers out straight and holding them parallel to the ground, checking the angle between the nailbed and finger, or the Schamroth’s window test. The latter test is done by holding two opposing fingers (such as the left and right index fingers) against each other nail to nail. The fingers are then held against the light so that the light can shine through the “window” that is made. If the window is not seen, the test is positive and the patient has clubbing.

What does clubbing suggest? Clubbing was first noticed by Hippocrates, the father of Western medicine, who observed that people with clubbing tended to grab their chest and fall dead. This is one of the most common associations to clubbing – a congenital cyanotic heart defect such as tetralogy of Fallot or patent ductus arteriosus. Other common associations are related to the lungs, such as lung cancer (one of the most common causes) and various other lung diseases such as interstitial lung disease, tuberculosis and other chronic infections. There are also a myriad of other diseases associated to clubbing, including but not limited to: Crohn’s disease, ulcerative colitis, cirrhosis, celiac disease, Graves disease and certain types of cancers (lung, gastrointestinal and Hodgkin’s lymphoma mainly). Clubbing can also be idiopathic, where there is no apparent cause for the clubbing and the person just has it (possibly just born with it).

Despite knowing about clubbing for over 2000 years, we still do not know the exact reasons for clubbing. There are theories that it is related to a fall in blood oxygen content leading to vasodilation in the peripheries. As the pathophysiology is not clear and so many diseases are associated with it, when clubbing is found in the patient the physician should investigate the related organ systems (heart, lungs, GI mainly) to narrow down the possible cause of it. As many of the causes (such as lung cancer) carry a rather morbid prognosis, it is quite important to notice whether the patient has clubbing when doing a physical examination.

Posted in Psychology & Medicine

Fugue State

Posted on by Jinavie

Any computer user would have had an (unfortunate) experience where their computer crashed and all the information there was destroyed in a second. You may still be able to format it and use it without problems, but the data you had on the computer and any customisation you made would be lost. But what if this exact thing could happen to a human being?

There are many types of amnesia, with causes ranging from neurobiological (where trauma to the brain, a drug or some other pathology causes memory loss) to psychogenic (where there is no apparent biological cause for the amnesia). With psychogenic amnesia, one only experiences retrograde amnesia, where they cannot recall memories from the past. However, anterograde amnesia, where you cannot form new memories and keep forgetting what happened, is absent in psychogenic amnesia. Psychogenic amnesia is often caused by extreme stress or a traumatic event. One type of psychogenic amnesia is situation-specific amnesia, as seen in post-traumatic stress disorder (PTSD) that occurs after a severely stressful experience such as war, rape, child abuse or witnessing a brutal death. In this case, the patient tends to only lose memories regarding the event, as if the brain is trying to protect the person from the hurtful memories.

A more interesting and much rarer type of amnesia is global psychogenic amnesia, also known as a fugue state or dissociative fugue. Unlike situation-specific amnesia, patients in fugue states have absolutely no memory of their original identity and personality. Simply put, they (usually) retain all their functions such as speaking and social interactions, but their persona has been wiped out like a formatted computer. Fugue states often develop after severe stress and can happen to anyone. Similar to situation-specific amnesia, the brain blocks all memories of the past in an attempt to protect the person’s psyche. Due to the “deletion” of the previous persona, patients in fugue states often generate new identities and begin wandering (sometimes even travelling to another country) away from the place they lost their memories. This is most likely the brain attempting to leave the environment to avoid the stressor that caused the event. 

Fugue states are often short-lived, lasting from days to months. However, very rarely they can last for years. Once out of a fugue state, the patient recovers all of their past memories but have no recollection of what happened during the fugue state. This creates a hole in their memory. For obvious reasons, this usually causes intense confusion and distress in the patient and treatment is often based around helping the person come to an understanding about the episode and cope with the stressor that caused it.

Posted in Science & Nature

Grandmother Hypothesis

Posted on by Jinavie

There are many physiological events that puzzle scientists. Menopause is one of these as it is very uncommon in other mammals. Why do human females stop having periods after aging? From an evolutionary point of view, an organism that has lost reproductive function cannot aid evolution and thus it is a mystery how a trait like menopause survived natural selection. The leading theory in how such a phenomenon happened is the grandmother hypothesis.

According to this hypothesis, as humans are social animals menopause can still be an evolutionary advantage despite not being able to produce offspring. This is because older women can invest the massive amount of energy and time required to upkeep childbearing in other places. For example, they can help their family and society grow by working or taking care of children instead. Furthermore, as the probability of miscarriages and congenital defects rise with aging (generally after a woman hits the age of 30, the chances of a healthy pregnancy decreases), menopause has the function of protecting the gene pool of the species. These facts combined lead to the conclusion that after an individual has reached a certain age, taking care of their children or grandchildren instead of birthing more offspring is more effective in propagating their own genes. Also, there is no one that can propagate massive amounts of wisdom and information to the next generation like the elderly.

In modern society, menopause has more significance than at any point in the history of human beings. As our average life span has surpassed 80 and heading towards 90, almost half of a woman’s life is post-menopause. In some ways, the grandmother hypothesis contains within it a certain philosophy regarding life. As we age, we give birth to children and raise them until they become independent, at which point we escape our basic biological duty of reproducing to lead our “own” lives. Senescence is like a second spring after one’s “biological” life. It is the start to a new life – a more “human” life of your own where you can focus on seeking pure happiness.

Posted in Science & Nature

Complementary Colours

Posted on by Jinavie

Red, green, blue, white… There are many colours that we can see and there are even more different combinations of colours possible. It is common knowledge that some colours clash with each other while some synergise very well. A common example of a “good combination” is when you use complementary colours. Complementary colours are two colours that oppose each other on the colour wheel, creating an effect where they brighten each other. This makes it very eye-catching and attracts people’s attention. For example, blue and orange make a bright contrast making them a popular colour choice for movie posters. Red and green, and yellow and purple are also examples of complementary colours. Complementary colours are an important concept in art and design as it helps the product stand out.

Complementary colours have an interesting relationship with our sense of sight. If you stare at a colour for a while then quickly look at a blank, white surface, you will see an afterimage of the complementary colour. A good example is when you have your eyes closed under bright sunshine and upon opening your eyes the world seems a blue hue (the blood vessels in your eyelid make the light appear orange as it reaches your eyes). This is because the retinas try to negate the intense colour by downregulating the nervous signals corresponding to that colour, which makes the complementary colour stand out. Furthermore, the photoreceptors in the retina become fatigued after stimulation, causing a reduction in the signals sent for that colour.

Knowing about complementary colours is very useful when designing a sign or poster that easily attracts people.

(Image source: http://bonka-chan.deviantart.com/art/Color-Wheel-136855103?q=boost%3Apopular%20color%20wheel&qo=3)

Posted in History & Literature

Earworm

Posted on by Jinavie

Everyone experiences the phenomenon of a tune being “stuck” in one’s head. This is when an addictive song or piece of music seems to play over and over in someone’s mind even when they are desperately trying to forget it. The Germans call this phenomenon ohrwurm, which translates into “earworm”. 

Having an earworm is not necessarily a pleasant thing, as the person with it may become irritated or agitated by the piece of music. It has been noted that the condition is much more common in people with obsessive-compulsive disorder (OCD), suggesting that earworms may be caused by the brain subconsciously obsessing over the piece of music. 

Because it is so common and addictive, earworms are extensively used in marketing in the form of hooks – music designed to stick in people’s heads. By associating the hook with the marketed brand or product, people cannot stop thinking about it and this subconsciously affects their buying habits.

The concept of earworms is also popular in literature, where authors become creative and explore the “potential” of an earworm. For example, Arthur C. Clarke wrote a short story titled The Ultimate Melody where a scientist invents a melody that compels the brain to become enraptured by it through synchronising with brainwave patterns. Interestingly, the scientist creates the melody simply to escape the barrage of pop music filled with hooks and catchy tunes. Ultimately, he is found catatonic as the melody completely takes over his mind.

Posted in Psychology & Medicine

Pulse

Posted on by Jinavie

Blood, which supplies all the cells in the human body with nutrients and oxygen, flows through the vessels due to the pumping of the heart. Thus, blood flow directly transmits the force generated by every heartbeat. As the blood ejected by the heart causes the arteries to “pulse” by stretching and relaxing. As some pulses can be felt over the skin, they are very useful in patient examinations, especially a clinical exam of the cardiovascular system. Although people commonly know how to take a pulse from the wrist or neck, there are many more places a pulse can be taken from.

  • Radial pulse: Taken from the inside of the wrist on the side of the thumb.
  • Brachial pulse: Taken from the inside of the elbow.
  • Carotid pulse: Taken from where the neck meets the jawline, or 2~3cm either side of the Adam’s apple to be precise.
  • Apex beat: This measures the heartbeats directly, taken on the left chest between the 4th and 6th ribs (around the left nipple).
  • Abdominal pulse: Taken from above the belly button of a lying patient, may be able to see the pulse.
  • Femoral pulse: Taken from the middle of the groin. 
  • Popliteal pulse: Taken from the inside of the knee.
  • Posterior tibial pulse: Taken from the inside of the ankle behind the bone.
  • Dorsalis pedis pulse: Taken from the back (upper side) of the foot along the middle.

When taking a pulse, you use your second and third fingers (and the fourth if you want) and press lightly on the pulse point. If you press too hard, you may stop the blood flow and obliterate the pulse. As a pulse is measured per-minute, it is often taken for 10 or 15 seconds and multiplied by 6 or 4 respectively. Also, it should be noted whether the pulse has a regular rhythm, and if it is irregular, whether it is regularly irregular or irregularly irregular. If the pulse is over 100 beats per minute, it is called tachycardia, while less than 60 beats per minute is referred to as bradycardia. If it is irregular, it is called an arrhythmia.

An experienced doctor can diagnose different conditions such as an aortic stenosis or atrial fibrillation just from taking the pulse of the patient. Taking a pulse is also a crucial diagnostic tool in traditional Korean and Chinese medicine.

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Posted in Science & Nature

Umami

Posted on by Jinavie

Normally when people think of “tastes”, they think of sweet, salty, sour and bitter (“spicy”, or piquance is not a taste). However, in 1985 the family of four basic tastes were introduced to a new member: umami. Umami, commonly known as “savouriness” is a taste that has had its own word in Asian countries (e.g. 감칠맛, or gamchilmaht in Korean) for thousands of years but has not had a proper English word until very recently (much like piquance). Umami is a portmanteau of two Japanese words: うまい(umai) and 味(mi), which means “delicious” and “taste” respectively.

Sweetness comes from glucose, saltiness from sodium and sourness from acids. Then where does umami come from? Umami is the taste born from glutamates, which is found in high concentrations in meat products, thus leading to the association between umami and the taste of meat. For example, bacon is known to have six different types of umami flavours, creating a unique and addictive taste. Another product high in glutamate is monosodium glutamate, or MSG. MSG is essentially glutamate plus a sodium ion and thus brings out the full taste of umami when added to food. As umami has a powerful effect of boosting appetite and having a slightly addictive property means that chefs like putting MSG in foods to boost sales. Contrary to popular belief that MSG is detrimental to your health, recent researches have shown that unless you have an allergy to it, MSG is safe to consume even in high concentrations.

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