Posted in Psychology & Medicine

Belladonna

The belladonna flower has a name that means “beautiful lady” in Italian. However, its other common name has a completely different meaning – the deadly nightshade. Both names can be explained by the uses of the flower throughout history. The deadly nightshade (Atropa belladonna) is a small shrub with purple bell-shaped flowers and shiny black berries. All parts of the plant contain various toxins such as atropine, scopolamine and hyoscyamine. These alkaloid toxins are included in a group of chemicals called anticholinergics, because they act on cholinergic receptors on neurons, which are involved in activating the parasympathetic nervous system. As cholinergic receptors are widely utilised throughout the body, anticholinergic toxicity causes a wide range of symptoms.

image

The main symptoms of anticholinergic toxicity are best remembered using the following mnemonic:

  • Hot as a hare (increased temperature – reduced temperature regulation)
  • Blind as a bat (blurred vision – dilated pupils)
  • Dry as a bone (dry skin, eyes and mouth – decreased secretions)
  • Red as a beet (flushing – dilation of blood vessels)
  • Mad as a hatter (hallucinations and agitation – neurological interaction)

The name deadly nightshade is obvious as severe toxicity leads to seizures, coma and death. The reason why the deadly nightshade is also called belladonna is that the diluted extract from the plant was used as an eye drop to dilate women’s pupils – a look considered beautiful then (nowadays the effect is used to examine the eye). The toxins extracted are used in other fields of medicine too. Although not used now, anticholinergics were used as an anaesthetic for surgery due to its neuropsychiatric effects. However, atropine is still used in the emergency setting to reverse bradycardia (excessively slow heart rate), as anticholinergics speed up the heart rate. This highlights the fundamental principle of medicine that “the dose makes the poison”. For the only difference between medicine and poison is the dose… and intent (Oscar G. Hernandez, MD).

image

Posted in Science & Nature

Honeybee Dance

How do honeybees share the location of a food source, such as a flower, to other bees of their colony? An Austrian biologist named Karl Von Frisch devised an experiment to learn how the honeybees communicated with each other. He set up two different food sources and tagged every bee that came to pot A green and bees that came to pot B red. He then studied the behaviour of these bees back at the hive. What he discovered was fascinating.

For millennia, beekeepers have noticed that some honeybees have a tendency of moving in a peculiar yet methodical way once they returned to their hive after foraging for flowers. The bees would move in a straight line while waggling their bottom (moving side-to-side), then walk in a semicircle back to where they started. They would then waggle in the same direction, then move in a semicircle on the opposite side, completing a figure-eight path. This is called a waggle dance.

image

Frisch noticed that bees with green spots and the bees with red spots both did the waggle dance once they returned to the hive, but in different directions. All bees with green spots danced so that the straight line pointed a certain direction, while the bees with red spots danced the same dance except pointing another direction. Amazingly, the angle between these two directions was exactly the same as the angle separating pot A and B (with the hive as a point of origin). Frisch deduced that the waggle dance was the language of honeybees.

Through further experimentation, Frisch was able to tease out the details of this “language”.

  • Honeybees’ eyes can see ultraviolet and polarised light, which allows them to see where the sun is in the sky at all times. This is because sunlight polarises so that it points towards the sun and honeybees can see this direction. Therefore, the bee’s eyes act as a solar compass that tracks the exact location of the sun in real-time.
  • Bees have a finely-tuned internal clock that allows them to predict exactly where the sun should be depending on time, season and latitude, as the sun moves through the sky.
  • Another point of reference that is used in the bees’ language is gravity. Gravity is a constant that does not change, meaning all bees know which direction is “up” and which is “down”. This also means they can use a vertical, perpendicular line as a standard zero-point.

By pairing the two global constants, gravity and the location of the sun, the bees can accurately signal to other bees the direction they should fly in to find the food source. If a bee does a waggle dance that points 60° right from the vertical “up” direction (as defined by gravity), it signals that the bees should fly 60° right from the direction of the sun. If the angle is 0°, the bees should fly directly towards the sun, and if the angle is 180°, the bees should fly directly away from the sun. The bees use their internal clock to calibrate the direction depending on the time of the day.

The straight line “waggle” part of the dance gives the information of distance. The longer the duration of the straight line, the further away the flower is. As a general rule of thumb, the duration of the straight line increases by 1 second for every 1 kilometre. When the food is within about 60m of the hive, the 8-shape waggle dance turns into an O-shape round dance. The bee deduces the distance by the energy required to fly to the location.

By encoding the two variables “direction” and “distance”, a bee can effectively use the waggle dance to accurately pinpoint the location of a food source. It is amazing to see that animals that we consider “primitive” such as bees have such an intricate method of communication.

image

(Image source: http://aireona93.deviantart.com/art/YAY-Waggle-Dance-146361214?q=boost%3Apopular%20waggle%20dance&qo=1)

Posted in History & Literature

Flower Language

Roses are the most common flowers used in modern society to profess one’s love. However, many people do not know the true meaning behind each flower. For example, every colour has a different meaning for roses.

  • Red rose: true love, passion
  • White rose: eternal love, innocence
  • Black rose: death, farewell
  • Yellow rose: friendship, jealousy, betrayal
  • Pink rose: grace, gratitude, youth
  • Mix of red and white roses: unity

As seen from above, a rose can mean love, friendship or even separation. It is also important to note that roses are traditionally given as a bouquet of one, six, dozen or any multiple of six. 
The following is a list of common flowers and what they symbolise:

  • Acacia: secret love
  • Bellflower: thinking of you
  • Cherry blossoms: beautiful mind, purity
  • Chrysanthemum: peace, love, mourning (used in funerals)
  • Cosmos: forever, devotion
  • Daffodil: Chivalry, respect, unrequited love
  • Daisies: innocence, modesty, beauty
  • Edelweiss: memories of an important person
  • Hibiscus: rare beauty
  • Lavender: silence, devotion
  • Lilac: memories of youth, first love
  • Lily: innocence, chastity, purity
  • Magnolia: unrequited love
  • Pansies: memories of love
  • Sunflower: happiness
  • Tulip: declaration of love (red), hopeless love (yellow), broken heart (white)
  • Violet: faithfulness