Thursday, 24 November 2016

How eyes work

Light enters our eyes. Light from the sun, or an artificial light, travels in a straight line, bounces off objects and into our eyes through the pupil. Depending on the amount of light, the iris changes the size of the pupil to let more or less light in. The images we see are made up of light reflected from the objects we look at. This light enters the eye through the cornea. Because this part of the eye is curved, it bends the light, creating an upside down image on the retina (this is eventually put the right way up by the brain). The retina is a complex part of the eye, but only the very back of it is light sensitive. This part of the retina has roughly the area of a 10p coin, and is packed with photosensitive cells called rods and cones. Cones are the cells responsible for daylight vision. There are three kinds – each responding to a different wavelength of light: red, green and blue. The cones allow us to see images in colour and detail. Rods are responsible for night vision. They are sensitive to light but not to colour. In darkness, the cones do not function at all.

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Sunday, 13 November 2016

A brief history of prosthetics

I am a makeup student at University and part of my course is called 'Anatomy and physiology' for this part of the course I have to do 15 (although not limited too) blog posts a year about you guessed it, anatomy and physiology.

Today's topic, or more correctly my first topic, is a very brief history of prosthetics. This is a fly by general overview of prosthetics from ancient times to more modern times.

Firstly it's important to understand a prosthetic before we talk about their history. The word prosthetic comes from the Ancient Greek word 'prosthesis' and means 'In addition' meaning things added. Therefore a prosthetic is an artificial body part that is added onto/into the body. So let's get started on the history shall we?

BC (Before Christ)
During this time Limbs were more often that not a luxury only wealthy could afford. One of the oldest prosthetics that has been recovered and kept preserved is a toe from a female noble woman buried near Luxor, Egypt. The toe is made of wood with leather bounding to connect the toe to the foot, it is believed to be made before 600BC although no date is exact. In the times of the Ancient Greeks a roman general by the name of Marcus Sergius, lost his right hand in the Punic War of 264BC and had a metal 'limb' for the purpose of holding his shield however it didn't serve much purpose in everyday life. Being a general he was wealthy enough to be able to afford a normal daily limb however the poor had crude often homemade 'limbs'.

The dark ages 450-1000 AD (Anno-Domini)
It can be said prosthetics took a step back as did most of life's advancements during this time. Prosthetics went from being decorative and have purpose during ancient Roman, Greek and Egyptian times. To being very simple often wooden peg legs or arms and these were for the wealthy. The poor could have prosthetics during this time but only if it was absolutely necessary and they were in battle such as a wooden limb with a mounting hook to hold a shield. However this wasn't very often for the poor, it was mainly the best fighters such as knights who got 'war prosthetics' most who lost limbs die from infection or became beggars unable to function in daily life.

The Renaissance 1400-1800 AD (Anno-Domini)
The Renaissance was a time period of great education everything from Arts to sciences. Medicine and arts being most popular combinations. Many artists studied the body in great detail therefore a new body understanding mixed with the desire to create new things lead to a great rebirth and advance of prosthetics. Prostheses during this period were made from strong materials such as; wood, copper, iron and steel. A german sell sword Gotz Von Berlichingen had an iron fashioned from iron in 1512AD after loosing his arm due to canon fire in a 1508 battle. Gotz arm had joints that moved separately thanks to inner springs. Although the movements were not entirely in sync with him this was an amazing advance for the time compared to the peg arms of the dark ages. Barber surgeon Ambroise Pare is said to be the father of amputation surgery, he made prostheses for upper and lower amputees in 1532. He invented a peg leg that could kneel with a foot that was for the more average person. The bending leg was fixed in place with an adjustable harness with hinges on the knee complete with lock control to allow the knee bend.

17th-19th Century
This was a time of not exactly advancement from the Renaissance more a time of fine tuning prosthetics making them more sleek and visually pleasing. As well as more available for the common man although many a common man still had no access to them, although attempts were made to made the prosthetics cheaper. Benajamin Palmer 1846 decided to fill in the large gaps in prosthetic limbs in particular a limb type called the 'Selpho leg' with springs or extra material to give the overall look a smoother sleeker appearance. In 1858 Douglas Bly invented a patented leg which was anatomically correct, he was quoted as saying that this limb was "The most complete and successful invention ever attained in artificial limbs."

In 1863, Dubois Parmlee invented an advanced prosthesis with a suction socket, polycentric knee and multi-articulated foot. Later, Gustav Hermann suggested in 1868 the use of aluminum instead of steel to make artificial limbs lighter and more functional. However, the lighter device would have to wait until 1912, when Marcel Desoutter, a famous English aviator, lost his leg in an airplane accident, and made the first aluminum prosthesis with the help of his brother Charles, an engineer.


I have really enjoyed doing anatomy and physiology in the form of blogs, I feel it has given me something to do peacefully at home following...