Continuing on our odyssey through the human body, we are now ready to discuss tissues and organs, having dealt with the plucky little cells last month.
Bridging the gap between cells and larger structures in the body, this study reports insight into limb formation in growing embryos. It shows that certain molecules, called FGFs, form on the ends of the limb buds of the embryo. These molecules serve to guide the growth of new cells along the future length of the bone. The genes that control this growth, as well as the involved molecules themselves are similar to ones that are involved in the regeneration of the limbs of amphibians. This is significant because the healing of wounds in adults uses the same molecular tools as the growth of the limbs in embryos; thus if these three phenomena could be linked, it may lead to a new range of treatments for lost limbs.
Now on to muscles and organs of circulation:
This article details how the muscles interact with the circulatory system to increase blood flow when needed. The key to this interaction lies in the ‘Extracellular Matrix’ or ECM, which is a structure of proteins that exists between all body cells. Once thought to be a mere liner or glue that holds the cells together, scientists have found that the ECM is a key carrier of signals. This signal is neither chemical nor electrical, but purely mechanical: the flexing muscle changes the shape of the protein matrix, which causes a the dilation of nearby blood vessels, increasing blood flow.
This is of interest to the researchers because they have also identified a chemical which duplicates the effect, which may lead to treatments for poor circulation, but is also of broader interest, because it shows another avenue for information to be carried between cells and organs, in addition to nerve signals and chemical means.
Human’s ability to smell odors has long been thought to be one of our weakest senses. However, scientists have long wondered why, seeing as we don’t seem to have significantly impaired smelling equipment relative to other mammals. This study seems to give some explanation; our sense of smell is not highly developed because we lack incentive to use it to its fullest.
The scientists took two similar odors, described as ‘grassy’, and exposed the test subjects to them. The subjects were unable to distinguish them at first, but acquired the ability to tell one from the other when it was accompanied by electric shocks. This ability was retained after the shocks stopped. So it is clear that the human sense of smell can be trained if there are the right incentives to do so.
Speaking of the nose and sinus, it’s for more than just smelling; it also acts as an early warning for the immune system. Viruses and other pathogens are detected in the sinuses, and this leads to a faster response by antibodies.
Unfortunately, this benefit comes with side effects. The immune system’s response can lead to inflammation of the nasal passages, runny nose, headaches, difficulty breathing, etc. Indeed, asthma and allergies are considered to be the result of the body’s overreaction to non-dangerous stimuli. This article describes how scientists are working on combating the side effects of this process, while not interfering with the desirable immune system response.
Speaking of inflammation of the breathing apparatus, there has been much written in recent years about the enormous increase in children diagnosed with asthma. And here’s another one! This one talks about a correlation that has been found between density of trees in the immediate vicinity, and a lower rate of childhood asthma cases. The exact cause has not been determined. Mostly, it seems that increased exposure to pollens reduce immune system overreaction.
Judging from these articles, the greatest threat to human health is the human immune system. That isn’t true, but check out this article, that explores the role of White Blood Cells with the spread of cancer throughout the body (Metastasis).
Cancer cells can fuse with White Blood Cells, exploiting the latter’s ability to move throughout the body via the blood stream and penetrate other tissues. As with most things in the body, you have to take the good with the bad.
To round out the month, here are some random articles:
This one has a study that shows a link between stomach size during middle age and risk of dementia in old age. Note; this link is for abdominal size, NOT total body fat. The theory is that fat in close proximity to the bodies organs, as is abdominal fat, causes a greater flow of toxins into the bloodstream, which effects the brain.
Here’s one I thought was interesting enough to include, even though it’s not strictly a ‘human’ organ issue. Desert gazelles can actually shrink their livers and hearts during dry spells. This reduces overall metabolic activity, resulting in reduced needs for food, water, and (less importantly) oxygen.
And lastly, here’s a stride in improving the diagnosis of intestinal disorder that is sure to improve people’s health while making them feel uncomfortable; a robot that crawls through the colon under its own power, and searches for malignant polyps and Sarah Connor.
So, after three months or so of human body science, I think I’m ready to move on to a different topic, at least until some more news builds up. So, don’t miss next month’s edition which will focus on High Energy Physics, with a special interest in Particle Colliders.