Enjoy Your Body Gifts
Posted on September 29, 2011.
When you eat right and exercise to do your body good, you may have little idea how much your body is giving back all the time. From recent scientific discoveries, here’s a look at a few mechanisms under our skin that not only keep us alive, but provide us with a shopping mall of good things.
Shock absorbers: Without tendons we could not handle a basketball game or even the stresses of ordinary activity. Science Daily reported on work at Brown University about how our limbs respond to sudden stresses. “Experiments showed that tendons absorb the initial burst of energy from impact before the leg muscles react,” the article said, based on work they did with turkeys, which have similar tendon-muscle groups as we do. “The tendons act as shock absorbers, protecting the leg muscle from damage at the moment of impact.”
An illustration accompanying the article shows a turkey coming in for a landing. The tendons first provide a “fast stretch” like coiled springs before the muscles absorb the blow. Then as the muscles do their part about a tenth of a second later, the tendons continue with a “slow stretch,” shunting the energy they absorbed to the muscles. The result is a soft landing that would otherwise cause serious damage. “It is becoming increasingly apparent that springy tendons are a big part of what makes us go,” said one of the Brown University biologists. The article stated that “The research may cross into biomimetics, used to make two-legged robot locomotion more similar to human locomotion, for example. It could even help in athletic training.” Another biologist gave us reason for thanks: “We can say that in real ways, the muscle has a safety net with the tendon there and protecting it.”
Colon police: We rely on microbes to help us digest our food, but there are good guys and bad guys in our inner subway tunnels. Fortunately, we have agents patrolling the corridors and checking their credentials. Live Science reported on work at the Washington University Medical School in St. Louis. The researchers hypothesize that a special population of white blood cells called Treg cells learns how to tell the good guys from the bad. If future work bears this out, it may become possible to help patients with autoimmune disorders by re-training cells to recognize and tolerate “self”.
Ear amplifiers: The motor protein prestin (2/21/2002, 2/13/2008) in the cochlea is part of an elaborate amplification system that lets us enjoy all the nuances of music. Sound pressure waves can be extremely faint, even after the eardrum and ossicles do their part to amplify them. Inside the cochlea, further amplification is needed. To get a feeling of how astonishing the mechanisms are inside those coiled organs inside your head, try to follow this abstract by Weddell et al. from Current Biology:1 (see footnote for glossary of terms):
The sensory hair cells of amniote hearing organs are usually distributed in tonotopic array from low to high frequencies and are very sensitively and sharply tuned to acoustic stimulation. Frequency tuning and tonotopicity of non-mammalian auditory hair cells is due largely to intrinsic properties of the hair cells , but frequency tuning and tonotopic organisation of the mammalian cochlea has an extrinsic basis in the basilar membrane (BM); a spiralling ribbon of collagen-rich extracellular matrix that decreases in stiffness from the high-frequency base of the cochlea to the low-frequency apex. Sensitive frequency tuning is due to amplification, which specifically boosts low-level input to the mechanosensitive hair cells at their tonotopic location to overcome viscous damping…. In the mammalian cochlea, amplification is the remit of the sensory-motor outer hair cells (OHCs), located within the organ of Corti to exercise maximum mechanical effect on the motion of the BM and transmit cochlear responses to the adjacent sensory inner hair cells (IHCs) and, consequently, to the auditory nerve (Figure 1A). OHCs behave like piezoelectric actuators, developing forces along their long axis in response to changes in membrane potential. These forces are due to voltage-dependent conformational changes in the motor molecule prestin, which is densely distributed in the OHC lateral membranes.
Remember that when you listen to your favorite music. The authors did not mention evolution except to speculate briefly in the last paragraph:
We conclude that prestin evolved in the mammalian cochlea to provide the basis for the amplified, impedance-matching mechanical link that enabled the OHCs of the organ of Corti to devolve responsibility for frequency tuning to the potentially enormous frequency range of the graded mechanical properties of the BM. In this scenario, prestin provides the rapid, voltage-dependent conformational changes that amplify and closely couple the movements of the BM to those of the OHCs, as part of a mechanosensory feedback loop, and the essential mechanical link between the movements of the BM and the excitatory shear of the IHCs. Prestin is therefore the key molecular element that has enabled the organ of Corti of the mammalian cochlea to exploit a mechanically-tuned extracellular matrix to provide mammals with the enormous apparent benefit of being able to listen to frequencies way beyond the auditory ranges of other amniotes.
Of codes and clocks: Caregivers who have to help seniors who have lost their sense of time know that we should never take our biological clock for granted. Our Sept. 9 entry discussed some of the mechanisms behind the body’s internal clock. Now, a new paper in Science links the clock to a code – the “histone code,” an epigenetic mechanism that regulates how genes are expressed.2 Steven Brown wrote that “the circadian clock that governs diurnal rhythms of physiology and behavior uses this histone code extensively. But how?” Evaluating research in a paper by DiTacchio in the same issue of Science,3 Brown was not quite ready to show a linkage to the histone code, but said another code may be waiting in the wings: “Perhaps circadian clock researchers are on the verge of discovering their own ‘nonhistone code.’”
Poison protection: Your body has mechanisms to protect you from low levels of carbon monoxide poisoning (PhysOrg). Normally, CO binds to haemoproteins readily, but when a haemoprotein senses carbon monoxide’s presence, “it changes its structure through a burst of energy and the carbon monoxide molecule struggles to bind with it at these low concentrations.” A researcher at the University of Manchester remarked, “This mechanism of linking the CO binding process to a highly unfavourable energetic change in the haemprotein's structure provides an elegant means by which organisms avoid being poisoned by carbon monoxide derived from natural metabolic processes.”
Cleanup crew: As a baby develops in the womb, and the stem cells differentiate into tissues and organs, a lot of cleanup is required. PhysOrg reported that “The body rids itself of damage when it really matters.” Not only are there molecular machines called proteasomes to clean up damaged proteins, there are other mechanisms to rejuvenate cells from inherited damage and give them a fresh start. A researcher at the University of Gothenburg said, “Quite unexpectedly we found that the level of protein damage was relatively high in the embryo’s unspecified cells, but then it decreased dramatically. A few days after the onset of cell differentiation, the protein damage level had gone down by 80-90 percent. We think this is a result of the damaged material being broken down” by these mechanisms.
Cool yawns: Why do we yawn? Surprisingly little research has been done to understand this common bodily action. Medical Xpress reported on research that yawning helps cool the brain. “The cooling effect of yawning is thought to result from enhanced blood flow to the brain caused by stretching of the jaw, as well as countercurrent heat exchange with the ambient air that accompanies the deep inhalation.” Whether this is true remains to be seen; at least the research avoided this year’s IgNobel Prize. At least now you at least have a story to tell at the water cooler, or an excuse to give your boss in the staff meeting.
1.Weddell et al., “Prestin links extrinsic tuning to neural excitation in the mammalian cochlea,” Current Biology Volume 21, Issue 18, R682-R683, 27 September 2011. Glossary: amniotes: egg-bearing animals. tonotopic: relating tone to location. viscous damping: the tendency for vibrations to lose energy in fluid. piezoelectric: producing an electric charge upon stimulation or compression.
2.Steven A. Brown, “Circadian Rhythms: A New Histone Code for Clocks?” Science, September 2011: Vol. 333 no. 6051 pp. 1833-1834, DOI: 10.1126/science.1212842.
3.DiTacchio et al., “Histone Lysine Demethylase JARID1a Activates CLOCK-BMAL1 and Influences the Circadian Clock,” Science 30 September 2011: Vol. 333 no. 6051 pp. 1881-1885, DOI: 10.1126/science.1206022.
For each of these wonders of the human body and countless others, evolutionists are challenged with explaining how undirected, purposeless, unguided, uncaring processes based on randomness produced them. Saying “it evolved” like the ear guys said above is just lazy (see cartoon by Brett Miller). Nothing in evolutionary theory “evolved to” do anything. That’s the language of teleonomy that Darwin wished to vanquish from biology. The fact is, our organs and tissues and cells do work for purposeful functions. Even talking about it has the purpose of trying to understand them. That presupposes that purpose and understanding are real. If evolutionists were consistent, they would just yawn and grab a banana. For the rest of us, enjoy and take care of your amazing gifts from your Maker.