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Showing posts with the label mammals

MYSTERIOUS DISCOVERY IN THE EYES

                                              Scientists have long known that the eyes of mammals contain neurons that respond to light and set the body’s internal, or circadian, clock. It was long assumed that this light-sensing function was performed by known visual cells called rods and cones. But in 1999, report the journal Science, researchers found that “mutant mice lacking all rods and cones [who are thus functionally blind] still have light-responsive clocks.” This led researchers to the conclusion that “some other cells in the eye had to be sensing light”            Now these elusive light sensors have been found. Although intermingled with the image-forming rods and cones, the sensors form “a separate visual circuit, running in parallel with this image-forming visual system,” explains Science. The newly discovered circuit’s functions include governing pupil size and melatonin release, synchronizing the body’s internal clock with the cycle of light and dark and other

AMAZING BIOLOGICAL STRUCTURES

                                     [1] THE BLUBBER OF MARINE MAMMALS          For decades, scientists could not understand how dolphins could swim at the speed of nearly 40 kilometers an hour. The animals simply did not have enough muscle, the scientists thought. But dolphins have a secret, part of which lies in their blubber, a complex substance also found under the skin of porpoises, whales, and other marine animals           Blubber is a thick, dense layer of highly organized connective tissue with a lot of fat cells. It covers practically the whole creature, and it is strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligament. These networks, in turns, are composed of elastic fibers and collagen, a protein that is also found in skin and bones. Blubber, therefore, is much more than a layer of insulating fat. It is a highly sophisticated combination of various living tissues.         How, though, does blubber hel

MYSTERIOUS DISCOVERY IN THE EYES

            Scientists have long known that the eyes of mammals contain neurons that respond to light and set the body’s internal, or circadian, clock. It was long assumed that this light-sensing function was performed by known visual cells called rods and cones. But in 1999, report the journal Science, researchers found that “mutant mice lacking all rods and cones [who are thus functionally blind] still have light-responsive clocks.” This led researchers to the conclusion that “some other cells in the eye had to be sensing light”            Now these elusive light sensors have been found. Although intermingled with the image-forming rods and cones, the sensors form “a separate visual circuit, running in parallel with this image-forming visual system,” explains Science. The newly discovered circuit’s functions include governing pupil size and melatonin release, synchronizing the body’s internal clock with the cycle of light and dark and other tasks. It may even play a role in