What is the life of a hair cell? What does it do in its time? Does it have close relatives?
819440
The growth of human hair\n\nEach human head carries roughly 100,000 hair follicles. \nEach follicle can grow many hairs over a lifetime: on average, each grows a new hair around twenty times. \nNot all these follicles are actively growing hairs at any one time. From the moment when it is first formed, each follicle undergoes repeated cycles of active growth and rest. The length of the cycle varies with the individual, and also with the part of the body on which the hair is growing. \nThe hairs on an adult scalp do not grow in unison, as they do in an unborn baby. They are 'out of cycle' with each other. If this were not so, everyone would go temporarily bald from time to time. \nThe growing and shedding of hair as a whole seems to happen at random, but for each hair follicle the process is precisely controlled. No one knows for certain, however, exactly how the body controls these cycles. \nPlucking a hair from a follicle brings forward the next period of hair growth in that follicle\nOver the years, the number of follicles capable of growing hair declines naturally. The decline is especially noticeable on the top of the head. Some follicles increasingly produce only fine, short non-pigmented hairs that look more like vellus hairs than terminal hairs. In older women, this leads to a general thinning of hair. In men it tends to lead to common baldness. If you look at a bald scalp you will see these fine, poorly pigmented hairs.
901324
check out this link \n\nhttp://en.wikipedia.org/wiki/Cell_biology#Notable_cell_biologists
742185
The dermal papillae would be akin to the root or the progenitor to the hair.  The cells of the dermal papillae control development, differentiation and cycling of the hair follicles
783710
Mouse.... animal.... right.\n\nThat is to say the aspects which make them part of the Kingdom Animalia...\n\nSimple:\n#1. They're eukaryotic. That is to say for the most part they're multicellular, and have a cell structure including mitochondria, a complete genome and organelles.\n#2. They're heterotrophic. They derive energy from outside sources, rather than making their own as plants and fungi do.\n#3. No cell walls... just cell membrane holding the cell contents in. Obviously none of the required organelles used by autotrophic life either, since as previously mentioned they're heterotrophic.\n\n\nThats the basic answer for you.\nAny further characteristics of mice will not be shared by ALL members of Animalia.... in some cases merely most (such as differentiated tissues) and in some cases not many at all (whiskers, for instance).
969513
Early embryonic cells are meristematic ("stem") and not specialized to do anything in particular. As the embryo develops these cells specialize to perform various specific or specialized functions. Examples: Muscle cells-contraction/movement ; nerve cells-carry impulses ; epidermal cells-covering ; gland cells-secretions, etc.\n  There are several theories as to how these unspecialized cells specialize (or differentiate).
879073
http://www.biotopics.co.uk/life/7chars.html
779752
A living cell (like a cell from the liver, lungs, brain, etc...) will die soon after it was removed from its original "place" (liver, lungs, brain, etc.) as it has no more nutrients-supply (by blood venes, for example!) except it is kept in an artificial environment, a culture medium, which is suited to it's very specific needs.\n\nA living cell that is an organism needs a special suited environment, too (a diatom won't survive in the desert...). But it is not depending on an EXTERNAL supply of nutrients, as it "searches" its nutrients on its own. Bacteria, for example, don't need blood venes to grow in order to make cell division, they just need an environment which supplies all the needed nutrients. That's why bacteria can grow nearly everywhere, while lung cells  would die short after you dispersed them on an old dank sponge.\n\nHope I helped you. Excuse my English, please, it's not my first language. Good luck for tomorrow! ;-)
281677
store information about the cell. its mostly hereditary.
162063
the end of a cell. It is used for locomotion of the cell
55416
read these sites they provide helpful information :\nhttp://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/hair.html\nhttp://dermatology.about.com/cs/hairanatomy/a/hairbiology.htm\nhttp://www.aad.org/professionals/Residents/MedStudCoreCurr/DCHairFollicles.htm\n\nGood luck
183338
Progenitor cells have the choice of becoming a neuron, and in some cases what kind of neuron.  A stem cell is generally a cell which can become any other cell-it may be found in the brain, but may have the option of becoming either a neuron or a glial cell.  In other words, progenitor cells are considered already partially on the road to specialization, while stem cells have a greater degree of freedom.
356064
A single cell from a snail is orders of magnitude more complex than the shuttle.  An easy way to think of it:  If we had never seen a shuttle before, but we were at the same level of technology we are now, how long would it take to figure out how the shuttle worked, and to reverse engineer an identical shuttle?  Now, ask the same question for a snail- We dont understand all the ins and outs of a cell yet, let along an entire animal...we can't even produce a bacteria, which is 1% the complexity of a eukaryotic cell.
885455
G'day Joanne F,\n\nThank you for your question.\n\nIt is essential if you are studying medicine to have a good understanding of how cells and tissues work. It is also useful to know how particular cells such as blood cells work.\n\nRegards
219439
There is debate about whether neural stem cells, or other types of adult stem cells exist. When talking about adult stem cells, it's important to define what a stem cell is. Cells can be totipotent, pluripotent, or multipotent.\n\nCells that are totipotent are capable of growing into a complete organism and can contribute to all tissues, including placenta. Cells that are pluripotent can contribute to all tissues, but cannot form placenta, and thus cannot form a complete organism. Cells that are multipotent can become more than one type of cell, but are already committed to a certain type of fate. An example would be a bone marrow stem cell that can become any of the types of blood cells, but can't become anything else.\n\nSome research has suggested that some multipotent cells can reverse their fate restrictions and become more types of cells. This is still very controversial and it may or may not actually happen. Something to keep in mind is that this is similar to what cancer cells do. Adult stem cells may have some strong similarities to cancer forming cells.\n\nEmbryonic stem cells remain the most viable scientific choice for therapeutics.
345920
It divides by mitosis then it begin to grow.According to which type of cell your referring to.That's what I think.
19843
YOU WILL LOVE THIS SITE.\nIT IS INTERACTIVE, ANIMATED & SOOO FULL OF KNOWLEDGE.\nTRUST ME!\nhttp://www.mhhe.com/biosci/esp/2002_general/Esp/default.htm
414049
The presence of two types of hair cells, the inner and outer hair cells, in the organ of Corti was appreciated nearly a 100 years ago but the function of the two has only become clear in the last 20 years. The first clue that they might play different roles in hearing came about 40 years ago as the result of a painstaking anatomical investigation which revealed that most of the nerve fibers that carry information to the brain contact only the inner hair cells. This meant that most the information about the acoustic world reached the brain via the inner hair cells. What then was the role of outer hair cells which are over three times more numerous? The mystery was compounded by the discovery that neural fibers originating from neurons deep in the brain, which send information back to the hair cells, only touch outer hair cells. It was later determined that outer hair cell stereocilia are firmly embedded in the overlying tectorial membrane while inner hair cell sterocilia make only a tenuous connection. The outer hair cells are located near the center of the basilar membrane where vibrations will be greatest while the basilar membrane is anchored under the inner hair cells (see Figure 5). These observations suggest that the movement of stereocilia and the resulting modulation of their ionic currents is likely to be greater for outer hair cells than for inner hair cells. Several studies that had examined the inner ears of deaf people shortly after they died demonstrated that outer hair cells were required for hearing. It was clear that the inner hair cells served to transmit information to the brain but the role of the outer hair cells remained a mystery. \n\nThe mechanical vibrations of the organ of Corti had been analyzed by engineers since the 1940s. Their analysis was able to explain the frequency selectivity originally measured by von Bekesy in cochlea obtained from cadaver ears. It was known at the time that the measured frequency selectivity and the frequency selectivity computed from the engineering analysis did not approach the frequency selectivity of the human hearing or the frequency selectivity that could be measured from individual nerve fibers. Shortly after WW2 an American astrophysicist who had worked on radar during the war suggested that the frequency selectivity of the cochlea could be enhanced if a source of mechanical energy were present in the cochlea. His suggestion was largely ignored until several engineering groups in the late 70s rediscovered the potential benefits of this hypothetical energy source. They were forced to consider the possible existence of this "cochlear amplifier" when improved measures from living (as opposed to dead) ears revealed that the mechanical frequency selectivity in the living ear began to approach that of human hearing. The concept that a source of mechanical energy exists in the cochlea appeared validated when in the late 70s it was discovered that sound is produced by the inner ear. These sounds can be measured by placing a sensitive microphone in the ear canal. They were called otoacoustic emissions and they are now routinely measured in the clinic to assess hearing. Their discovery was amazing for sensory physiology because it was equivalent to finding that light comes out of the eye (which has never been observed). Within five years it was discovered that the outer hair cell could be made to elongate and shorten by electrical stimulation. The function of the outer hair cell in hearing is now perceived as that of a cochlear amplifier that refines the sensitivity and frequency selectivity of the mechanical vibrations of the cochlea.