Answer:
Until recently, most neuroscientists thought we were born with all the neurons we were ever going to have. As children we might produce some new neurons to help build the pathways - called neural circuits - that act as information highways between different areas of the brain. But scientists believed that once a neural circuit was in place, adding any new neurons would disrupt the flow of information and disable the brain’s communication system.
In 1962, scientist Joseph Altman challenged this belief when he saw evidence of neurogenesis (the birth of neurons) in a region of the adult rat brain called the hippocampus. He later reported that newborn neurons migrated from their birthplace in the hippocampus to other parts of the brain. In 1979, another scientist, Michael Kaplan, confirmed Altman’s findings in the rat brain, and in 1983 he found neural precursor cells in the forebrain of an adult monkey.
These discoveries about neurogenesis in the adult brain were surprising to other researchers who didn’t think they could be true in humans. But in the early 1980s, a scientist trying to understand how birds learn to sing suggested that neuroscientists look again at neurogenesis in the adult brain and begin to see how it might make sense. In a series of experiments, Fernando Nottebohm and his research team showed that the numbers of neurons in the forebrains of male canaries dramatically increased during the mating season. This was the same time in which the birds had to learn new songs to attract females.
Why did these bird brains add neurons at such a critical time in learning? Nottebohm believed it was because fresh neurons helped store new song patterns within the neural circuits of the forebrain, the area of the brain that controls complex behaviors. These new neurons made learning possible. If birds made new neurons to help them remember and learn, Nottebohm thought the brains of mammals might too.
Other scientists believed these findings could not apply to mammals, but Elizabeth Gould later found evidence of newborn neurons in a distinct area of the brain in monkeys, and Fred Gage and Peter Eriksson showed that the adult human brain produced new neurons in a similar area.
For some neuroscientists, neurogenesis in the adult brain is still an unproven theory. But others think the evidence offers intriguing possibilities about the role of adult-generated neurons in learning and memory.
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The answer is: 'constrict the blood vessels in their large ears to reduce transfer of external heat to the blood in their ears.' This is an example of thermoregulation. Thermoregulation is the ability of the<span> </span>body to keep body temperature<span> within certain boundaries, even when the temperature of the surrounding environment is very different. The regulation of temperature by thermoregulating organisms is one aspect of </span>homeostasis. By using heat exchange systems, such as employed in this example, the animal will need to expend less energy on behavioural adaptations to maintain a constant body temperature.
<span>A cell with a large surface area or with microvilli (which increase surface area) are specialized for absorption. Many cells have different protein markers on their surface to accept certain specific hormones and allow them into the cell, like muscle cells reacting to adrenaline. Muscle cells are long and able to contract, allowing for overall muscle contraction and body movement. </span>
<span>I guess the hormone part I mentioned applies to chemicals; endocrine cells produce hormones that other cells would not. </span>
<span>For organelles, muscle cells don't have many of the organelles that other cells do because of their very specialized functions. </span>
<span>I hope this helps, it would literally take volumes of text books to answer this question completely.</span>
Possesses the characteristic of compartmentalization of organelles,wherein the organelles are bound by membranes
Answer:
<h2>An activated B cell divides into cells that give rise to memory B cells and plasma cells.</h2>
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