The ability to culture stem cells<span> has </span>important <span>implications, as they contain all of the genetic material needed for the formation of every </span>cell<span> type within the body. :)</span>
Tryptophan self-controls its synthesis. If we have a large amount of tryptophan in the sense that it exceeds, tryptophan would act as a co-repressor which prevents synthesis of more enzymes for its production. Hope this answers the question.
Answer:
True
Explanation:
Some deviations from normal homeostasis activate the positive feedback loops to control the conditions which are otherwise regulated by negative feedback mechanisms.
For example, the blood levels of respiratory gases and H+ ions are regulated by a negative feedback system via chemoreceptors. The increased partial pressure of carbon dioxide gas and lowered pH or lowered partial pressure of oxygen in the blood are sense by central and peripheral chemoreceptors which in turn activate the neurons of the dorsal respiratory group (DRG).
The activated DRG triggers an increased in the rate and depth of the breathing to facilitate the inhalation of more oxygen and exhalation of CO2 to restore the normal levels.
However, hypocapnia inactivates the chemoreceptors and does not allow negative feedback to restore the normal CO2 levels in the blood.
Under such conditions, the positive feedback loop stimulates the DRG neurons more strongly in response to the increased partial pressure of CO2 above the normal levels than when the partial pressure of oxygen falls below the normal level. These dangerously lowered oxygen levels may also cause fainting.
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A neurotransmitter can have an excitatory or inhibitory effect on the postsynaptic cell, depending on <u>which of its </u><u>receptor(s</u><u>) are present on the </u><u>postsynaptic</u><u> (target) cell.</u>
<h3>How do excitatory and inhibitory neurotransmitters act?</h3>
Sometimes neurotransmitters can bind to receptors and cause an electrical signal to be transmitted through the cell (excitatory). In other cases, the neurotransmitter can prevent the signal from continuing, preventing the message from being carried (inhibitory).
With this information, we can conclude that a neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse.
Learn more about neurotransmitter in brainly.com/question/9725469
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