Hello!
I believe a woman can be described pregnant after about 13 weeks or so, because this is when the unpleasant effects of pregnancy start to lessen, and the mother starts to get used to the hormonal changes.
I hope you found this helpful! :)
Ch.5: Synaptic Activity
<span>Introduction<span>Otto Loewi studied the heart of the frog, which-like our own hearts- is supplied by two different peripheral nerves. One, the sympathetic nerve, excites the heart and makes it beat more rapidly; the other , the vagus, shows the heart. The problem was to discover the mechanism by which the effects of nerve impulses in either of these nerves are communicated to the heart muscle. Many believed that the electrical nerve impulse spread from the nerve to the muscle as an electrical wave; Loewi thought otherwise.Loewi tested two isolated frog hearts, one with the sympathetic and vagus nerves intact, the other with the nerves removed. A small tube containing salt water was placed in the heart with the nerves attached. When he stimulated the vagus nerve, the heartbeat slowed, as expected. Then he took salt solution that had been in the stimulated heart and placed it inside the heart without nerves. It too immediately slowed- exactly as if its own (missing) vagus nerve had been stimulated.He repeated the same procedure, stimulating the sympathetic nerve instead. The effect was again as if the nerve of the denervated heart itself were stimulated: the denervated heart began beating faster. These results could not be explained electrically; the nerves must have secreted chemicals into the salt solution that directly affect the muscles of the denervated heart.In one simple experiment, Loewi had demonstrated three important findings: (1) that communication at the gap between nerve and heart muscle was chemical, (2) that each nerve released a different transmitter substance, and (3) that it was the characteristics of the different transmitter substances that caused the increase or decrease in heart rate. This was the first direct experimental evidence of the action of chemical neurotransmitters.<span>Like the junction between nerve and heart muscle that Loewi studied, nerve cells communicate with each other at special junctions called synapses. </span></span></span><span><span> thanks and i hope this helps you.....
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Answer:
DNA damage signaling processes are essential foe regulating the G0 transition within the cell cycle.
Explanation:
Cell cycle is a process which prepares a cell for division.Cell cycle has various phases G0 phase,G1 phase,S phase,G2 phase and M phase.Each phase is specialized for its particular function.
Every phases of a cell cycle is under tight regulation of various proteins and this regulation is very much important to maintain the normal level of principle constituents of a cell.
DNA damage is detected by G1 cyclin CDK protein which transit the cell containing the damaged DNA into the G0 phase or quiescent phase for repair and if the damage cannot be repaired then the cell containing damaged DNA is targeted for destruction by ubiquitin pathway.
A violent volanic eruption occurs due to magma with high viscosity. Especially when their is a lot of pressure inside thr volcano.
Answer:
Creo que es la Energía química