Answer:
E. All of the above
Explanation:
In cardiac contractile cells there is rapid depolarization, then a plateau phase and repolarization.
when an action potential stimulates the cell, voltage-gated channels open quickly commencing the positive-feedback mechanism of depolarization. This in turn raises the membrane potential to approximately +30 mV, and this closes the sodium channels. Next comes the plateau phase, where membrane potential declines relatively slowly due to the opening of the slow Ca2+ channels, allowing Ca2+ to enter the cell while few K+ channels are open, leading to K+ to exit. Once the membrane potential reaches approximately zero, the Ca2+ channels close and K+ channels open, allowing the exit of K+. The repolarization lasts approximately for a while and here is when the membrane potential drops until it reaches resting levels once more and repeats the cycle.
Answer;
The nervous system is composed of two basic cell types, namely, the Neurons and the neuroglial cells.
Explanation;
The nervous tissue is the main component of the nervous system which includes the brain, spinal cords and the nerves. It is a specialized tissue found in the central nervous system (brain and the spinal cord) and the peripheral nervous system (nerves). It consist of the neurons and the supporting cells called neuroglia.
The neurons are responsible for conducting and generating nerve impulses.
Neuroglial or glia cells are involved in many specialized functions apart from supporting of the neurons. There are six in number; four in the CNS and two in the PNS.
The answer is "Retaining water"
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-Payshence xoxo
Why they go into the sea first, and wjat helps their swimming abilities