D. He was successful in building s new political center in the East, unified by the Christian religion.
This question refers to the Byzantine Empire, which lasted past the fall of the Western Roman Empire.
Their is no way to answer this question, because I do not know the context of the question and what’s it asking about.
Answer:
After C14, Uranium238 is most widely used mineral in geological or archaeological dating.
Explanation:
U238 is generally used to date the rock materials, to know the age. As we know the half-life of U238, it is easy to identify the age of the materials containing uranium 238. It can be called as absolute dating method as it determines the exact age of the uranium contained material. It is a type of radiometric dating.
Answer:
The prolonged electrical depolarization of cardiac muscle cells -that occurs during contraction- is due primarily to the persistent influx of calcium ion
Explanation:
The action potential of the heart muscle is longer with respect to skeletal muscle (around 300 milliseconds), and this is due to the activity of calcium (Ca⁺⁺ ) in the intracellular compartment.
The initial depolarization of cardiac muscle fiber depends on the entry of sodium (Na⁺) into the cell. However, for the action potential to occur and be maintained, Ca⁺⁺ must increase its cytoplasmic levels, which depends on:
- The increase in intracellular sodium induces the release of Ca⁺⁺ from the sarcoplasmic reticulum.
- Calcium entry from the extracellular space through the voltage dependent Ca⁺⁺ channels.
- The entry of extracellular Ca⁺⁺ causes the release of more Ca⁺⁺ ions by the sarcoplasmic reticulum, further increasing its intracellular concentration.
This is how the ion that guarantees the duration of the action potential of the cardiac muscle cell is the Ca⁺⁺.
Learn more:
Calcium, sodium and cardiac muscle cells brainly.com/question/4473795
