The answer is Spiral. Spiral does not represent a type of nebula. There are only 3 types of nebula : Reflection, Emission & Dark. Reflection Nebulaedoes not emit its own light. Instead, it scatters the blue light from a nearby cool star. Emission Nebulae emits own light. Glow very brightly, and are frequently the birthplace of stars. Dark Nebulae also called "absorption nebulae", they block light from brighter objects behind them and can only be seen as an outline in front of a bright nebula or field of stars.
Explanation: The biological fitness of an organism is dependent on its ability to survive and reproduce in a given environment. A trait that increases ability to survive, but makes an individual sterile, decreases fitness because the organism cannot produce offspring to carry on the trait.
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The last suggestion is correct....when you have setes of rest in between workouts..you allow the lactic acid to seep into your muscles and ensure that the muscle protein is broken down properly.
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
