Answer:
D. Calcium ions.
Explanation:
Here we are talking about the mechanism of muscle contraction. The most accepted theory of muscle contraction is sliding filament theory. It was given by Huxley and Huxley. During the process actin filaments slides over myosin filament by forming cross bridges. The sequence of events are as follows:
a. An action potential propagates through the motor nerve and reach the nerve endings on the muscle fiber at neuro-muscular junction.
b. Neurotransmitter called acetylcholine is released by the nerve endings.
c. Acetylcholine binds to the receptors on muscle fiber and opens the gated channels which causes flow of Na+ ions into the muscle fiber.
d. This influx of sodium ions initiates an action potential in the muscle fiber which reaches the T- tubules or transverse tubules. Here it causes the sarcoplasmic reticulum to release large amounts of calcium ion.
e. Calcium ions are responsible for initiating the attractive forces between actin and myosin filaments. Cross bridges are formed, actin slides over myosin causing the contraction of muscle.
Answer:
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Higher pitched sounds have waves of a higher frequency and they have shorter wavelengths.
Hope that helps.
Answer:
A good example of scientific theory repeated many times is the “theory of relativity” proposed by Albert Einstein in 1915 which was tested and repeated in 1919 at the time of solar eclipse which was later repeated again by many scientists.Explanation:
It's a good fact. Hope this helps
Answer:
gene
A gene is a functional segment of DNA that provides the genetic information necessary to build a protein. Each particular gene provides the code necessary to construct a particular protein.
Explanation:
