Excitation-contraction coupling refers to the series of events that begins with the excitation of the sarcolemma in response to stimulation by a neurotransmitter, and results in the release of calcium ions from the sarcoplasmic reticulum.
Hence, option D is the 1st process that starts the excitation-contraction coupling.
1. Chromosome condense (Prophase)
2. Spindle fibers form (Prophase)
3. Chromosomes allign in the center of the cell (Metaphase)
4. Chromosomes separate (Anaphase)
5. Cell membrane pinches (Telophase and Cytokenesis)
6. Spindle fibers disappear (Conclusion of Cytokenesis)
Storage. Vacuoles store water and waste.
Explanation:
Receptors = Sensory neurons
Relay = Relay neurons
Effectors = Motor neurons
Cell bodies of sensory neurons are only found in the root ganglion. (F)
Cell bodies of relay neurons are only found is the grey matter of the spinal cord. (G)
Cell bodies of motor neurons are also found at G.
Hence the answer is Option D.
