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.
Atom refers to a tiny particle, which is the basic building block of all the substances and whose properties determine the characteristics of an element made up of only of those atoms.
All the living and nonliving matter in this world are made up of atoms and elements. Everything in the universe is matter, and matter comprises elements. Some of the elements are important to living things.
Elements are formed by atoms, and atoms comprise protons, electrons, and neutrons. The number of protons in an element's atom signifies the identity of the element.
Answer:
The pulmonary veins carry oxygenated blood to the heart. Air enters the bronchioles in the lungs and reaches the alveoli. The capillaries join together to reach the arteries, transferring the oxygen. The oxygen-rich blood moves from the aorta and reaches the kidneys through a series of blood vessels.
D they are easily contained charges so on and off is no problemo
