The rapid depolarization phase
of myocardial contractile cells is due to the Na+ ions. Sodium ions are essential
for regulation of blood and body fluids, communication of nerve impulses, heart
activity, and metabolic purposes. Physiologically, it survives as an ion in the
body. Sodium is needed by
animals but is not needed by plants. The human prerequisite for sodium<span> must be less
than 500 mg per day. </span>
Answer:
The answer is Atom.
Explanation:
The atom is the smallest constituent unit of matter that has the properties of a chemical element and that it is not possible to divide by chemical processes. The atom is formed by a nucleus with protons and neutrons and several orbital electrons (subatomic particles); whose number varies according to the chemical element. Atoms combine to form molecules that then interact to form solids, liquids and gases.
Answer and Explanation:
The steps of the sliding filament theory are:
Muscle activation: breakdown of energy (ATP) by myosin.
Before contraction begins, myosin is only associated with a molecule of energy (ATP), which myosin breaks down into its component molecules (ADP + P) causing myosin to change shape.
Muscle contraction: cross-bridge formation
The shape change allows myosin to bind an adjacent actin, creating a cross-bridge.
Recharging: power (pulling) stroke
The cross-bridge formation causes myosin to release ADP+P, change shape, and to pull (slide) actin closer to the center of the myosin molecule.
Relaxaction: cross-bridge detachment
The completion of the pulling stroke further changes the shape of myosin. This allows myosin and ATP to bind, which causes myosin to release actin, destroying the cross-bridge. The cycle is now ready to begin again.
The repeated cycling through these steps generates force (i.e., step 2: cross-bridge formation) and changes in muscle length (i.e., step 3: power stroke), which are necessary to muscle contraction.
Answer:
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The organisms<span> that eat the producers are the primary consumers. They tend to be small in size and </span>there<span> are many of them. ... Because of this inefficiency, </span>there<span> is only enough </span>food<span> for a </span>few top<span> level consumers, but </span>there<span> is lots of </span>food<span> for herbivores lower down on the </span>food chain<span>.</span>
