The activity recorded by the electromyogram corresponds to: Select one: a. The electrical impulse of a single motor unit. b. The electrical impulses generated in many muscle fibers simultaneously. c. Only the positively charged repolarization of the muscle fibers. d. The electrical impulse of a single muscle fiber. e. Skin impulses generated by the mechanical energy of muscle movement.

B.The electrical impulses generated in many muscle fibers simultaneously.

Explanation:

Electromyography  is the process of  measuring the the voltage changes elicited in muscle fibres due to electrical stimulation of the muscle  fibres cells.

When a  single muscle fibre  is stimulated  it  generates  a  very weak voltage  (< 100 microvolts),however when more muscle fibres are stimulated  the voltage produced is large enough to produce action potential.Therefore, if an electrode is placed on the muscle cells under electrical  stimulation,a graphical display  is obtained on the screen with the x-axis of the graph corresponding to the time of  the electrical stimulation, and the y-axis to the internal   voltage potential of the muscle fibres.

Then the graph obtained corresponds to the  action potential generated  by the muscle fibres stimulated. This display is called Electromyogram.

Thus records and evaluation of the action potential generated is obtained.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.