Which of the following best describes pulmonary ventilation?

A. Cardiac muscle: Cardiac muscle is involuntary and found only in the heart. It contracts automatically to pump blood and cannot be consciously controlled, so it does not contribute to voluntary movements.

B. Smooth muscle: Smooth muscle is also involuntary and is found in the walls of internal organs such as the intestines, blood vessels, and bladder. Its contractions are automatic and not under conscious control.

C. Skeletal muscle: Skeletal muscle is under voluntary control and is attached to bones via tendons. Contraction of skeletal muscles allows deliberate movements such as walking, lifting, and writing, making it responsible for voluntary actions.

D. Striated smooth muscle: Striated smooth muscle is not a recognized type of muscle tissue. Striated muscles refer to skeletal and cardiac muscle, whereas smooth muscle is non-striated and involuntary.

A. An ion is a charged particle, while an electrolyte is a solution that conducts electricity: Ions are atoms or molecules that carry a positive or negative charge. Electrolytes are substances that dissociate into ions in a solution, enabling the conduction of electrical current.

B. Ions are formed only in solid states, while electrolytes are only in liquids: Ions can exist in solid, liquid, or gaseous states depending on the compound, and electrolytes are defined by their ability to dissociate in a solution, not by state alone.

C. Ions are found only in non-metals, while electrolytes are found in metals: Ions can form from both metals and non-metals, and electrolytes result from ionic compounds dissolving in a solvent, regardless of whether the elements are metallic or non-metallic.

D. An ion is always positive, while an electrolyte is always negative: Ions can be either positive (cations) or negative (anions), and electrolytes contain both types of ions to maintain electrical neutrality in solution.