Final answer:
The ion that is essential for blood clotting is calcium (Ca²+). It plays a critical role in blood coagulation, as well as in muscle contraction, nerve function, and bone structure.
Step-by-step explanation:
The ion essential for blood clotting is calcium. Calcium ions (Ca²+) are crucial for several bodily functions including muscle contraction, enzyme activity, stabilizing cell membranes, and notably for blood coagulation. Calcium is also a significant component of bone and tooth structure and is involved in the release of neurotransmitters and hormones.
Applications of these cations highlight their vital roles in various physiological processes. For instance, potassium, sodium, and magnesium are integral to blood pressure regulation and muscle contraction, while calcium ions contribute to bone density and are essential for blood clotting mechanisms.
In the context of blood coagulation, removing calcium ions from the serum can prevent clotting, which is why substances like potassium oxalate are used during blood draws to keep the sample from clotting. This underlines the importance of calcium in the clotting process.