Podcast
Questions and Answers
What did Ringer demonstrate about Ca2+ in 1883?
What did Ringer demonstrate about Ca2+ in 1883?
What aspect of Ca2+ did McLean and Hastings find to be proportional to frog heart contraction amplitude?
What aspect of Ca2+ did McLean and Hastings find to be proportional to frog heart contraction amplitude?
What was the mean concentration of blood-ionized Ca2+ in humans, as identified in the studies?
What was the mean concentration of blood-ionized Ca2+ in humans, as identified in the studies?
Why is it important to maintain ionized Ca2+ levels during surgery?
Why is it important to maintain ionized Ca2+ levels during surgery?
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What clinical symptom may result from decreased ionized Ca2+ concentrations in blood?
What clinical symptom may result from decreased ionized Ca2+ concentrations in blood?
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Which of the following forms of Ca2+ was shown to have no effect on frog heart contraction?
Which of the following forms of Ca2+ was shown to have no effect on frog heart contraction?
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Study Notes
Calcium Physiology
- Ringer demonstrated in 1883 that calcium is essential for myocardial contraction.
- McLean and Hastings investigated the impact of bound and free calcium on frog heart contraction.
- They found a direct correlation between ionized calcium concentration and the amplitude of frog heart contraction.
- Protein-bound and citrate-bound calcium had no effect on contraction.
- This discovery led to the development of the first assay for ionized calcium using frog hearts.
- This early method, although not precise by modern standards, revealed the tight regulation of blood-ionized calcium.
- The average ionized calcium concentration in humans is approximately 1.18 mmol/L.
- Maintaining near-normal ionized calcium levels is crucial during surgery and in critically ill patients due to its impact on myocardial function.
- Low ionized calcium can cause neuromuscular irritability, manifested as irregular muscle spasms (tetany).
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Description
This quiz explores the essential role of calcium in myocardial contraction as demonstrated through historical research, including key findings on ionized calcium's effects on frog hearts. It highlights the importance of maintaining normal ionized calcium levels in surgical and critical care settings, as well as the consequences of low calcium levels in muscle function.
