Podcast
Questions and Answers
What percentage of calcium in the body is primarily found in bone?
What percentage of calcium in the body is primarily found in bone?
- 1%
- 50%
- 99% (correct)
- 5%
Which form of calcium accounts for the largest percentage of total calcium in blood?
Which form of calcium accounts for the largest percentage of total calcium in blood?
- Free Ca2+ ions
- Bound to proteins (correct)
- Cytosol calcium
- Bound to anions
What is the significance of the large gradient of ionized Ca2+ between blood and cytosol?
What is the significance of the large gradient of ionized Ca2+ between blood and cytosol?
- It maintains essential rapid inward flux of Ca2+. (correct)
- It facilitates calcium storage in bone.
- It allows calcium binding to proteins.
- It prevents calcium from entering the blood.
How does the distribution of calcium in the blood change during critical care?
How does the distribution of calcium in the blood change during critical care?
Why can't ionized Ca2+ be reliably calculated from total Ca2+ measurements in acutely ill individuals?
Why can't ionized Ca2+ be reliably calculated from total Ca2+ measurements in acutely ill individuals?
Flashcards
Calcium distribution in the body
Calcium distribution in the body
The majority of calcium in the body is found in bones, with only a small percentage circulating freely in the blood or inside cells.
Calcium gradient between blood and cells
Calcium gradient between blood and cells
The concentration of free calcium ions (Ca2+) in the blood is much higher than inside cells, especially in muscles. This difference is essential for muscle function.
Forms of calcium in blood
Forms of calcium in blood
Most of the calcium in blood is not free but bound to proteins, like albumin, or to anions, such as bicarbonate, citrate, and phosphate.
Calcium distribution changes in disease
Calcium distribution changes in disease
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Reliability of total calcium measurements
Reliability of total calcium measurements
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Study Notes
Calcium Distribution in the Body
- Approximately 99% of body calcium is in bones.
- The remaining 1% is primarily in blood and extracellular fluid (ECF).
- Cytosol of most cells contains very little calcium.
- Blood ionized calcium concentration is significantly higher than in cardiac or smooth muscle cells (5,000-10,000 times higher).
- Maintaining this gradient is crucial for a rapid calcium influx.
Forms of Blood Calcium
- About 45% of blood calcium is free ionized calcium.
- 40% is bound to proteins, mainly albumin.
- 15% is bound to anions like bicarbonate, citrate, phosphate, and lactate.
Implications for Disease and Treatment
- The distribution of blood calcium can change due to disease.
- Concentrations of citrate, bicarbonate, lactate, phosphate, and albumin can fluctuate significantly during critical illnesses or procedures (e.g., surgery).
- Ionized calcium cannot be accurately calculated from total calcium measurements, especially in acutely ill patients.
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Description
Explore the vital role of calcium in the human body, focusing on its distribution between bones, blood, and cells. This quiz also examines the implications of blood calcium forms for disease and treatment, highlighting the complexities of calcium measurement during critical illnesses.
