Calcium is essential not only for building bones and teeth but also for blood clotting, muscle contraction, heart function, and nerve signaling. This lesson explains how the skeletal, endocrine, digestive, and urinary systems work together to keep blood calcium within a healthy range.
Calcium is the most abundant mineral in the human body and a major component of bone. It is also required for tooth health, blood coagulation, contraction of smooth and skeletal muscles, regulation of heart rate and contraction strength, and conduction of nerve impulses.
All flashcards
What is calcium homeostasis?
It is the coordinated regulation of calcium levels in the blood. The bones, endocrine glands, digestive tract, and kidneys all contribute to this regulation.
What are major functions of calcium in the body?
Calcium supports blood coagulation, muscle contraction, heart rate and contraction strength, nerve impulse conduction, and tooth health.
How does PTH respond to low blood calcium?
PTH stimulates calcium release from bone, promotes calcium reabsorption by the kidneys, and stimulates vitamin D synthesis so the small intestine absorbs more calcium from food.
How does vitamin D contribute to calcium balance in this regulatory cycle?
PTH stimulates vitamin D synthesis, and vitamin D increases calcium absorption from digested food in the small intestine.
How does calcitonin lower blood calcium?
Released by the thyroid when blood calcium is high, calcitonin inhibits osteoclast activity, encourages calcium uptake into bone, and decreases calcium reabsorption by the kidneys.
Quiz questions
About what is the typical level of calcium in the blood?Answer: About 10 mg/dL.
What does hypocalcemia mean?Answer: An abnormally low level of calcium in the blood.
What change prompts the parathyroid glands to release PTH?Answer: Low blood calcium reduces calcium binding to receptors on parathyroid cells.
How does PTH raise blood calcium through its effects on the kidneys and digestive system?Answer: It promotes kidney calcium reabsorption and stimulates vitamin D synthesis, increasing intestinal calcium absorption.
Which response helps lower high blood calcium?Answer: The thyroid releases calcitonin, which inhibits osteoclasts, promotes calcium uptake by bone, and reduces kidney calcium reabsorption.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.