Ai Flashcards
What is the function of calcium ion in the body?
Formation of bone and teeth, essential for blood coagulation, release of chemical transmitters and hormones, muscle contraction, common second messenger, affects nerve excitability.
Increased Ca²⁺ reduces excitability, while decreased Ca²⁺ increases it.
What are the two forms of calcium in plasma?
Diffusible ionized active Ca²⁺ and non-diffusible bound to plasma proteins.
Diffusible non-ionized makes up 50%.
What are calcitropic hormones?
Hormones concerned with calcium regulation, including Vitamin D, parathyroid hormone (PTH), and calcitonin.
What is the effect of Vitamin D on calcium levels?
Increases calcium levels.
Vitamin D2 (calciferol) and D3 (cholecalciferol) are the main forms.
Fill in the blank: The normal level of calcium in plasma is _______.
10 mg% or 10 mg/dl.
What is the effect of Vitamin D deficiency on calcium absorption?
Decreases calcium absorption from the intestine, leading to hypocalcemia.
This results in demineralization of bone.
What are the manifestations of Vitamin D deficiency?
Rickets in children and osteomalacia in adults.
What is the role of calcitonin hormone?
Lowers calcium and phosphate levels in blood by reducing osteoclast activity and increasing urinary excretion of calcium and phosphate.
Calcitonin is more active in younger individuals.
What is the primary function of parathyroid hormone (PTH)?
Increases calcium levels and decreases phosphate levels to maintain constant solubility product.
PTH is essential for life and regulates calcium and phosphate concentrations in extracellular fluids.
What actions does PTH have on the bones?
Increases bone resorption by enhancing osteoclast activity, leading to demineralization and increased blood calcium levels.
Vitamin D3 is essential for PTH action on bone.
How does PTH affect the kidneys?
Increases calcium reabsorption and decreases phosphate reabsorption.
How does PTH influence the intestine?
Increases calcium absorption by enhancing Vitamin D3 formation.
