40 Questions
What is the primary function of calcitriol, the active form of vitamin D?
To increase calcium absorption in the gastrointestinal tract
Which of the following best describes the relationship between parathyroid hormone (PTH) and the kidneys?
All of the above
Which of the following cell types is responsible for the destruction and reabsorption of bone tissue?
Osteoclasts
What is the primary function of calcitonin, a hormone produced by the thyroid gland?
To counter the effects of parathyroid hormone (PTH) and decrease ionized calcium levels in the blood
Which of the following is the primary source of vitamin D2 for humans?
Dietary sources only, as vitamin D2 cannot be produced within the body
What is the primary function of osteoblasts in bone metabolism?
To create bone tissue and matrix
How does parathyroid hormone (PTH) affect the kidneys' role in vitamin D metabolism?
PTH stimulates the kidney enzyme 1-alfa-hydroxilase to convert calcidiol to calcitriol
Which cell type is responsible for the biomineralization process and maintenance of bone tissue?
Osteocytes
What is the role of chief cells in the parathyroid gland?
Secrete PTH
Where is pre-prohormone synthesized in the parathyroid gland?
By rER
What triggers the release of PTH from the parathyroid gland?
Low levels of ionized calcium
Where does PTH have a direct impact on metabolism?
Bones
Which hormone is NOT involved in maintaining calcium homeostasis?
Aldosterone
What are the actions of oxphil cells in the parathyroid gland?
oxidative and hydrolytic enzymatic activity
What is the role of calcitriol in calcium metabolism?
Regulates blood calcium levels
What happens when calcium and phosphate levels are imbalanced?
Body takes calcium from bones
What is the primary effect of decreasing calcium movement from bones to the ECF?
Inhibits osteoclast reabsorption
Which hormone is released in response to excessive calcium absorption in the intestines?
Calcitonin
What is the main role of calcitriol in calcium regulation?
Promotes active transport of dietary calcium across intestinal epithelium
How do hind gut fermenters regulate blood calcium levels?
Decreasing or increasing urine loss of calcium
Which of the following is a direct effect of increasing phosphate movement into bones from the ECF, due to calcitonin?
Increased calcium storage in bones
What is the consequence of insufficient calcitriol in animals?
Inadequate support for bone structure
Which hormone indirectly affects calcium levels by acting on the GI tract?
PTH
In hind gut fermenters, what is a unique characteristic of their urine when regulating calcium?
"Chalky white" appearance
What is the primary cause of primary hyperparathyroidism?
Abnormal chief cells within the parathyroid gland
How does primary hyperparathyroidism impact the kidneys?
Leads to polydipsia and polyuria
What is a common symptom of primary hyperparathyroidism related to the urinary system?
Crystalluria
How does primary hyperparathyroidism affect the excitability of the PNS/CNS?
Decreases excitability
What is a potential cardiovascular manifestation of primary hyperparathyroidism?
Bradycardia
How is primary hyperparathyroidism typically diagnosed?
Urinalysis (crystalluria)
In horses, what is another term for secondary hyperparathyroidism?
"Big Head Disease"
"Nutritional secondary hyperparathyroidism" is a condition in horses resulting from:
"Hyper mobilization of calcium from the skeleton under the influence of PTH"
What is the main cause of Nutritional Metabolic Bone Disease (NMBD) in reptiles and amphibians?
All of the above
What is the main function of oxalates in the diet of reptiles and amphibians?
Oxalates prevent the digestion and absorption of calcium
What is the alternative name for Nutritional Metabolic Bone Disease (NMBD) in reptiles and amphibians?
Nutritional secondary hyperparathyroidism (NSHP)
What is the main cause of hypoparathyroidism in reptiles and amphibians?
Idiopathic destruction of the parathyroid gland
What is the effect of low PTH levels in reptiles and amphibians?
Decreased calcitriol production, hypocalcemia, and hyperphosphatemia
What is the main symptom of severe hypoparathyroidism in reptiles and amphibians?
All of the above
How is hypoparathyroidism diagnosed in reptiles and amphibians?
Serum biochemistry showing hyperphosphatemia, decreased calcium, and undetectable PTH
What is the main cause of Nutritional Secondary Hyperparathyroidism (NSHP) in reptiles and amphibians?
All of the above
Test your knowledge of parathyroid anatomy and hormone synthesis in different species. Learn about the chief cells that secrete PTH and the oxphil cells with unknown functions. Explore the chemical structure and synthesis process of parathyroid hormones.
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