endocrine 4

A type of receptor that detects changes in blood calcium levels, triggering responses to maintain calcium homeostasis.

The main hormone involved in increasing blood calcium levels. It is secreted by the parathyroid glands.

A process that breaks down bone to release calcium into the bloodstream. This is one of the ways PTH increases blood calcium levels.

The cells responsible for resorbing bone tissue, breaking it down to release calcium.

The primary target of PTH that is responsible for increasing calcium reabsorption in the kidneys, thus increasing blood calcium levels.

Calcium (Ca2+) is vital for bone health, cell signaling, nerve function, muscle contraction, and blood clotting.

Vitamin D is synthesized in the skin with sunlight exposure. It is then activated in the kidneys to increase calcium absorption from the gut, ultimately leading to higher blood calcium levels.

Calcitonin, produced by the thyroid gland, works opposite of PTH by decreasing blood calcium levels. It primarily inhibits bone resorption, reducing the release of calcium from bones.

High blood calcium causes hypercalcemia, leading to soft tissue mineralization, excess urination and thirst, and cardiac problems. Low blood calcium results in hypocalcemia, causing weakness, tetany (muscle spasms), low blood pressure, and compromised heart function.

Calcium (Ca2+) exists in three forms in the body: Free ionized (45%), Protein-bound (50%), and Complexed (5%). Only the free ionized form is biologically active.

Calcium is vital for various bodily functions, including bone formation, muscle contraction, nerve impulse transmission, and blood clotting.

The parathyroid glands produce parathyroid hormone (PTH), which plays a crucial role in regulating calcium levels in the blood.

PTH increases blood calcium levels by promoting calcium release from bones, decreasing calcium excretion in the kidneys, and enhancing calcium absorption in the intestines.

PTH is secreted in response to low blood calcium levels, providing a feedback mechanism to restore normal calcium balance.

PTH increases renal excretion of phosphate, which aids in raising blood calcium levels. This effect is less prominent than its effect on calcium.

The parathyroid glands are small, oval-shaped structures located on the posterior surface of the thyroid gland.

The parathyroid glands are vital regulators of calcium homeostasis, ensuring that the appropriate amount of calcium is available for essential bodily functions.

Parathyroid hormone (PTH) is a hormone produced by the parathyroid glands. It plays a crucial role in regulating blood calcium levels by stimulating calcium release from bones, increasing calcium reabsorption in the kidneys, and promoting calcium absorption in the intestines.

Active vitamin D, also known as calcitriol, is a steroid hormone produced primarily in the kidneys. It stimulates calcium absorption in the intestines, helping to maintain healthy blood calcium levels.

Low calcium levels (hypocalcemia) trigger the release of PTH and active vitamin D, which work to increase blood calcium levels. PTH stimulates bone resorption, kidney reabsorption, and intestinal absorption of calcium. Active Vitamin D enhances calcium absorption by the intestines.

High calcium levels (hypercalcemia) trigger the release of calcitonin, a hormone produced by the thyroid gland. Calcitonin lowers blood calcium levels by inhibiting bone resorption, increasing calcium excretion by the kidneys, and reducing calcium absorption in the intestines.

Rickets is a bone disorder in children caused by vitamin D deficiency, leading to soft and weak bones. It is characterized by bowed legs, skeletal deformities, and delayed growth. Osteomalacia is the adult equivalent of rickets, also caused by vitamin D deficiency but results in softening of bones.

PTH increases the reabsorption of calcium in the distal tubules of the kidneys, effectively reducing calcium excretion.

PTH promotes the excretion of phosphate in the kidneys, which helps to increase the amount of free calcium in the bloodstream.

PTH plays a vital role in activating vitamin D, a key player in calcium absorption from the gut.

A steroid hormone that acts like a vitamin, essential for calcium absorption in the gut and bone health.

The liver adds the first hydroxyl group to vitamin D, converting it into 25-hydroxyvitamin D (25-OH D3).

The kidneys add the second hydroxyl group to vitamin D, converting it into 1,25-dihydroxyvitamin D (Calcitriol), the active form.

The enzyme responsible for the final step in vitamin D activation, converting 25-OH D3 into calcitriol.

Active vitamin D (calcitriol) promotes the absorption of calcium from the intestines by increasing expression of calcium transport proteins.

Active vitamin D (calcitriol) promotes osteoclast activity in bones, causing bone resorption and release of calcium into the bloodstream.

A peptide hormone produced by the parafollicular cells of the thyroid gland, responsible for lowering plasma calcium levels.

Calcitonin inhibits the activity of osteoclasts, reducing bone resorption and the release of calcium from bones.

Calcitonin reduces calcium reabsorption in the kidneys, leading to increased calcium excretion.

Calcitonin inhibits the absorption of calcium from the gut.

A condition characterized by abnormally low levels of PTH, leading to hypocalcemia and potentially life-threatening tetany.

A condition characterized by abnormally high levels of PTH, typically caused by a tumor in the parathyroid gland. Can lead to hypercalcemia.