calcium homeostasis

Examples of calcium homeostasis in the following topics:

• Bone and Calcium Homeostasis

  • Calcium metabolism or calcium homeostasis is the mechanism by which the body maintains adequate calcium levels.
  • Calcium metabolism or calcium homeostasis is the mechanism by which the body maintains adequate calcium levels.
  • Bone serves as an important storage point for calcium, as it contains 99% of the total body calcium.
  • Removal of calcium from the bone is also inhibited.
  • This results in the removal of calcium from the bone to correct blood calcium levels.

• Overview of the Thyroid Gland

  • The thyroid also produces calcitonin, which plays a role in calcium homeostasis.

• Overview of the Parathyroid Glands

  • Parathyroid glands control the amount of calcium in the blood and within the bones.
  • When blood calcium levels drop below a certain point, calcium-sensing receptors in the parathyroid gland are activated to release parathyroid hormone (PTH) into the blood.
  • PTH modulates calcium and phosphate homeostasis, as well as bone physiology.
  • PTH has effects antagonistic to those of calcitonin by increasing blood calcium levels by stimulating osteoclasts to break down bone and release calcium.
  • PTH also increases gastrointestinal calcium absorption by activating vitamin D, and promotes calcium conservation by re-absorption in the kidneys.

• Control of Homeostasis

  • Homeostasis is maintained by negative feedback loops within the organism.
  • Homeostasis is controlled by the nervous and endocrine systems in mammals.
  • Another example of an increase as a result of a feedback loop is the control of blood calcium.
  • If calcium levels decrease, specialized cells in the parathyroid gland sense this and release parathyroid hormone (PTH), causing an increased absorption of calcium through the intestines and kidneys.
  • The effects of PTH are to raise blood levels of calcium.

• Overview of the Urinary System

  • The urinary system maintains blood homeostasis by filtering out excess fluid and other substances from the bloodstream and secreting waste.
  • Regulation of acid-base homeostasis and blood pH, a function shared with the respiratory system.
  • The primary function of the kidneys is to maintain a stable internal environment (homeostasis) for optimal cell and tissue metabolism.
  • Many hormones involved in homeostasis will alter the permeability of these tubules, changing the amount of water that is retained by the body.
  • Besides ADH secretion, the renin-angiotensin feedback system is critically important to maintain blood volume and blood pressure homeostasis.

• Sodium, Electrolytes, and Fluid Balance

  • Electrolytes play a vital role in maintaining homeostasis within the body.
  • Electrolytes play a vital role in maintaining homeostasis within the body.
  • The most serious electrolyte disturbances involve abnormalities in the levels of sodium, potassium, and/or calcium.

• Development of the Endocrine System

  • The endocrine system regulates growth, metabolism, and body homeostasis using hormones that effectively target organs via the bloodstream.
  • The ability to maintain homeostasis and respond to stimuli is largely due to hormones secreted within the body.
  • The thyroid also produces and releases the hormone calcitonin (thyrocalcitonin), which contributes to the regulation of blood calcium levels.
  • Thyrocalcitonin decreases the concentration of calcium in the blood.
  • Most of the calcium removed from the blood is stored in the bones.

• Parathyroid Hormone

  • Parathyroid hormone maintains the body's calcium levels by increasing absorption of calcium from the bones, kidneys, and GI tract.
  • When blood calcium levels drop below a certain point, calcium-sensing receptors in the parathyroid gland are activated, and the parathyroid glands release parathyroid hormone (PTH) into the blood.
  • Parathyroid hormone acts to increase blood calcium levels, while calcitonin acts to decrease blood calcium levels.
  • Parathyroid hormone acts on the bone to increase blood calcium levels by stimulating osteoclasts to break down bone, releasing calcium into the bloodstream.
  • It acts on the kidneys to increase blood calcium levels by promoting calcium reabsorption in the nephrons.

• Hormonal Control of Blood Calcium Levels

  • PTH is released in response to low blood calcium levels.
  • In the intestines, PTH increases dietary calcium absorption and in the kidneys, PTH stimulates re-absorption of the calcium.
  • PTH release is inhibited by rising blood calcium levels.
  • Calcitonin decreases blood calcium levels by inhibiting osteoclasts, stimulating osteoblasts, and stimulating calcium excretion by the kidneys.
  • It increases blood calcium levels by stimulating the resorption of bones, increasing calcium resorption in the kidneys, and indirectly increasing calcium absorption in the intestines.

• Regulation of Urine Concentration and Volume

  • In a way, urine volume regulation is part of homeostasis, in that it directly regulates blood volume, because greater amounts of urine will reduce the volume of waters in blood.
  • As the fluid flows along the proximal convoluted tubule useful substances like glucose, water, salts, potassium ions, calcium ions, and amino acids are reabsorbed into the blood capillaries that form a network around the tubules.
  • Describe how regulating the amount of water excreted in urine is an essential component of homeostasis that is regulated by the antidiuretic hormone (ADH)