shortly explain mechanism of pth hormone on bone kidney and intestine
The parathyroid hormone (PTH) is produced by the parathyroid glands and plays a crucial role in maintaining blood calcium levels.
1. Bone: PTH stimulates bone resorption, which is the breakdown of bone tissue. It does so by activating cells called osteoclasts, which release enzymes that break down the bone matrix. This process releases calcium into the bloodstream, increasing its levels.
2. Kidney: PTH acts on the kidneys to enhance calcium reabsorption. It decreases the excretion of calcium in urine, preventing its loss from the body. Additionally, PTH promotes the conversion of inactive vitamin D into its active form, calcitriol. Calcitriol increases calcium absorption from the intestines and enhances its reabsorption from kidneys.
3. Intestine: PTH indirectly affects the intestine by promoting the production of calcitriol, which increases calcium absorption from the intestines. Calcitriol stimulates the synthesis of proteins that transport calcium across the intestinal cells, allowing it to enter the bloodstream.
Overall, the mechanism of PTH hormone on bone, kidney, and intestine involves increasing calcium release from the bone, enhancing calcium reabsorption in the kidneys, and stimulating calcium absorption in the intestines. This coordinated action helps to maintain appropriate blood calcium levels for optimal body functions.
The parathyroid hormone (PTH) plays a crucial role in regulating calcium and phosphate levels in the body. It exerts its effects on the bone, kidney, and intestine through a complex mechanism. Let's break it down:
1. Bone: PTH stimulates bone resorption, which is the process of breaking down bone tissue to release calcium ions into the bloodstream. This is achieved by activating specialized cells called osteoclasts, which break down the bone matrix and release calcium into the bloodstream.
2. Kidney: PTH acts on the kidneys in two ways:
a. Increased calcium reabsorption: PTH stimulates the reabsorption of calcium ions from the kidney tubules back into the bloodstream. By doing so, it prevents excessive calcium loss in the urine, ensuring that calcium is conserved for other functions in the body.
b. Increased phosphate excretion: PTH inhibits the reabsorption of phosphate ions in the kidney tubules, leading to increased excretion of phosphate in the urine. This helps to regulate phosphate levels in the blood.
3. Intestine: PTH indirectly influences the absorption of calcium in the intestines. It stimulates the production of an active form of vitamin D called calcitriol, which enhances the absorption of calcium from the diet in the intestines. Vitamin D acts on the intestinal cells, promoting the synthesis of proteins that facilitate calcium absorption.
Overall, PTH acts to raise calcium levels in the bloodstream through bone resorption, while regulating phosphate levels by affecting kidney reabsorption and intestine calcium absorption. Remember that this is a simplified explanation, and the actual mechanism involving numerous signaling pathways and feedback loops is much more complex.
Sure! Here is a step-by-step explanation of how parathyroid hormone (PTH) affects the bone, kidney, and intestine:
1. When blood calcium levels drop below the normal range, the parathyroid glands, located in the neck, secrete PTH into the bloodstream.
2. PTH has several effects on bone. It stimulates osteoclasts, which are cells responsible for breaking down bone tissue. This releases calcium and phosphate from the bone matrix, increasing the blood calcium concentration. Additionally, PTH inhibits osteoblasts, which are cells responsible for bone formation.
3. PTH also acts on the kidneys. It increases the reabsorption of calcium in the nephrons of the kidney, reducing the excretion of calcium in urine. At the same time, PTH promotes the excretion of phosphate in the urine, reducing blood phosphate levels.
4. In the intestine, PTH indirectly enhances the absorption of calcium. It stimulates the production of 1,25-dihydroxyvitamin D, also known as calcitriol or active vitamin D, in the kidneys. Calcitriol allows for increased absorption of calcium from the intestinal lumen into the bloodstream.
To summarize, PTH stimulates the release of calcium from the bone, increases the reabsorption of calcium in the kidneys, and indirectly promotes calcium absorption in the intestine by enhancing vitamin D production.