Calcitonin Calcitonin By: Narjes lavasani

What is Calcitonin? Calcitonin is peptide hormone CT Synthesized and Secreted by the c cells (Clear cell)or Para follicular cells of thyroid gland CT reduce calcium blood level opposed to parathyroid hormone Calcitonin Gene-Related Peptide (CGRP) is an alternative product of the calcitonin gene that CGRP does not bind to the calcitonin receptor. CGRP in thyroid, heart, lungs, GI tract, and nervous tissue act as a neurotransmitter, not as a regulator of Ca.

Calcitonin secreted by Parafollicular cells

Basic Structure of Calcitonin A polypeptide chain of 32 amino acids An intramolecular disulfide bridge between the cysteine residues at positions 1 and 7 make a circular shape,

Calcium concentration In hormonal regulation of calcium and phosphate concentration in the body, three hormones are involved: 1. Parathyroid hormone= Increase the concentration of calcium in the plasma 2. Calcitonin=Decrease the concentration of calcium in the plasma 3.Vitamin D= Increase the calcium and phosphate concentration Calcitonin is involved in helping to regulate the level of calcium and phosphate in the blood against the action of parathyroid hormone. If the body sense high concentration of calcium in the plasma this stimulate the thyroid gland to secrete calcitonin

How does calcitonin reduces the level of Calcium in the blood? Calcitonin reduces the blood calcium level by acting on: Bones Kidneys Intestine

Bone resorption In response to high concentration of blood calcium, calcitonin released. Calcitonin directly inhibits the activity of osteoclasts(resorb bone), and stimulating osteoblast(bone forming) directly reduces the amount of calcium released into the blood.  Calcitonin hormone receptor is G protein Use cAMP pathway  

Bone resorption It decrease the calcium reabsorption in the kidney, and leading to lower blood calcium levels by increasing the calcium excretion in the urine. Gastrointestinal hormones (gastrin and cholecystokinin) release calcitonin during digestion of food with calcium calcitonin Inhibit calcium absorption by the intestine

i Calcitonin is degraded by liver, and is cleared from the blood by the kidney

Negative feedback mechanism

Calcitonin blood test is a preventive measurement for screening of people who have a family history of medullary thyroid cancer. Normal Plasma level of Calcitonin is less than 14pg/ml(female) less than 19pg/ml(male)

An injection of manufacture form of calcitonin can be given to the patients with postmenopausal osteoporosis(low estrogen), hypercalcemia (high calcium levels in the blood) and Paget's disease (bone). and Paget's disease (bone). Intramuscular or subdermal

http://www. biosupply. co http://www.biosupply.co.uk/content/14-calcitonin-a-regulator-of-calcium-metabolism https://www.ncbi.nlm.nih.gov/pubmed/7588259 https://www.ncbi.nlm.nih.gov/pubmed/17114906 http://www.yourhormones.info/hormones/calcitonin.aspx