Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH).Its importance in humans has not been as well established as its importance in other animals, as its function is usually not significant in the regulation of normal calcium homeostasis. It belongs to the calcitonin-like protein family. Historically calcitonin has also been called thyrocalcitonin. Biosynthesis and regulation
Calcitonin is formed by the proteolytic cleavage of a larger prepropeptide, which is the product of the CALC1 gene (CALCA). It is functionally an antagonist with PTH and Vitamin D3. The CALC1 gene belongs to a superfamily of related protein hormone precursors including islet amyloid precursor protein, calcitonin gene-related peptide, and the precursor of adrenomedullin. Secretion of calcitonin is stimulated by:

an increase in serum [Ca2+]
gastrin and pentagastrin. Function
The hormone participates in calcium (Ca2+) metabolism. In many ways, calcitonin counteracts parathyroid hormone (PTH) and vitamin D.
More specifically, calcitonin lowers blood Ca2+ levels in two ways:

Major effect: Inhibits osteoclast activity in bones, which break down the bone
Minor effect: Inhibits renal tubular cell reabsorption of Ca2+ and phosphate, allowing them to be excreted in the urineHigh concentrations of calcitonin may be able to increase urinary excretion of calcium and phosphate via the renal tubules. leading to marked hypocalcemia. However, this is a minor effect with no physiological significance in humans.
Greek-Cypriot model Sophia Hadjipanteli is also known for her unibrow.It is also the trademark of NBA player Anthony Davis, football player Marouane Fellaini and YouTuber ElectroBOOM. Famous boxer Roberto Elizondo also famously sported a unibrow during his professional boxing fighting days.Bert, Herry Monster, and Oscar the Grouch from Sesame Street, Muppets Sam Eagle, Statler and Animal, Tim Lockwood from Cloudy with a Chance of Meatballs, Spanky Ham from Drawn Together, Squilliam Fancyson from SpongeBob SquarePants, Helga Pataki from Hey Arnold!, and Baby Gerald from The Simpsons are fictional characters with a unibrow. Medicine
Genetics
The unibrow is a genetic trait. It is associated with the PAX3 gene. Medical conditions
A unibrow is part of normal human variation, but can also stem from developmental disorders. A unibrow is a recognized feature of Cornelia De Lange syndrome, a genetic disorder whose main features include moderate to severe learning difficulties, limb abnormalities such as oligodactyly (fewer than normal fingers or toes), and phocomelia (malformed limbs), and facial abnormalities including a long philtrum (the slight depression/line between the nose and mouth). Other medical conditions associated with a unibrow include:

Waardenburg syndrome;
Patau syndrome;
Smith-Lemli-Opitz syndrome;
Sanfilippo syndrome;
3p deletion syndrome;
Chromosome Deletion Dillan 4p Syndrome (Wolf–Hirschhorn syndrome);
Gorlin syndrome (Basal Cell Nevus Syndrome);
Cornelia de Lange Syndrome
Frontometaphyseal dysplasia;
ATRX syndrome;
Chromosome 9q34 Microdeletion Syndrome or Kleefstra syndrome. 17q12 microduplication syndrome

See also
Glabella

References
External links
 Media related to Unibrows at Wikimedia Commons