Peptide hormone growth hormone, which acts on bone, muscle, and the liver. The posterior pituitary gland secretes antidiuretic hormone, also called vasopressin, and oxytocin. The parathyroid gland secretes parathyroid hormone, the main hormone responsible for regulating serum calcium and phosphorus levels. Peptide hormones are also produced by many different organs and tissues, including the heart (atrial-natriuretic peptide (ANP) or atrial natriuretic factor (ANF)) and pancreas (glucagon, insulin and somatostatin), the gastrointestinal tract (cholecystokinin, gastrin), and adipose tissue stores (leptin). Peptide hormone Peptide hormones or protein hormones are hormones whose molecules are peptides or proteins, respectively. The latter have longer amino acid chain
Uropygial gland nine families of birds lack a uropygial gland, mostly the ones unable to fly or the ones that produce powder down for feather maintenance. These include kiwis ("Apterygidae"), emu ("Dromaiidae"), ostriches ("Struthionidae"), rheas ("Rheidae"), cassowaries ("Casuariidae"), mesites ("Mesitornithidae"), bustards ("Otididae"), pigeons and doves ("Columbidae"), amazon parrots ("Psittacidae"), frogmouths ("Podargidae"), and woodpeckers ("Picidae"). These birds typically find other means to stay clean and dry, such as taking a dust bath. Researchers have been unable to correlate the presence or absence of the uropygial gland with factors such as distribution, climate, ecology, or flightlessness. The uropygial gland secretes an oil (preen oil)