Insulin signal transduction pathway is secreted after glucose enters the beta cell and that triggers several other processes in a chain reaction. While insulin is secreted by the pancreas to lower blood glucose levels, glucagon is secreted to raise blood glucose levels. This is why glucagon has been known for decades as a counter-regulatory hormone. When blood glucose levels are low, the pancreas secretes glucagon, which in turn causes the liver to convert stored glycogen polymers into glucose monomers, which is then released into the blood. This process is called glycogenolysis. Liver cells, or hepatocytes, have glucagon receptors which allow for glucagon to attach
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)