Hormones Essay Example | Topics and Well Written Essays - 500 words

Hormones - Essay faceWhen calcium levels fall below 9mg/100 ml of blood, the parathyroid gland is stimulated to release the parathyroid ductless gland or PTH. This endocrine gland stimulates the activity of osteoclasts to break bone and bone matrix down so as to release more calcium into the blood. It acts on PTH 1 receptor in the kidney and bone, as surface as PTH 2 receptor on the testis, pancreas and nervous system to increase calcium levels. Parathyroid hormone has a half life of four hours after which it decreases its own production by dint of a contradict feedback mechanism when calcium levels stabilize (Bronner, 2012 p45).Oxytocin acts on various body organs, including the uterus and breasts, especially as a mediator of human behaviour, lactation and, in this case, confinement and childbirth. It is controlled via a positive feedback mechanism, in which the hormones release leads to an action that stimulates additional release of oxytocin. When uterine contractions begin , for instance, oxytocin release is mediated through positive feedback, in which release of oxytocin leads to more release of the same (Poulain et al, 2012 p55). This mechanism allows for the uterine contractions during labour and childbirth to increase in frequency and intensity, which stops at childbirth.A rats testicles, in comparison to human testicles, are much larger, which is because they have patterns of mating that involve multiple males breeding with females as they come into heat. In addition, they produce more sperm to increase the odds that they will be successful. some other difference between testes in humans and rats is that the testes form part of a urogenital aperture in rats, which is not the case for humans (Soder, 2013 p66). Finally, the testes of rats can retract back to the abdominal cavity when they are not breeding, which is not the case for