- know that growth hormone is secreted in a pulsatile fashion
- know when growth hormone levels are at their peak in the human body
- know some other stimuli that can effect growth hormone secretion besides our circadian rhythms (biological clock)
This packet covers the regulation of growth hormone secretion
In the early days of endocrinology scientists used to believe growth hormone stopped being secreted altogether once we finished growing. *This obviously is not true, thanks to research science, but growth hormone levels do decline as we age to about 25% of our adolescent levels once we reach old age.
Growth hormone is secreted on a regular basis during the day; its peak levels are reached about 2 hours into our deep sleep. The hypothalamus regulates growth hormone secretion by using specific releasing and inhibiting hormones called growth hormone-releasing hormone and growth hormone inhibiting hormone (somatostatin). It is believed that growth hormone is controlled more by the releasing hormone than by the inhibiting hormone. Another thing to keep in mind is what happens to these if a person takes growth hormone injections. Growth hormone injections to hinder the body's natural production of growth hormone by influencing the levels of the inhibiting and releasing hormones. If a person takes growth hormone injections in the blood this will cause the hypothalamus to decrease its production of these hormones and greatly hinder a person's natural ability to make growth hormone on their own. This could make a person dependent on growth hormone injections for more than cosmetic purposes if they aren't careful.
There are other stimuli which influence growth hormone levels in the body that I'll highlight here and elaborate more on within the video below:
* Hall, Arthur C Guyton. Textbook of Medical Physiology. Philadelphia: Elsiver Saunders, 2006. Print
Source: Mind of Aaron
Source: Self made
Source: Self made