endocrine system Flashcards
endocrine system
A system of glands that are responsible for the release of hormones into the bloodstream. These hormones then regulate the activity of cells or organs in the body.
feedback
The endocrine system is regulated by feedback to ensure stable concentration of hormones, e.g. a signal is sent from the hypothalamus to the pituitary gland in the form of a ‘releasing hormone’.
Causes the pituitary gland to secrete a ‘stimulating hormone’ into the bloodstream. This hormone then signals the target gland to secrete its hormone.
As levels of this hormone rise in the bloodstream, the hypothalamus shuts down secretion of the releasing hormone and the pituitary gland shuts down secretion of the stimulating hormone.
This slows down secretion of the target gland’s hormone, resulting in the stable concentration of hormones circulating the bloodstream.
pituitary gland
The ‘master gland’.
Produces hormones whose primary function is to influence the release of hormones from other glands, and in so doing regulate many of the body’s functions.
Controlled by the hypothalamus, a region of the brain just above the pituitary gland.
adrenal gland
Sit on top of the kidneys.
Two parts - the outer part = adrenal cortex, and the inner region = adrenal medulla.
The adrenal cortex and adrenal medulla have very different functions.
One of the main distinctions is that the adrenal cortex releases hormones necessary for life, whereas the adrenal medulla releases hormones that are not.
hormones
Behaviour is influenced by hormones, and each hormone has a different effect.
There has to be particular receptors for particular hormones. Cells that don’t have such a receptor cannot be influenced directly by that hormone. When enough receptor sites are stimulated, this results in a physiological reaction in the target cell.
thyroid
secrets thyroxine which increases metabolism and regulates growth
