Video Transcript
The pituitary gland secretes growth
hormone, GH, and thyroid-stimulating hormone, TSH, both of which influence growth
and development. Do these hormones have the same
target tissues? (A) No, TSH acts only on the
thyroid, while GH acts on all tissues of the body. Or (B) yes, both TSH and GH act on
all tissues of the body.
This question asks us to
differentiate between the target tissues of two hormones secreted by the pituitary
gland: thyroid-stimulating hormone, TSH, and growth hormone, GH. In order to answer this question
correctly, let us review the pituitary gland and its functions.
The pituitary gland is an endocrine
gland, which means it releases hormones. And it’s located just under the
brain, as you can see here. Despite its very small size, the
pituitary gland is often considered the master gland. This is because it has numerous
effects on organs and tissues and also because it controls the activity of other
endocrine glands in the body. It secretes various types of
hormones that regulate many different bodily functions such as growth, metabolism,
reproduction, blood pressure regulation, or even our emotions.
Now let’s have a look at these two
hormones, which are both secreted by the anterior, or front, lobe of the gland,
starting with thyroid-stimulating hormone, or TSH. The primary target of TSH, as
indicated by its name, is the thyroid gland, which you can see here. TSH stimulates the thyroid gland to
produce more of its own hormones, the main one being thyroxine, which is also called
T4. Thyroxine regulates, among others,
our temperature, heart rate, and metabolism.
Now, growth hormone, or GH, is also
released by the anterior pituitary. But its target tissues are much
more varied and they are not limited to another endocrine gland of the body. In fact, GH acts on pretty much all
the tissues within our body, our muscles and bones, for example, and it stimulates
the growth of these tissues.
As our question asks if these
hormones have the same tissue target, the correct answer is (A). No, TSH acts only on the thyroid,
while GH acts on all tissues of the body.
