Interactive Physiology Worksheet:
Endocrine System: Biochemistry, Secretion, and Transport of Hormones
1. Place the following hormones into one of the three categories of hormones (peptides, amines, or
steroids): T4 (thyroxine), estradiol, norepinephrine, insulin, aldosterone, glucagon, cortisol, growth
hormone, T3 (triiodothyronine), epinephrine, testosterone, and vasopressin (ADH).
Peptides Amines Steroids
2. Peptide hormones are synthesized as large precursor hormones called __________________.
The hormones (or prohormones) are stored in _________________ __________________ and
released from the cell by _______________________. Do peptide hormones require a carrier in the
bloodstream? _____________________________________________________
3. Catecholamines are produced in the ____________________ of the adrenal gland and are –
classified as _________________ hormones because they are derived from __________________.
Stimulation of the chromaffin cells causes an influx of ____________________ ions, which causes the
vesicles to merge with the plasma membrane and release the hormone by ____________________.
Are catecholamines water soluble or lipid soluble? ________________________________________.
4. Thyroid hormones include two molecules called __________________ and _________________.
T3 consists of two _______________ molecules plus _____ iodine molecules and is _______________
abundant than T4. Are carriers required for the transport of thyroid hormones?
________________________________________________
5. All steroid hormones are derived from _____________________; which steroid hormone is
produced is determined by the _________________ present in the cell. The common precursor
molecule for all steroid hormones is ______________________. Steroid hormones enter the
Page 1 of 2 BIO1014 Anatomy and Physiology II Lab
© 2013 South University
bloodstream by _______________ and ________________ require a carrier. The rate of secretion of
steroid hormones is ______________________ than that of catecholamines because steroid
hormones are not ______________________.
6. Preganglionic sympathetic fibers trigger the release of ___________________ and
____________________ (hormones) from the ________________ ________________ (gland). This is
an example of neural regulation of hormone secretion.
7. Two examples of hormonal regulation of hormone secretion include: (1) the negative feedback
of T3 and T4 to decrease ________________ levels; and (2) the negative feedback of cortisol, which
decreases both _________________ and ________________________ levels.
8. Besides increased levels of plasma glucose and amino acids (humoral regulation), increased
levels of ____________________ (hormone) and stimulation of the __________________ nervous
system also increase plasma insulin levels.
9. Some hormones are released in rhythmic 24-hour patterns known as ______________________
rhythms. _________________________ is a hormone allowing stressful stimuli to override this
pattern and increase the plasma hormone levels. In contrast, _________________ hormones (amine
hormones) are an example of large amounts of the hormones being bound to carrier proteins in the
plasma, forming a large circulating reservoir. Thus, acute changes do not produce large changes in
the plasma levels of these hormones.
10. The _____________________ and ______________________ are the major organs that
metabolize hormones. The type of hormone determines how fast they are metabolized.
__________________ and _______________________ are rapidly metabolized, while
__________________ and _____________________ take longer to metabolize.
Page 2 of 2 BIO1014 Anatomy and Physiology II Lab
