Endocrine System: Biochemistry, Secretion and Transport of Hormones

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 (thyroxin), estradiol, norepinephrine, insulin, aldosterone, glucagon, cortisol, growth hormone, T3

(triiodothyronine), epinephrine, testosterone and vasopressin (ADH).

Peptides

Steroids

Insulin

Glucagon

Growth Hormone

Vasopressin (ADH)

2.

Amines

Norepinephrine

Epinephrine

Triiodothyronine (T3)

Thyroxin (T4)

Estradiol

Aldosterone

Cortisol

Testosterone

Peptide hormones are synthesized as large precursor hormones called _Preprohormones_. The

hormones (or prohormones) are stored in _Secretory_ Vesicles_ and released from the cell by

_Exocytosis_. Do peptide hormones require a carrier in the blood stream? No.

3.

Catecholemines are produced in the _Medulla_ of the adrenal gland and are classified as _Amine_

hormones since they are derived from _Tyrosine_. Stimulation of the chromaffin cells causes an influx

of _Calcium_ ions, which causes the vesicles to merge with the plasma membrane and release the

hormone by _Exocytosis_. Are catecholemines water-soluble or lipid-soluble? Water-soluble.

4.

Thyroid hormones include two molecules called _T3_and _T4_. T3 consists of two _Tyrosine_

molecules plus _3_ iodine molecules and is (more or less) abundant than T4. Are carriers required for the

transport of thyroid hormones? Yes.

5.

All steroid hormones are derived from _Cholesterol , which steroid hormone is produced is determined

by the _Enzymes_ present in the cell. The common precursor molecule for all steroid hormones is

_Pregnenelone_. Steroid hormones enter the blood stream by _Diffusion_ and __Do_ (do or do not)

require a carrier. The rate of secretion of steroid hormones is (faster or slower) than catecholemines

because steroid hormones are not _Stored in Secretory Vesicles_.

6.

Preganglionic sympathetic fibers trigger the...