B6 Hormones

B.6.1 Outline the production and function of hormones in the body.

Hormones are chemical messengers in the endocrine system. They are secreted directly into the blood by endocrine glands. Examples include ADH, aldosterone, estrogen, progesterone and testosterone, insulin, epinephrine (adrenaline) and thyroxine.

Some are proteins/steriods/modified amino acids/ fatty acids

Hormones circulates body, but only brings out responses in their target cells (cells that only have receptors for them)

Summary of important hormones and their functions and target cells
Source: IB Chemistry Textbook

B.6.2 Compare the structures of cholesterol and the sex hormones.

Stress the common steroid backbone but the difference in functional groups.

Both steriod based and have similar structures

- 4 fused hydrocarbon ring

- but different side chains and functional groups = different properties

e.g. sex hormones

Comparison of the structure of cholesterol and the sex hormones
Source: IB Chemistry Textbook

Estradiol (estrogen)

- benzene ring

- 2 OH groups (hence called '-diol')

Progesterone is only slightly different to testosterone

- there is a ketone in place of a OH group

B.6.3 Describe the mode of action of oral contraceptives.

One of the most effective methods

- prevents ovulation

- contains progesterone and estrogen, acts to suppress secretion of other hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone) which usually triggers ovulation

- basically stimulates hormonal condition of a pregnancy

- in many countries, its only available through doctor prescription, so side-effects can be monitored

'Morning after' pill

- higher concentration of hormones

- may prevent pregnancy from unprotected intercourse

- only for emergency use

B.6.4 Outline the use and abuse of steroids.

Female steroid hormones (like oral contraceptives)

- prescribed also to alleviate menopausal symptoms

- called HRT (hormonal replacement therapy), hormones replace those secreted prior to menopause (also monitored for side-effects)

Male steroid hormones (called androgens)

Testosterone

- used in treatments for disorder of testes and breast cancer

- also called anabolic steriods, promotes tissue growth especially in muscles

- synthetic forms used medically to help gain weight after debilitating diseases

Modified synthesis forms

- athletes: build up muscles, increase endurance

Medical + ethical issues

- anabolic steriods can cause many changes in secondary sexual characteristics because of systemic hormone changes e.g. hair distribution, sexual desire, fertility

- hormones are toxic to the liver and increases risk of liver cancer