Option B.6 – Hormones
B.6.1 – Outline the production and function of hormones in the body
Hormones are chemical messengers in the body, used to regulate various functions. They are produced in the endocrine glands, which secrete hormones into the blood. The hormones travel through the blood to their target cells, which have specific receptors for them. Some of the endocrine glands in the body include the pituitary gland, adrenal glands,pancreas, thyroid gland, ovaries and testes.
B.6.2 – Compare the structures of cholesterol and the sex hormones
Cholesterol and the sex hormones have very similar structures, as they are all steroids. The only difference is their respective side chains.
Cholesterol
Oestrogen
Oestrogen has an aromatic ring
Progesterone
Progesterone has a ketone group
Testosterone
Testosterone has an alcohol group
B.6.3 – Describe the mode of action of oral contraceptives
Female oral contraceptives contain the hormones progesterone and oestrogen. These reduce the secretion of follicle stimulating hormone (FSH) and luteinising hormone (LH), thereby preventing ovulation. Ovulation is when an unfertilised ovum (or egg) is released. If no ovum is released, fertilisation and pregnancy are not able to take place.
The increased levels of progesterone and oestrogen simulate the conditions during pregnancy, so it can be said that oral contraceptive ‘trick’ the body into thinking that the woman in already pregnant.
The most common form of the pill is taken each day for three weeks and then stopped for a week to allow for menstruation according to a normal cycle. Since the pill can still have side-effects, it is a prescription-only medicine in many countries, allowing doctors to monitor these side-effects.
Another form is tagged the ‘morning-after pill,’ which has higher concentrations of the hormones, preventing pregnancy if unprotected intercourse has taken place.
B.6.4 – Outline the use and abuse of steroids
Female Steroid Hormones
In addition to the pill, there are also medications that contain steroid hormones to reduce the unpleasant symptoms of menopause. This is called hormone replacement therapy
(HRT), replacing the hormones that would be secreted in menopause which cause the symptoms. However, the use of this medication must be monitored to ensure no negative side-effects occur.
Male Steroid Hormones
Male steroid hormones, or androgens, include testosterone. This can be used to treat breast cancer and testicle disorders. It is called an anabolic steroid because it promotes tissue growth. Synthetic forms are hence used to aid weight gain during recovery from debilitating disease.
Synthetic Steroids
Other forms of anabolic steroids are used by athletes to build muscles and increase endurance. However, this presents medical problems, causing changes to secondary sexual characteristics, including hair distribution, sexual desire and fertility. They are also toxic to the liver, linked to liver cancer.
Most sporting bodies have banned the use of steroids due to the ethical issues they present, and the health problems that can ensue. Urine testing for such drugs is common at sporting events.