affects our whole body. Understanding can place us more in touch with the miracles going on within our cells each day. Endometriosis has the ability to mess up what should be a perfectly normal reproductive system, causing the wrong hormonal messages to be sent. The body always tries to get things right, so we have to enhance what it is attempting to do by natural means wherever possible.
THE REPRODUCTIVE SYSTEM
The menstrual or reproductive cycle of women is a complex process that involves many different endocrine glands and the hormones they secrete. These hormones all work together in a 28-day menstrual cycle that prepares the uterus for a possible pregnancy.
Women menstruate for about 40 years of their life. It is during this stage of their life that the symptoms of endometriosis will appear. The normal age for a girl’s first period (menarche) occurs between 9.1 and 17.7 years with a median age of 12.8, while a woman’s last period (menopause) occurs between 48 to 55 years with a median age of 51.4.
What is fascinating is that when women are assembled together, such as in schools, colleges and hospitals, their menstrual cycles align so that they all have a period at the same time. This is felt to be due to pheromones and an olfactory link to the pituitary gland.
The major organs of the reproductive system are the hypothalamus, pituitary gland, thyroid, ovary, uterus (womb), endometrium and Fallopian tubes. To understand how the menstrual cycle works, we need to look at where the various endocrine glands are located (figure 2.1). The glands control the whole reproductive cycle. People often assume that only the uterus and ovaries are involved. However, several endocrine glands control the system and they trigger the menstrual cycle. After we have familiarized ourselves with the reproductive system, this chapter will discuss how the glands and the hormones they produce interact during the reproductive cycle, and how endometriosis interferes with this cycle.
THE ENDOCRINE SYSTEM
It is the correct balance of hormones that controls this whole system. The endocrine system is scattered throughout the body and usually works perfectly, sending hormone messages from one gland to another via the bloodstream. Occasionally this system may go wrong and a polyendocrine disorder, where one or more glands are affected, can lead to illness. The thyroid, pancreas, adrenals and ovaries may all malfunction under stress.
HYPOTHALAMUS AND PITUITARY GLAND
The control centre for the reproductive cycle is the hypothalamus and the pituitary gland in the brain. The hypothalamus secretes hormones (chemical messengers) which control the timing and the amount of hormone produced by the pituitary gland in the brain (figure 2.1). The pituitary gland can be viewed as the ‘master gland’ of the endocrine system, since its hormones orchestrate the activity of most of the other endocrine glands of the body, including the ovaries in women and testes in men. Think of the pituitary gland as the conductor of the orchestra, wielding the baton, telling the other glands what to do and when.
The pea-sized pituitary gland nestles in a bony cavity at the base of the skull (figure 2.2). It has a rich blood supply that allows it to distribute its hormones rapidly throughout the body. The pituitary gland is divided into two parts: the anterior and posterior pituitary.
1 The anterior pituitary secretes several protein hormones which affect a variety of glands and tissues of the body. However, the two major hormones of the anterior pituitary that affect the reproductive system are follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These two hormones control the activity of the ovaries, and are very important controls for fertility.
2 The posterior pituitary also secretes several protein hormones. Oxytocin is the hormone that most directly affects the reproductive system. Oxytocin causes the smooth muscle of the uterus to contract during the birthing process. Oxytocin production is dependent on sufficient levels of the mineral manganese. It is thought to be important for bonding at birth and oxytocin levels are known to be increased in the brain when we fall in love.
Figure 2.1
Diagram of the major endocrine organs involved in endometriosis, infertility and the menstrual cycle.
THE THYROID GLAND
The thyroid is dealt with in detail in chapter 10. This gland can have an effect upon fertility; and lower than normal thyroid hormone levels (hypothyroid) cause infertility in both men and women. Indeed, auto-antibodies to the thyroid are used to predict which women are at risk from miscarriage.
Oestrogen acutely inhibits the rate of thyroid hormone release in adults.1 In subclinical hypothyroidism, abnormal circadian TSH rhythm, elevated basal serum TSH concentrations and elevated titres of antithyroid antibodies are frequently seen.2 Women with mild hypothyrodism have prolonged and heavy menstrual bleeding with a shorter menstrual cycle.3 The thyroid enlarges in pregnancy and takes up more iodine as it makes more thyroxine.
THE OVARIES
The ovaries contain the female sex cells, also known as oocytes or eggs (see figures 2.2 and 2.3). All of the eggs that a woman has in her ovaries were produced while she was developing as a fetus in her mother’s womb. The health of each egg inside a baby girl is therefore dependent upon the health of the mother. When a female fetus develops in her mother’s uterus, her eggs increase in numbers until the seventh month of pregnancy, and then their numbers decline throughout the remainder of the pregnancy and throughout her life. As many as seven million eggs are present in a female fetus by the seventh month of pregnancy, but there are fewer than one million eggs at birth.4
From birth to puberty, the number of eggs declines further, from one million to about 400,000, which is the total number of eggs available to a woman during her reproductive years. During the reproductive years one egg is selected every month to develop to a stage that allows for ovulation, fertilization and conception. When a woman reaches 50 to 55 years of age, the supply of eggs is exhausted and the reproductive cycle stops. This is, of course, the time of natural menopause.
At any given time, two major structures, each about 1cm in diameter, can be seen within the ovary – the follicle and the corpus luteum (figures 2.2 and 2.3). Each follicle contains an egg surrounded by granulosa cells or ‘nurse cells’. During the menstrual cycle the follicle becomes filled with follicular fluid and looks like a small cyst, about one centimetre in diameter. The granulosa cells of the follicle secrete the steroid hormone oestrogen; the corpus luteum produces the hormone progesterone.
Oestrogen has several roles:
1 It stimulates the endometrium to grow from day 1 to 14 of the cycle and replace the endometrial cells that were shed during menstruation. It is produced in the follicle of the ovary and in fat cells, and by the adrenal glands.
2 It enhances the contractions of the uterus and is required during the birthing process.
3 Too much oestrogen acts as an abortant. Too much produced very early in the pregnancy and not balanced by sufficient progesterone from the corpus luteum could trigger the loss of the pregnancy, as it is an abortive in high doses.
4 It increases the levels of neurotransmitters in the brain, improving mood and memory. If oestrogen is out of balance, it can trigger mood swings.
5 It is synthesized in the ovary from cholesterol, and secreted from the granulosa cells inside the follicles, the corpus luteum and the placenta.
6 It causes the liver to produce hormones.
7 It increases cholesterol production, produces weight gain and determines fat distribution.
8 It causes cell proliferation.
9 It