The Endocrine System
Every living being has an endocrine system that consists of a number of glands: the hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, adrenals, pancreas and gonads. Endocrine means to secrete within.
These endocrine glands are ductless and they produce and secrete hundreds of hormones directly into your blood stream. These hormones each have their own purpose in a specific target organ like the liver, kidneys, brain etc. Hormones are special chemical substances. The word “hormone” means “to spur on”.
You may have heard about chemical imbalances, usually referred to in context of the brain. What this means is that the hormones are not balanced. The only way you can know this is by the proper testing of your hormones. There is nothing mysterious about it, despite the fact that it may leave a person feeling like they have some mysterious disease or genetic fault.
Hormones are biochemical substances that get secreted by your glands into your bloodstream and travel to target organs so those organs can carry out their own specialized function. Many people associate hormones only with sex hormones but there are hundreds of other hormones, each with their own special function.
Functions regulated by hormones include metabolism (the breaking down or building of chemical elements); water and mineral balance; growth and sexual development; and the body’s reaction to stress; digestion of food, sleep, and many more.
Definition of biochemical: bio- comes from the Greek word meaning “life” and a chemical is any substance that can undergo a chemical process or change.
Each hormone has a different shape as it has to be able to “dock” into the “receptor site” of the target organ. Not only does this hormone have to “dock” into the receptor site but it also has to “turn” like a key. You’ve probably experienced this. You have a key that goes into the lock perfectly but won’t turn because it’s the wrong key? In the same way, these hormones have to “dock” and “turn” to fully complete their task or to “open the door”.
That’s why synthetic hormones can cause problems. The hormones can “dock” but can’t “turn” the “key”. It is vital for a healthy body that these “keys” can turn so that the proper hormones can be sent to the target organs to carry out the hundreds of body functions such as sleep, digestion, energy, metabolism, falling pregnant, delivering the baby, controlling weight etc.
Some hormones come in “opposing” pairs or what is known as antagonistic pairs. In other words, they oppose each other. For example, if your blood sugar goes too high, insulin (a hormone) will tell your liver to lower your blood sugar but if it drops too low, glucagon (another hormone) will tell your liver to raise your blood sugar.
This is so your body can maintain an optimum balance known as homeostasis. Homeostasis is the ability or tendency of an organism or cell to maintain internal equilibrium – balance – by adjusting its physiological processes regardless of external influences. Your body will do everything it can to maintain homeostasis.
The Different Glands of the Endocrine System
Listed below are the glands that form part of your endocrine system. Definitions for each one are covered lower down.
8. Pancreas (partly gland, partly organ)
9. Gonads (ovaries and testes)
Constantly living under conditions of stress, excesses, trauma, hazards, pollution, drugs (medical and other) and chemicals eventually weakens and undermines the efficient functioning of these glands. So, let’s get to understand their functions. Hormones are very powerful chemicals and when they are in sync and in the right quantity, the body purrs. These tiny glands are small wonders and they need to be in good working condition to maintain good health.
The Master Hormone Gland – The Pituitary – And Its Connector – The Hypothalamus
The hypothalamus is a portion of the brain that links the nervous system to the endocrine system via the pituitary gland. It is called “hypo”-thalamus because it is below the thalamus which is an area of the brain where pain and other sensory information is interpreted and recognized.
The secretion of hormones from the anterior (front portion) pituitary is controlled by the production of hormones by the hypothalamus, which can be split roughly into two main types of hormones:
• hormones that tell the pituitary to switch on production of a hormone (a releasing hormone); and
• hormones that tell the pituitary to switch off production of a hormone (an inhibiting hormone)
The hormones secreted by the posterior pituitary are produced in the hypothalamus and then passed down a tube between the hypothalamus and the pituitary (the pituitary stalk) from whence they are then secreted into the blood.
The hypothalamus’ hormones cause smooth muscle to contract, control water balance, are responsible for breast milk, the body’s temperature control, gastric reflexes, maternal behavior, blood pressure, feeding, immune responses. They’re also responsible for manufacturing neurotransmitters that allow the messages to be passed along the nervous system.
The pituitary puts out hormones that break down stored fat, increase the production of protein and muscles, and stimulate all junior glands such as the ovaries, testicles, thyroid and adrenals. It also contracts the uterus during childbirth and stimulates milk production.
The pituitary is known as the master gland, the top executive of your hormonal system. It is no larger than a pea, is located in the brain and has two sections called the anterior and posterior – anterior means toward the front and posterior towards the back. These two sections of the pituitary gland produce a number of different hormones which act on different target glands or cells. Hormones produced by them are:
* Adrenocorticotrophic Hormone (ACTH)
* Thyroid-Stimulating Hormone (TSH)
* Luteinising hormone (LH)
* Follicle-stimulating hormone (FSH)
* Prolactin (PRL) * Growth hormone (GH)
* Melanocyte-Stimulating Hormone (MSH)
* Posterior Pituitary
* Anti-diuretic Hormone (ADH)
When a body has abnormally low or high levels of hormones, it indicates a possible problem with the hormone boss, the pituitary gland.
The Pineal Gland – Your Body’s Night/Day Switch
The pineal gland is situated in the middle of your brain and is about the size of a pea. It is a light-sensitive organ that produces a hormone called melatonin when it’s dark. Human beings start producing melatonin from as early as 3 months old and continue until about the age of 20 years at which point production begins to decrease.
Melatonin is the hormone that influences sleep!
It also affects temperature, helps to fight a wide range of cancers and guards the nervous system against degeneration from such things as Alzheimer’s disease and strokes. Being low on melatonin can cause such things as depression, bone loss, insomnia, fibromyalgia, some seizure disorders and migraines.
For melatonin production to occur, it is important to go to bed without any lights, electronic equipment of any sort – including TV’s, cell phones, computers etc – in the room. The darker it is the better for melatonin production. Lights can prevent it from being produced.
Since the advent of all the modern electronic devices and lighting, more people than ever experience problems with insufficient melatonin production and, as a result, sleep.
If you’re having difficulty sleeping, make sure your room is dark, has no electric clock, TV, computer, cell phones or any other electronic devices in it. In fact, make your bedroom into a space of tranquility and keep all devices in other parts of your home.
The other important factor is that you need enough sleep. Your body repairs itself during sleep. Just like you can’t drive your car while it is in the repair shop, so your body needs to be inactive and resting for repair to take place so get enough sleep. Ideally, bodies need about 9 – 10 hours of melatonin production per day. This means that the light going into your eyes needs to be low to none for 9 – 10 hours per day. When a body has abnormally low or high levels of hormones, it indicates a possible problem with the hormone boss, the pituitary gland.
The Thyroid Gland – Your Metabolism Controler (And Energy Producer)
The word thyroid merely means “shield-shaped”. Look at pictures of the thyroid and you will see why this is so. It produces hormones which do two important things:
1. They help the necessary enzymes and electrolytes pass into the cell 2. They help the actual processes of energy production in the mitochondria. (See below for definition.)
Your metabolism – the rate at which you produce and use energy – is regulated by the pituitary and thyroid glands, and the hypothalamus (in the brain), but the actual energy release occurs inside the body’s individual cells. It is here that the thyroid’s role is actually felt. Each cell has an “energy-generating station” called the mitochondrion, which uses enzymes to combine carbon, hydrogen, and oxygen atoms, forming carbon dioxide and water, and releasing chemical energy.
The thyroid produces four hormones – T4 (thyroxine), T3 (tri-iodothyronine or liothyronine), T2 (di-iodothyronine), and T1 (mono-iodothyronine) – and these regulate all the processes of energy release within the body’s cells.
Some symptoms of poor thyroid function include:
• feeling tired and sleeping a lot
• feeling the cold easily
• dry and/or pale skin
• coarse, thinning hair and brittle nails
• sore muscles, slow movements and weakness
• a hoarse or croaky voice
• a change in facial expression
• problems with memory and concentration
• weight gain
• fertility problems and increased risk of miscarriage
• heavy, irregular or prolonged menstrual periods
• a slow heart rate
Overactive and underactive thyroid
The opposite condition to hypothyroidism is hyperthyroidism. This happens when the thyroid is overactive and produces too much thyroid hormones. This speeds up your body’s metabolism, leading to symptoms such as weight loss and anxiety.
Iodine Deficiencies or Insufficiencies
The body needs iodine, which is a mineral, to make thyroid hormones. Deficiencies or insufficiencies of iodine are the leading cause of hypothyroidism – underactive thyroid.
Parathyroid Glands – Your Calcium Regulators
The parathyroid glands are four small glands located in the neck behind the thyroid. (The prefix “para-“ simply means alongside of, beside, near, resembling, beyond, apart from, or abnormal.)
The thyroid and parathyroid are NOT related. The parathyroid glands are named because they are adjacent to the thyroid. They’re behind the thyroid but have completely unrelated functions.
The ONLY purpose of the parathyroid glands is to regulate the calcium level within a very narrow range in the body so that the nervous and muscular systems can function properly. That’s all they do. No other element in your body has its own personal regulator but calcium balance is that important that it got one. This does not mean that the other minerals are not also vital for life.
The parathyroid glands measure the amount of calcium in the blood every minute of every day and if the calcium levels go down a little bit, the parathyroid glands note it and make parathyroid hormone (PTH) which goes to the bones and withdraws calcium (makes a withdrawal from the calcium vault) and puts it into the blood. When the calcium in the blood is high enough, then the parathyroids shut down and stop making PTH.
The Adrenal Glands – Your “Stress” Glands
The adrenal glands are small, triangular glands located above both kidneys. They are separate glands to the kidneys but take their name from being close to the kidneys (or renals as the kidneys are also known, hence the word ad-renal). The adrenal glands work interactively with the hypothalamus and pituitary glands in the following process:
1. Help the hypothalamus produce certain hormone-releasing hormones (corticotropin-releasing hormone), which stimulate the pituitary. 2. Help the pituitary, in turn, to produce the necessary hormones (corticotrophin hormones) that stimulate the adrenal glands to produce cortisol.
The adrenal glands consist of two parts, the cortex or outer portion and the medulla, the inner portion.
The adrenal cortex (the outer portion) releases:
1. Corticosteroid hormones: a. Hydrocortisone hormones, also known as cortisol, controls the body’s use of fats, proteins and carbohydrates. b. Corticosterone which, together with cortisol, suppresses inflammatory reactions in the body and also has an effect on the immune system. 2. Aldosterone hormone which inhibits the level of sodium excreted into the urine, maintaining blood volume and blood pressure. 3. Androgenic steroids (androgen hormones) which have a minimal effect on the development of male characteristics.
The adrenal medulla (the inner portion of the adrenals) releases:
1. Epinephrine (also called adrenaline) increases the heart rate and force of the heart contractions, facilitates blood flow to the muscles and brain, causes relaxation of smooth muscles, helps with conversion of glycogen to glucose in the liver – plus other activities. 2. Norepinephrine (also called noradrenaline) has strong vasoconstrictive (vaso = blood vessel and constrictive = constriction). effects, thus increasing blood pressure.
The Thymus Gland
The thymus gland is a relatively unknown gland so there is not much to say about it other than that it is very involved in immune function. It is a pink-grey organ that lies underneath the top of the breast bone.
The thymus processes a type of white blood cell known as a T-lymphocyte. These T-lymphocytes govern cellular immunity which means they help cells recognize and destroy invading bacteria, virus, etc as well as abnormal cell growths such as cancer and foreign tissue.
The thymus gland is involved in antibody production. When you are exposed to bacteria, your thymus gland should immediately get the lymphatic system to start producing antibodies. It takes about seven days to completely produce enough antibodies to destroy the bacteria.
As we get older, our thymus gland tends to dry up. It’s not as active as it was when we were younger. A child has a large thymus gland, often twice the size of an adult’s. As we get older, we tend to lose the ability to build antibodies. If a person has an infection that lasts more than seven days, his antibody production is not at full strength.
To be continued ……