Hormones elicit physical responses in the body (e.g., growth, mobilization of the immune system against stress, maintenance of balance in blood chemistry, and control of the use of oxygen). The endocrine system integrates other body functions through its hormonal control. The endocrine system is much like the nervous system in terms of controlling the body, but with a significant difference - the endocrine system is much slower than the nervous system, so it regulates slower processes, like metabolism and cell growth; whereas, neurological functions are nearly instantaneous, like muscle contractions.
Endocrine cells are located differently than other organs/systems in the body. They reside both in their own organs (like the pituitary gland at the base of the brain, the pineal gland in the brain, the thyroid and parathyroid glands in the neck, and the adrenal glands on the kidneys); and in other organs/systems like the pancreas, thymus, and gonads, among others, including the hypothalamus in the brain.
Endocrine glands have liberal blood supplies to help distribute released hormones. Endocrine cells are generally located close to capillary beds, where they can easily get into the bloodstream for bodywide distribution.
Hormones generally fall within one of two molecular categories: 1) amino acid based molecules, or 2) steroid molecules.
Amino-acid based hormones include modified amino acids (amines), peptides (short-chain amino acids), and long-chain amino acids.
Steroids, on the other hand, are lipid (fat) molecules produced from cholesterol.
As previously stated, most hormones circulate through the body in the bloodstream. They enter nearly all body tissue, through capillaries; but each hormone acts only on specific tissues - target cells. Cells have receptors which attract only a specific hormone. Hormones act only as they are programmed by their target cells. In other words, hormones are triggers, but carry no information.
Hormone secretion occurs in three ways. One is from endocrine glands precipitated by changing ion or nutrient levels in the blood. An example is the famous "fight or flight" syndrome, which is triggered by nerve impulses that result in release, in the brain, of epinephrine and norepinephrin. The third cause of hormonal release comes from release of hormones from other sources within the body (i.e., the job of some hormones is just to release other hormones).
Regardless of the stimulus, hormone secretion is "turned off" by a process called "negative feedback." More simply put, hormone levels are allowed to reach a predetermined level, at which point, further secretion is strictly controlled in order to remain within a specific range in the blood.
Pituitary Gland
This important endocrine organ, about the size of a pea, secretes at least nine major hormones.
In females, FSH and LH stimulate maturation of ovarion follicles, and secretion of estrogen and progesterone. Also, during menstruation, a large amount of LH is released to induce ovulation. In males, LH signals the secretion of androgens - mainly testosterone - and FSH stimulates maturation of sperm cells and secretion of sex hormones.
This gland, located in the neck, is the largest endocrine gland, and has a very large blood supply.
The main task of the thyroid gland is to produce and secrete thyroid hormone (TH ) called thyroxine, of which there are two forms: T3 and T4. They are constructed of a pair of amino acids and contain iodine. The primary job of TH is to increase the basal metabolism rate (BMR), now often called resting metabolism rate (RMR)). Abnormal TH production causes hyperactivity, nervousness, a constant feeling of warmth; or sluggishness, and a feeling of being cold.
The Parathyroid Glands
They are attached to, or next to, the thyroid gland, but are distinctly separate.
The parathyroid hormone (PT, or PTH) increases calcium in the blood when its level falls below its norm. As you all know, calcium is intimately involved in muscle contractions; therefore, an inadequate amount causes neuro-muscular malfunctions - potentially death. An inadequate calcium supply is "shored up" by: 1) calcium release from bone, 2) more calcium saved from the kidneys - it doesn't get urinated away, and 3) vitamin D is activated, which promotes calcium absorption. Don't worry, there is also a way that too much calcium is avoided - calcitronin, which is produced in the thyroid gland, reduces it.
The Adrenal Glands
These glands (now sometimes called suprarenal glands) "sit" on top of the kidneys and help us humans deal with bigtime stress - danger, terror, really scary stuff.
A primary function is to secrete catecholamines (epinephrine and norepinephrine that elicit the legendary "fight-or-flight" response).
In addition, a number of steroid hormones are secreted (corticosteroids): sex hormones, aldosterone (which is secreted in response to a low blood volume or pressure, and results in collection of water and sodium in the blood), glucocorticoids (which help weather stress by keeping high glucose levels available for the brain, and, at-the-same-time forcing other body cells to switch to fats and amino acids for food). Too many glucocorticoids depress inflammatory response and inhibit immune system activity.
The Pineal Gland
This gland secretes the hormone melatonin, which helps regulate our circadian rhythms (like the sleep-wake cycle).
The Pancreas
This is the house of A-cells, which secrete glucagon, which tells the liver to release glucose from stored glycogen to raise blood sugar levels when they go too low; and B-cells, which secrete insulin, which tells body cells to collect glucose from the blood, and thereby lower high blood sugar levels.
The Thymus
This organ builds T-cells - immune cells. The thymus is most active in children, and shrinks with age; although it remains active, to some extent. This organ works at helping T-cells to mature - gain immunocompetence .
The Gonads
These are the main source of the steroid sex hormones - mainly testosterone, estrogen, and progesterone. Testosterone maintains male sex organs, secondary sex characteristics, and sperm production. In females, estrogen and progesterone maintain reproductive organs, secondary sex characteristics, and signal the uterus to prepare for pregnancy.
As previously mentioned, some endocrine cells are scattered around in the body in non-endocrine organs. They are the:
When you breathe,
you inspire.
when you don't breathe,
you expire.
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I recently came across an article about Nike, which has convinced me to boycott their products, and to speak out against them. I have no corroborating evidence that the allegations are true, but somehow I do believe them, at least until proven otherwise. The American way, you know. It isn't, you say. Well, I learned it from an official government source - the IRS.
Here is a summary of the article, published in the July 7, 1996 San Jose Mercury News The author claims that Nike was started by Phil Knight with a $500 investment, and that it is now worth $4.5 billion.
Allegedly, this fortune has been built on child labor, worker ex ploitation, and huge payoffs to sports stars (e.g., Michael Jordan, Andre Agassi, the Dallas Cowboys, and others) to influence children to become Nike product consumers. Nike has won an award as one of the Top 10 worst companies, but far worse is their corruption and exploitation of child ren - in the U.S. as consumers, and in Third World countries as workers.
Nike manufacturing is done in countries like South Korea, Pakistan, Indonesia, China, and Vietnam - all very lax with child labor and worker exploitation in general.
Reportedly, Nike has even hired "goon squads" to suppress worker protests. It appears that Nike specializes in management by exploitation, terror, and browbeating.
Another favorite tactic seems to be to hire college coaches, who then force their players to wear Nike shoes - the ones made by children in sweatshops, mainly in Asia.
I urge everyone to boycott Nike products.
W.B., Eugene, OR
It seems that melatonin is all the rage these days as a sleep aid. Here is some information about it that happened to come across my path recently, that I will pass along to you. It is a hormone produced in the pineal gland in the brain, and regulates sleep cycles. As we age, less is produced, and that seems to be what got entrepreneurs and the media into the melatonin business. Anyway, I have information from two articles to pass along.
The first source is somewhat suspect, because is a combination of a company that sells melatonin supplements, and Newsweek magazine; neither of which could be considered a reliable source on this subject. I will give you a summary, but it is on the Net, in all its glory, if you have access. It is called "Melatonin Central." The second source is the magazine HEALTH (July/August 1996), and includes doctor's testimony, and real studies - seems more legitimate to me.
From Melatonin Central, lets first talk about dosage. Reportedly, as little as 100 MCG has been successful for some people. Others have gone as high as 100 MG (where 1 MG = 1,000,000 MCG). "They" recommend that you start low and increase dosage as needed.
Possible side-effects according to one study: about 10% of users experienced no effect at all; another 10% had side-effects like headaches, nightmares, morning groginess, mild depression, and low sex drive. In some cases very high dosages have been used with no toxicity, and side-effects lasted about one or two days. It should be noted that no long-term studies have been done, so anyone who chooses to use this stuff should be conservative.
The safety factor - melatonin is one of the least toxic substances known. It is reported that amounts ranging from 600-3000 times the normal dose (whatever that is?) have shown no toxicity. This product has been on the market for four years in parts of Europe, and for two years in the U.S., with no ill-effects.
Note that there are lots of "mays" and "cans," but no "it does" statements.
Now for the HEALTH article. It says that, unfortunately, melatonin seems to induce only light sleep. There are five stages of sleep: 1 = light sleep; when you first drop off. There is a lot of brain wave activity, which may carry into stage 2, where the brain waves start to level out. About 15-20 minutes after sleep starts, the brain waves are about like a resting heart beat - stage 3 and 4. The brain waves are slow and steady and the body is still. At this point, it is thought that the brain shifts from catabolic metabolism, like digestion; to anabolic metabolism, like repair/restoration of muscles, bones, immune system, etc. Then there is a journey back to stage 1, and then a "leap" into stage 5, or REM. Most dreaming comes in the REM cycle, and all stages are recycled during a night.
REM is a kind of psychological restoration period, and deep sleep is a physical restoration period. Past the age of 30, deep sleep is lessened, so that at age 65 we get only about 30 minutes, as opposed to age 20, where one spends an hour or two in deep sleep.
The point here is that we need to maximize deep sleep, which melatonin does not seem to do. Here are some non-drug therapies that might work:
An article in the publication Healthnews, July 1996, suggested that high levels of a substance called homocysteine, or low levels of folic acid may be a major risk factor, along with high blood pressure, smoking, high cholesterol, excess fat, or lack of exercise; for heart attack, stroke, and other circulatory diseases.
Homocysteine is produced by the breakdown of protein. Folic acid, found in many fruits and vegetables (e.g., orange juice, banana, spinach, broccoli, whole wheat bread), on the other hand, prevents homocysteine from accumulating. It still isn't clear whether high levels of homocysteine are a cause or an effect of heart disease; but, regardless, a common prescription is to eat more fruit and vegetables, just as a general rule.
(Q) I get an almost constant ringing in my ears. What causes it, and what can I do about it?
M.F., Sunnyvale, CA
(A) According to the Mayo Clinic Health Letter (Jun 1996), the condition that you are describing is called tinnitus, and is marked by noise - ringing, buzzing, roaring, chirping, humming, etc. - in one's ears. This condition is annoying, but only rarely is a signal of a true health problem. It is a fairly common problem, but is not a disease.
The two most common causes are: 1) age-related hearing loss, and 2) damage to the inner ear from exposure to loud noise. Microscopic hairs in the inner ear are responsible for transmitting sound. Normally, these hairs move in response to pressure from sound waves. Their movement triggers electrical discharge from the auditory cells in our inner ears, which is then interpreted by the brain as sound. If the hairs are damaged, they move randomly and create "noise."
Tinnitus can also be caused by longterm use of some drugs (e.g., aspirin, quinine, anti-inflammatories). Many times, cessation of drug use results in the disappearance of the noise.
Other possible causes are wax buildup, infection, perforated eardrum, TMJ problems, stiffening of the bones of the inner ear, or head or neck injuries. And there are other causes, including high blood pressure. During sleeping, head position changes can often make it go away.
Other than learning to live with it, sometimes avoiding loud noise helps - ear plugs, ear phones. A hearing aid may help; also stress management.
In time, most people simply outgrow it as a nuisance factor, because of increased tolerance - less awareness - of irritants. And, in my own experience, two major sources are thunderously loud movie theaters, which I avoid by rarely going to them; and the loud "music" that is played at the gym I go to, which can be mitigated by use of ear plugs.
(Q) Can folate help reduce risk of heart attack or stroke?
H.G., San Jose, CA
(A) Maybe. Coincidentally (Was it Yung who said there is no such thing? That it should be called "synchronicity?" No matter.) there is a Letter To The Editor on this subject in this issue, but it talks about folic acid. Don't be confused. It is variously called folate, folic acid, or vitamin B-folate, which are all the same.
In the August 1996 Tufts University DIET & NUTRITION LETTER, it is said that evidence is mounting which suggests that high levels of folate can help prevent heart disease. A Canadian study lasting 15 years indicated that those with the highest amount of folate in their blood, were 70% less likely than those with lower levels to die from heart attacks, strokes, or other coronary problems. Folate keeps homocystiene (a compound thought to increase artery narrowing) levels down. SOOooo, eat those veggies - green ones like spinach, asparagus, spinach, broccoli - and chickpeas, lentils, and other beans. And, as the earlier letter noted, oj is good.
(Q) I WANT flat, washboard abs. I do 500 abdominal crunches a day, but I haven't seen any improvement. When I started exercising I was about 20? pounds over-weight, and that has not substantially changed. A friend told me to get one of those ab machines that are advertised incessantly on TV. That they are more-or-less guaranteed to give results. So I did, but with nothing to show for my time (three months) and money. Did I get the wrong machine?
Big Al, Mendocino, CA
(A) No, you didn't get the wrong machine, but probably the wrong parents.
There are a couple of problems here (at least). One is that your abdominal exercise does not target abdominal fat. Even if it did, not much fat is burned by resistance exercise. You need to do aerobic exercise to get the most calories (from whatever source) burned. Sessions of 30-40 minutes or more, would be ideal, but doing anything is better than nothing.
Now the "flat" part. Lose the fat, and you'll be flat. Usually. There are anatomical reasons why some people will never have flat abs. They can just be the best they can be; whatever that happens to be. I'm sorry for the cliche's, but they can't always be avoided.
Now for the mom and dad part, if you don't have a genetic propensity for building muscle, you won't develop the washboard look, but there will be some visible lines in the abs. A vertical "division" (the linea alba, a tendonous material) will appear between the left and right sides of the rectus femoris (but it is still all one muscle), and there will also be a couple of similar horizontal lines. If you are very lean, you get the lines, but without the genes, you won't get the washboard.
Now, back to the machines. They won't do anything for you, as far as muscle development goes - or losing abdominal fat either. But they can help with head support, but usually so can proper technique. And remember that abdominal training should include the whole abdominal cavity. Yes, that includes the lower back. You don't (or shouldn't) train abs just for cosmetic reasons - trunk support is more important. The bottom line is that you don't have to spend money to effectively train your abdominal muscles, but you can if you want.
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