Thyroid Hormone, Thyroid Stimulating Hormone, and More...

I am particularly interested in the thyroid gland, since I have been diagnosed with hypothyroidism, which means my body is not making enough thyroid hormone. In Anatomy & Physiology, we have identified the thyroid gland on various models in lab, and we have also learned about the physiology of the thyroid gland. I am surprised to find out that many people I talk to are either being treated for hypothyroidism, or think they have it, so I thought I would share what I know here.

The first picture is a model of the larynx. The thyroid gland is the big yellow blob in the lower left corner of the picture. The second picture is the neck and chest of a torso model. The thyroid gland is the big yellow blob attached to the larynx!



Hormones made by the Thyroid Gland
Calcitonin works with Parathyroid Hormone (which is made by the Parathyroid Glands) to regulate calcium in the bloodstream and calcium in the bones. Calcitonin stimulates osteoblasts (causing bone formation by increasing calcium in the bone matrix and removing calcium from the bloodstream). In other words, irregular levels of these hormones could lead to osteoporosis.

What about other hormones made by the thyroid gland?
At the microscopic level, the thyroid gland has Thyroid Follicles surrounded by Follicular Cells. The Follicular Cells make Triiodothyronine (T3) and Tetraiodothyronine, also known as Thyroxine (T4). Together these 2 hormones are referred to as “Thyroid Hormone”.

These thyroid hormones are mainly regulated by Thyroid Stimulating Hormone (TSH), which is produced at the Anterior Pituitary Gland. In my case, my TSH was recently at 6.69, which is considered elevated. According to Medline, normal TSH values are .4 to 4.0. If your TSH is high, it means your thyroid hormones are low. Your doctor may prescribe a synthetic thyroid hormone known as Synthroid, which I had a bad reaction to, or a natural (but less used) thyroid hormone known as Armour Thyroid.

What do increases in “Thyroid Hormone” cause?
1. Nervous System – Increases activity and necessary also for proper fetal development of the nervous system (also necessary after birth for normal nervous system)

2. Skeletal System – Promotes normal bone growth while growing in height AND promotes remodeling of bone after a fracture or as a result of change in weight, etc.

3. Cardiovascular System - Increases Heart Rate, Force of contraction of cardiac muscle and blood pressure

4. Respiratory System – Increases respiratory rate and depth of respiration

5. Increases Metabolic Rate – Increases heat production AND Increases rate of catabolism of carbohydrates, proteins and lipids

Patent Foramen Ovale & Fetal Circulation

When my mom was in the hospital for four months, after having an ischemic stroke that blocked blood flow to the right side of her brain, I kept hearing doctors say things about the reasons for my mom’s stroke—things like, “she has a PFO.” I had no idea what this term meant, but I later found out that PFO stands for “patent foramen ovale.” It’s a hole between the right and left atrium in the heart, which allows blood to bypass the lungs during fetal development. The foramen ovale is supposed to close on its own at birth, when the baby begins to breathe on her own, but in 20% of the population, the hole never closes, resulting in a patent foramen ovale, a hole between the atria of the heart. Since it can be hereditary, doctors recommended that my sisters and I be evaluated for a PFO. A transthoracic echocardiogram with a bubble study confirmed that I do have a PFO, and neither of my sisters do. There is no treatment and usually no symptoms, although doctors suspect that a PFO can allow blood to pool and form clots, and therefore increase the risk of stroke.

Our method of studying this in A&P involved text and a couple heart models in lab (our class is pretty much devoid of technology), but as I suspected, a search of “fetal circulation” on YouTube reveals many creative approaches to understanding fetal circulation and the changes that occur at birth. The foramen ovale is supposed to close at birth and be replaced by a flap of tissue called the fossa ovalis. And there are several other unique characteristics of fetal circulation similar to the foramen ovale, such as the ductus arteriosus, which allows blood to bypass the lungs by shunting blood from the pulmonary trunk to the aorta, and on to systemic circulation. When the ductus arteriosus closes at birth, it becomes the ligamentum arteriosum. These videos also discuss the umbilical vein, ductus venosus, and the umbilical arteries.

The following YouTube clips show fetal circulation in a creative and interesting way. I think it also says a lot for how audio and images can be paired with text to demonstrate a process or complex concepts in ways that are easy to understand. These are relatively simple projects that involve still images and audio, and no actual video footage. It’s exciting to see that some educators are taking advantage of technology-based assignments that students will enjoy much more than sitting idly in a lab and identifying numbers on plastic models. These projects would also help students learn about processes and how different parts of anatomy are related, rather than just focusing on identification and rote memorization. Do you think my A&P teacher would be offended if I sent her links to these YouTube videos?! Probably.

Taxes

As I dropped my $1000 check in the mail today for taxes owed to the federal government, I had one lingering, selfish, menacing feeling: I should get tax credits for NOT having kids.

Power & Privilege

I had a meeting yesterday with the powers that be to discuss “what we can do on campus” regarding LTE rights. I went into the meeting hopeful, yet they made it clear they did not want to talk about state-regulated things that are out of their control, you know, the small things like inequitable wages, no vacation or sick time, and no representation. I suggested that, despite state regulations, UW-Madison has set an admirable model regarding LTE hiring and retention, yet that was quickly dismissed in favor of the next topic…

Immediately, one of the powers that be stated that she CANNOT discourage LTE hiring on this campus because it is the ONLY option, given the FTE restrictions set by the state. I was so dumbfounded I couldn’t even think of what I wanted to say, that I don’t truly believe hiring LTEs is our ONLY option. I know people have been hired under Project positions and other special contract positions, which gave them more benefits than LTE status. We should promote consideration of other hiring options before taking the LTE route, which gives the employee the least amount of equity and the lowest wages. I had hoped they would want to encourage a hiring model where “just hiring an LTE” is not our default protocol, but rather a last resort and truly for limited term positions.

When discussing that LTEs make 20 percent less than the minimum starting wage for permanent employees in the same job classification, she looked up the lowest wage, subtracted 20 percent and arrived at roughly $9.00/hr. She then stated that this is “not a bad gig” for a wage in this area. She then did concede that making this wage with no benefits is not so good. In her huge window-paneled office I wanted to scream, “Really, with your Juris Doctor and your life and position of privilege, you know what it would be like to live off of $9/hour with no sick time or vacation? To support a family on these wages? To take unpaid leave if your child got sick?????” The other side of this is that the LTE's maximum wage is the minimum starting wage for a permanent employee, so there is a very small window in which to increase the LTE's wages (e.g., $10.14-$12.67/hour for a University Services Associate 1).

She then stated what initiatives she is willing to support and they include the following bold initiatives. A weekly email from HR that details open positions and upcoming Civil Service examinations. A new LTE excellence award, to complement the awards that have existed for years for faculty, instructional and academic staff, and classified staff. And some related items, such as encouraging Directors that LTEs deserve regular performance reviews. When I emphasized that there are no standards of treatment for LTEs, that they can be let go at any time for any reason, and that LTEs worry about losing their jobs when asking to take any time off, she stated that a Director or Manager wouldn’t just go out and hire someone else because they would have to retrain the person. I should have told her that the office across the hall from me has gone through three LTEs in the past few months, hiring them and discarding them as they see fit…

She also told me I had upset the people in the HR department. Oh well. I guess, at least they are willing to do some things, and change happens slowly, but I still left the meeting feeling like I have lost my faith in something I used to believe in.

Playing the Game

My goals for the winter were to stay healthy, lose weight, write regularly…so far I have not managed to accomplish any of those goals, really. Thankfully I have managed to keep my rosacea in check this winter (but that’s another posting).

Here’s what I really want to say right now. There are a lot of things that have been going on around here that I need to write about. But here is what is on my mind first and foremost. Over winter break, I was asked to take a freelance job in which I read a text book and wrote quizzes. The book was for business communicators, and included things like how to facilitate effective business meetings, how to write effective meeting minutes, how to stick to a meeting agenda when one person dominates the meeting….the list goes on. I found myself thinking, really? Is this really necessary? Isn’t this common sense? And then I remembered how lost and befuddled I felt when I started my first job after college, how the whole corporate culture (and later, higher education) was so foreign to me (especially since I had been a liberal arts English major).

So then I started thinking…what would have prepared me for the culture of corporate America or higher education? And I had a sad thought, which was recently only further confirmed for me based on something that is happening to a friend. In school, you’re judged by your performance. You do the work, participate, follow the rules and requirements, and then receive graded feedback. But in the professional world, you’re judged not so much by your talent or your impact on the people you are serving as you are judged by your capacity to play the game. Your best chance of survival and advancement lies in your ability to form alliances with key people who are in the best position to get you what you want, to secure a prominent place in the valuable flow of information known as the grapevine, so that you are always poised to make your next power play, and to recognize and be alert for the power plays that are constantly going on around you so that you may use them to your advantage…..you must become intricately connected to the politics of the culture and play the game at all times. On a daily basis I watch this going on—it usually involves pitting people against each other—and I try not to get pulled in to it.

The sad truth is…if you refuse to play the game, if you actually choose to be the bigger person and focus on your job, you will eventually be knocked out of the game.

Recent Events in Anatomy & Physiology

What I am studying in Anatomy & Physiology....in pictures. I wrote detailed captions for each picture--if you'd like to see those then click on the picture and view the slideshow directly on flickr.

This post is for my friend H—here’s to healthy bones and calcium levels!

I always thought of bones as dense and unchanging. As with many things I’ve been learning about in my Anatomy & Physiology course (and in Biochemistry), the human body is constantly changing and adapting…right down to specific tissues and types of cellular reactions, the body knows exactly what needs to be done in any given situation. As you’ll see in this post, hormones, calcium levels, diet, and other factors all come together to influence bone health.

What are bones made of? Bone has organic and inorganic components:

• The organic portion decays after death and constitutes 1/3 of the bone weight, consisting mostly of protein fibers that provide flexibility
• The inorganic portion is 2/3 of the bone weight, composed of mineral salts, called the bone matrix. This inorganic portion is 85% hydroxyapatite (the primary way that calcium and phosphorus are stored in bone). This is the part of the bone that remains after death, and it provides strength and storage of minerals while you’re alive.

The living cells of bone are osteogenic cells (osteo means “bone” and genic means “genesis,” which means to make or create). Perhaps now you can infer where the term “osteoporosis” comes from? Osteoblasts make bone matrix; osteoclasts break down bone matrix.

What function do bones have (besides the obvious)?
Bones provide attachment for muscles that produce movement, and provide protection for delicate structures (e.g., brain, lungs), but bones also do the following:

• Act as storage repositories for mineral salts such as calcium and phosphorus
• Produce all formed elements in blood by red bone marrow (hemopoiesis)
• Assist in acid/base balance by controlling release of minerals from storage
• Detoxify: If you have been exposed to environmental toxins, the bones are one place to look for their storage. For example, your bones could store heavy metals until they can be slowly excreted by the kidneys

Most importantly, your bones are a storage repository for minerals that are constantly being exchanged between bones, muscles, and blood, depending on the needs of your body. Calcium is stored in the bone until needed (constantly replaced and removed through the action of osteoblasts and osteoclasts). Calcium is needed for proper function of the following:

• Blood clotting
• Nervous system function
• Cardiac function
• Skeletal muscle function
• Smooth muscle function (found in your digestive tract, reproductive system—smooth muscle can contract, such as during digestion or labor)
• Cofactor for many enzymes (enzymes facilitate numerous biochemical reactions in your cells)
• Second messenger in many hormone systems (e.g., epinephrine).
• Proper tendon and ligament health

What types of stressors do bones respond to?
Some of the osteogenic cells can sense strain on bone, adding or subtracting bone matrix, thus changing bone density and remodeling bone.

• Gravitational stress: Weight gain/loss, pregnancy, fluid gain/loss, eating more/less, all influence bone density. Weightlessness in outer space caused osteoporosis in the early astronauts
• Functional stress: Use of muscles (not to an extreme) causes increase in osteoblast activity. Increases bone mass as muscle mass and strength increase. Overtraining reduces bone mass
• Research shows that as little as 15 minutes of exercise changes calcium levels in the blood of the lower leg

What factors influence bone health? Diet affects bone health. Vitamins A, C, and D are essential for bone health. For instance, Vitamin A and D in milk and Vitamin C in fruit and fruit juices. Specifically, what does Vitamin D do?

• Increases absorption of calcium, phosphorus, and magnesium from your small intestine into the bloodstream, controlling the availability of these for matrix formation
• Controls whether calcium and phosphate are deposited in bone or released from bone
• Causes less calcium to be lost from the body in the urine—so influences kidney function

Hormones Affect Bone Health. The following are a few of more than 20 hormones known to affect bone health.

Calcitonin Affects Bone Health. Calcitonin is made by the thyroid gland. Calcitonin is released into the blood from the thyroid gland if calcium is too high in the blood. This causes a decrease in blood calcium, by causing calcium to be stored into the bone matrix. (Remember, osteoblasts generate bone matrix, while osteoclasts break down bone matrix). Calcitonin increases osteoblast activity and decreases osteoclast activity. Calcitonin is important in growing children and also in adults, in response to specific physical and/or mental stressors. For example, during pregnancy and lactation.

Parathyroid Hormone (PTH) Affects Bone Health:

• Made by the parathyroid glands, which are part of the thyroid gland
• Released into the bloodstream if blood calcium is too low, causing blood calcium to increase (increases osteoclast activity, which breaks down matrix to release calcium into blood Decreases osteoblast activity, which prevents calcium from being removed from the blood in order to build matrix)
• Inhibits calcium excretion in urine, to keep calcium in the body and not be lost in urine
• Promotes phosphate excretion in urine, which inhibits matrix formation

Hypersecretion (overproduction) of PTH weakens bones, similar to osteoporosis caused by menopause. In addition, this can cause metastatic calcification (e.g., kidney stones).

Growth Hormone Affects Bone Health. Made by the anterior pituitary gland, growth hormone is not a steroid, but is often confused by the public with testosterone, which is a steroid. You may have heard of growth hormone used in cows—bovine growth hormone. Growth hormone levels usually fluctuate on a daily basis but can increase dramatically with physical or mental stress. At normal levels, with small daily fluctuations, growth hormone is important for the following:

• Important during childhood for proper growth in height, proper development of the skeleton
• Stimulates cartilage proliferation in the epiphyseal plates (growth plates in bone)
• Increases absorption from small intestine of nutrients important for bone health and growth
• Stimulates osteoblasts (matrix formation in bone)
• Even in adults, growth hormone is still important to bone health and metabolism…not just for growth in height

People experiencing extraordinary physical and mental stressors may experience hypersecretion (overproduction) of growth hormone, also known as the General Adaptation Syndrome, or stress response. This has been seen among prisoners of war, such as Vietnam, or in the Nazi death camps of World War II. This stress response includes other hormonal changes, such as increased Cortisol, Epinephrine, Norepinephrine, and Aldosterone. The result is a form of osteoporosis and derangements in metabolism.

In general, hypersecretion of growth hormone in children or adults results in osteoporosis—brittle bones/fractures. This can be caused by stress (physical or mental), tumors, or other causes. (High levels of growth hormone have a paradoxical effect on the body—producing the opposite effect of what happens at normal levels of growth hormone).

Sex Hormones (Testosterone or Estrogen) Affect Bone Health. Sex hormones produce a growth spurt at puberty. At menopause, estrogen levels decrease for women….osteoblasts become less active, so less bone matrix is made, so in some women there is not enough estrogen to maintain bone health. Treatments include calcium supplements, less caffeine and less alcohol, and possibly estrogen supplements. Men typically do not experience a drop in testosterone, and therefore would not experience osteoporosis as the result of changes in their levels of sex hormones.

Cortisol Affects Bone Health. Cortisol is made by the adrenal cortex of the adrenal glands. It fluctuates throughout the day, but can become quite elevated under unusual physical and mental stressors. Normal cortisol levels are important to carbohydrate, lipid, and protein metabolism, and bone health (increases osteoblast activity and decreases osteoclast activity). For post-menopausal osteoporosis, mild exercise and a happy situation would increase cortisol levels slightly, contributing to bone health. At vastly increased levels, cortisol has a paradoxical effect, negatively affecting bone health, similar to growth hormone. Cortisol levels can increase with too much athletic training, trauma, or surgery.

Thyroid Hormones and Thyroid Stimulating Hormone Affect Bone Health. Thyroid hormones (triiodothyronine T3 and tetraiodothyronine, also called thyroxine T4) are made by the follicular cells of the thyroid gland, both of which contain iodine. (This is the main reason for iodized salt, to supply iodine to the thyroid gland to manufacture the hormones). Thyroid Stimulating Hormone (TSH) is made by the anterior pituitary gland. TSH travels to the thyroid gland, where it increases production of thyroid hormones. Without TSH, you can’t stimulate the thyroid to create thyroid hormones.

Hypersecretion of these hormones causes a form of osteoporosis…too much calcium lost from the body in urine. You need proper levels of TSH to get normal levels of T3 and T4 and need proper levels of all three for normal bone growth and maintenance.