Thyroid Hormones and their control Thyroid hormones control

Thyroid Hormones and their control Thyroid hormones control your metabolic rate. But what controls your thyroid hormone levels?

In this thyroid tutorial, you should learn to: – Explain how thyroid activity is regulated – Predict and explain hormone levels in different thyroid imbalances – Predict and explain signs and symptoms of hyperand hypo-thyroidism – Identify the emergency complications of hyperand hypo-thyroidism. – To start, just click the forward arrow. To return to this menu at any time, click the home button.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH What’s the next step? Thyroid secretes T 3 and T 4 Hypothalamus secretes TSH (thyroid stimulating hormone) Hypothalamus secretes TRH (thyrotropin releasing hormone) Good work! The hypothalamus secretes RELEASING hormones. In this case, the hypothalamus is trying to stimulate thyroid – so it secretes Thyrotropin releasing hormone. Thyrotropin means ‘thyroid growth-causer. ’ So TRH is going to tell some other organ to RELEASE a THYROID GROWTH-CAUSER. Click on the forward arrow to go on.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH travels to anterior pituitary What’s the next step? TRH travels to anterior pituitary Hypothalamus secretes TSH (thyroid stimulating hormone) Hypothalamus secretes T 3 and T 4 Good work! The hypothalamus secretes RELEASING hormones. to tell some other organ to RELEASE a THYROID GROWTH-CAUSER. The organ that releases stimulating hormones for the hypothalamus is the anterior pituitary - just about an inch below it. The TRH travels from the hypothalamus to the pituitary through a tiny portal system of blood vessels.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH travels to anterior pituitary What’s the next step? anterior pituitary releases TSH (thyroid stimulating hormone) pituitary Thyroid secretes T 3 & T 4 T 3 and T 4 anterior pituitary releases TSH Good work! When it receives the Thyrotropin Releasing hormone, the anterior pituitary releases a thyrotropin, or thyroid stimulating hormone.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH What’s the next step? pituitary secretes T 3 & T 4 Thyroid stimulated by TSH Thyroid stimulated by TRH travels to anterior pituitary releases TSH Thyroid stimulated by TSH Good work! Thyroid stimulating hormone does just what its name says – stimulate thyroid.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH What’s the next step? Thyroid produces only T 3 Thyroid produces T 3 & T 4 Thyroid produces TRH travels to anterior pituitary releases TSH Good work! The thyroid produces 2 hormones. Thyroid stimulated by TSH T 3 is tri-iodothyronine – 3 iodine atoms T 4 is tetra-iodothyronine – 4 iodine atoms Thyroid produces T 3 & T 4 T 3 is the active form. T 4 is an inactive backup form; your tissues can convert it into T 3 by taking off an iodine atom.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH travels to anterior pituitary releases TSH What’s the next step? Thyroid Hypothalamus measures T 3 & and pituitary T 4, stops making detect T 3 & T 4; them when secrete more there is enough TRH and TSH. Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. Good work! Thyroid stimulated by TSH When T 3 & T 4 levels return to normal, the hypothalamus and pituitary no longer need to stimulate thyroid. Thyroid produces T 3 & T 4 That is, T 3 & T 4 exert negative feedback on the hypothalamus and pituitary. Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH travels to anterior pituitary releases TSH Thyroid stimulated by TSH Thyroid produces T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. The thyroid is the PRIMARY organ making the thyroid hormones.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH travels to anterior pituitary releases TSH The anterior pituitary is the SECONDARY organ responsible for making thyroid hormones. Thyroid stimulated by TSH The thyroid is the PRIMARY organ making the thyroid hormones. Thyroid produces T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH The hypothalamus is the TERTIARY organ responsible for making thyroid hormones. TRH travels to anterior pituitary releases TSH The anterior pituitary is the SECONDARY organ responsible for making thyroid hormones. Thyroid stimulated by TSH The thyroid is the PRIMARY organ making the thyroid hormones. Thyroid produces T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH.

Hypothalamus detects low thyroid hormones A man has high T 3 & T 4 levels, because of a problem with his thyroid. What’s his diagnosis? Hypothalamus releases TRH Tertiary Secondary Primary hyperthyroidism hypothyroidism hyperthyroidism TRH travels to anterior pituitary releases TSH Thyroid stimulated by TSH Thyroid produces Excess T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. Good work! It’s called hyperthyroidism because there is too much T 3 & T 4. It’s called primary because the problem is in the primary organ making T 3 & T 4 – the thyroid itself.

Hypothalamus detects low thyroid hormones A man has high T 3 & T 4 levels, because of a problem with his anterior pituitary. What’s his diagnosis? Hypothalamus releases TRH Tertiary Secondary hyperthyroidism hypothyroidism TRH travels to anterior pituitary releases Excess TSH Thyroid overstimulated by excess TSH Thyroid produces Excess T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. Good work! It’s called hyperthyroidism because there is too much T 3 & T 4. It’s called secondary because the problem is in the secondary organ stimulating T 3 & T 4 production – the anterior pituitary.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH A man has primary hyperthyroidism. What will his levels of TSH be like? Normal High Low TRH travels to anterior pituitary releases TSH Thyroid stimulated by TSH Thyroid produces Excess T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. Good work! With primary hyperthyroidism, this man has too much T 3 & T 4 because of a problem with his thyroid. The hypothalamus and anterior pituitary are still working. They will detect these high levels of T 3 & T 4, and stop secreting TRH and TSH. Therefore, the levels of TRH and TSH will be lower than normal.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH A man has secondary hyperthyroidism. What will his TSH levels be like? Low Normal High TRH travels to anterior pituitary releases TSH Thyroid stimulated by TSH Thyroid produces T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. Good work! In secondary hyperthyroidism, the T 3 & T 4 levels are elevated because the anterior pituitary is producing too much TSH, over-stimulating the thyroid. TSH levels are higher than normal.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH A man has secondary hyperthyroidism. What will his TRH levels be like? Normal Low High TRH travels to anterior pituitary releases TSH Good work! Thyroid stimulated by TSH In secondary hyperthyroidism, the T 3 & T 4 levels are elevated because the anterior pituitary is producing too much TSH, over-stimulating the thyroid. Thyroid produces T 3 & T 4 But there is nothing wrong with the hypothalamus, so it will still detect the high T 3 & T 4 levels, and stop producing TRH levels will be low. Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH.

Hypothalamus detects low thyroid hormones Hypothalamus releases TRH A man has tertiary hypothyroidism. What will his TRH levels be like? Normal Low High TRH travels to anterior pituitary releases TSH Good work! Thyroid stimulated by TSH Hypothyroidism means the thyroid hormone levels are low. Thyroid produces T 3 & T 4 Tertiary means the organ at fault is the hypothalamus. It isn’t creating enough TRH to stimulate thyroid. Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH.

Hypothalamus detects low thyroid hormones A man has low T 3 & T 4 levels, but high TSH levels. What’s his diagnosis? Hypothalamus releases TRH Tertiary Secondary Primary hypothyroidism hyperthyroidism hypothyroidism TRH travels to anterior pituitary releases TSH Thyroid stimulated by TSH Thyroid produces T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. Good work! It’s called hypothyroidism because there is too little T 3 & T 4. you can tell it’s primary because the pituitary is doing its job – making TSH to stimulate thyroid. But the thyroid isn’t responding! The problem must be with the thyroid itself.

Hypothalamus detects low thyroid hormones A man has low T 3 & T 4 levels, and low TSH levels. When he is given an injection of TRH, his T 3 & T 4 go back to normal. What’s his diagnosis? Hypothalamus releases TRH travels to anterior pituitary Tertiary Secondary Tertiary hypothyroidism hyperthyroidism anterior pituitary releases TSH Good work! Thyroid stimulated by TSH It’s called hypothyroidism because there is too little T 3 & T 4. Thyroid produces T 3 & T 4 you can tell it’s tertiary - involving failure of the hypothalamus - because when you give him the hormone the hypothalamus should be making, you fix his problem. Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH.

Hypothalamus detects low thyroid hormones In Grave’s disease, antibodies shaped like TSH attach to TSH receptors on the thyroid and cause it to make excess T 3 & T 4. What kind of imbalance results? Hypothalamus releases TRH travels to anterior pituitary Primary Secondary Tertiary hyperthyroidism anterior pituitary releases TSH Good work! Thyroid stimulated by TSH Thyroid produces T 3 & T 4 Hypothalamus and pituitary detect T 3 & T 4; stop secreting TRH and TSH. It’s called hyperthyroidism because there is too much T 3 & T 4. It’s called primary because there’s nothing wrong with the pituitary or the hypothalamus. They are just doing their jobs as usual.

Hypothyroid: low thyroid hormones What is most likely to happen to someone who is hypothyroid? Decreased aerobic metabolism Decreased temperature Elevated WBC count Hypertension Good work! Your body is warm because heat is produced as a byproduct of aerobic metabolism. If you are doing less aerobic metabolism, your temperature will decrease.

Hypothyroid: low thyroid hormones What is most likely to happen to someone who is hypothyroid? Decreased aerobic metabolism Decreased temperature Fatty stools Weight loss Weight gain Good work! When metabolic rate decreases, less food is burned to make ATP. The unused food is stored in the body – leading to weight gain.

Hypothyroid: low thyroid hormones What is most likely to happen to someone who is hypothyroid? Decreased aerobic metabolism Decreased temperature Fast reflexes Diarrhea Constipation Weight gain Constipation Good work! When metabolic rate decreases, muscles are less active. Bowel movement decreases.

Hypothyroid: low thyroid hormones What is most likely to happen to someone who is hypothyroid? Decreased aerobic metabolism Decreased temperature Strong heartbeat Wide pulse pressure Weak heartbeat Weight gain Constipation Weak heartbeat Good work! When metabolic rate decreases, muscles are less active. Heart movement decreases, weakening the heartbeat.

Hypothyroid: low thyroid hormones Decreased aerobic metabolism Hypothyroidism also causes a condition called myxedema, or mucusy edema. Decreased temperature In myxedema, mucus builds up under the skin, giving it a dry, puffy look. Weight gain Constipation Weak heartbeat Dry, puffy skin Enlarged tongue Croaking voice The myxedema may also affect the tongue, making it larger. The vocal cords may swell, making the voice croaky.

Hypothyroid: low thyroid hormones Decreased aerobic metabolism Which of the signs and symptoms listed is most likely to cause a severe complication? Click on the one that worries you most. Decreased temperature Weight gain Constipation Weak heartbeat Dry, puffy skin Enlarged tongue Croaking voice Good work! When metabolic rate decreases, muscles are less active. Heart movement decreases, weakening the heartbeat. If somebody with hypothyroidism catches an additional illness, their condition may get worse. Their heart might slow so much that it causes vascular collapse. This is called myxedema coma.

Hyperthyroid: high thyroid hormones What is most likely to happen to someone who is hyperthyroid? Increased aerobic metabolism Increased appetite Elevated WBC count Decreased temperature Good work! A person with a high metabolism is always hungry – the food is being burned up to make ATP as fast as the person can eat it!

Hyperthyroid: high thyroid hormones What is most likely to happen to someone who is hyperthyroid? Increased aerobic metabolism Increased appetite Fatty stools Weight gain Weight loss Good work! When metabolic rate increases, more food is burned to make ATP.

Hyperthyroid: high thyroid hormones What is most likely to happen to someone who is hyperthyroid? Increased aerobic metabolism Increased appetite Constipation Sweating Decreased temperature Weight loss Sweating Good work! When metabolic rate increases, more food is burned to make ATP. This produces more heat, which means the person will be overheated and sweating.

Hyperthyroid: high thyroid hormones What is most likely to happen to someone who is hyperthyroid? Increased aerobic metabolism Increased appetite Lethargy Tremor Hypotension Weight loss Sweating Tremor Good work! When metabolic rate increases, muscles and nerves make more ATP and are more active. This can present as tremor and anxiety.

Hyperthyroid: high thyroid hormones What is most likely to happen to someone who is hyperthyroid? Increased aerobic metabolism Increased appetite Somnolence Anorexia Tachycardia Weight loss Sweating Tremor Tachycardia Good work! When metabolic rate increases, cardiac muscles make more ATP and are more active. This can present as tachycardia, a strong pulse, and a widened pulse pressure.

Hyperthyroid: high thyroid hormones Increased aerobic metabolism Which of the signs and symptoms listed is most likely to cause a severe complication? Click on the one that worries you most. Increased appetite Weight loss Good work! Sweating If somebody with hyperthyroidism catches an additional illness, their condition may get worse. Their heart might speed up so much that there isn’t time for it to fill between beats. This causes vascular collapse. At the same time, their fever might soar to dangerous levels. This is called thyroid storm. Tremor Tachycardia Exophthalmos

This is the end of the thyroid tutorial. • You should be able to: – Explain how thyroid activity is regulated – Predict and explain hormone levels in different thyroid imbalances – Predict and explain signs and symptoms of hyperand hypo-thyroidism – Identify the emergency complications of hyperand hypo-thyroidism. • Not sure? Just click on the topic you want to review.