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21 Cards in this Set

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  • Back
What is TSH?
It is from the anterior pituitary(basophil cells)
Structure is glycoprotein.
It is regulated as its secretion is stimulated by hypothalamic TRH.
Thyroid hormone appears to act directly on the anterior pituitary TSH secreting cells.
What is the function of TSH?
It controls production of thyroid hormone. This hormone is stored in the form of thyroglobulin in the colloid of thyroid follicles.
TSH stimulates all aspects of thyroid hormone synthesis, including the uptake of iodide, its incorporation into thyroglobulin, and the breakdown of thyroglobulin to release thyrotoxin(T4) and triiodothyronine(T3), the active forms of thyroid hormone which enter the blood stream.
What else does TSH stimulate?
It also stimulates the proliferation of the thyroglobulin-synthesizing cuboidal cells of the thyroid follicles, contributing to goiter(enlarged thyroid) in cases of excess TSH production.
What happens to T3 and T4 once they are in the bloodstream?
T3 and T4 combine with and are transported by a glycoprotein, thyroxine-binding globulin(TBG). It is only the free circulating hormone, as opposed to the TBG bound portion that is metabolically active and directly enters cells.
Therefore, the measurement of free T4 is a more reliable index of thyroid hormone function than measurement of total serum T4, which includes the TBG fraction.
Thyroglobulin often leaks into the bloodstream following inflammation of the thyroid gland. TRUE/FALSE
TRUE. Infact, the measurement of thyroglobulin levels can be useful in diagnosis of such inflammation as well as recurrence of malignancy.
Where is melanocyte stimulating hormone secreted from?
Ant. lobe of pituitary.
Structure is peptide.
Promotes melanin pigmentation.
What is ADH?
It originates in the hypothalamus(stored in axon endings in posterior pituitary).
Structure is polypeptide
It is regulated by osmotic changes in blood Na+ neural input to hypothalamus.
Function promotes resorption of water.
What does oxytocin do?
It is a polypeptide.
regulated by sucking reflex via hypothalamus.
What is the structure of melatonin?
It originates in the pineal gland.
It is a derivative or tryptophan and serotonin.
may function as well in regulating adrenal and gonadal functioning.
What is thyroid hormone?
It is an amino acid derivative of tyrosine.
regulated by TSH.
Its function is to increase body metabolic rate by increasing protein, particularly enzyme, synthesis through increased DNA transcription to RNA.
What is Grave's disease?
Is demonstrated by increased heart rate and metabolism, weight loss goiter and thyroid gland enlargement and exopthalamos.
Although elevated TSH levels can cause hyperthyroidism, in most cases TSH levels are low, indicating a primary cause in the thyroid gland from which the excess thyroid hormone feeds back to the pituitary to decrease TSH levels.
What is the cause of hyperthyroidism in most cases?
It appears to be an abnormal antibody(LATS, long acting thyroid stimulator) that acts like TSH and stimulates the thyroid gland to produce thyroid hormone.
What causes the exopthalamos?
Antibody to retroorbital tissues appears to be a factor in the development of exopthalamos.
How can hyperthyroidism be diagnosed?
By measuring blood levels of free thyroxine, the active form that is unattached to thyroid binding globulin.
One can also measure an increased uptake of radioactive iodide by the thyroid gland.
Treatment of hyperthyroidism consists of...
partial thyroidectomy or by administration of radioactive iodine 131 to ablate thyroid tissue.
Propylthiouracil can be employed to block thyroid hormone synthesis, by blocking peroxidase activity.
What is myxadema?
In hypothyroidism there is weakness, decreased mentation and tendon reflexes, cold intolerance and myxadema, which is a non pitting edema from, mucopolysaccharide deposition, thick dry skin, puffy face.
Thyroid hormone stimulates the breakdown of fats for energy utilization. Hypothyroidism is associated with fat accumulation and is a cause of hypercholesteremia, when TSH is elevated. TRUE/FALSE
What causes an increase in TSH in hypothyroidism?
It results from lack of the normal suppression of TSH production by T3 and T4 feedback to the hypothalamus.
What causes low TSH levels in hypothyroidism?
This suggests a primary problem of decreased functioning at the hypothalamic pituitary level.
High TSH levels suggests a primary thyroid deficiency with lack of suppressor feedback to the pituitary gland.
What is parathyroid hormone?
Its structure is polypeptide.
It increases blood calcium levels by stimulating bone breakdown, and kidney and intestinal absorption of calcium.
Although PTH also increases entry of phosphate into the blood from bone absorption, blood phosphate levels decrease, because PTH stimulates renal excretion of phosphate.
How does PTH contrast with Vit. D?
Vitamin D promotes increases in both calcium and phosphate levels in the blood, through bone absorption, renal absorption and intestinal absorption.