Term
| What effects does thyroid hormone have on the anterior pituitary? On the hypothalamus? |
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Definition
inhibits responsiveness to TRH, prevents TSH secretion
inhibits secretion of TRH |
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Term
| What is the largest purely endocrine gland? |
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Definition
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Term
| The 2 lobes of the thyroid are connected by the... |
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Definition
|
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Term
| Describe the pathway leading to the release of thyroid hormone |
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Definition
Hypothalamus - TRH
Ant Pituitary - TSH
Thyroid - Thyroxine |
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Term
| What else happens in response to stimulation of the thyroid by TSH? |
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Definition
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Term
| What does the parathyroid gland do? |
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Definition
| secretes parathyroid hormone to increase Ca2+ concentration in the blood |
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Term
| Describe the process of thyroid hormone production |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| How do we end up with T4 vs T3? |
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Definition
DIT + DIT = T4
MIT + DIT = T3 |
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Term
| How do T3/ T4 enter the bloodstream? |
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Definition
TSH stimulates follicular cells to take up colloid, which causes T3 & T4 to be hydrolyzed from thyroglobulin & released into blood
(they need carrier proteins to be transported within the bloodstream) |
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Term
| Which is the 'active' form, T3 or T4? |
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Definition
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Term
| What effect does thyroxine have? |
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Definition
increases BMR by:
-increasing cellular respiration rate
-increasing protein synthesis
-promoting nervous tissue maturation |
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Term
True or False
calcitonin is essential in regulating Ca2+ concenrations in the blood |
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Definition
false
unlike parathyroid hormone, calcitonin is not essential to regulate Ca2+ |
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Term
| Calcitonin is an ______ to parathyroid hormone |
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Definition
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Term
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Definition
-inhibits osteoclast activity
-promotes urinary excretion of Ca2+ |
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Term
| What converts iodide to iodine? |
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Definition
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Term
What transporter brings iodide into the follicular cells?
The colloid? |
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Definition
sodium-iodide transporter
pendrin transporter |
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Term
True or False
All thyroid hormones are bound to carriers in the blood |
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Definition
false
a small percentage are free |
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Term
| Are thyroid hormones inactive active when bound to TBG? |
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Definition
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Term
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Definition
| binds thyroxine to transport it within the blood |
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Term
| In humans, secretion of thyroid hormones is highest when? |
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Definition
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Term
| How is thyroid hormone secretion regulated? |
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Definition
-TRH is secreted in pulsatile fashion
-young animals secrete more
-stress/cold increases secretion |
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Term
| Fetal development of what system relies on thyroid hormone in particular? |
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Definition
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Term
| Can the gonads function properly without thyroid hormone? |
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Definition
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Term
| What hormone elevates BMR? |
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Definition
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Term
| If a person has weight gain/low BMR, is not tolerant of the cold, and is lethargic, what disease do they likely have? |
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Definition
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Term
| If a person has weight loss/high BMR, muscular weakness, nervousness etc., what disease do they likely have? |
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Definition
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Term
| Bulging eyes is a sign of what disease? |
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Definition
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Term
| What is the common cause of cretinism? what else can cause it? |
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Definition
maternal hypothyroidism
lack of iodine in the diet |
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Term
| How could you distinguish between cretinism & dwarfism? |
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Definition
| cretinism also has severe mental deficiency, dwarfism does not |
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Term
| What phase of brain development relies on thyroid hormone, during pregnancy or after birth? |
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Definition
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Term
| What parts of brain formation rely on thyroid hormone? |
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Definition
-growth of dendrites & axons
-myelin formation
-synapsis formation
-neuronal migration |
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Term
| At what age must cretinism be treated in order for this to be effective? What is the treatment? |
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Definition
| -providing T4 at less than 1 month of age can restore normal function by age 5 |
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Term
|
Definition
-lack of dietary iodide = low T3/T4 production
-TRH is produced in excess
-causes TSH to be produced in excess
-thyroid gland grows to try and produce more T3/T4 |
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Term
| Is graves disease associated with hypo or hyperthyroidism? |
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Definition
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Term
| Is high TRH & TSH associated with hypo or hyperthyroidism? |
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Definition
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Term
_____thyroidism is more commmon in cats
_____thyroidism is more common in dogs |
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Definition
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Term
| What causes primary hypothyroidism in dogs? |
|
Definition
destruction of the thyroid:
-lymphocytic thyroiditis
-idiopathic thyroid atrophy |
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Term
| What causes secondary hypothyroidism in dogs? |
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Definition
-neoplasia causes secondary thyroid destruction
-congenital hypothyroidism/cretinism |
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Term
| What dog breed is particularly susceptible to primary hypothyroidism? |
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Definition
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Term
| What stimulant might you administer to treat hypothyroidism? What does it do? |
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Definition
furosamide
increases conversion of T4 to T3 |
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Term
| What percentage of the thyroid must be damaged before signs of hypothyroidism become clinical? |
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Definition
|
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Term
|
Definition
| swelling of tissues seen with severe hypothyroidism |
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Term
| What drug therapy can be used to treat hyperthyroidism? |
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Definition
| administer thiocarbamides to decrease conversion of T4 to T3 |
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