Thyroid meds Flashcards
What are the two thyroid hormones? What is the difference between the two?
T3 and T4
T3 have three iodines, T4 has four
What are the four general function of thyroid hormones?
growth
Development
Body temp
Energy metabolism
How are thyroid hormones taken up by thyroid follicles?
Na/I symporter
What causes the change from iodide to iodine?
Thyroid peroxidase
What do the thyroid follicles surround?
Follicle lumen (colloid)
What is organification of iodide?
Iodination of tyrosine residues within the thyroglobulin molecule
What are the amino acids that comprise thyroglobulin?
Tyrosine
What are the molecules that are combined to form thyroid hormones?
MIT and DITs
What is the ratio of T4:T3?
5:1
What does the thyroid follicle take up from the follicular space? How? What does this do?
Thyroglobulin
Phagocytosis
Degradation to T4
What molecule does T3/4 bind to in the blood?
Thyroxine binding globulin
Where is the T3 receptor found? What does it do there?
T3 receptor sits on the DNA on thyroid response element (TRE)
Represses gene expression
What happens to T4 when endocytosed into the cell?
Changed to T3 by 5’-deiodinase
Which form of thyroid hormone is the active one? Which is found in the highest amounts in the blood?
T3 is active form
T4 is highest in the blood
Describe the HPA axis in regards to the thyroid expression
TRH expressed by the hypothalamus, promotes TSH release by pituitary. This causes the release of thyroid hormone from the thyroid, which will feed back to the hypothalamus to inhibit further secretion
What is the effect of high iodide concentration?
Negative feedback on the thyroid
What is the effect of Low iodide concentration?
Promotes hormone synthesis
What are the two effects of the thyroid hormone on the sympathetic nervous system?
- Increase beta adrenergic receptors
2. Decrease alpha adrenergic receptors
What are the effects of the thyroid hormone on: growth and development?
- Brain development and neurogenesis
2. Bone growth and skeletal maturation
What are the effects of the thyroid hormone on: thermogenesis?
Increases cellular engery consumption
What are the effects of the thyroid hormone on: Respiratory?
Increase O2 consumption, causing increase RR
What are the effects of the thyroid hormone on: CNS?
- Rapidity of cerebration
2. Effect spinal cord synapses that control muscle tone
What are the effects of the thyroid hormone on: the GI tract?
Increase secretions and motility
What are the effects of the thyroid hormone on: skin and hair?
!. trophic effect
2. Prevent accumulation of glycosaminoglycans (causes water retention)
What are the effects of the thyroid hormone on: the CV system?
- Increase HR
- Increase contraction
- Increase CO
- Increased BP
- Decrease resistance
What are the effects of the thyroid hormone on: metabolism
Increase BMP
Increased protein synthesis
Decreased Fat level
Atherosclerosis is seen in hypo or hyperthyroidism
Hypo
Cold intolerance is seen in hypo or hyperthyroidism
Hypo
Low respiratory rate is seen in hypo or hyperthyroidism
Hypo
Diarrhea is seen in hypo or hyperthyroidism
Hyper
Dry and scaly skin, depressed hair and nail growth is seen in hypo or hyperthyroidism
Hypo
Fluid retention is seen in hypo or hyperthyroidism
Hypo
MR is seen in hypo or hyperthyroidism
Hypo
Vitamin deficiency is seen in hypo or hyperthyroidism
Hyper