Thyroid Physiology

Question 1

TSH receptor type

Answer 1

G-coupled
PKA activated
increase cAMP
release of thyroid hormones

Question 2

Thyroid hormone cascade

Answer 2

TRH from hypothalamus onto anterior pituitary
TSH released from anterior pituitary into blood
TSH binds receptors in thyroid gland
thyroid hormones released

Question 3

T3 vs T4 in blood

Answer 3

T3 more active
T4 => T3 intracellularly
*both heavily bound to plasma proteins

Question 4

TSH mechanisms in thyroid

Answer 4

thyroid peroxidase synthesis
thyroglobulin transcription
Na+/I- transporter activity

Question 5

Thyroid hormone actions

Answer 5

increase basal metabolic rate
increase β-receptor expression (sympathetics)
brain development

Question 6

Deficiency of thyroid hormones from birth can lead to

Answer 6

cretinism
retardation and stunted physical growth
due to absence of thyroid hormones

Question 7

Heat and cold intolerance

Answer 7

heat intolerance: hyperthyroidism

cold intolerance: hypothyroidism

Question 8

Thyrotoxicosis

Answer 8

severe: thyroid storm

high thyroid hormone concentrations

Question 9

Goiter caused by

Answer 9

hyperthyroid or hypothyroid

Question 10

Graves disease

Answer 10

production of thyroid-stimulating immunoglobulins
T-cells become sensitive to thyroid antigen
antibodies produced

Question 11

If abnormal TSH found

Answer 11

find free serum T3 and T4

Question 12

Thyroid scan

Answer 12

uses 123I

look where radioactive iodine it taken up