Thyroid

Question 1

Anatomy thyroid gland

Answer 1

visceral compartment neck C5-T1
inf art from subclav
Sup art from common carotid
Thyroid IMA from BC trunk

Question 2

Thyroid Cells

Answer 2

hormone production from acini (follicles)
thyrocytes around colloid centre (thyroglobulin)
inactive large follicles lots of colloid flat epithelium
active small cuoid/ columnar
microvilli

Question 3

Thyroid hormone synthesis

Answer 3

ACTIVE TRANSPORT - iodide into cell (Na/I symporter and Cl/I exchanger)
THYROGLOBULIN formed in ribsomes
EXCOCYTOSIS thyroglobulin
IONDINATION thyroid peroxidase activates iodide to iodine and binds to tyrosine residues
COUPLING DIT DIT, MIT DIT
ENDOCYTOSIS to cell and proteolysis freeing T4 and T3

Question 4

Protein binding

Answer 4

Albumin highest capacity, takes T3
TBG - highest affinity takes T4
99% protein bound

Question 5

Metabolism by deiodination

Answer 5

T4 -> 33% T3, 45% RT3
D1 liver, kidney thyroid
D2 brain, pituitary, brown fat
D3 brain and reproductive

n.b. starvation decreased T3

Question 6

TSH

Answer 6

alpha and beta subunits
half life 60m
degraded in kidney and liver
Most excreted 9pm to midnight
GPCR activates adenyl cyclase

Question 7

Hypothyroid effects

Answer 7

increased protein CSF, slow everything
brain development - mentl retardation, motor rigidity (basal ganglia) and deaf mutism

Question 8

Types hypothyroid

Answer 8

1 - thyroid hormone deficiency
2 - TSH deficiency
3 - TRH deficiency

TRH stimulation test
1 - high TSH
2 - no response
3 - delayed TSH

Question 9

Thyroid cancer order of commonness

Answer 9

Papillary (80) - assox ionising radiation
Follicular (10-20)
Medullary (5) - 20% fanilial men syndrome
Anaplastic (0-5) - elderly