Thyroid Gland: Basic Anatomy, Physiology and Action

Question 1

What is the embryological cell type of thyorid gland?

*different for lateral and median

Answer 1

• Lateral: Neural crest cells
• Median: Pharynx

Question 2

What is the embryological course of thyroid gland?

Answer 2

1. Back of tongue
2. Migrates downwards to midline
3. Sits anteriorly to thyroid cartilage

Question 3

What embryological defect can arise from thyroid migration?

Answer 3

• lingual thyroid
• thyroglossal cyst

Question 4

What nerve lies laterally on each side of thyroid?

Answer 4

• Recurrent laryngeal nerve

Question 5

What does the recurrent laryngeal nerve innervate?

Answer 5

• innervates all intrinsic muscles of larynx - except cricothyroid
• Sensory to subglottis and glottis

Question 6

What are the signs of RLN lesion

Answer 6

• Hoarse cough
• ineffective cough
• airway obstruction - if bilateral RLN palsy

Question 7

What arteries supply the thyrid gland?

Answer 7

• Inferior & superior thyroid arteries

Question 8

What cells are found in the thyroid? State their function

Answer 8

• Follicular cells
  
  • synthesise thyroglobulin
• Neuroendocrine cells (C Cells)
  
  • secrete calcitonin

Question 9

What are tthyroid hormones made of?

Answer 9

• iodinated tyrosine molecule
• thyroxine: T4
• triiodothyronine: T3

Question 10

What is the main circulating hormone?

Answer 10

• T4
• Converted peripherally to T3

Question 11

What are the features of T3 that is different to T4?

Answer 11

• More potent
• Shorter half-life

Question 12

What proteins do Thyroid hormone bound to?

Answer 12

• Thyroxine Binding Globulin TBG
• Trasthyretin
• Albumin

Question 13

What are the types of thyroid receptor?

Answer 13

• TRa
• TRb