Topic 18: Endocrine System - Thyroid and Parathyroid Gland

Question 1

Where is the thyroid gland? (2)

Answer 1

• on anterior surface of the superior part of the trachea
• butterfly shaped

Question 2

What is does the thyroid gland contain? (2)

Answer 2

• follicles
• Parafollicular cells

Question 3

What are the follicles in the thyroid gland made of?

Answer 3

• walls are made of epithelial cells (follicle cells)

Question 4

What do the follicles in the thyroid gland produce?

Answer 4

• T4

Question 5

Where are the parafollicular cells of the thyroid gland?

Answer 5

• between follicles

Question 6

What do the parafollicular cells secrete?

Answer 6

• calcitonin

Question 7

What is the function of calcitonin? (2)

Answer 7

• increase calcium uptake into bone (bone formation)
• thus lowering calcium in blood

Question 8

What are parathyroid glands?

Answer 8

• 4 (usually) glands embedded in posterior thyroid

Question 9

What do parathyroid glands secrete? What does it do?

Answer 9

• parathyroid hormone (PTH)
• increases blood calcium levels

Question 10

How does PTH increase calcium levels in blood? (5)

Answer 10

1. increases Calcium release from bone (bone resorption)
   - activates osteoclasts
2. Decrease calcium loss in urine (kidney)
3. increase Vitamin D activation (kidney)
   - vitamin D increases calcium absorption at small intestine