Thyroid

Question 1

Where is the thyroid gland?

Answer 1

In the neck

Question 2

What is the thyroid composed of?

Answer 2

• Midline isthmus
• Right lobe
• Left lobe

Question 3

Where is the midline isthmus?

Answer 3

Just below Adam’s apple (cricoid cartilage)

Question 4

How are thyroid cells arranged?

Answer 4

In follicles

Question 5

What do thyroid cells produce?

Answer 5

Thyroid hormones

Question 6

What are the two forms of thyroid hormones? What % do they make up?

Answer 6

T4 (inactive form) and T3 (active form)
T3 - 20% or thyroid hormones
T4 - 80% of thyroid hormones

Question 7

How is T3 derived?

Answer 7

Majority derived from T4

Question 8

Thyroid also contains C cells. What hormone do C cells produce?

Answer 8

Calcitonin for calcium metabolism

Question 9

What effect does too much thyroid hormone production have on the heart?

Answer 9

Tachycardia

Question 10

What effect does too little thyroid hormone production have on the heart?

Answer 10

Bradycardia

Question 11

What is the route of thyroid hormone production?

Answer 11

1. Hypothalamus secretes TRH
2. This tells the pituitary gland to secrete TSH
3. This tells the thyroid to secrete thyroid hormones (T3 and T4)
4. T3 and T4 return to the hypothalamus and pituitary, switching off the production (negative feedback)

Question 12

What happens to thyroid hormone production if pituitary stops working?

Answer 12

TSH not secreted so thyroid hormones not secreted, low TSH, T3 and T4

Question 13

What happens to thyroid hormone production if there is a problem with the thyroid gland?

Answer 13

Low T3 and T4 but high TSH