Thyroid Gland

Question 1

Where is the thyroid located?

Answer 1

• superficial to and just above the trachea

Question 2

Different parts of the thyroid

Answer 2

• Parafollicular cells - produces Calcitonin
• Follicle
• Epithelial cells - site of T3 and T4 synthesis
• Colloid - site of T3 and T4 storage

Question 3

What is the general effect of T3 and T4?

Answer 3

• increase in metabolism

Question 4

How does the feedback loop work?

Answer 4

• when T3 and T4 levels are high, TRH secretion is suppressed so homeostasis is maintained

Question 5

Hyperthyroidism vs Hypothyroidism

Answer 5

Hyperthyroidism - increase in T3 and T4, resulting in a high metabolic rate, increased body temp, weight loss, rapid heart rate etc…

Hypothyroidism - decrease in T3 and T4, resulting in low metabolic rate, sensitive to cold temperatures, low blood pressure, easily fatigued, lethargic

Question 6

Possible causes of hypo- and hyperthyroidism

Answer 6

Hypothyroidism - Iodine deficiency
Hyperthyroidism - Tumour in hypothalamus

Question 7

What is Goiter syndrome?

Answer 7

• enlarged thyroid
• caused due to lack of iodine which means a lack of thyroid hormone
• treated using thyroxine, which acts like T4 in the body and inhibits TSH release

Question 8

What is Graves’ disease?

Answer 8

• autoimmune disease which results in the thyroid being over activated (hyperthyroidism)

Question 9

What does calcitonin do?

Answer 9

• released when calcium levels are high
• inhibits more calcium from being released into blood stream

Question 10

What does parathyroid hormone do?

Answer 10

• opposite of calcitonin
• released when calcium levels are too low
• antagonist to calcitonin