Endocrinology (Thyroid Gland)

Question 1

Where is the thyroid gland found

Answer 1

-lower neck below the thyroid cartilage

Question 2

What is the structure of the thyroid follicle

Answer 2

-made of follicular cells that surround the colloid

Question 3

What do follicular cells secrete?

Answer 3

-thyroid hormone

Question 4

What is the colloid made of?

Answer 4

-glycoprotein

Question 5

How many thyroid hormones do we have? What are they called?

Answer 5

-2: T3, T4 (thyroxine)

Question 6

What structures are part of thyroid synthesis?

Answer 6

• follicular cells

- colloid

Question 7

What is needed to make thyroid hormone?

Answer 7

• iodine; obtained through food (salt)

- absorbed through digestive system > blood stream

Question 8

Thyroid synthesis process

Answer 8

1) Na+- symporter brings I- into the cell. The pending transporter moves I- into the colloid
2) Follicular cell synthesizes enzymes and thyroglobulin for colloid
3) Thyroid peroxidase adds iodine to tyrosine to make T3 and T4
4) Thyroglobulin is taken back into the cell in vesicles
5) Intracellular enzymes separate T3 and T4 from the protein
6) Free T3 and T4 enter the circulation

Question 9

How are the thyroid hormones classified?

Answer 9

• amino acid derived

- tyrosine

Question 10

What is the function on thyroglobulin?

Answer 10

-allow tyrosine, iodine to grab on

Question 11

What is TRH?

Answer 11

• thyroid releasing hormone
  
  • produced in the hypothalamus
  • stimulates anterior pituitary gland

Question 12

The TRH stimulates the anterior pituitary to produce what?

Answer 12

• TSH (thyroid stimulating hormone)

- stimulates the thyroid gland

Question 13

What does the thyroid gland produce?

Answer 13

• T4: travels to target > cell takes it in > removes Iodine to make T3
• T3(active form),

Question 14

When do we see negative feedback in a loop?

Answer 14

-when the last hormone level is too high

Question 15

What is hyperthyroidism?

Answer 15

-overproduction of thyroid hormone

Question 16

What causes hyperthyroidism?

Answer 16

-thyroid cancer

• Graves’ disease (autoimmune disease)
  
  • stimulates thyroid gland

Question 17

What are the effects of Graves’ disease?

Answer 17

-immune system is producing ‘thyroid stimulating immunoglobulin’ (TSI)

Question 18

What is the other term for immunoglobulin?

Answer 18

-antibody

Question 19

What are the symptoms of hyperthyroidism?

Answer 19

• increase in O2 consumption
  
  • increase in metabolic heat production/ heat intolerant
• Increase in protein catabolism/ weight loss
• irritable/ insomnia
• tachycardia (increase in heart rate)
• goiter (enlargement of the thyroid gland)
• exophthalmus (bulging of the eye)

Question 20

What is the cause of hypothyroidism?

Answer 20

-lack of iodine in diet

Question 21

What are the symptoms of hypothyroidism?

Answer 21

• decrease in O2 comsumption
  
  • decrease in metabolic heat production/colt intolerant
• decrease in protein synthesis= dry/thin skin, brittle nails, thinning hair ( decrease in protein keratin)
• slow speech/thought process
• fatigue
• bradycardia (slow heart rate)
• goiter (enlargement of thyroid gland)
• myxedema (fluid accumulation under the eye)
• cretinism (hypothyroidism during infancy)