Chapter 6 Study Questions (Part 2)

Question 1

how are Hashimoto’s disease and Graves’ disease similar?

Answer 1

autoimmune diseases of the thyroid gland

Question 2

how are Hashimoto’s disease and Graves’ disease different?

Answer 2

H: low thyroid. targets thyroglobulin –> hypothyroid. lose ability to make thyroid.

G: high thyroid. body overproduces thyroid, agonist that binds to thyroid stimulating receptor and triggers hormone synthesis.

Question 3

in endocrine diseases, what is a primary defect? please provide one example

Answer 3

involves the hormone source cell.

thyroid gland stops making thyroid hormone.

Question 4

in endocrine diseases, what is a secondary defect? please provide one example

Answer 4

involves an endocrine gland that regulate the source gland. upstream.

a problem with circulating thyroid hormone levels could be due to a problem with low thyroid releasing hormone from the hypothalamus

Question 5

what is the cause of goiter?

Answer 5

inability to shut off TRH and TSH. iodine deficiency in diet

Question 6

how is the thyroid gland impacted in goiter?

Answer 6

enlarges in response to continuous stimulation from TSH, to try to match the perceived demand for thyroid hormone

Question 7

why does iodine deficiency disrupt thyroid hormone negative feedback inhibition in goiter? what happens normally?

Answer 7

normally, TH negatively feeds back on hypothalamus and ant. pit. to shut down TRH and TSH.

with iodine deficiency, INACTIVE TH is made. inactive TH is not recognized as TH, and doesn’t cause negative feedback.

Question 8

how is goiter treated?

Answer 8

radioactive iodine therapy

Question 9

why isn’t Graves disease subject to negative feedback inhibition?

Answer 9

TH does not inhibit antibodies that bind to TSH receptors

something is still binding to the receptor. you don’t need thyroid stimulating hormone; antibodies bind instead. not impacted by the level of thyroid hormone.

Question 10

describe a negative feedback mechanism

Answer 10

product of a reaction leads to a decrease of that reaction

Question 11

describe a positive feedback mechanism

Answer 11

product of a reaction leads to an increase of that reaction

Question 12

T or F: tropic hormones are chemical messengers that are only produced by neurons

Answer 12

F

Question 13

why can thyroid hormone be taken orally in spite of the fact that it is made from a protein?

Answer 13

usually, peptide bonds are degraded.

TH is made from proteins, but you didn’t cleave the R group, you cleaved the peptide bonds on either side, so they’re not getting degraded

Question 14

what two hormones made by the pancreas work opposite of each other to maintain the blood glucose level?

Answer 14

glucagon vs. insulin

Question 15

blood glucose level = ?

Answer 15

90-100 mg/dL

Question 16

in which cell type is glucagon made?

Answer 16

pancreatic alpha cell

Question 17

in which cell type is insulin made?

Answer 17

pancreatic beta cell

Question 18

why is the circulating blood glucose concentration normally kept much higher than brain glucose?

Answer 18

in the brain, glucose is moved through transporters.

in general circulation, brain is moved through simple diffusion because of the gaps in endothelial cells

simple diffusion requires a gradient, so having a higher concentration in the circulating blood glucose allows for a gradient

Question 19

describe Hashimoto’s disease

Answer 19

hypothyroidism, caused by antibodies being made against thyroglobulin

Question 20

what is thyroglobulin?

Answer 20

a protein present in the thyroid gland that makes TH

Question 21

describe Grave’s disease

Answer 21

overproduction of thyroid hormone.

our bodies make autoantibodies that bind to TSH receptors on thyroid gland.

unlike TSH, there is no feedback inhibition.

so, TH is overproduced, and thyroid can be enlarged.

Question 22

why is there no negative feedback in Grave’s disease?

Answer 22

TH does not inhibit antibodies that bind to TSH receptors