endocrinology lecture 2

Question 1

where is the thyroid gland found? what connects it?

Answer 1

either side of the trachea

connected by isthmus

Question 2

what is the thyroid gland organized into?

Answer 2

follicles

balls of follicular cells, single layer forms ball

Question 3

what is found in the middle of a thyroid follicle?

Answer 3

colloid

fluid filled inner portion filled with proteins

Question 4

the colloid fluid is made by __________

Answer 4

made by follicular cells

Question 5

follicular cells regulate the production of which two iodine-containing hormones?

Answer 5

T3 and T4

Question 6

thyroid hormones are ____ based hormones

Answer 6

lipid soluble, amine based hormones

Question 7

why is a colloid storage mechanism needed in the thyroid?

Answer 7

prevents diffusion of the hormones out of the cells

Question 8

______ stimulates the thyroid gland to take up iodine with sodium (Na+)

Answer 8

TSH

Question 9

follicular cells also secrete __________, which has many tyrosine residues

Answer 9

thyroglobulin

Question 10

what is iodine oxidized by? what happens after oxidation?

Answer 10

oxidized by THYROID PEROXIDASE

linked to thyroglobulin (on the tyrosine residues)

Question 11

what molecules combine to form T3 and T4?

Answer 11

MITs and DITs

mono or di thyrotyrosine

Question 12

thyroid hormone is stored in colloid attached to __________

Answer 12

thyroglobulin

Question 13

what stimulates thyroid hormone release?

Answer 13

TSH (from pituitary gland)

Question 14

droplets of thyroglobulin fuse with ______ and T3 & T4 are released

Answer 14

lysosomes

Question 15

_______ of T4 is converted to T3 in the liver and kidneys

Answer 15

80%

Question 16

thyroid hormone exerts a negative feedback effect on the secretion of ___ and ___

Answer 16

TRH and TSH

Question 17

what are the forms of thyroid hormone receptors? what are they encoded by?

Answer 17

alpha and beta forms

encoded by 2 different genes

Question 18

a dimerized receptor + TH will regulate ____________

Answer 18

gene transcription

Question 19

how does TH stimulate cellular metabolism?

Answer 19

1) increase Na/K-ATPase activity
2) increase substrate availability
3) produces heat

Question 20

t/f: Thyroid hormone can upregulate beta-adrenergic receptors

Answer 20

true

Question 21

the effect of up regulating beta-adrenergic receptors leads to an increased sensitivity to ___________

Answer 21

catecholamines

NE and E

Question 22

TH is important for neuron _______ and _______

Answer 22

growth and development

Question 23

insufficient TH during fetal development causes ________

Answer 23

cretinism

Question 24

what are the most common endocrine diseases?

Answer 24

diseases of the thyroid gland

Question 25

both hypo-, and hyperthyroidism can lead to ______ development

Answer 25

goiter

Question 26

what is the consequence of hyper- or hypothyroidism?

Answer 26

Thyroid hormone normally inhibits TSH & TRH - too much, or too little, of TH will disrupt this balance

Question 27

Hypothyroidism is most often caused by what?

Answer 27

a primary defect in the thyroid gland

Question 28

T/F: 95% of the defects that cause hypothyroidism are due to a Iodine deficiency

Answer 28

True

Question 29

what effect does a lack of thyroid hormone have on TRH and TSH?

Answer 29

causes an increase in TRH and TSH due to a lack of feedback inhibition

Question 30

why does hypothyroidism cause a goiter?

Answer 30

unregulated TSH stimulation (due to lack of TH release)

Question 31

what are the effects of cretinism? (fetal iodine deficiency)

Answer 31

short stature mental retardation

Question 32

besides iodine deficiency, what are the other defects leading to hypothyroidism?

Answer 32

A) autoimmune thyroiditis B) damage or destruction of gland C) dysfunction associated with other illness

Question 33

what are the MILD symptoms/consequences of hypothyroidism?

Answer 33

- related to metabolic effects of TH | - sensitive to cold, slight weight gain

Question 34

what are the MODERATE symptoms of hypothyroidism?

Answer 34

- enough of a deficiency to cause lack of catacholamine response - fatigue, reduction in: blood flow, skin tone, GI & mental function

Question 35

the SEVERE effects of hypothyroidism include _______ due to an accumulation of what?

Answer 35

myxedema (bloating of soft tissue) accumulation of glycosaminoglycans (GAGs) in ECF

Question 36

t/f: hyperthyroidism is more common than hypothyroidism

Answer 36

false

Question 37

what are the primary defects that cause hyperthyroidism?

Answer 37

1) thyroid tumor 2) Graves disease (autoimmune) 3) thyroiditis (inflammation of Thyroid) 4) thyrotoxicosis factitia (too much TH is EATEN)

Question 38

symptoms/concsequences of hyperthyroidism

Answer 38

A) abnrmal concentrations of circulating hormones- high TH, low TSH B) goiter (only in graves disease) C) up-regulation of metabolic and nervous systems D) ocular symptoms

Question 39

how is hyperthyroidism treated?

Answer 39

1) surgery, radioactive iodine 2) remove entire gland 3) treat with drugs

Question 40

how do the drugs that treat hyperthyroidism work?

Answer 40

they block activity of enzyme in the TH production sequence

Question 41

why is hyperthyroidism of special concerns to dental care

Answer 41

- you must avoid catecholaminergic drugs (their receptors are overly expressed in the body) - thyroid storm - salivary glands can be damaged after radiation therapy