Thyroid Gland

Question 1

This gland releases which hormone?

Answer 1

Thyroid hormone. T3 & T4

Question 2

T3 is also known as?

Answer 2

Triiodothyronine. 3 atoms of iodine

Question 3

T4 is also known as?

Answer 3

thyroxine or tetraiodothyronine. 4 atoms of iodine.

Question 4

What do T3 & T4 do?

Answer 4

increase metabolism & increase delivery of oxygen to support metabolism

Question 5

When TH levels increase what kind of feedback inhibits the release of ___ & ___?

Answer 5

negative feedback; TSH, TRH

Question 6

Although T3 & T4 get secreted, it is mostly which that gets secreted?

Answer 6

T4

Question 7

Thyroid hormones, just like steroid hormones, are…

Answer 7

lypophilic

Question 8

What is the structure of the thyroid gland?

Answer 8

two large lobes connected by broad isthmus. follicles on outside of gland, follicles filled with colloid. colloid filled with thyroglobulin.

Question 9

What are the other hormone-secreting cells on the outside of the thyroid gland referred to as?

Answer 9

extrafollicular cells (C cells)

Question 10

How is T3 & T4 produced?

Answer 10

food –> absorbed by intestine –> blood carries as iodide to thyroid gland –> iodide pump moved them into follicular cells _> oxidized to put in reactive form -> thyroglobulin released into lumen -> enzyme on cell surface adds iodine to it

Question 11

When one iodine is added?

Answer 11

MIT (monoiodotyrosine)

Question 12

When 2 iodines added?

Answer 12

DIT (diodotyrosine)

Question 13

T3 when broken down is just ..

Answer 13

MIT + DIT

Question 14

T4 when broken down is just..

Answer 14

DIT + DIT

Question 15

When the thyroid cells get TSH, they do what to thyroglobulin?

Answer 15

absorb it by pinocytosis

Question 16

How does TH get to target cells?

Answer 16

lysosomal enzyme hydrolyzes peptide chain of thyroglobulin which frees TH. TH goes into blood & binds w/ transport protein so it can get to target cells.

Question 17

Oxytocin is unusual in that it has a ___ feedback loop

Answer 17

positive

Question 18

Growth hormone, unlike other pituitary hormones, has a ___ effect

Answer 18

widespread

Question 19

What does growth hormone do?

Answer 19

stimulates bone, cartilage, muscle, fat, liver. causes liver to secrete IGF-1 & IGF-2

Question 20

IGF-1 & IGF-2 are known as? They do what?

Answer 20

somatomedins. mediate effects of growth hormone

Question 21

what is an effect of IGF?

Answer 21

prolongs behavior of GH, half life only 6-20 mins

Question 22

what does IGF-1 do?

Answer 22

accelerates bone growth in response to GH, epiphyseal plates, osteogenic/chondrocytes stimulated.

Question 23

GH & IGF turn on what?

Answer 23

protein synthesis

Question 24

GH plays a role in __ metabolism

Answer 24

lipid; stimulate adipocytes to catabolize fat. releases triglycerides into fatty acids & glycerol. protein sparing effect

Question 25

GH shuts down ___ catabolism

Answer 25

protein

Question 26

GH turns on ___ synthesis in liver

Answer 26

glucose

Question 27

GH impacts ___ balance. how?

Answer 27

electrolyte; promotes retaining of them

Question 28

GH promotes ___ retention

Answer 28

Ca; small kidney

Question 29

GH also plays a role in ___ metabolism.

Answer 29

carbohydrate; glucose-sparing effect mobilizes fatty acids, cells don’t depend on glucose to make ATP

Question 30

GH stimulates protein ___ so cartilage & bone can lay down more Ca & cartilage to support bone

Answer 30

protein

Question 31

exercise secretes __

Answer 31

GH

Question 32

hypoglycemia can trigger __

Answer 32

GH

Question 33

high carb meals suppress ___ because?

Answer 33

GH; stimulates glucose production in liver

Question 34

highest level of GH is when you __

Answer 34

sleep