Exam 3 Endocrine System

Question 1

What type of hormone is Vitamin D?

Answer 1

steroid

Question 2

What is the second step in steroid synthesis?

Answer 2

pregnenolone

Question 3

What are the 3 primary classes of steroid hormone?

Answer 3

• mineralocorticoids
• glucocorticoids (cortisol)
• sex hormones (chiefly androgens)

Question 4

Where are steroid hormones produced?

Answer 4

• synthetic enzymes are in mitochondria and SER
• chiefly in gonads and adrenal cortex
• but may also be produced in adipose tissue, liver, and skin

Question 5

All peptides are unbound except-

Answer 5

IGF and about 1/3 of GH

Question 6

What hormones use the PKA pathway?

Answer 6

• Pituitary hormones (ACTH, FSH, LH, TSH)
• catecholamines
• Glucagon
• Calcitonin
• PTH

Question 7

What hormones use the PLC pathway?

Answer 7

• Hypothalamic hormones (TRH, GnRh, oxytocin, ADH)

- Catecholamines

Question 8

What is the 2nd messenger in the PLC pathway?

Answer 8

• IP3

- then calcium

Question 9

In the PLC pathway, ___ triggers release of calcium from the ____.

Answer 9

IP3; ER (or mitochondria in the anterior pituitary)

Question 10

List the sequence of molecules activated in the PKA pathway before phosphorylation cascade.

Answer 10

1) receptor
2) G-alpha-s subunit
3) adenylate cyclase
4) cAMP
5) Protein kinase A

Question 11

List the sequence of molecules activated in the PLC pathway before the release of calcium.

Answer 11

• receptor
• g protein subunit
• Phospholipase C
• IP3

Question 12

Kinases phosphorylate proteins at which amino acids?

Answer 12

• serine
• threonine
• tyrosine

Question 13

What are 3 ways kinases can be activated?

Answer 13

• hormones if receptor is also a kinase
• second messengers
• other kinases (cascades)

Question 14

What is a response element?

Answer 14

specific regions of DNA that proteins bind to modify transcription

Question 15

Which hormones use the tyrosine kinase signaling pathway?

Answer 15

• most growth factors e.g. IGF and epidermal growth factor (EGF)
• GH and insulin use a variant

Question 16

What is the pathway of hypothalamic hormones to the anterior pituitary?

Answer 16

ventral hypothalamus> parvocellular neurons> hypothalamic hypophyseal portal system>endocrine cells of anterior pituitary

Question 17

What is the pathway of hypothalamic hormones to the posterior pituitary?

Answer 17

hypothalamic nuclei> magnocellular neurons> hypothalamic hypophyseal tract

Question 18

What hormones are secreted from the anterior pituitary?

Answer 18

• TSH
• FSH
• GH
• ACTH
• prolactin
• LH

Question 19

CRH stands for

Answer 19

corticotropin-releasing hormone

Question 20

TRH stands for

Answer 20

thyrotropin-releasing hormone

Question 21

GnRH stands for

Answer 21

gonadotropin-releasing hormone

Question 22

PRF and PIH stand for

Answer 22

• prolactin-releasing factor

- prolactin-inhibiting hormone

Question 23

What is the abbreviation for prolactin?

Answer 23

PRL

Question 24

Name all the hypothalamic hormones.

Answer 24

• GnRH
• GH-RH
• GH-IH
• PRF
• PIH
• TRH
• CRH

Question 25

Name the primary hormones.

Answer 25

- androgens - estrogens, progesterone - cortisol - thyroid hormones - IGFs

Question 26

what is somatostatin?

Answer 26

GH-IH

Question 27

What is somatotropin?

Answer 27

GH-RH

Question 28

What is somatomedin?

Answer 28

IGF-1

Question 29

What processes does growth hormone upregulate?

Answer 29

- fat oxidation and lipolysis - gluconeogenesis and glycogenesis - insulin resistance - insulin secretion in the pancreas

Question 30

What processes does growth hormone downregulate?

Answer 30

- glucose uptake from muscle and fat | - lipogenesis in fat

Question 31

What pathway does growth hormone use?

Answer 31

tyrosine kinase pathway

Question 32

In terms of feedback, what will happen if IGF levels are elevated?

Answer 32

GH-IH levels will increase, in turn lowering GH levels

Question 33

What are two potential meanings of elevated TSH levels?

Answer 33

- thyroid hormone level could be is low (hypothyroidism) | - less commonly, TRH levels are high

Question 34

What hormone classification are thyroid hormones? Are they hydrophilic or lipophilic? How do they enter the cell and where do they bind?

Answer 34

- they are amines - they are lipophilic - they use a transporter - they bind to nuclear receptors

Question 35

What is the function of CREB signaling pathways?

Answer 35

regulate transcription

Question 36

What pathway enduces exocytosis of TSH?

Answer 36

PLC

Question 37

What pathway enduces synthesis of T3 and T4?

Answer 37

PKA

Question 38

What is the difference between Tg and TBG?

Answer 38

- Tg is precursor for T3 and T4 | - TBG binds t3 and T4

Question 39

Thyroid receptors heterodimerize with-

Answer 39

retinoic acid receptors (RXR)

Question 40

What are the manifestations of hypothyroidism?

Answer 40

- Hair loss - Goiter - reduced HR - constipation

Question 41

What are the manifestations of hyperthyroidism?

Answer 41

- Hair loss - bulging eyes - Goiter - palpitations - diarrhea

Question 42

What is the pathway for iodine from the blood to the pendrin transporter?

Answer 42

- "trapping" by sodium-dependent transporter into follicle cell - "activation" of iodine molecule and transepthelial diffusion to pendrin

Question 43

In TH synthesis, what happens in the colloid once iodine enters?

Answer 43

- Organification: thyroperoxidase (TPO) attaches iodine to Tg by means of H202 forming regions of 3 (MIT) & 4 (DIT) iodides - Modified Tg gets endocytosed back into follicle cell by pendrin transporter

Question 44

What happens once modified Tg is transported back into follicle cell from colloid?

Answer 44

- lysozyme cleaves it into 6 molecules of T3 or T4 (variable combination) - T3 and T4 released into general circulation, bound to TBG or albumin

Question 45

Which hormones cannot use PLC or PKA pathway?

Answer 45

steroids, but some can use CREB