Intro to Endocrine- Teresa

Question 1

What are the three types of hormones?

Answer 1

Steroid, Amine, and Protein

Question 2

What organ is the integrator of many homeostatic and reproductive signals?

Answer 2

Hypothalamus

Question 3

How does the hypothalamus interact differently with the posterior vs anterior pituitary?

Answer 3

In posterior pituitary, hypothalamic neurons produce the ADH and oxytocin and project it to the posterior pituitary. The hormones are then stored in the posterior pituitary. This is fast acting.

Question 4

What is the action of hypothalamic neurons in the hypothalamo-hypophyseal portal system?

Answer 4

Hypothalamic neurons secrete a releasing or inhibitory hormone into the hypothalamo-hypophyseal portal system which bathes the anterior pituitary

Question 5

Which is faster generally- the actions of the posterior or anterior pituitary?

Answer 5

Posterior is faster.

Question 6

What hormones are secreted by the anterior pituitary?

Answer 6

1. Prolactin
2. TSH
3. ACTH
4. GH
5. Gonadotropins: FSH and LH

Question 7

What is the most common way to regulate hormone secretion?

Answer 7

Negative feedback- the final hormone typically feeds back to the start or middle of the hormone axis

Question 8

What type of hormone are all the hypothalamic and pituitary hormones?

Answer 8

Proteins- so they act on receptors in the outside membranes of cells

Question 9

Where are pre-prohormones cleaved into prohormones?

Answer 9

Rough ER

Question 10

Are protein or steroid hormones soluble in water?

Answer 10

Proteins are water soluble, the steroid hormones are lipophilic

Question 11

Are steroid hormones produced in advance or as needed?

Answer 11

On demand (as needed)

Question 12

Which endocrine organs synthesize steroid hormones?

Answer 12

Adrenal and Gonads

Question 13

Which major type of hormone is an amine based hormone?

Answer 13

Catecholamines and Thyroid hormones

Question 14

How do catecholamines act?

Answer 14

Like protein hormones (though they are amines)

Produced in neurons, and packaged in vesicles for intermittent release on demand

Question 15

How do thyroid hormones act?

Answer 15

Like steroid hormones (though they are amines)
Control of production is thus based on enzymatic activity and iodine availability
Secreted along diffusion gradient

Question 16

What are the 4 types of GPCRs?

Answer 16

Gas- stimulates adenylyl cyclase
Gaq- activates PLC to form IP3 and DAG
Gai- inhibits adenylyl cyclase
Gat- transducin; triggers the breakdown of cGMP

Question 17

What type of receptors do steroid hormones act on?

Answer 17

Nuclear receptor superfamily receptors- these are inside the cells and cause transcriptional response via homodimers of receptor:hormone

Question 18

How do steroid and thyroid hormones get to their target cells?

Answer 18

Often bound to protein in serum since they are poorly soluble
Free hormone diffuses across cell membrane and binds to cytoplasmic receptor
receptor:hormone complex enters nucleus and dimers act as transcriptional factors

Question 19

What are the three mechanisms of hormone clearance?

Answer 19

1. Liver metabolism
2. Urinary/biliary excretion
3. Target cell uptake and degradation following receptor binding and signaling

Question 20

Are hypothalamic hormones secreted at a low base-level or in pulses?

Answer 20

Pulses- often based on circadian rhythm; this prevents desensitization to downstream organs

Question 21

How can hormones interact? What types of responses are possible?

Answer 21

1. additive/synergystic
2. Permissive- allows a second hormone to have its full effect
3. Antagonistic