Endocrine System: Mechanisms of Hormone Action (HY)

Question 1

what is a hormone?

Answer 1

signalling molecule secreted into the bloodstream to travel to a distant target tissue

Question 2

What are three types of hormones?

Answer 2

1. peptide hormones
2. steroid hormones
3. amino acid derivative hormones

Question 3

What is the process of peptide hormone formation?

Answer 3

1. large polypeptide translation
2. cleavage of large polypeptide in post-translational modification
3. smaller peptide sent to Golgi Apparatus for processing (more modifications, direct cellular localization)
4. exocytosis through vesicle

Question 4

A polypeptide hormone is a charged first messenger that binds to extracellular receptor. What are three examples of second messengers?

Answer 4

1. cAMP (cyclic AMP)
2. IP3 (inositol triphosphate)
3. calcium

Question 5

Compare polypeptide hormone and steroid hormone on method of action, speed of action, and how long the effect lasts.

Answer 5

Peptide hormones bind extracellular receptors and act through second messengers. They illicit fast but short responses. (ex. insuling released after every meal)

Steroid hormones bind intracellular or intranuclear receptors and directly bind to DNA. They illicit slow but longer-lasting response (ex. estrogen and testosterone).

Question 6

From what are steroid hormones made, and in what two places are steroid hormones primarily produces?

Answer 6

steroid hormones are made from cholesterol, and they are primarily made in the gonads and adrenal cortex (outer and largest part of the adrenal gland)

Question 7

what are amino acid-derivative hormones?

Answer 7

hormones derived from one or two amino acids, often with modifications

Question 8

what are catecholamines? what do they bind to?

Answer 8

catecholamines are amino acid-derivative hormones: epinephrine and norepinephrine
they bind to G-protein coupled receptors

Question 9

what are four important amino acid-derivative hormones?

Answer 9

1. epinephrine
2. norepinephrine
3. triiodithyronine
4. thyroxine

Question 10

what do thyroid hormones bind to?

Answer 10

thyroid hormones, which are amino acid-derivative hormones, bind intracellularly

Question 11

What is the difference between direct hormones and tropic hormones?

Answer 11

direct hormones are secreted and directly act on a target tissue themselves (ex. insulin from pancreas causes muscle glucose uptake).
But tropic hormone have an intermediary act on a tissue (ex. GnRH from hypothalamus stimulates release of LH and FSH, which then indirectly act on physiology during puberty)

Question 12

from what two places do tropic hormones primary originate?

Answer 12

brain and anterior pituitary gland

Question 13

How do peptide hormones and steroid hormones travel in the bloodstream?

Answer 13

peptide hormone are charged and are soluble in the bloodstream.

steroid hormones are non-polar and insoluble in bloodstream, so they require protein carriers. when steroid hormones are being carried by proteins, they are not active.