1412 endocrine system

Question 1

endocrine system overview

Answer 1

-regulates growth, reproduction, and metabolism
-glands and tissues secrete hormones which travel in blood to target cells where they will bind to receptors and change cell activity

Question 2

target cells

Answer 2

cells of an effector tissue/organ that have specific receptors for that hormone

Question 3

receptor proteins are found

Answer 3

on the cell membrane or intracellular (nuclear)

Question 4

water soluble hormones

Answer 4

-not able to cross hydrophobic part of the phospholipid bilayer, so it must bind to receptors on cell membrane

Question 5

what do water soluble hormones include

Answer 5

peptides, proteins, catecholamines that act as FIRST MESSENGERS in a signaling cascade

Question 6

water soluble hormones MECHANISMS OF ACTION:

Answer 6

1. hormone binds to cell membrane receptors (do not enter the cell for their actions)
2. hormone-receptor complex ACTIVATES membrane proteins e.g. G-proteins
   3.membrane proteins like G-proteins then activate 2ND MESSENGER SYSTEMS

Question 7

examples of 2ND MESSENGER SYSTEMS

Answer 7

cAMP , Ca+

Question 8

example using cAMP (cyclic adenosine monophosphate) as 2ND MESSENGER

Answer 8

1. hormone binds to cell membrane receptor which activates G-protein

2.G-protein activates adenylate cylcase (membrane protein)

3. Adenylate cyclase converts ATP -> cAMP (=2ND MESSENGER) *increases cAMP con. in cytosol
4. cAMP activates protein kinases (in cytosol)
5. Protein kinases acts on other proteins (phosphorylates) to alters their activity and change cell activity

Question 9

e.g epinephrine action on liver cells (activates cAMP)

Answer 9

1. cAMP activates protein kinases

2.protein kinases activates metabolic proteins (enzymes) that cause breakdown of glycogen to glucose

3. glucose is released into blood

Question 10

why use 2ND MESSENGERS?

Answer 10

-hormone cant enter cell (water soluble)
-rapid acting ( enzymes already present, just needs to be activated
-1 hormone molecule activates many enzyme molecules (cascade) which multiplies signal
-limited - messenger broken down or removed e.g cAMP broken down by phosphodiesterase in the cell

Question 11

lipid soluble hormones

Answer 11

-steroids (cortisol) and thyroid hormones
-triggers protein synthesis
->takes time, slow, long lasting response

Question 12

lipid soluble hormones
MECHANISMS OF ACTION:

Answer 12

1. enter target cell and bind to intracellular (nuclear receptors) in cytosol or nucleus
2. hormone-receptor complex binds to a specific region on DNA (activates genes) => start gene transcription - produces mRNA

3.mRNA attaches to ribosomes to produce proteins (translation)