Unformatted text preview: level is not even that high, in reality. It would not cause all of these problems What are the three main types of hormones? Peptide/Protein
(3 or more amino acids)
Steroid (derived from cholesterol)
(derived from single amino acids) Peptide/Protein Hormones e.g. glucagon Most hormones
Made in advance
Synthesized like secreted proteins
Stored in vesicles
a Steroid Hormone:
Release by exocytosis upon a signal Compare tohormone will last about
Water soluble (dissolved in plasma) an hour or more
minutes in the plasma.
Short half life in plasma -Lasts only will be cleared quickly We need to understand that this
Bind to membrane receptors (next lecture)
-Cause intracellular signalling (like steroid hormones) Peptide/Protein Hormones: synthesis, packaging
and release How do we know what kind of hormone a cell makes via microscopy?
ROUGH ER: Produces peptide hormone
SMOOTH ER: Produces steroid hormone PATHWAY: mRNA translates the hormone right inside the ER --> A Preprohormone is produced -->
The signal sequences that translocated the protein to the ER is cleaved --> This leaves a
Prohormone --> The Prohormone is transported in a vesicle to the Golgi --> In the Golgi, the
Prohormone is processed into an active Hormone and is transported into the blood stream
-Importane of the Peptide By-Products:
-Insulin produces C Peptide as a by product --> When insulin is released, 50% of it is absorbed in the
l iver, but C Peptide isn't
-If you want to get an idea of how much endogenous insulin someone is producing (while you are
s upplementing them with Exogenous Insulin), we can measure how much C Peptide is (in order to
m ake an estimate of how much Endogenous Insulin is being produced) Single preprohormone can contain: Several copies of the same hormone More than one type of hormone -Multiple peptides produced by the same
p reprohormone -Don't focus on what these do
-The IMPORTANT POINT:
-The same pre-prohormone will be
responsible for producing multiple
h ormones or peptides "Two peptides I want you to know from this: POMC, ACTH and MSH"
- Look at the next slide to understand **QUESTION ABOUT POM C AND THIS
PATHWAY WILL BE ON THE EXAM Addison's Disease: Adrenal Gland stops working and stops producing Glucocorticoids
-The negative feedback is gone!
-CRH and ACTH will continue to increase because the Adrenal Cortex will not be able to turn off
t he loop
-We are stimulating ACTH, but we cant **JUST** stimulate ATCH!
-We are actually stimulating the Pre-Progene POMC
-A by-product is an increase in all of these others : MSH, ACTH
-An Increase in MSH: stimulates melanin and will darken the skin
-UNDERSTAND: atrophy of this gland (reducing glucocorticoids) will increase ACTH, CRH AND
e verything that POMC encodes for --> MSH leads to darkening of the skin
-If we understand the pre-prohormone, we can understand the downstream effects when its
regulation is lost Peptide/Protein Hormone (Processing)
Glycosylation Formation of disulf...
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- Summer '12
- Endocrine System, Anterior pituitary