PSL300H1 Study Guide - Final Guide: Lipotropin, C-Peptide, Proopiomelanocortin
ProfessorHae- Young Kee
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What are some features of hormones?!
can be produced in diff parts of the body.
chemicals are made by cells in specific endorcine glands or tissues. (when hormone produced in wrong part of
body → tumour!)
transported through blood to distant targets where they bind to specific receptors. can act on multiple tissues and
alter activity of target cells.
actions must be terminated.
What are the three main types of hormones?! ***
peptide/protein → 3+ amino acids. make up majority of hormones and are made in advance. synthesized like
secreted proteins and stored in vesicles. released by exocytosis upon signal (e.g. depolarization). water soluble
(dissolve in plasma), short half life in plasma (minutes, steroids can last between 1 hour to 90 minutes). bind to
synthesis, packaging and release: start off in mRNA. bundled up into transport vesicle. pass through
ER/golgi apparatus, where separated into protein fragment and active hormone and bundle into secretory
vesicle, which is released upon signal.
smooth ER → steroid produced cell. rough ER → peptide producing cell.
protein fragments (such as C-peptide, a byproduct of insulin) can help us determine how much of a product
is being produced, since the active hormone is usually absorbed by the target organ asap.
a single prepohormone can contain several copies of the same hormone:
prepohormone → hormone + other peptides + signal sequence
and produce more than one type of hormone:
prohormone → active hormones + other protein fragments
(ex. POMC → ACTH + γ lipotropin + β endorphin + fragment) ****
γ lipotropin → stimulates melanin.
ACTH → involved in cortisol stimulation
the products can also cleave and produce other hormones. ACTH → alpha-MSH and CLIP.
beta-lipotropin → γ lipotropin + β endorphin. γ lipotropin → β MSH.
steroid → can only be synthesized from cholesterol. made on demand. released from cells by simple diffusion
and not vesicles. water insoluble (bound to carriers in the blood). has a long half life. acts of cytoplasm, nucleus
and plasma receptors. causes intra cellular signaling.
pathways of biosynthesis occur in mitochondria and smooth endoplasmic reticulum
cholestrol always converts into progesterone as a first step.
aldosterone regulates BP, and electrolyte homeostatis.
cortisol regulates glucose homeostasis, stress response (if hypertension is high), metabolic phenotype ( if
estradiol regulates gynoecomastia, testicular atrophy and frontal balding.
the types hormones made depends on which enzymes are present in the cell.
ACTH will stimulate the gland that produce the hormones.
Adrenal cortex made of 3 different layers (GFR):
1) Zona glomerulosa -> aldosterone
2) Zona fisiculata -> cortisol
3) Zona riticularis -> androgen(steroid)
Each responsible for producing a specific hormone. if cortex isn't functioning properly → hyperpigmentation.
the medulla will produce adrenaline and NA.
ovaries produce estradiol, via FSH and LH.
Steroid hormones are metabolized by P450 enzymes. oxidation of sterioids will form bile acids, bile acids
are secreted from the liver into the duodenudem.
amine → derived from one single a.a: either tryptophan or tyrosine.
tryoptophan → melatonin (behaves like peptides or steroids). produced from pineal gland, involved with circadian
rhythm. increases at night.
tyrosine → catecholamines (behave like peptides, bind to receptors on cell membrane)
thyroid hormones (behave like steroids, work on cell membrane. T3/T4 enter cell,
receptor in cells or nucleus, directly affect transcription.
How is hormone release controlled?!
endocrine cells directly sense stimuli, then secrete the hormone (integrating center).
stimuli (metabolite [a.a., fatty acids], hormones [insulin, glucagon, somatostatin], neurohormone,
neurotransmitter) → endocrine cell → hormone release.
if you knock out 17 - alpha hydroxylase → you can only produce aldosterone (exccessive =
hypertensive). no production of cortisol or estradiol.
high estrogen in males:
- testicule shrinking (atrophy), breast development, frontal balding.
high levels of DHT in females (in females):
- abnormal facial hair growth, overweight, stop menstruating.
BP cases have to do with aldosterone.
hyperglycemia case → cortisol. (overweight, stria or purple streaks across adomen,
Classification of Hormones and Control of Release
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