The Endocrine Syste, Flashcards
Glands
organs of the endocrine system that secrete hormones
Hormones
signaling molecules that are secreted directly into the bloodstream to travel to target tissue
they bind to receptors and induce a change in gene expression or cellular function
Hormones can be classified into the following:
Peptides
Steroids
Amino Acid Derivatives
Peptide hormones
made up of amino acids and can be small to large
derived from larger precursor polypeptide cleaved during posttranslational modification; small units go to golgi apparatus for modifications to activate hormone and released by exocytosis
rapid but short lived effects as they act through transient second messenger system meaning easier to turn on and off
water soluble and do not require carriers, travel through blood stream
Because peptide hormones are ____, they cannot pass through the plasma membrane and must bind to _____
charged
extracellular receptor
First messenger
ie. peptide hormones
bind to receptor and trigger transmission of second signal/second messenger
Signaling Cascade
connection between hormone and the effect caused by the secon messengers
Amplification
one hormone may bind to multiple receptors before degradation
each receptor will activate multiple enzymes and trigger production of large quantities of second messengers
each step increases intensity of signal
Common Secondary Messnegers
cyclic adenosine monophosphate (cAMP)
inositol triphosphate (IP3)
Calcium
G Protein Coupled Receptor
1) Peptide hormone binds and triggers receptor to EITHER ACTIVATE OR INHIBIT adenylate cyclase
2) this raises or lowers levels of cAMP
3) cAMP binds to protein kinase A and phosphorylates transcription factors such as cAMP and then exert hormones true effect
Steroid Hormones
derived from cholesterol and produced in gonads/adrenal cortex
non polar molecules that easily cross the cell membrane
slower but longer lived than peptide hormones as they alter mRNA and protein present by affecting DNA
non water soluble and carried by protein
Receptors of steroid hormones are usually _____ or ______.
The hormone-receptor complex undergoes ______ which can the bind directly to ______ resulting in increased or decreased _________
intracellular (cytosol) or intranuclear (nucleus)
conformational change
DNA
transcription of genes
Dimerization
pairing of two receptor-hormone complezes
Steroid Carrying Proteins
specific and cary only one specific hormone
non specific
Note, homrones are inactive while in carrier protein
LEVELS OF CARRIER PROTEIN CAN IMPACT LEVELS OF ACTIVE HORMONE (more carrier protein, less hormone as it is bound to protei)
Amino Acid Derivative Hormones
less common than peptide and steroid hormones
derived from one or two amino acids with a few modifications