6. The Endocrine System Flashcards
What are the two major control systems of the body?
nervous system
endocrine system
What is the main signal of the endocrine system?
hormones
What is a hormone?
molecule which is secreted into the bloodstream by an endocrine gland and has its effects upon a distant target possessing the appropriate
What is an endocrine gland?
ductless gland whose secretary products are picked up by capillaries supplying blood to the region
What is an exocrine gland?
gland that secretes products into the external environment by way of ducts which empty into the GI lumen or the external world
What is a hormone receptor?
polypeptide that possesses a ligand-specific binding site
What is autocrine activity?
signaling molecules that modify that activity of the cell which secreted them
What are the two groups of hormones?
hydrophilic hormones = peptides and amino acid derivatives
hydrophobic hormones = steroid derivatives
Where are peptide hormones synthesized?
rough ER
Where are steroid hormones synthesized?
smooth ER
How are peptides hormones transported?
freely in the bloodstream
How are steroid hormones transported?
stuck to protein carrier in the bloodstream
What is the regulation of release for peptide hormones?
stored in vesicles until signal for secretion is received
What is the regulation of release for steroid hormones?
synthesized only when needed, used immediately
What is the mechanism of effect for peptide hormones?
bind to receptors that generate second messengers which result in modification of enzyme activity
