18 Overview of endocrine system Flashcards
what is the endocrine system
a group of glands that secrete hormones into the circulatory system in response to their specific signals
what does the circulatory system do
carry the hormones to their target organs
what do target cells/organs express
specific hormone receptors that allow them to respond to hormones
what do exocrine glands do
secrete their products via. duct into some other location in the body
what do hormones regulate
- homeostasis
- energy metabolism
- growth and development
- reproduction
- behaviour
what are peptide hormones made up of
a chain of amino acids (short peptides and proteins)
peptide and protein hormones are same thing
can peptide hormones diffuse across membrane
no because they are hydrophilic
what are steroids hormones derived from
cholesterol
can steroid hormones diffuse across the membrane
yes as they are lipophilic
what are amine hormones derived from
amino acids (tyrosine and tryptophan)
how are steroid hormones transported
since its not very soluble its bound to specific proteins in the circulation
how do steroid hormones leave the cell
steroid hormones are lipophilic and leaves the cell by diffusion
secretion of steroid hormone is enhanced by increasing its synthesis (not stored)
how do peptide hormones travel in blood
freely as they are hydrophilic
where are peptide hormones stored
in secretory vesicles
what do the secretory vesicles do to release the peptide hormone
they fuse with the plasma membrane to release the hormone into the blood (exocytosis)
what does secretion and transport of amine hormones depend on
the specific amine hormone
transport and secretion of catecholamines
leave by exocytosis
dissolve in plasma
secretion and transport of amine hormones
leave by transporter proteins
travel bound to carrier proteins
where are peptide hormone receptors found
at the plasma membrane of the target cell
where are steroid hormone receptors found
in the target cell
where are amine hormone receptors found
either in the cell or on the membrane, depends on hormone
what do steroid hormones do
bind to intracellular receptors and modulate gene transcription
steps of steroid hormones modulating gene transcription
- steroid enters cell
- steroid binds to receptor
- steroid-receptor complex enters nucleus and modulates gene transcription
do amine hormones act via cell surface or intracellular receptors and what do they do
catecholamines
cell surface receptor
activation of second messenger systems
thyroid hormones
nuclear receptor
gene transcription
