Endocrine I Flashcards
what are the functions of the endocrine system?
regulation of body processes such as reproduction, growth and development
water, electrolyte and nutrient balance
regulation of cellular metabolism/ energy balance
mobilization of body defenses
how fast does nervous system work
within millliseconds with electorchemical impulses through neurons
how fast does endocrine system work
minutes, hours, days.
influences metabolic activity through hormones
what are endocrine glands
small masses of secreting epithelial cells, ductless, release hormones
specifics of endocrine glands
rich vascular supply and lymphatic drainage to distribute hormones
how do exocrine and endocrine glands differ
exocrine glands have ducts carrying non-hormones secretions to a membrane surface
definition of hormones
chemicals produced by one set of cells that travel through the body to change the metabolic activity (up or down) of a different set of cells which are called the target cells
what are autocrines
chemicals produced by a set of cells that effect the same kind of cell
what are paracrines
chemicals produced by a cell that effect neighboring cell populations
amino acid based hormones
derived from the AAs themselves. water soluble. faster acting by binding with a surface receptor
short chain of AAs
peptide
long chain of AAs
protein
steroid based hormones
assembled using a cholesterol component (lipids can penetrate cell membranes
slower acting by binding to internal cell receptors and activating genes
eicosanoids
non-steroid lipids which signal nearby cells to action (localized reactions)
mechanisms of hormone action
target cells
tissue response
plasma membrane receptors and second messenger systems
intracellular receptors and direct gene activation
target cells
while hormones will circulate throughout the body, only cells with the appropriate internal or external receptor for that specific hormone will be targeted for effect
example of tissue response
the tissue response is dependent upon the tissue type
common target cell responses for specific hormones
opens/closes ion channels which may increase or decrease plasma membrane potential
stimulates synthesis or activity of proteins or regulatory molecules like enzymes within cell
stimulates mitosis
summary of the second messenger signaling mechanisms
hormone (first messenger) binds to external receptor
engaged external recpetor activates internal G proteins which trigger seconday messengers, eventualy producing intracellular changes in metabolic activites
quick on & of - repeated surgace receptor stimulation needed to prolong a response
2 common intracellular secondary messengers
cAMP signaling mechanism
PIP2-Calcium signaling mechanism
cAMP signaling mechanism
cAMP -> activates protein kinases -> activates enzymes triggering cells internal responses
PIP2-Calcium signaling mechanism
PIP2-Calcium -> activates enzymes triggering cells internal responses
what response does Ca++ trigger in muscles cells?
contraction
summary of internal receptor and direct gene activation
being lipid soluble, steroid hormones diffuse through the plasma membrane and bind to internal receptors
receptor hormone complex then enters nucleus and activates “recipes” stred on molecules as “genes”
then transcription -> mRNA -> translation -> protein synthesis
