Endocrine System Flashcards
Function of the endocrine system
Work with the nervous system to respond to internal and external changes
Differences between the endocrine system and the nervous system
Nervous system uses NTs
Endocrine uses hormones
Nervous is a more localised response
Endocrine is a global response
Nervous system is fast but short lasting
Endocrine response is slow but long lasting
Both cause change in target cells by binding to receptors
Circulating Hormones
released from secretory cells and travel in the blood stream and have their effect in another part of the body
Local Hormones
act locally on neighbouring cells (paracrines)
or on the same cell that produces them (autocrines)
How can hormones affect cells
stimulating the synthesis of enzymes
increasing/decreasing the rate of enzyme synthesis
activating/deactivating an existing enzyme or membrane channel
Protein based hormones overview
water soluble
chains of amino acids
cannot cross cell membranes
bind to receptors outside the cell
examples: sex hormones, peptide hormones, ADH, oxytocin
Lipid based hormones overview
Lipid soluble
can cross membranes
goes into cells
remain in circulation longer
examples: thyroid hormones and nitric oxide
What happens when protein based hormones attach to receptors
activated G proteins causing a cascade of intracellular reactions
Lipid based hormones attaching to receptors
go through phospholipid bilayer
bind to receptors inside the cell to create a hormone-receptor complex that enters the nucleus
Process of negative feedback
the body recognises a change in environment
hormone is released
hormone acts on target cells
restoration of equilibrium
hormone production stops
Examples of things controlled by a negative feedback mechanism
Temperature, BGL & BP
Process of positive feedback
a change occurs, causing a secretion of hormones
hormones act on the original site of the stimulus and increase the reaction causing more secretion
