Question | Answer |
hormones | chemical messengers released into the blood to be transported throughout the body |
What classes are hormones divided into? | amino acid based, steroids |
hormonal stimulus typically produces one or more of the following changes | alters PM, stimulates synthesis of proteins or or activates enzymes in the cell, induces secretory activity, stimulates mitosis |
Name the two second messenger systems used by amino acids | cyclic AMP, PIP Calcium Signal |
Steroid Hormones use this action mechanism | direct gene activation |
The concentration of a circulating hormone in the blood at any time reflects: | its rate of release, the speed at which it is activated and removed from the blood |
Permissiveness | the situation when one hormone cannot exert its full effects without another being present |
Example of Permisiveness | reproductive hormones and thyroid hormone |
Synergism | more than one hormone produces the same effects at the target cell and their combined effects are amplified |
Example of Synergism | glucagon, and epinephrine |
Antagonism | when one hormone opposes the action of another |
Example of Antagonism | insulin, glucagon |
Humoral Stimuli | hormones secreted in direct response to changing blood levels of certain ions and nutrients |
Example of Humoral stimuli | parathyroid cells releasing PTH in response to low blood calcium levels |
Neural stimuli | nerve fibers stimulate hormone release |
example of neural stimuli | sympathetic nervous system stimulation of the adrenal medulla to release catecholamines |
hormonal stimuli | endocrine glands release their hormones in response to hormone produced by other endocrine organs |
example of hormonal stimuli | release of most ant. pituitary hormones is regulated by releasing and inhibiting hormones produced by the hypothalamus |