Second messengers
a. are substances that interact with first messengers inside cells
b. are substances that bind to first messengers in the cell membrane
c. are hormones secreted by cells in response to stimulation by another hormone
d. mediate the intracellular responses to many different hormonesand neurotransmitters
e. are not formed in the brain
a. are substances that interact with first messengers inside cells
b. are substances that bind to first messengers in the cell membrane
c. are hormones secreted by cells in response to stimulation by another hormone
d. mediate the intracellular responses to many different hormonesand neurotransmitters
e. are not formed in the brain