Hormones are chemical messengers released by glands of the endocrine system; AP Psychology requires five: adrenaline, ghrelin, leptin, melatonin, and oxytocin.
Unlike neurotransmitters, hormones travel through the bloodstream, making them slower but often longer-lasting.
Adrenaline prepares the body for stress or danger, similar to the neurotransmitter norepinephrine, showing how the nervous and endocrine systems work together during stress.
Ghrelin signals hunger and leptin signals fullness, while melatonin regulates the sleep-wake cycle and oxytocin is involved in social bonding.
Key terms
hormones
Chemical messengers released by endocrine glands that travel through the bloodstream to cells throughout the body.
endocrine system
The system of glands that release hormones.
adrenaline
A hormone that helps prepare your body to respond to stress or danger.
ghrelin
A hormone that helps signal hunger (ghrelin makes your stomach growl).
leptin
A hormone that helps signal that you're full after eating enough.
melatonin
A hormone that helps regulate the sleep-wake cycle; more is released in the dark, promoting sleep.
oxytocin
A hormone involved in social bonding; also important in childbirth and breastfeeding.
Watch out
Ghrelin vs. leptin: ghrelin makes your stomach growl (hunger), leptin signals you're full.