Psychology: Hormones and Neurotransmitters

Hormones and Behavior

• Hormones are chemicals that affect behavior, but unlike neurotransmitters, they are secreted by glands in the endocrine system, not released by neurons.
• Hormones are released directly into the bloodstream, which means they take longer to produce changes in behavior than neurotransmitters, but their effects can last longer.

Types of Hormones

• Adrenaline (Epinephrine): secreted by the adrenal glands, responsible for arousal and the "fight or flight" response, and plays a role in emotional memory formation.
• Cortisol: secreted by the adrenal glands, helps control blood sugar levels, regulate metabolism, reduce inflammation, and assist with memory formation.
• Melatonin: secreted by the pineal gland, signals relaxation and lower body temperature, helping with restful sleep.
• Neuropeptide Y (NPY): produced by the hypothalamus, acts as a neurotransmitter in the brain, stimulates food intake, reduces anxiety and stress, reduces pain perception, and affects circadian rhythm.
• Oxytocin: produced by the hypothalamus and secreted by the pituitary gland, acts as a neurotransmitter, plays a role in mother-child attachment, and social bonding and trust between people.
• Testosterone: produced by the testes, plays a facilitative role in aggressive behavior, higher levels of testosterone result in higher levels of aggression.

Adrenaline and the Fight or Flight Response

• Adrenaline activates the fight-or-flight response, a hormone cascade where hormones trigger more hormones.
• The release of adrenaline is part of the hypothalamic-pituitary-adrenal axis (HPA axis).
• When a stimulus threatens us, the hypothalamus responds by activating the pituitary gland, which releases a hormone that activates the adrenal glands, releasing cortisol and adrenaline into the bloodstream.