The Endocrine System (College Board AP® Psychology): Study Guide

The endocrine system

• The endocrine system provides another way by which various parts of the body communicate with one another

  • It works alongside the nervous system to regulate behavior and mental processes

• The nervous system communicates via electrical and chemical signals between neurons

• The endocrine system communicates via hormones, which:

  • are chemical messengers secreted directly into the bloodstream

  • are carried through the bloodstream to target organs and tissues throughout the body, where they produce their effects

  • carry chemical messages that influence behavior and mental processes

Hormones vs. neurotransmitters

The pituitary gland

• The pituitary gland is a small gland located at the base of the brain, just below the hypothalamus

  • It is often referred to as the "master gland" because it regulates and controls the activity of other endocrine glands throughout the body

• The hypothalamus monitors the body's internal state and sends signals to the pituitary gland

  • The pituitary gland then releases hormones that trigger responses in other glands and organs

Hormones related to behavior and mental processes

• Adrenaline (also called epinephrine)

  • Secreted in response to stress, threat, or excitement

  • Activates the sympathetic nervous system's fight-or-flight response, which increasing heart rate, breathing rate, and alertness to prepare the body for action

  • Works in conjunction with the nervous system to produce rapid physical responses to perceived danger

• Melatonin

  • Regulates the sleep/wake cycle (circadian rhythm)

  • Secretion is sensitive to light levels, as melatonin levels rise in darkness to promote sleep and fall in daylight to promote wakefulness

  • Disruptions to melatonin production can affect sleep patterns and overall wellbeing

• Oxytocin

  • Often referred to as the "bonding hormone"

  • Plays a key role in social bonding, trust, and attachment

    • It is released during childbirth and promotes bonding between a mother and her newborn

    • It is also involved in romantic attachment and prosocial behavior

    • It is also involved in regulating stress responses in social contexts

• Leptin

  • Produced by fat cells and signals to the brain that the body has sufficient energy stored

  • Plays a key role in regulating hunger and satiety, as high leptin levels signal fullness and suppress appetite

  • Disruptions to leptin signaling are associated with overeating and obesity

• Ghrelin

  • Produced primarily in the stomach and signals to the brain that the body needs food

  • Known as the "hunger hormone," as ghrelin levels rise before meals and fall after eating

  • Works in opposition to leptin; leptin suppresses appetite, ghrelin stimulates it

  • Sleep deprivation has been shown to increase ghrelin levels, which may explain why poor sleep is associated with increased appetite