• The main purpose of the endocrine system is to allow for inter-body communication

• The simple idea is that glands use hormones to talk to other glands and other parts of the body such as muscles, the stomach, blood vessels, and more via the blood stream

• It also affects our mental processes, behaviors, and therefore relates to psychology

• The endocrine system does not stand alone, and communicates as well as affects the nervous and other bodily systems, like the digestive, reproductive, circulatory, and integumentary

Communication

• The hypothalamus controls the pituitary gland, which is like the master gland, regulating and talking to all other glands

• Glands are like centers of communication

  • They both receive and send out messages for bodily maintenance or action

Purposes

• We’ll briefly cover what the major glands do

  • The pituitary, as mentioned above, regulates other glands

  • The pineal is involved in producing melatonin

  • The thyroid regulates bodily metabolism

  • The adrenal produces adrenaline is times of perceived crisis

  • The pancreas produces insulin, and helps get energy from food

  • The ovary produces estrogen and progesterone

  • The testes produce testosterone, a kind of androgen

• And the hormones…

  • Adrenaline is involved in the fight or flight response, is beneficial in short bursts

  • Oxytocin is the ‘us vs them’ hormone, allowing us to recognize family and changes the body in response to them

  • Cortisol, the stress hormone, is like adrenaline in that it is supposed to help the body with threats

  • Testosterone causes sexual arousal and competition

    • It is a misconception that testosterone causes aggression

  • Estrogen is a category of hormones involved in reproduction and sexual arousal

  • Leptin regulates sustenance by diminishing hunger

  • Ghrelin regulates sustenance by increasing hunger

  • Melatonin helps us sleep, dimming arousal

    • Note that arousal can mean any state of heightened energy and activity; it is not always in a sexual context in psychology

Differences

• In the endocrine system, hormones move through the blood stream and talk to glands

  • This is a relatively slow process

• In the nervous system, neurotransmitters talk to neurons

  • They travel a fraction of the distance in a fraction of the time

• The two systems can talk to each other because some neurotransmitters can fit into gland receptor sites, and some hormones can fit into neuron receptor sites

How and Why

• We know how the hypothalamus communicates with the adrenal gland, but we don’t exactly know why

  • Does the mind think and the brain activate, or is it the other way around?

  • Why do some people break down into hysterics at the sight of a snake, while others keep them as companions?

  • This can all relate to how mind-body, emotion-hormone interaction differs in people, and we must always keep that in mind

• In terms of how, the hypothalamic-pituitary-adrenal axis is structured top-down

  • Glands communicate to the brain eventually, but then the brain communicates to the glands

  • The body is constantly talking to its self in a feedback loop to keep you in the best shape it can