Stimuli, Emotions, and the Body's Response
 

Fear

Laughter

Love

Major Stimulus

 A scary experience/or object. A tickling sensation/or the pun of a joke. In males and females: Sexual climax. In females only: Childbirth and breastfeeding.

How the brain responds

 Switches body to full alert. Incorporates experience into memory. Interprets input from senses via high/or low road (High road goes from the senses to the thalamus to the visual cortex, then the amygdala, and finally, the rest of the body. Low road travels same route, except that it goes from the thalamus to the amygdala without visiting the visual cortex.)

When the ears hear a joke, a message is sent to the neocortex, where the brain "gets it". In the case of a tickle, a message is sent to the somatosensatory cortex via the nerves, where it is interpreted as a tickle. Then, (in both cases) the supplementary motor area activate muscles needed for smiling and laughing, while the brain stem temporarily disrupts normal breathing patterns.

 

 The limbic system of the brain incorporates signals from other organs, produces and regulates secretion of oxytocin, and cements various objects of social attachment into memory. The nucleus accumbens contains receptors for both oxytocin and dopamine; makes social interaction feel good and causes us to seek more. The neocortex allows us to turn our impulses into love sonnets.

How the body responds

 Blood pressure/heart rate spikes. Hair stands on end. Adrenaline : Blood ratio rises. Bladder prepares to void contents. Lungs accelerate the body's air exchange, forcing higher blood : oxygen levels. Heart rate rises to fuel bronchial muscle spasms needed for laughter. Blood : adrenaline ratio rises. Tear ducts activate during vigorous laughter. Sphincter relaxes.

After prolonged exposure to oxytocin, the breathing rate in the lungs slows over time. The heart makes small quantities of oxytocin that may help repair damaged cardiac cells. Dramatically lowered levels of adrenaline and cortisol in the bloodstream drops the blood pressure and heart rate. Recurring high levels of oxytocin interfere over time with the production of adrenaline and cortisol in the adrenal glands.

(All who find the 'Love' section appauling in a way that they feel they must act against, please file all complaints with Doug. I just do this to get my Master's Degree.)