1. You have been to an ‘eat all you can’ buffet and have consumed large amounts of food. After returning home, you recline on the couch to watch television. Which division of the nervous system will be handling your body’s after-dinner activities? List several organs involved, the major nerve supply to each organ, and the effects of the nervous system on their functions.
The parasympathetic nervous system is responsible for the “after-dinner activities” in the body or the digestion of the food consumed from the buffet. When this is dominant in the body, it conserves energy, slows heart rate, increases digestion, and relaxes the sphincter muscles. The organs involved are the salivary glands (CN IX), esophagus (CN X), stomach (CN X), pancreas (CN X), liver (CN X), gallbladder (CN X), small intestine (CN X), large intestine (CN X), and rectum (superior rectal artery). There are various effects of the nervous system on the functions of the aforementioned organs. The salivary glands make your mouth water to prepare you to eat, meaning that the PNS affects these glands to secrete more saliva. The PNS allows the esophagus to control peristalsis, a series of wave-like muscle contractions to move the food through the digestive tract. There is an increase in the contraction of the muscles that mix and propel the food in the GI tract due to the nervous system. The pancreas stimulates insulin and digestive enzyme secretion, while the liver influences ketone body metabolism and increased bile secretion. The gallbladder is affected in such a way that it contracts then releases bile needed to digest fat. The PNS causes the contraction of the rectum and the relaxation of the internal anal sphincter.
2. Your friend is driving home from work, listening to her favorite music, when suddenly a bicycle came out of nowhere. She manages to swerve avoiding hitting the bicycle. She continued to drive home but she noticed that her heart is beating fast, she had goose bumps, and her hands were sweaty. How would you explain these effects?
The sympathetic nervous system helps support actions which are emergent in nature, hence it is responsible for the “fight or flight” response of the body. Her heart beats fast, her hands became sweaty, and she had goosebumps as responses to the acute threat to her survival. Physical changes (nervous and endocrine changes) are tell-tale signs that the sympathetic nervous system is responding to this occurrence. The sudden appearance of the bicycle became a threat to her safety while driving and, in turn, became a stressor that was detected immediately.