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 division of the Autonomic Nervous System (ANS)
will be handling the body's after-dinner activities.
The organs involved are the heart, salivary glands, stomach, small and large intestines, pancreas, liver, gallbladder, ureters, and urinary bladder.
The following are the effects of the Parasympathetic Nervous System on each organ:
- Heart - Heart rate and atrial contraction is decreased.
- Salivary glands - increased secretion of saliva through vasodilation
- Stomach - Motility and tone are increased, and the sphincters are relaxed
- Small and large intestines - Similar to the stomach, there is an increase in motility and tone as well as the relaxation of sphincters
- Pancreas - Insulin and digestive enzymes are secreted
- Liver - Glycogen is synthesized and there is an increase in bile secretion
- Gallbladder - Bile is released in the small intestine
- Ureters - Increased motility
- Urinary bladder - contraction of muscular walls and relaxation of internal urethral sphincter
The major nerve supply of most of the above organs is the Vagus (X) Nerve, the salivary gland, however, is supplied by the cranial Facial (VII) Nerve.
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 goosebumps, and her heads were sweaty. How would you explain these effects?
These effects are caused by the Sympathetic Nervous System, which is known for fight-or-flight responses. Due to the stress of almost hitting a bike, the sympathetic nervous system was stimulated and it dominates the parasympathetic nervous system. The activation triggered the release of hormones by the adrenal medullae. This prompts a series of responses from the rest of the body including the dilation of pupils, increased heart rate, airway dilation, slowed digestion, increased blood supply to muscles, flexion of arrector pili muscles (resulting in goosebumps), and an increase in sweat.