ACTIVITY 3
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.
Increased stimulation of the parasympathetic division of the autonomic nervous system regulates digestion and relaxation.
Organs involved:
a) Salivary glands
- Major Nerve Supply: facial (VII) nerves and glossopharyngeal (IX) nerves
- Effect: increased secretion of saliva
b) Pancreas
- Major Nerve Supply: vagus (X) nerves
- Effect: increased secretion of digestive enzymes and insulin
c) Liver
- Major Nerve Supply: vagus (X) nerves
- Effect: increased secretion of bile and glycogen synthesis
d) Stomach
- Major Nerve Supply: vagus (X) nerves
- Effect: increased motility and tone; relaxation and closing of sphincter
e) Intestines
- Major Nerve Supply: vagus (X) nerves
- Effect: increased activity (for digestion, water absorption, and elimination); increased motility and tone; relaxation and closing of sphincter
f) Gallbladder
- Major Nerve Supply: vagus (X) nerves
- Effect: increased contraction and secretion of bile to the small intestines
g) Heart
- Major Nerve Supply: vagus (X) nerves
- Effect: heart contractions will have decreased force and rate
h) Rectum
- Major Nerve Supply: pelvic plexus
- Effect: increased peristaltic movement in the colon, pushing feces into the anus
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 heads were sweaty. How would you explain these effects?
My friend experienced an emergency situation, which triggered the fight-or-flight response of the sympathetic division of the autonomic nervous system.
The sympathetic nervous system is activated by the hypothalamus following a distress signal from the amygdala. The autonomic nerves carry messages from the hypothalamus to the adrenal glands. In response, these glands release the hormone epinephrine, also referred to as adrenaline, into the bloodstream. Several physiological changes are brought about while adrenaline circulates throughout the body.
A rise in heart rate, palm perspiration, and contraction of the arrector pili muscles, which results in goose bumps, are some symptoms of heightened sympathetic activity. These responses will be intensified and prolonged by the release of epinephrine and norepinephrine from the adrenal medullae.
References:
Cheng, H. M., Mah, K. K., & Seluakumaran, K. (2020). Defecation Reflex: Parasympathetic Defecation Reflex, Intrinsic Myenteric Defection Reflex. Defining Physiology: Principles, Themes, Concepts. Volume 2, 75–77. https://doi.org/10.1007/978-3-030-62285-5_21
Harvard Health Publishing. (2020, July 6). Understanding the stress response. Harvard Health; Harvard Health. https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response#:~:text=The%20sympathetic%20nervous%20system%20functions,system%20acts%20like%20a%20brake.
Tortora, G. J., & Derrickson, B. (2014). Principles of Anatomy and Physiology (14th ed.). Wiley.