Control Of The Digestive Tract - Tutorial 1

Question 1

Name the main cranial nerve involved in regulating the digestive system

Answer 1

Vagus Nerve = CN (X)

Question 2

Name the two main reflexes that affect motility in the intestines

Answer 2

1. Gastroileal reflex - It intensifies peristalsis in the small intestine so chyme is moved into the caecum.
2. Gastrocolic reflex - It stimulates mass peristalsis in the colon

Question 3

State two situations that impact on the functioning of the defecation reflex

Answer 3

Elimination of faeces cannot occur if there is damage to the neurons involved in the reflex arc or nerves that control the external anal sphincter (eg. spinal injury or multiple sclerosis)

Question 4

Describe five effects of ageing on the digestive system

Answer 4

1. Decreased gustation and olfaction - impact on the pleasure associated with food
   - Many older persons have reduced appetite and require smaller portions due to decreased activity
2. Altered dental function - resulting in decreased biting and chewing
   - Increased risk of gum disease if unable to attend to oral hygiene
   - Poorly fitting dentures
3. Decreased secretion of digestive enzymes - limits digestive functions
   - Inadequately digested food results in decreased nutrition
4. Decreased motility - and loss of smooth muscle tone
   - May result in delayed passage of chyme and faeces
   - Increased risk of constipation (also associated with decreased intake of food and fluids and activity levels)
   - May have altered voluntary control of external anal sphincter resulting in faecal incontinence
5. Decreased neural and hormonal control