MLT GlobePhysiology: Digestive physiology & nutrition – page 2
28 Physiology MCQs on Digestive physiology & nutrition with answers and explanations.
A man weighs 81 kg and is 1.80 m tall. How is his body mass index calculated?
BMI = weight (kg) / height squared (m2). Here 81 / 3.24 = 25 kg/m2, at the border between normal weight and overweight.
During the involuntary pharyngeal phase of swallowing, what prevents food from entering the nasal cavity?
In the pharyngeal stage the soft palate is elevated to close off the nasopharynx, while respiration is briefly inhibited and the larynx rises. Voluntary tongue movement belongs to the oral stage.
Stimulation of the myenteric (Auerbach) plexus produces which effect on the gut?
The myenteric plexus governs motility: it raises wall tone, rhythmic contraction strength and conduction velocity. Secretion and local absorption are regulated mainly by the submucosal (Meissner) plexus.
Which nutrient can humans do without most easily, because the body synthesises all it needs from other substrates?
No carbohydrate is dietary-essential; glucose can be made by gluconeogenesis. Dietary lipid supplies essential fatty acids, protein supplies essential amino acids, and iodine cannot be synthesised.
A snack contains 10 g protein, 20 g carbohydrate and 5 g fat. Its approximate energy content is:
Protein and carbohydrate give about 4 kcal/g and fat 9 kcal/g: 40 + 80 + 45 = 165 kcal. Using 9 kcal/g for protein gives the higher distractors.
Shortly before vomiting, antiperistalsis begins in the gut and pushes contents back towards the stomach. Where can it start?
Before vomiting, reverse peristalsis can begin as low as the ileum and drives intestinal contents back to the duodenum and stomach, distending them and triggering the vomiting act.
Which statement about the pharyngeal stage of swallowing is correct?
Once the bolus touches the pharynx, swallowing becomes an automatic brainstem reflex: the nasopharynx closes, the larynx rises and the vocal cords come tightly together to protect the airway.
When a strong antral peristaltic wave meets a closed pylorus, most chyme is pushed back toward the body of the stomach. What is this mixing action called?
With the pylorus shut, the contracting ring squeezes antral contents upstream (retropulsion), which grinds and mixes food. Gastric emptying requires the pylorus to let chyme into the duodenum.