MBBS The Digestive System — practice questions

1. The digestive system carries out six fundamental activities in sequence. 2. The first, ingestion, refers to the entry of food into the alimentary canal through the mouth. 3. Propulsion then moves this food along the tract, and later absorption transfers nutrients into the bloodstream before defecation removes waste. 4. Propulsion, absorption, and defecation are each distinct, later steps in the sequence rather than the initial entry of food. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.2, p. 1094_

1. Several hormones produced by the duodenum help regulate digestion once chyme arrives from the stomach. 2. Secretin stimulates a watery, bicarbonate-rich secretion from the pancreas. 3. Cholecystokinin (CCK) is the hormone that stimulates secretion of pancreatic enzymes and release of bile from the liver and gallbladder. 4. Gastrin instead mainly stimulates gastric acid secretion in the stomach, and gastric inhibitory peptide inhibits gastric secretion and motility so neither matches the enzyme- and bile-stimulating role described here. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.2, p. 1097_

1. Saliva is mostly water, with the remaining fraction containing ions, enzymes, and other components. 2. Among these components, the most important ingredient for digestion is the enzyme salivary amylase. 3. Salivary amylase initiates the breakdown of carbohydrates and continues acting until inactivated by stomach acid. 4. Pepsin and trypsin act later in the stomach and small intestine on proteins, and lingual lipase, while also secreted in the mouth, acts on lipids and is not the enzyme called the most important for digestion overall. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.3, p. 1099_