The three parts of the human small intestine is the duodenum, jejunum, and what?

• Correct Answer: ileum
• cecum
• appendix
• colon

Explanation: Which of the following statements about the small intestine is false? a. Absorptive cells that line the small intestine have microvilli, small projections that increase surface area and aid in the absorption of food. The inside of the small intestine has many folds, called villi. Microvilli are lined with blood vessels as well as lymphatic vessels. The inside of the small intestine is called the lumen. The human small intestine is over 6m long and is divided into three parts: the duodenum, the jejunum, and the ileum. The “C-shaped,” fixed part of the small intestine is called the duodenum and is shown in Figure 34.11. The duodenum is separated from the stomach by the pyloric sphincter which opens to allow chyme to move from the stomach to the duodenum. In the duodenum, chyme is mixed with pancreatic juices in an alkaline solution rich in bicarbonate that neutralizes the acidity of chyme and acts as a buffer. Pancreatic juices also contain several digestive enzymes. Digestive juices from the pancreas, liver, and gallbladder, as well as from gland cells of the intestinal wall itself, enter the duodenum. Bile is produced in the liver and stored and concentrated in the gallbladder. Bile contains bile salts which emulsify lipids while the pancreas produces enzymes that catabolize starches, disaccharides, proteins, and fats. These digestive juices break down the food particles in the chyme into glucose, triglycerides, and amino acids. Some chemical digestion of food takes place in the duodenum. Absorption of fatty acids also takes place in the duodenum. The second part of the small intestine is called the jejunum, shown in Figure 34.11. Here, hydrolysis of nutrients is continued while most of the carbohydrates and amino acids are absorbed through the intestinal lining. The bulk of chemical digestion and nutrient absorption occurs in the jejunum.

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