22.7 Flashcards
Which enzyme catalyzes the reaction of lactose into glucose and galactose?
maltase
sucrase
lipase
lactase
Which enzyme catalyzes the reaction of lactose into glucose and galactose?
maltase
sucrase
lipase
lactase
Emulsification requires:
nuclease.
enzymes.
bile salts.
bile pigments.
Emulsification requires:
nuclease.
enzymes.
bile salts.
bile pigments.
22.7.2 Carbohydrate Digestion and Absorption
Carbohydrate digestion begins in the mouth with salivary amylase
→ continues in the small intestine with pancreatic amylase and the brush border enzymes lactase, maltase, and sucrase.
22.7.3 Protein Digestion and Absorption
Protein digestion begins in the stomach with the enzyme pepsin.
→ It continues in the small intestine with pancreatic enzymes such as trypsin and brush border peptidases.
- Amino acids are absorbed across the enterocyte’s apical and basal membranes primarily by facilitated diffusion.
Absorbed amino acids and carbohydrates enter the capillaries in the villus, and are delivered to the hepatic portal system.
22.7.4 Lipid Digestion and Absorption
Lipid digestion is more complicated because lipids are nonpolar.
- Lipid globules are broken apart physically by chewing, by churning, and by emulsification by bile salts.
- Emulsified lipids are broken down in reactions catalyzed by pancreatic lipase into two free fatty acids and a monoglyceride.
- Digested lipids remain associated with other lipids and bile salts to form micelles.
Digested lipids are absorbed into the enterocyte by diffusion. In the cytosol, fatty acids are reassembled into triglycerides and packaged into chylomicrons.
- Chylomicrons exit the enterocyte by exocytosis and enter a lacteal, where they travel through the lymph before being delivered to the blood.
Water is absorbed across the small and large intestines by osmosis.
Electrolytes are absorbed across the small and large intestines as well by passive and active transport mechanisms.
What enzyme catalyzes reactions that initiate carbohydrate digestion?
trypsin
pepsin
salivary amylase
pancreatic amylase
What enzyme catalyzes reactions that initiate carbohydrate digestion?
trypsin
pepsin
salivary amylase
pancreatic amylase
Absorption is best described as the:
elimination of feces and some metabolic wastes.
reactions that break chemical bonds of food particles.
movement of food particles through the wall of the alimentary canal.
passage of foods and liquids from one digestive organ to the next.
Absorption is best described as the:
elimination of feces and some metabolic wastes.
reactions that break chemical bonds of food particles.
movement of food particles through the wall of the alimentary canal.
passage of foods and liquids from one digestive organ to the next.
Damaged hepatocytes will impair:
the defecation reflex.
carbohydrate digestion.
protein digestion.
bile production.
Damaged hepatocytes will impair:
the defecation reflex.
carbohydrate digestion.
protein digestion.
bile production.
