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Unformatted text preview: membrane of the epithelial cells.
(b) Chylomicrons: These aggregations of fats are
coated with protein in such a way that the fat
remains in suspension during transport. 2. It is important that nutrient-rich blood from the gut
is taken directly to the liver so that the nutrients
can be removed and processed most rapidly and
efficiently. Nutrient-rich blood has a high osmotic
potential and therefore also represents a potential
threat to homeostasis. Rapid removal of nutrients
from the blood is desirable in terms of maintaining
homeostasis. Site: Pancreas
Purpose: Digestion of proteins to polypeptides.
Enzyme: pancreatic lipase
Purpose: Digestion of fats to fatty acids and glycerol.
Purpose: Digestion of polypeptides to amino acids. The Control of Digestion (page 185)
1. (a) Food in the mouth causes a reflex stimulation of
salivary glands and stomach (parasympathetic
stimulation via the vagus). The effect is a marked
increase in salivary and gastric secretion.
(b) Presence of fat and acid in the small intestine
stimulates release of cholecystokinin and secretin
from the intestinal mucosa. These hormones
inhibit gastric motility and stimulate the secretions
of the pancreas, the production and release of
bile, and the secretions of the intestinal glands.
(c) Stretching of the stomach stimulates the reflex
secretion of the hormone gastrin from the gastric
mucosa. Gastrin acts back on the stomach to
increase gastric secretion and motility. 2. The vagus nerve provides the parasympathetic
innervation of the gut, stimulating salivary, gastric, and
pancreatic secretion. Anatomy and Physiology Site: Intestinal mucosa
Purpose: Digestion of polypeptides to amino acids.
Site: Intestinal mucosa
Enzymes: maltase, lactase, sucrase
Purpose: Digestion of carbohydrates (maltose,
lactose, sucrose respectively) into their constituent
4. (a) The enzymes involved in digestion in different
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- Winter '13