BIOS 256 (A&P 4) WEEK 2 STUDY GUIDE
1.Absorption
Most digestion and absorption of nutrients occur in a long tube called the small
intestine
Functions of the Small Intestine
1.Segmentations mix chyme with digestive juices and bring food into contact with
mucosa for absorption; peristalsis propels chyme through small intestine.
2.Completes digestion of carbohydrates, proteins, and lipids; begins and completes
digestion of nucleic acids.
3.Absorbs about 90% of nutrients and water that pass through digestive system.
Absorptive cells of the epithelium contain enzymes that digest food and possess
microvilli that absorb nutrients in small intestinal chyme.
Circular folds Folds of mucosa and submucosa that increase surface area for
digestion and absorption.
Villi Fingerlike projections of mucosa that are sites of absorption of digested food
and increase surface area for digestion and absorption.
Microvilli Microscopic, membrane-covered projections of absorptive epithelial
cells that contain brush-border enzymes (listed in Table 24.5) and that increase
surface area for digestion and absorption.
Bile aids in the digestion and absorption of fats.
The pancreas:
Is a gland that lies posterior to the stomach
Produces enzymes that digest carbohydrates, proteins, fats, and
nucleic acids
Produces sodium bicarbonate which buffers stomach acid
Empties its contents into the duodenum
, 2.Enzymes
The principal enzyme that digests triglyceride is produced in the pancreas is called
pancreatic lipase
Enterokinase- turns trypsinogen into trypsin: Produces o produce chymotrypsin,
carboxypeptidase, and elastase
starch-digesting enzyme called pancreatic amylase;
enzymes that digest proteins into peptides called trypsin, chymotrypsin,
carboxypeptidase, and elastase
3.Lacteals
Nutrients absorbed by the epithelial cells covering the villus pass through the wall
of a capillary or a lacteal to enter blood or lymph,
Long-chain fatty acids and monoglycerides are absorbed into lacteals;
chylomicrons enter lacteals
4.Processes
5.Digestion
6.Chemical digestion
Chemicals needed for digestion:
-Water -Bile – Gastric acid – Bicarbonate ions
7.Functions of liver
1.secretes bile
Each day, hepatocytes secrete 800–1000 mL (about 1 qt) of bile, a yellow,
brownish, or olive-green liquid. It has a pH of 7.6–8.6 and consists mostly of
water, bile salts, cholesterol, a phospholipid called lecithin, bile pigments, and
several ions.
2. Carbohydrate metabolism. The liver is especially important in maintaining a
normal blood glucose level. When blood glucose is low, the liver can break down
glycogen to glucose and release the glucose into the bloodstream. The liver can
1.Absorption
Most digestion and absorption of nutrients occur in a long tube called the small
intestine
Functions of the Small Intestine
1.Segmentations mix chyme with digestive juices and bring food into contact with
mucosa for absorption; peristalsis propels chyme through small intestine.
2.Completes digestion of carbohydrates, proteins, and lipids; begins and completes
digestion of nucleic acids.
3.Absorbs about 90% of nutrients and water that pass through digestive system.
Absorptive cells of the epithelium contain enzymes that digest food and possess
microvilli that absorb nutrients in small intestinal chyme.
Circular folds Folds of mucosa and submucosa that increase surface area for
digestion and absorption.
Villi Fingerlike projections of mucosa that are sites of absorption of digested food
and increase surface area for digestion and absorption.
Microvilli Microscopic, membrane-covered projections of absorptive epithelial
cells that contain brush-border enzymes (listed in Table 24.5) and that increase
surface area for digestion and absorption.
Bile aids in the digestion and absorption of fats.
The pancreas:
Is a gland that lies posterior to the stomach
Produces enzymes that digest carbohydrates, proteins, fats, and
nucleic acids
Produces sodium bicarbonate which buffers stomach acid
Empties its contents into the duodenum
, 2.Enzymes
The principal enzyme that digests triglyceride is produced in the pancreas is called
pancreatic lipase
Enterokinase- turns trypsinogen into trypsin: Produces o produce chymotrypsin,
carboxypeptidase, and elastase
starch-digesting enzyme called pancreatic amylase;
enzymes that digest proteins into peptides called trypsin, chymotrypsin,
carboxypeptidase, and elastase
3.Lacteals
Nutrients absorbed by the epithelial cells covering the villus pass through the wall
of a capillary or a lacteal to enter blood or lymph,
Long-chain fatty acids and monoglycerides are absorbed into lacteals;
chylomicrons enter lacteals
4.Processes
5.Digestion
6.Chemical digestion
Chemicals needed for digestion:
-Water -Bile – Gastric acid – Bicarbonate ions
7.Functions of liver
1.secretes bile
Each day, hepatocytes secrete 800–1000 mL (about 1 qt) of bile, a yellow,
brownish, or olive-green liquid. It has a pH of 7.6–8.6 and consists mostly of
water, bile salts, cholesterol, a phospholipid called lecithin, bile pigments, and
several ions.
2. Carbohydrate metabolism. The liver is especially important in maintaining a
normal blood glucose level. When blood glucose is low, the liver can break down
glycogen to glucose and release the glucose into the bloodstream. The liver can
