Digestive System: Digestion and Absorption Flashcards
is the breakdown of food to molecules small enough to be absorbed into the circulation.
Digestion
breaks large food particles into smaller ones.
mechanical digestion
breaking of covalent chemical bonds in organic molecules by digestive enzymes.
Chemical digestion
side that faces the digestive tract lumen
apical membrane
side that faces the circulation
basolateral membrane.
products of lipid metabolism are coated with proteins and transported into lymphatic capillaries
lacteals
consist primarily of polysaccharides, such as starches; disaccharides, such as sucrose (table sugar) and lactose (milk sugar); and monosaccharides, such as glucose and fructose (the sugar found in many fruits).
Ingested carbohydrates
A minor amount of carbohydrate digestion begins in the oral cavity with the partial digestion of starches by ____________
salivary amylase
Carbohydrate digestion is resumed in the small intestine by ____________
pancreatic amylase
Carbohydrate digestion is resumed in the small intestine by _________
pancreatic amylase
are bound to the microvilli of the intestinal epithelium digest disaccharides into monosaccharides.
disaccharidases
located on the basolateral membrane.
sodium-potassium pump
The rate of glucose transport into most types of cells is greatly influenced by________ and may increase 10-fold in its presence
insulin
are molecules that are insoluble or only slightly soluble in water.
lipids
digests lipid molecules
Lipase
The vast majority of lipase is secreted by the pancreas and is referred to as ____________
pancreatic lipase
which is secreted in the oral cavity and swallowed with food, digests a small amount (<10%) of lipid in the stomach. The
lingual lipase
The stomach also produces very small amounts of
gastric lipase
key step in lipid digestion which bile salts transform large lipid droplets into much smaller droplets.
emulsification
Once lipids are digested in the intestine, bile salts aggregate around the small droplets to form_________
micells
Proteins synthesized in the epithelial cells attach to droplets of triglycerides, phospholipids, and cholesterol to form______
chylomicrons
major transport lipoproteins which is 92% lipid and 8% protein;
very low-density lipoprotein (VLDL),
major transport lipoproteins which is 75% lipid and 25% protein;
low-density lipoprotein (LDL)
major transport lipoproteins which is 55% lipid and 45% protein
high-density lipoprotein (HDL)
LDL is delivered to cells of various tissues through the circulation.
Cells have __________ in “pits” on their surfaces, which bind the LDL. Once LDL is bound to the receptors, the pits on the cell surface become endocytotic vesicles, and the cell takes in LDL by receptor-mediated endocytosis.
LDL receptors
are taken into the body from a number of dietary sources.
proteins
secreted by the stomach catalyzes the cleavage of covalent bonds in proteins to produce smaller polypeptide chains.
pepsin
These are broken down into tripeptides, dipeptides, and amino acids by______ bound to the microvilli of the small intestine.
peptidases
(TRUE OR FALSE)
About 9 L of water enter the digestive tract each day as a combination of ingested and secreted fluids. Of this 9L, about 92% is absorbed in the small intestine, and another 6-7% is absorbed in the large intestine
true
Active transport mechanisms for ______ ions are present within the epithelial cells of the small intestine.
sodium
(TRUE OR FALSE)
Potassium, calcium, magnesium, and phosphate are also actively transported.
TRUE
ions move passively through the intestinal wall of the duodenum and the jejunum following the positively charged sodium ions, but chloride ions are actively transported from the ileum.
chloride
