Absorptive state
Encyclopedia
Absorptive state is the period in which the gastrointestinal tract
is full and the anabolic processes exceed catabolism
. The fuel used for this process is glucose
.
. The glucose then travels to the blood or is converted to glycogen
and fat (triglyceride
). The glycogen and fat will be stored in the liver and adipose tissue, respectively, as reserves for the post-absorptive state. The remaining glucose is taken in for use by body cells or stored in skeletal muscle as glycogen.
Triglycerides - Chylomicrons, the main product of fat digestion, are first broken down to fatty acids and glycerol through hydrolysis
using Lipoprotein lipase
. This allows them to freely pass through capillary walls. Most of this will be reconstituted as triglycerides and stored in adipose tissue. The rest is used for energy in adipose cells, skeletal muscle, and hepatocytes. In a low carb environment, other body cells will also begin to use triglycerides as energy sources.
Amino Acids - The liver deaminates amino acids to keto acids to be used in the krebs cycle in order to produce ATP
. They may also be converted to fat stores. Some are used to make plasma proteins, but most leave through liver sinusoids to be used by body cells to construct proteins.
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
is full and the anabolic processes exceed catabolism
Catabolism
Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy. In catabolism, large molecules such as polysaccharides, lipids, nucleic acids and proteins are broken down into smaller units such as monosaccharides, fatty acids, nucleotides, and amino...
. The fuel used for this process is glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
.
Nutrient Processing in The Absorptive State
Carbohydrates - Simple sugars are sent to the liver where they are converted to glucoseGlucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
. The glucose then travels to the blood or is converted to glycogen
Glycogen
Glycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
and fat (triglyceride
Triglyceride
A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
). The glycogen and fat will be stored in the liver and adipose tissue, respectively, as reserves for the post-absorptive state. The remaining glucose is taken in for use by body cells or stored in skeletal muscle as glycogen.
Triglycerides - Chylomicrons, the main product of fat digestion, are first broken down to fatty acids and glycerol through hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
using Lipoprotein lipase
Lipoprotein lipase
Lipoprotein lipase is a member of the lipase gene family, which includes pancreatic lipase, hepatic lipase, and endothelial lipase. It is a water soluble enzyme that hydrolyzes triglycerides in lipoproteins, such as those found in chylomicrons and very low-density lipoproteins , into two free...
. This allows them to freely pass through capillary walls. Most of this will be reconstituted as triglycerides and stored in adipose tissue. The rest is used for energy in adipose cells, skeletal muscle, and hepatocytes. In a low carb environment, other body cells will also begin to use triglycerides as energy sources.
Amino Acids - The liver deaminates amino acids to keto acids to be used in the krebs cycle in order to produce ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
. They may also be converted to fat stores. Some are used to make plasma proteins, but most leave through liver sinusoids to be used by body cells to construct proteins.