0
The gluconeogenesis is the production of glucose from other non-glucidic substances.
This is the process by which the body obtains its needed glucose supplies by making it from protein rather than taking it directly from the blood sugar which is dumped into the bloodstream by the ingestion of sugars or the breakdown of starches.
This is why it has been clinically shown that people can eat more calories on a low carb diet and still lose more weight. It really isn't "calorie in-calorie out." The body uses extra calories to make glucose from protein, while not needing extra calories to make glucose from sugar/starch sources.
Cats, for instance, rely on this process almost exclusively, lacking the enzymes to process carbohydrates, and, in fact, having no taste buds to detect the presence of sugar in their food.
What else can I help you with?
How is the reduction of plasma alanine concentration caused by gluconeogenesis?
Alanine is the major gluconeogenic amino acid. Plasma alanine is used to make glucose in the liver (Glucose-Alanine Cycle), and thus when this occurs plasma alanine concentration is decreased.
Are amino acids the building block of sugar?
No, amino acids are the building blocks of proteins, not sugar. Sugars are made up of carbon, hydrogen, and oxygen atoms, and are a type of carbohydrate. Both amino acids and sugars are essential components of biological molecules and play important roles in the body.
Which organs is classified as obligate glucose consumer?
The brain and liver are the two main obligate glucose users. The brain can use ketone bodies derived from fatty acid beta-oxidation in severe hypoglycemic states (prolonged starvation) after gluconeogenic and glycogenolic mechanisms have been depleted.
How is the reduction of plasma alanine concentration caused by gluconeogenesis?
Alanine is the major gluconeogenic amino acid. Plasma alanine is used to make glucose in the liver (Glucose-Alanine Cycle), and thus when this occurs plasma alanine concentration is decreased.
Are amino acids the building block of sugar?
No, amino acids are the building blocks of proteins, not sugar. Sugars are made up of carbon, hydrogen, and oxygen atoms, and are a type of carbohydrate. Both amino acids and sugars are essential components of biological molecules and play important roles in the body.
Why does your body use Muscle tissue for energy?
'coz it does... u got prob??': Yeah, I'm sure that wasn't a particularly enlightening answer...So, I'll have a stab at it below. Muscle tissue, specifically, skeletal muscle, is used for energy during starvation. This is simply because muscle tissue contains a (relatively) great deal of non-essential structural protein, that can be used to provide energy without *immediately* causing death. Amino acids derived from hydrolyzed muscle protein can actually be used as sources of energy. Indeed, amino acids are classified as ketogenic and glucogenic, depending on if they can yield ketone bodies (acetoacetate, 3-hydroxybutarate) and acetyl-CoA or carbohydrate precursors (eg. oxaloacetate; pyruvate), respectively. But what's the energy liberated from muscle tissue used for? Simply, to provide energy for organs more crucial than skeletal muscle, basically the brain. The amino acids from skeletal muscle can be converted to carbohydrate precursors which enter the gluconeogenic pathway, creating new glucose, which the brain can use for energy (brain-and nervous tissue-prefer glucose to all respiratory substrates). In addition, cells and organs without mitochondria, such as red blood cells, the kidney cotex and testes, better known as balls (yeah, that's right: its done for the family jewels too) can ONLY use glucose for energy, as only glucose can be anaerobically respired. In fact, some types of skeletal muscle fibres (type 1/white/fast twitch/glycolytic) too can only use glucose for energy as they have little to no mitochondria. The ketones derived from muscle protein are alternate sources of energy for the brain, kidneys (excluding their cotices, as aforementioned) and...skeletal muscle. So that, in a nutshell, is why the body uses muscle tissue for energy.
Why can't fatty acids be converted directly to glucose?
Oh my god, this has confused me for months and I finally think I get it, so I hope I can explain it decently. When fatty acids are oxidized, the acetyl-CoA can enter the Krebs cycle, and one would think that the oxaloacetate generated by the Krebs cycle could be converted to acetyl-CoA, which could then be converted to pyruvate for gluconeogenesis. This can't happen, though, because even though oxaloacetate is made, there is no net increase in oxaloacetate (two carbons are lost in the Krebs cycle for every two in the acetyl-CoA coming in). Oxaloacetate can't be taken out of the cycle, then, because then the cycle would be depleted and the only way to replenish it is through one of the anapleoritic reactions, which involve products of glycolysis (PEP and pyruvate). If there is enough PEP or pyruvate around to replenish the oxaloacetate you're taking out to make glucose, chances are you don't need to make glucose in the first place. Pyruvate from glucose or amino acids can be used to make sugars before it is converted to acetyl-CoA, but the pyruvate dehydrogenase complex reaction is irreversible, so once pyruvate is made into acetyl-CoA it cannot be used to make glucose; it is committed to either fatty acid synthesis or the Krebs cycle. Plants can make glucose from fatty acids, but this is only because they are able to use the glyoxlyate cycle instead of the Krebs cycle. The glyoxylate cycle bypasses the step in the Krebs cycle (the alpha-ketoglutarate dehydrogenase step) in which the two carbons are lost as CO2, so when plant acetyl-CoA enters the glyoxylate cycle there IS a net increase in oxaloacetate which can be used to make pyruvate.
