BRAIN METABOLISM➢ Fuels used by brain:1- Glucose. 2-Ketone bodies. 3-Amino acid• Nervous system closely depends on the availability of glucose, the lack ofwhich quickly results in death.• Glucose is brought to the brain by blood flowing through a special network ofarteries and is quickly catabolized by the glycolytic and tricarboxylic acidcycle pathways to synthesize energy.• It is also used in the synthesis of amino acids, nucleotides and NADPH (HMPpathway).• Glucose can be converted into glycogen in the brain.• The nerve tissue is capable of synthesizing glucose-6-phosphate in thegluconeogenic pathway• Brain carbohydrate metabolism is thus in many ways similar to livercarbohydrate metabolism.• The astrocyte constitutes the main cell implicated in this metabolism.➢ Brain Energy Metabolism• Brain is one of the most metabolically active organs in the body.• The brain stores little energy as glycogen and relies almost entirely oncirculating glucose for fuel.BIOCHEMISTRYNEUROSCIENCE-2023 2• Inside neurons, glucose is metabolized by cytoplasm & mitochondria in anumber of steps (glycolysis & Kreb’s cycle) to produce cellular energy, asATP.➢ Role of Oxygen to Brain• Having enough oxygen in the brain is crucial to brain function, and therefore,to the body as a whole.• The brain requires a constant supply of both oxygen and glucose.• Some brain cells start dying less than 5 minutes after their oxygen supplydisappears.• Without enough oxygen or with low blood-oxygen levels, lead to brain death.➢ Importance of Glucose1. Major source of energy for RBC and CNS.2. The only source of energy for skeletal muscle during exercise.3. Lipogenesis formation.4. Kreb’s cycle.➢ Fuel of brainA-General: use glucoseB-During Starvation: utilize ketone bodies➢ Amino Acid Content In Cerebral TissueBIOCHEMISTRYNEUROSCIENCE-2023 3• The three amino acids with the highest levels in brain tissues areGLUTAMIC ACID, GLUTAMINE, and ASPARTIC ACID.• Metabolism of glutamic acid and related substances plays a role in regulatingbrain functions➢ Fed Starvation CycleFate of glucose in Fed StateFate of glucose in liver:A- Make Glycolysis then Kreb’s CycleB-Excess glucose: stored in liver as Glycogen which used to maintain blood glucosebetween mealC-More excess glucose: converted to TriAcylGlycerol (TAG) synthesisFate of glucose in other tissues• Brain: make Glycolysis then Kreb’s Cycle• RBC: make Anaerobic Glycolysis end by lactic acid• Muscle:1- Make Glycolysis then Kreb’s Cycle2- Excess glucose: stored in muscle as Glycogen
Question
BRAIN METABOLISM➢ Fuels used by brain:1- Glucose. 2-Ketone bodies. 3-Amino acid• Nervous system closely depends on the availability of glucose, the lack ofwhich quickly results in death.• Glucose is brought to the brain by blood flowing through a special network ofarteries and is quickly catabolized by the glycolytic and tricarboxylic acidcycle pathways to synthesize energy.• It is also used in the synthesis of amino acids, nucleotides and NADPH (HMPpathway).• Glucose can be converted into glycogen in the brain.• The nerve tissue is capable of synthesizing glucose-6-phosphate in thegluconeogenic pathway• Brain carbohydrate metabolism is thus in many ways similar to livercarbohydrate metabolism.• The astrocyte constitutes the main cell implicated in this metabolism.➢ Brain Energy Metabolism• Brain is one of the most metabolically active organs in the body.• The brain stores little energy as glycogen and relies almost entirely oncirculating glucose for fuel.BIOCHEMISTRYNEUROSCIENCE-2023 2• Inside neurons, glucose is metabolized by cytoplasm & mitochondria in anumber of steps (glycolysis & Kreb’s cycle) to produce cellular energy, asATP.➢ Role of Oxygen to Brain• Having enough oxygen in the brain is crucial to brain function, and therefore,to the body as a whole.• The brain requires a constant supply of both oxygen and glucose.• Some brain cells start dying less than 5 minutes after their oxygen supplydisappears.• Without enough oxygen or with low blood-oxygen levels, lead to brain death.➢ Importance of Glucose1. Major source of energy for RBC and CNS.2. The only source of energy for skeletal muscle during exercise.3. Lipogenesis formation.4. Kreb’s cycle.➢ Fuel of brainA-General: use glucoseB-During Starvation: utilize ketone bodies➢ Amino Acid Content In Cerebral TissueBIOCHEMISTRYNEUROSCIENCE-2023 3• The three amino acids with the highest levels in brain tissues areGLUTAMIC ACID, GLUTAMINE, and ASPARTIC ACID.• Metabolism of glutamic acid and related substances plays a role in regulatingbrain functions➢ Fed Starvation CycleFate of glucose in Fed StateFate of glucose in liver:A- Make Glycolysis then Kreb’s CycleB-Excess glucose: stored in liver as Glycogen which used to maintain blood glucosebetween mealC-More excess glucose: converted to TriAcylGlycerol (TAG) synthesisFate of glucose in other tissues• Brain: make Glycolysis then Kreb’s Cycle• RBC: make Anaerobic Glycolysis end by lactic acid• Muscle:1- Make Glycolysis then Kreb’s Cycle2- Excess glucose: stored in muscle as Glycogen
Solution
The brain relies on various fuels for its metabolism, including glucose, ketone bodies, and amino acids. Glucose is particularly important for the nervous system and its lack can lead to death. Glucose is transported to the brain through arteries and is quickly broken down through glycolysis and the tricarboxylic acid cycle to produce energy. It is also used in the synthesis of amino acids, nucleotides, and NADPH. The brain can convert glucose into glycogen and can also synthesize glucose-6-phosphate through gluconeogenesis. Brain carbohydrate metabolism is similar to liver carbohydrate metabolism, with astrocytes playing a key role.
The brain is one of the most metabolically active organs and relies mainly on circulating glucose for energy. Inside neurons, glucose is metabolized through glycolysis and the Krebs cycle to produce ATP, the cellular energy currency. Oxygen is crucial for brain function as it requires a constant supply of both oxygen and glucose. Without enough oxygen, brain cells can start dying within minutes, leading to brain death.
Glucose is important for various functions in the body, including being a major source of energy for red blood cells and the central nervous system. It is also the sole source of energy for skeletal muscles during exercise and is involved in lipogenesis and the Krebs cycle. In times of starvation, the brain can utilize ketone bodies as an alternative fuel source.
The amino acid content in cerebral tissue is high, with glutamic acid, glutamine, and aspartic acid being the most abundant. The metabolism of these amino acids plays a role in regulating brain functions.
In the fed state, glucose has different fates in different tissues. In the liver, it can undergo glycolysis and the Krebs cycle, be stored as glycogen to maintain blood glucose levels between meals, or be converted into triglycerides. In the brain, glucose is metabolized through glycolysis and the Krebs cycle. Red blood cells rely on anaerobic glycolysis, and muscles can use glucose for glycolysis and the Krebs cycle or store it as glycogen.
Similar Questions
Which item is used to supply some of the fuel needed by the brain only after the body has been fasting for a while?Group of answer choicesGlycerolFatty acidsProteinKetonesAmino acids
BRAIN METABOLISM
Protein can serve as an energy substrate ifGroup of answer choicescertain amino acids are presentit is utilized by the brainit is phosphorylated firstit is first converted to glucose
Item11Item 11The main provider of energy for the brain and nervous system isMultiple Choicelactose.glucose.galactose.sucrose.
some glucose bypasses liver to provide fuel for brain anderythrocytes in hepatocytes– glucose is actively phosphorylated by the action of glucokinase– glucose‐6‐phosphate may be converted to: glycogen to replenish liver stores glucose via glucose‐6‐phosphatase if blood glucose < 4 mM pyruvate via glycolysis, hence to acetyl‐CoA, but fatty acids are preferredfuel for liver cells PPP intermediates providing NADPH for reductive biosyntheses andpentose phosphates for nucleotide biosynthesis
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