Question: Role of the triacyl glycerol cycle. Summarize the cycle referring to Figure 19.9. What role does the cycle play in metabolism? Here are some infromation: Metabolic integration within the human body depends on the redistribution of metabolites, ions, and hormones by the circulatory system. This complex network consists of ∼150,000 km of blood vessels (from major veins and arteries to microcapillaries) that recycle 6 L of blood every minute throughout the body. The circulatory system links together the major tissues and organs of the body in such a way that biochemical pathways in different cells share metabolites, ensuring that the metabolic efficiency of the whole organism is greater than the sum of its parts. This process of maintaining optimal metabolite concentrations and managing chemical energy reserves in tissues is called metabolic homeostasis. This term describes steady-state conditions that apply to a wide variety of physiologic parameters. Metabolic homeostasis is affected by physical activity, psychological stress, timing and extent of feeding, and tissue dysfunction. The liver is the control center of this metabolic network and plays a crucial role in regulating metabolite flux among tissues and organs under normal homeostatic conditions. The six primary functions together required to maintain metabolic homeostasis under normal conditions are illustrated in figure 19.9: The primary role of the liver in this metabolic network is to export glucose, ketone bodies, and triacylglycerols to the peripheral tissues for use as metabolic fuel. The brain requires a constant input of glucose, one of the body’s most precious metabolites. Though considered to be the most vital human organ, the brain is also an energy drain on the metabolic system. Cardiac muscle uses fatty acids and ketone bodies for most of its energy needs but also uses small amounts of glucose. The exchange of fatty acids and triacylglycerols between the liver and adipose tissue is an ongoing process called the triacylglycerol cycle, which maintains circulation of high-energy fatty acids, as described shortly. Skeletal muscle uses glucose and fatty acids derived from both the liver and dietary sources for ATP synthesis. In turn, skeletal muscle exports lactate back to the liver to complete the Cori cycle during times of prolonged physical exertion (see Figure 14.23). The amino acids glutamine and alanine transport excess nitrogen obtained from protein degradation in the muscle to the liver and kidneys for excretion as nitrogen waste in the form of urea. Metabolite exchange between tissues is critical to optimizing available energy stores at the physiologic level. For example, the brain requires a constant supply of glucose to ensure high-fidelity neuronal transmissions, and skeletal muscle must have enough glycogen to permit rapid muscle contraction in response to imminent danger or to obtain food. Similarly, adipose tissue must be able to control the release and storage of triacylglycerols obtained from the diet to manage this high-energy metabolic fuel effectively. An important component of physiologic energy homeostasis is the triacylglycerol cycle, which is an interorgan process that continually circulates fatty acids and triacylglycerols between adipose tissue and the liver. Under homeostatic conditions, ∼75% of the fatty acids released from adipocytes into the blood is returned to adipose tissue as triacylglycerols through the systemic route. Theetriacylglycerol cycle provides an important homeostatic function by maintaining energy-rich fatty acids in circulation so that they can be used by peripheral tissues such as skeletal muscle
Question: Role of the triacyl glycerol cycle. Summarize the cycle referring to Figure 19.9. What role does the cycle play in
Here are some infromation: Metabolic integration within the human body depends on the redistribution of metabolites, ions, and hormones by the circulatory system. This complex network consists of ∼150,000 km of blood vessels (from major veins and arteries to microcapillaries) that recycle 6 L of blood every minute throughout the body. The circulatory system links together the major tissues and organs of the body in such a way that biochemical pathways in different cells share metabolites, ensuring that the metabolic efficiency of the whole organism is greater than the sum of its parts. This process of maintaining optimal metabolite concentrations and managing chemical energy reserves in tissues is called metabolic homeostasis. This term describes steady-state conditions that apply to a wide variety of physiologic parameters. Metabolic homeostasis is affected by physical activity, psychological stress, timing and extent of feeding, and tissue dysfunction. The liver is the control center of this metabolic network and plays a crucial role in regulating metabolite flux among tissues and organs under normal homeostatic conditions. The six primary functions together required to maintain metabolic homeostasis under normal conditions are illustrated in figure 19.9:
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The primary role of the liver in this metabolic network is to export glucose,
ketone bodies, and triacylglycerols to the peripheral tissues for use as metabolic fuel. -
The brain requires a constant input of glucose, one of the body’s most precious metabolites. Though considered to be the most vital human organ, the brain is also an energy drain on the metabolic system.
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Cardiac muscle uses fatty acids and ketone bodies for most of its energy needs but also uses small amounts of glucose.
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The exchange of fatty acids and triacylglycerols between the liver and adipose tissue is an ongoing process called the triacylglycerol cycle, which maintains circulation of high-energy fatty acids, as described shortly.
-
Skeletal muscle uses glucose and fatty acids derived from both the liver and dietary sources for ATP synthesis. In turn, skeletal muscle exports lactate back to the liver to complete the Cori cycle during times of prolonged physical exertion (see Figure 14.23).
-
The amino acids glutamine and alanine transport excess nitrogen obtained from protein degradation in the muscle to the liver and kidneys for excretion as nitrogen waste in the form of urea.
Metabolite exchange between tissues is critical to optimizing available energy stores at the physiologic level. For example, the brain requires a constant supply of glucose to ensure high-fidelity neuronal transmissions, and skeletal muscle must have enough glycogen to permit rapid muscle contraction in response to imminent danger or to obtain food. Similarly, adipose tissue must be able to control the release and storage of triacylglycerols obtained from the diet to manage this high-energy metabolic fuel effectively. An important component of physiologic energy homeostasis is the triacylglycerol cycle, which is an interorgan process that continually circulates fatty acids and triacylglycerols between adipose tissue and the liver. Under homeostatic conditions, ∼75% of the fatty acids released from adipocytes into the blood is returned to adipose tissue as triacylglycerols through the systemic route. Theetriacylglycerol cycle provides an important homeostatic function by maintaining energy-rich fatty acids in circulation so that they can be used by peripheral tissues such as skeletal muscle
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