Nutrient homeostasis
- Created by: kpritchard16
- Created on: 23-12-18 21:18
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- Nutrient homeostasis
- Nutrient source
- Glycogenesis
- formation of glycogen from glucose
- Lipogenesis
- formation of triglycerides from fatty acids and glycerol
- Glycogenolysis
- breakdown of glycogen to glucose
- Lipolysis
- triglycerides broken down into fatty acids and glycerol
- Gluconeogenesis
- formation of glucose from non -carbohydrate sources
- Glycogenesis
- Catabolic reactions
- Complex molecules are broken down to simpler ones and energy is released.
- Glucose sensing
- Beta cells in pancreas
- Glucose is phosphorylated and is oxidised to produce ATP
- ATP drives closure of potassium/ATP-channels
- This causes the opening of voltage-dependent calcium channels
- Ca moves into the cell which drives insulin secretion (exocytosis of insulin)
- in liver
- glucose-sensitive vagal afferent nerve is excited by increase in glucose - sends signal to hypothalamus which increases food intake
- in brain
- glucose sensitive neurones via altering firing rates in response to ambient glucose levels
- Beta cells in pancreas
- Anabolic reactions
- build up metabolites and require energy
- Metabolic efficiency
- amount of 'work' achieved for a given amount of energy expended
- Turnover of nutrient stores
- Daily fluctuations in nutient homeostasis
- Mainly nutrient anabolism ( > catabolism)
- Glucose intake: replacement of glycogen stores and fuel processes. Glucose and FFA stored as triglyceride in adipose tissue
- Insulin role
- key regulator of fuel selection and balance of anabolism to catabolism
- Stimulate
- glycogenesis, lipogenesis and reduced lipid catabolism
- Inhibit
- lipolysis, gluconeogenesis and protein catabolism
- Action
- Inhibits lipolysis in liver and adipose tissue
- Facilitates transport of glucose into cells
- Inhibits glycogenolysis in liver and muscle
- Increases the uptake of amino acids by cells and increases the rate of protein synthesis
- Glucagon actions
- Stimulates gluconeogenesis in liver
- Increases lipolysis
- Binds to receptor on liver cells, stimulating glycogenolysis
- Nutrient source
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