Hoạt động trao đổi chất của các cơ quan quan trọng trong nhà nước ăn. Các hoạt động tương đối của các con đường chuyển hóa chính hoặc các quá trình trong các cơ quan được chỉ định bởi kích thước chữ của họ. Việc trao đổi vật liệu dinh dưỡng và các phân tử nhiên liệu thông qua máu minh họa mối tương quan của các cơ quan này. | 60 USMLE Road Map Biochemistry Blood BRAIN Glycolysis Protein Synthesis ADIPOSE TAG FA synthesis TAG FA degradation LIVER Glycogenesis FA synthesis Gluconeogenesis Glycogenolysis MUSCLE Glycogenesis Glycogenolysis Protein degradation Figure 5-4. Metabolic activities of major organs in the fed state. The relative activities of major metabolic pathways or processes in each of the organs are indicated by their font sizes. The exchange of nutrient materials and fuel molecules through the bloodstream illustrates the interrelationships of these organs. In the absorptive condition all organs share the bounty of nutrients made available by digestion of food by the intestine. PPP pentose phosphate pathway FA fatty acids TAG triacylglycerol. s b. The pentose phosphate pathway is stimulated to produce NADPH which may be needed later for fatty acid synthesis. 2. There is net synthesis of triacylglycerols for storage. a. Free fatty acids delivered by the bloodstream and derived from dietary fats are attached to a glycerol backbone for storage as triacylglycerol in the large fat droplet of each adipocyte. b. Breakdown of the stored triacylglycerols is inhibited at this time. D. Skeletal muscle utilizes and stores glucose in the fed state. 1. As it does in adipose tissue insulin promotes increased glucose uptake by skeletal muscle. Chapter 5 Metabolic Interrelationships and Regulation 61 a. The glucose is converted to glucose 6-phosphate by hexokinase and some is metabolized through glycolysis and oxidative phosphorylation for energy. b. The glycogen stores of muscle are not extensive and can be depleted within a few minutes of intensive exercise but the high level of glucose 6-phosphate availability after a meal allows glycogen synthesis to replenish the stores. 2. Insulin action and the availability of adequate energy and amino acids stimulate net synthesis of muscle protein with suppression of protein degradation. E. The fuel needs of the brain are both large and of very high
