CH27 Metabolic Integration and Organ Specialization 第32組 黃政堯0993B025 薛智元0993B034

CH27 AMPK PPAR Brain Muscle Major organ systems’ metabolic roles Heart Liver Adipose tissue CH27 Hormones That Control Eating Behavior Ghrelin Cholecystokinin PPAR PYY3-36 Leptin Insulin

AMPK AMP-activated protein kinase Cellular energy sensor AMPK active ,增加能量的合成(異化作用↑) ,減少能量的消耗(同化作用↓)

Heterotrimer (Catalytic subunit) (含allosteric site, where ATP or AMP binds, 決定其活性)

ATP濃度↑, ATP binding, AMPK inactive ; AMP濃度↑,AMP binding, AMPK active (AMP與γ subunit binding →α subunit上的Thr172被磷酸化 →AMPK active)

增加能量的合成(異化作用↑) 減少能量的消耗(同化作用↓)

Major organ systems’ metabolic roles 動物儲存能量之形式與位置 能量使用順序: Glycogen → Triacylglycerol → Protein 能量 器官組織 Glycogen(肝醣) Liver and muscle Triacylglycerol(三酸甘油) Adipose tissue(脂肪組織) Protein Muscle

Brain 只接受glucose(normal diet) or β-Hydroxybutyrate(starvation) 為其能量來源 腦部消耗大量能量使其神經細胞內外的鈉鉀離子維持濃度差

飢餓狀態時, β-Hydroxybutyrate 由liver運至腦部, 並以citric acid cycle 形成acetyl-CoA供腦部使用

Muscle ￭神經釋放Ca+至肌肉上的受體 ￭肌肉收縮(粗絲與細絲的滑動) ￭肌肉放鬆(Ca+回到神經細胞裡) 皆需消耗ATP

Cori Cycle Glucose-Alanine Cycle 飢餓或劇烈運動時會消耗muscle protein

Heart Aerobic organ, rich in mitochondria Major fuel Liver

Adipose tissue 由肝臟的glucose and few fatty acids 合成並儲存Triacylglycerol Liver

Liver Body’s metabolic processing center, 除了脂質, 養份皆以肝門靜脈(portal vein)送至肝臟

Glucose 6-phosphate in Liver 維持血糖平衡 Glucose 6-phosphate in Liver

Glucokinase vs. Hexokinase Km: Hexokinase> Glucokinase 血糖低時, Glucokinase( 肝臟)不使用glucose 血糖高時,glucose-6-phosphate會抑制Hexokinase(一般細胞)但不抑制Glucokinase ( 肝臟), 使肝臟儲存glucose,降低血糖 Only in liver

當身體對能量需求大時, adipose tissue裡的Triacylglycerol會被分解,其中的fatty acid會在肝臟中degrade成acetyl-CoA 並形成 Ketone bodies 當能量需求小時, fatty acid則被運回adipose tissue並以Triacylglycerol儲存 Fatty Acids in Liver

Amino Acids in Liver

Hormones That Control Eating Behavior NPY/AgRP-producing neurons 釋放 NPY(neuropeptide Y)刺激吃的行為及AMPK Eat (orexic) NPY/AgRP-producing neurons 釋放AgRP(agouti-related peptide)阻擋melanocortin-producing neurons 的活性 Don’t eat (anorexic)

Ghrelin, Cholecystokinin, PYY3-36 (short-term regulator) 當腸子進食一段時間後,腸子的內分泌腺會分泌PYY3-36, 抑制NPY/AgRP-producing neurons, 且可長達數小時 (long-term regulator) 當胃部沒有食物時,胃部會分泌ghrelin刺激NPY/AgRP-producing neurons及AMPK ; 吃進食物則快速降低 (short-term regulator)

Leptin, Insulin 當越多的fat被儲存在脂肪細胞, 脂肪細胞裡的leptin會升高並擴散至血液 血液中的leptin 含量低時,會刺激食慾; 含量高時,則食慾降低並抑制AMPK 血糖升高時, insulin(long-term regulator) 會由胰臟裡的β-cell分泌, 刺激血糖儲存也刺激fat tissue 分泌leptin

Eating Behavior Influenced by Ghrelin and Insulin 刺激食慾 降低食慾

Q1. All are uses of glucose-6-phosphate in liver EXCEPT 1. catabolized to acetyl-CoA for fatty acid biosynthesis  2. generate NADPH and pentoses.  3. released as glucose to blood stream.  4. converted to glycogen.  5. all are true. 

catabolized to acetyl-CoA for fatty acid biosynthesis  2. generate NADPH and pentoses.  released as glucose to blood stream.  4. converted to glycogen.  5. all are true. 

Q2. All of the following are paired with their preferred substrate EXCEPT: 1. brain: glucose  2. heart: fatty acids  3. resting skeletal muscle: glucose  4. anaerobic skeletal muscle: glucose  5. adipose tissue: fatty acids 

1. brain: glucose 2. heart: fatty acids 3 1. brain: glucose  2. heart: fatty acids  3. resting skeletal muscle: glucose  4. anaerobic skeletal muscle: glucose  5. adipose tissue: fatty acids