Lecture 26: Liver and Metabolism

Question 1

Describe the 4 important functions in the liver

Answer 1

whole body metabolism - amino acids, regulate glucose levels
digestion - gluconeogenesis, glycogen storage, form bile salts, ketogenesis
detoxification - removal of hormones, proteins
excretion of waste - ammonia

Question 2

Explain what happens to amino acids, glucose, and fatty acids in the fed state in the muscle, liver, adipose tissue

Answer 2

amino acids converted to proteins, glucose goes to glycogen, fatty acids go to fats

muscle: glucose goes to ATP, production of protein and glycogen
adipose tissue: fatty acids and glycerol form fats
liver: amino acids go to keto acids to fatty acids to fats, amino acids go to proteins, amino acids go to keto acids to ATP, glucose goes to glycogen and glycerol to fats

Question 3

Explain what happens to proteins, triglycerides, and glycogen in the post-absorptive (fasting) state

Answer 3

Proteins get broken down to amino acids (this is worst case scenario), triglycerides broken down to fatty acids to keto acids, glycogen broken down to glucose

Muscle: glycogen to glucose
Adipose tissue: fatty acids to keto acids then ATP
Neural tissue: receives all blood glucose
Liver tissue: glycogen breakdown, fat breakdown to keto acids, takes pyruvate/lactic acid and performs gluconeogenesis, fat breakdown to glycerol to glucose

Question 4

Describe how insulin and glucagon are secreted, how secretion is regulated, and how hormone is regulated

Answer 4

Insulin secreted from beta cells of islets of Langerhans. glucose enters through glut2, phosphorylated by glucokinase, production of ATP closes Katp channels, this depolarizes VCa then causes exocytosis of insulin vesicles. causes uptake of glucose to form glycogen.

glucagon secreted from alpha cells. causes breakdown of glycogen into glucose. acts mainly at the liver. increases fatty acids and ketones, inhibits anabolism, also works for gluconeogenesis.

delta cells of islets of langerhans secretes somatostatin