Lecture 21 3/7/24 Flashcards
What are the main secretory products of the endocrine pancreas?
-insulin (prod. by beta cells)
-glucagon (prod. by alpha cells)
Which molecule is produced by pancreatic delta cells?
somatostatin
Which molecule is produced by PP cells?
pancreatic peptide
Which molecules are secreted by enterochromaffin cells?
-serotonin
-substance P
What are the potential sources for glucose?
-food (exogenous)
-glycogen (endogenous)
Which element is needed for glucose absorption?
Na+
What can potentially form glucose?
-glycogen
-glucogenic amino acids
-glycerol
-propionate (ruminants)
What is the principal product of carb. digestion and principal circulating sugar?
D-glucose
What are the characteristics of the liver and glucose homeostasis?
-liver takes up glucose and coverts it to glycogen and fatty acids
-liver glycogen is broken down to glucose via glucagon and catecholamines
-liver mass sustains glycemia
What process is driven by glucagon?
glycogenolysis
What process is driven by insulin?
glycogenesis
Why is it important that the liver contains glucose-6-phosphatase, but the brain and muscle do not?
-this enzyme allows for release of glucose into blood
-liver drives blood levels of glucose
-muscle and brain want to keep glucose and use it
Which enzymes are most important for glycogen synthesis?
-hexokinase
-glycogen synthase
What are the characteristics of glucokinase?
-hexokinase found in liver and pancreas
-higher activity when glucose concentrations are higher compared to other hexokinases
Which enzymes are involved in the release of glucose into the blood from glycogen?
-glycogen phosphorylase
-glucose-6-phosphatase
How does insulin impact the enzymes that function in glucose storage and release?
-increases glycogen synthase activity
-inhibits glycogen phosphorylase activity
How does glucagon impact the enzymes that function in glucose storage and release?
-increases glycogen phosphorylase activity
-inhibits glycogen synthase activity
What are the normal ranges for glucose in the blood in animals?
domestic animals: 60-120 mg/dl
ruminants: 40-80 mg/dl
What range of blood glucose is seen in diabetes?
200-700 mg/dl
What blood glucose level indicates hypoglycemia?
40 mg/dl or less
Why does starvation not cause a dramatic drop in glucose?
liver glycogen can provide glucose for up to 12 hours