L15 Flashcards
how does digestion of carbohydrates begin?
in the mouth, salivary alpha-amylase breaks down polysaccharides
continues in the small intestine with pancreatic a-amylase breaking it down to monosaccharides
glucose and galactose leave the cell via ______
GLUT-2
contrast how glucose/galactose and fructose are absorbed
glucose/galactose - secondary active transport
fructose - facilitated diffusion
fructose enters the epithelial cells via ____ and enters the blood via _____
GLUT-5; GLUT-2
glycogenesis
synthesis of glycogen, stimulated by insulin
glycogenolysis
glycogen –> glucose
stimulated by glucagon and epinephrine
gluconeogenesis
synthesis of glucose from noncarbohydrates, such as fats and amino acids
____ ATPs generated per glucose
38
When blood glucose levels begin to fall, glucagon does 3 things:
- stimulates glycogenolysis in the liver by activating enzymes that hydrolyze glycogen and release
glucose - activates hepatic gluconeogenesis - amino acids –> glucose
- enhances lipolysis of triglyceride in adipose tissue as an additional way of conserving blood glucose.
______ and ______ are the primary sites where glycogen is found
liver and skeletal muscle
[alpha/beta] cells secrete [insulin/glucagon]
alpha cells secrete glucagon; beta cells secrete insulin
delta cells secrete _______
somatostatin
three enzymes required for glycogen breakdown
- Glycogen phosphorylase
– Glycogen debranching enzyme
– Phosphoglucomutase
what is PEPCK?
key enzyme in gluconeogenesis, catalyzes the conversion of oxaloacetate to phosphoenolpyruvate.
what hormones inhibit transcription of PEPCK?
insulin
what hormones stimulate transcription of PEPCK?
thyroid hormone, glucagon, glucocorticoids
how do glucocorticoids stimulate PEPCK expression?
by binding to a specific DNA sequence termed a glucocorticoid response element (GRE)
contrast type 1/2 diabetes
In type 1 diabetes, pancreatic β-cells are destroyed by immune cells, such as T cells, macrophages, and the cytokines produced by these immune cells, resulting in an absolute deficiency of insulin, leading to hyperglycemia.
In type 2 diabetes, pancreatic β-cells are damaged by hyperglycemia, hyperlipidemia, cytokines, and amyloids. Although pancreatic β-cells produce insulin, the insulin level is insufficient to compensate for insulin resistance, resulting in a relative insulin deficiency, leading to hyperglycemia
role of incretins in glucose homeostasis (3)
Incretins, gut-derived hormones like GLP-1 and GIP:
1. stimulating insulin secretion in a glucose-dependent manner
2. suppressing glucagon release, both of which lead to lower blood glucose levels
3. also decreased gastric emptying.
________ is the first line medication for the treatment of type 2 diabetes. It works by _____
Metformin. decreases hepatic gluconeogenesis and intestinal absorption
how is DPP-4 inhibition expected to improve blood glucose control?
by preventing the breakdown of incretin hormones (GLP-1 and GIP), which leads to increased insulin secretion and reduced glucagon secretion, ultimately lowering blood sugar levels
other effects of insulin resistance
Endothelial dysfunction, Atherosclerosis, Hypertension, etc.
3 major points of regulation of glycolysis - enzymes activated by insulin
hexokinase, phosphofructokinase, pyruvate kinase
