L8 Plasma Glucose Flashcards
What should fasting glucose levels be?
70-100mg glucose/100cm^3
3.9-5.5mmol/L
How is glucose stored?
As glyocgen
What is glycogenesis?
The conversion of glucose to glycogen in the liver.
Stored in skeletal muscle and liver.
What is glycogenolysis?
The breakdown of glycogen into glucose.
The liver and kidneys can release glucose into circulation in response to low plasma glucose.
What is gluconeogenesis?
Production of glucose from a non-carbohydrate source e.g. proteins and lipids
How is glucose stored if glycogen stores are fully saturated?
Glucose is converted to free fatty acids and stored in adipocytes in the form of triglycerides.
What is classed as hypoglycaemia?
BGL < 3.9mmol/L
What is classed as hyperglycaemia?
BGL > 7mmol/L
What factors influence blood glucose levels?
- How much and what type of food is eaten
- Amount of physical and mental activity
- Hormones
What is the function of the exocrine pancreas?
Production of pancreatic enzymes.
Describe the cellular composition of the endocrine pancreas.
Islets of Langherhans (highly vascularised and innervated) 3 types:
- Alpha cells: secrete glucagon
- Beta cells: secrete insulin
- Delta cells: secrete somatostatin
What type of hormones are secreted from the alpha, beta and delta cells?
Peptide hormones (fast acting)
When is insluin secreted from beta cells?
- When plasma glucose is high the beta cells are depolarised
- Causes opening of Ca volatge gated channels, influx of calcium and release of insulin by exocytosis
What are the principle actions of insulin?
- Stimulates liver to convert glucose to glycogen (glycogenesis)
- Stimulates excess glucose to be converted to fat
- Activates glycolysis
- Inhibits gluconeogenesis and glycogenlysis
- Binds to insulin dependent receptors and forces fat and muscle cells to take up glucose from the blood through the GLUT4 transporter
Lowers BGL
What are incretins?
Hormones which enhance the beta cell response to glucose, allows cells to respond better to insulin.
