Endocrine System - Pancreas Flashcards
What are the main factors affecting blood glucose concentration?
Dietary intake
Insulin - promotes uptake of glucose into cells.
Glucagon - promotes release of glucose from liver
Physical activity
Stress and illness - can increase blood glucose levels due to increased release of stress hormones
Liver and kidney function
What are the effects of hypoglycemia?
Neuroglycopenic symptoms - cognitive impairment, dizziness
Autonomic symptoms - sweating, palpitations
Visual disturbances
Behavioural changes
Adrenergic symptoms - fight or flight response.
What is the role of glucagon in starvation?
Gluconeogenesis stimulation - occurs in the liver, where glucagon activates enzymes involved in the conversion of substrates like lactate, amino acids, and glycerol into glucose.
Glycogenolysis activation - glucagon signals the liver to break down glycogen into glucose molecules.
Lipolysis stimulation - breakdown of stored triglycerides into fatty acids and glycerol.
Ketogenesis promotion.
What is diabetes mellitus?
Most common disease resulting from impaired pancreatic hormone release.
Type 1 diabetes aka insulin-dependent diabetes mellitus results from B-cell destruction.
Type 2 diabetes results from a loss of normal regulation of insulin secretion.
What is insulin?
Insulin is a peptide hormone produced by beta cells located in the islets of Langerhans within the pancreas.
Its primary role is to regulate glucose metabolism by promoting the uptake of glucose into cells, where it can be used for energy or stored as glycogen (in the liver and muscles) or fat.
Insulin also inhibits the breakdown of glycogen (glycogenolysis) and the production of glucose from non-carbohydrate sources (gluconeogenesis) in the liver.
Overall, insulin acts to lower blood glucose levels by promoting glucose uptake and storage.
What is glucagon?
Glucagon is a peptide hormone produced by alpha cells in the pancreatic islets.
Its primary role is to raise blood glucose levels when they are low by stimulating the breakdown of glycogen (glycogenolysis)
Stimulates the production of glucose from non-carbohydrate sources (gluconeogenesis) in the liver.
Inhibits glycogen synthesis.
Overall, glucagon acts to increase blood glucose levels by mobilizing glucose from storage and promoting its release into the bloodstream.
Describe the role of insulin in the regulation of glucose after a meal.
Insulin promotes the uptake of glucose into cells, particularly muscle, fat, and liver cells, by increasing the translocation of glucose transporter proteins (GLUT4) to the cell membrane.
Promotes glycogen synthesis in muscle and liver cells, glucose stored as glycogen.
In fact cells, promotes lipogenesis.
Describe the role of insulin in the regulation of amino acids after a meal.
Insulin stimulates the uptake of amino acids into cells, particularly muscle cells, by increasing the activity of amino acid transporters.
Promotes conversion of amino acids into proteins and
Inhibits proteolysis - protein degradation.
Describe the role of insulin in the regulation of fat after a meal.
Insulin inhibits lipolysis, the breakdown of triglycerides into fatty acids and glycerol, in fat cells by suppressing the activity of hormone-sensitive lipase.
Insulin promotes the storage of fatty acids as triglycerides in fat cells through lipogenesis, the synthesis of new fat molecules from glucose.
Insulin also inhibits ketogenesis - beta oxidation of fatty acids to form ketones
