Glucose Homeostasis Flashcards
(20 cards)
What is the normal plasma glucose concentration in the body?
The normal plasma glucose concentration is around 5 mmol/L.
What is the critical plasma glucose concentration for hypoglycaemia?
The critical plasma glucose concentration for hypoglycaemia is approximately 2.5 mmol/L.
What can chronic hyperglycaemia lead to?
Chronic hyperglycaemia can lead to protein damage via non-enzymatic glycation reactions, which can result in tissue death.
What are the two main sources of plasma glucose?
The two main sources of plasma glucose are diet and organs that can export glucose into the circulation.
What are the two phases of metabolism?
The two phases of metabolism are the absorptive phase and the post-absorptive phase.
What occurs in the absorptive phase of metabolism?
In the absorptive phase, nutrients are stored and energy is being processed for later use.
What happens in the post-absorptive phase of metabolism?
In the post-absorptive phase, the release of nutrients occurs to provide energy.
Which hormones promote nutrient storage and decrease plasma glucose levels?
Insulin promotes nutrient storage and decreases plasma glucose levels.
Which hormones counteract insulin and increase plasma glucose levels?
Counter-regulatory hormones like glucagon, adrenaline, cortisol, and growth hormone (somatotrophin) promote nutrient release and raise plasma glucose levels.
What are the primary circulating and stored nutrients in the body?
The primary circulating nutrients are glucose, fatty acids, amino acids, ketone bodies, and lactate. The stored nutrients are glycogen, triglycerides, body proteins, and ketone bodies.
What metabolic pathway is responsible for the synthesis of glycogen from glucose?
Glycogenesis is the pathway responsible for synthesizing glycogen from glucose.
What is lipogenesis?
Lipogenesis is the synthesis of fatty acids from acetyl CoA.
What is the role of insulin in the body?
Insulin inhibits nutrient release by suppressing hepatic glucose production, lipolysis, and proteolysis. It also promotes nutrient storage by stimulating glycogenesis, lipogenesis, and glucose uptake in muscle and adipose tissue.
What is the short-term defense against hypoglycaemia?
The short-term defense against hypoglycaemia involves increasing hepatic glucose output through glucagon, adrenaline, and the sympathetic nervous system.
What is the long-term defense against hypoglycaemia?
The long-term defense against hypoglycaemia involves proteolysis.
Where is insulin secreted from in the body?
Insulin is secreted from the pancreas.
How does the pancreas release insulin into the circulation?
The pancreas is supplied by branches of the coeliac, superior mesenteric, and splenic arteries, with venous drainage through the portal system. Half of the secreted insulin is metabolised by the liver during first-pass metabolism, while the rest enters peripheral circulation.
How do beta cells sense an increase in glucose levels?
Beta cells sense an increase in glucose levels through GLUT 2 or glucokinase, which act as glucose sensors. The effector is the rise in ATP due to glucose oxidation.
How does glucose enter cells?
Glucose enters cells through sodium-glucose cotransporters (SGLTs) via secondary active transport, or through glucose transporters (GLUTs).
What are the different types of GLUTs and where are they found?
GLUT 1: Found in the brain and erythrocytes, has a high affinity for glucose, and constantly uptakes glucose at 2-6 mM.
GLUT 2: Found in the liver, kidney, pancreas, and gut, with low affinity for glucose; glucose equilibrates across the membrane, regulating insulin release in the pancreas.
GLUT 3: Found in the brain with a high affinity for glucose.
GLUT 4: Found in muscle and adipose tissue, with medium affinity for glucose. Insulin recruits these transporters for insulin-dependent glucose uptake.
