Lecture 31 - Coordinating metabolism Insulin and Glucose transport Flashcards
What is metabolic homeostasis
It is the body’s ability to maintain metabolic processes to ensure that essential molecules are kept at optimal levels, involving digestive, endocrine and nervous systems, along with various signal transduction events.
What happens if the metabolic homeostasis is disrupted
Disruptions in metabolic homeostasis can lead to metabolic disorder such as diabetes, obesity, metabolic syndrome
What tissues cannot use fatty acids as fuels
Brain, because fatty acids cannot cross the blood brain barrier and red blood cells
What is preferred fuel of the brain
Glucose and ketones bodies during fasting
What is insulin
Insulin is a peptide hormone synthesised in the pancreas by B cells and secreted in response to high glucose levels after meals
What are main tissues insulin acts on
Insulin acts on liver, muscle and adipose tissue to promote glucose transport and utilisation
How is glucose taken up into pancreatic B cells
Glucose enters B-cells via GLUT1 transporter, leading to glycolysis and an increase in ATP, triggering insulin secretion
What happens when ATP levels rise in B cells
The ATP ratio increases, closing ATP gated K+ channels, depolarising the membrane, opening voltage-gates CA2+ channels, which induces insulin secretions.
How is insulin Processed in B cells
Insulin is synthesised as pre-proinsulin, which is processed into proinsulin, folded and stabilised in the ER, finally cleaved into insulin and C-peptide in secretory vesicles
What is Type 1 Diabetes
An autoimmune condition leading to the destruction of pancreatic B cells, resulting in no insulin secretion
How does insulin facilitate glucose transport
Insulin triggers a phosphorylation cascade causing GLUT 4 vesicles to move to the plasma membrane enabling glucose uptake in muscle and adipose tissue
What is GLP-1
GLP1 is a peptide hormone synthesised in the intestine that stimulates insulin secretion and improves glucose control in Type 2 diabetes.
How does GLP-1 Potentiate insulin secretion
GLP-1 acts through its receptor on pancreatic B cells to enhance glucose stimulated insulin release
What are GLUT4 storage vesicles
They are intracellular vesicles that store GLUT4 transporters and move to the plasma membrane upon insulin signalling to facilitate glucose uptake
What are the effects of type 1 diabetes
It leads to glycosuria, extreme thirst, frequent urination, weight loss, and complications
