Body Weight And Obesity/diabetes SEM2 Flashcards
What is the “set-point” of body weight
Predetermined set point which the body seeks to maintain homeostasis
What are the key brain regions involved in appetite control
Hypothalamus
Brainstem
Reward and sensory processing areas
What is the hypothalamuses involvement in appetite regulation
Central to appetite regulation
Contains arcuate nucleus
What are the two important neurone types in the arcuate nucleus
Anorexigenic - satiety
Orexgingenic - hunger
What can removing orexigenic arcuate neurones result in
Can result in starvation
What does the use of optogenietic approaches allow for
Control of specific population of neurones, activation of orexigenic arcuate AgRP neurones increase in food intake
What leads to a reduction in food intake and body weight
Stimulating the anorexigenic POMC in the arcuate nucleus
What are NPY/AgRP neurones
Orexigenic
What are POMC neurones
Anorexigenic
What occurs if the gene of leptin is removed
The leptin hormone is no longer able to send signals to the brain to inhibit hunger
What are the results of leptin acting on arcuate POMC cells
Leptin increases POMC mRNA expression
Leptin excites POMC cells electrophysiologically
What happens to leptin activity in relation to obesity
Leptin target sites can become insensitive to leptin in obesity
What can partial leptin reduction restore
Restores hypothalamic leptin sensitivity and leads to reduced food intake
What does the binding of leptin lead to
Leads to dimerisation (pairing) of the receptor - essential for activation of the signalling pathway
What does the activation of the leptin receptor trigger
Triggers the activation of JAK2 which phosphorylates itself and other proteins (+ leptin receptor)
What is a important pathway activated by JAK2
The STAT3 (signal transducer and activator of transcription 3) pathway
What does SOCS3 act as in the leptin signalling pathway
Acts as a negative feedback regulator by inhibiting JAK2 activity - can lower the leptin signalling pathway
What may happen to SOCS3 levels with chronically high levels of leptin (seen in obesity)
SOCS3 levels elevated contributing to leptin resistance by inhibiting leptin signalling pathways
What is hyperglycaemia and how its caused
Hyperglycaemia is excessive circulating glucose
Mainly caused by fluid loss via an osmotic effect
What is hypoglycaemia and how is it caused
Hypoglycaemia is insufficient circulating glucose
Mainly caused by lack of glucose
How is insulin synthesised
Synthesised in β cells in the pancreas
What is insulin released in response to
Released in response to an increase in blood glucose
Where is glucagon synthesised
Synthesised in α cells in the pancreas
What is glycogen
A polymer of glucose stored and released by the liver
What is gluconeogenesis
The process of generating new glucose molecules from non-carbohydrate sources by the liver
How does glucagon act
Acts to oppose insulin actions by stimulating hepatic glucose synthesis and mobilisation
What does the pancreas release
Insulin and glucagon
What is type 1 diabetes a result of
Result of deficiency in insulin production due to autoimmune destruction of β cells in the pancreas
Onset in childhood
What is type 2 diabetes a result of
Result of a lack of sensitivity to insulin
Insufficient insulin production from β cells after period of insulin resistance
