Body Weight And Obesity/diabetes SEM2

Question 1

What is the “set-point” of body weight

Answer 1

Predetermined set point which the body seeks to maintain homeostasis

Question 2

What are the key brain regions involved in appetite control

Answer 2

Hypothalamus
Brainstem
Reward and sensory processing areas

Question 3

What is the hypothalamuses involvement in appetite regulation

Answer 3

Central to appetite regulation
Contains arcuate nucleus

Question 4

What are the two important neurone types in the arcuate nucleus

Answer 4

Anorexigenic - satiety
Orexgingenic - hunger

Question 5

What can removing orexigenic arcuate neurones result in

Answer 5

Can result in starvation

Question 6

What does the use of optogenietic approaches allow for

Answer 6

Control of specific population of neurones, activation of orexigenic arcuate AgRP neurones increase in food intake

Question 7

What leads to a reduction in food intake and body weight

Answer 7

Stimulating the anorexigenic POMC in the arcuate nucleus

Question 8

What are NPY/AgRP neurones

Answer 8

Orexigenic

Question 9

What are POMC neurones

Answer 9

Anorexigenic

Question 10

What occurs if the gene of leptin is removed

Answer 10

The leptin hormone is no longer able to send signals to the brain to inhibit hunger

Question 11

What are the results of leptin acting on arcuate POMC cells

Answer 11

Leptin increases POMC mRNA expression
Leptin excites POMC cells electrophysiologically

Question 12

What happens to leptin activity in relation to obesity

Answer 12

Leptin target sites can become insensitive to leptin in obesity

Question 13

What can partial leptin reduction restore

Answer 13

Restores hypothalamic leptin sensitivity and leads to reduced food intake

Question 14

What does the binding of leptin lead to

Answer 14

Leads to dimerisation (pairing) of the receptor - essential for activation of the signalling pathway

Question 15

What does the activation of the leptin receptor trigger

Answer 15

Triggers the activation of JAK2 which phosphorylates itself and other proteins (+ leptin receptor)

Question 16

What is a important pathway activated by JAK2

Answer 16

The STAT3 (signal transducer and activator of transcription 3) pathway

Question 17

What does SOCS3 act as in the leptin signalling pathway

Answer 17

Acts as a negative feedback regulator by inhibiting JAK2 activity - can lower the leptin signalling pathway

Question 18

What may happen to SOCS3 levels with chronically high levels of leptin (seen in obesity)

Answer 18

SOCS3 levels elevated contributing to leptin resistance by inhibiting leptin signalling pathways

Question 19

What is hyperglycaemia and how its caused

Answer 19

Hyperglycaemia is excessive circulating glucose
Mainly caused by fluid loss via an osmotic effect

Question 20

What is hypoglycaemia and how is it caused

Answer 20

Hypoglycaemia is insufficient circulating glucose
Mainly caused by lack of glucose

Question 21

How is insulin synthesised

Answer 21

Synthesised in β cells in the pancreas

Question 22

What is insulin released in response to

Answer 22

Released in response to an increase in blood glucose

Question 23

Where is glucagon synthesised

Answer 23

Synthesised in α cells in the pancreas

Question 24

What is glycogen

Answer 24

A polymer of glucose stored and released by the liver

Question 25

What is gluconeogenesis

Answer 25

The process of generating new glucose molecules from non-carbohydrate sources by the liver

Question 26

How does glucagon act

Answer 26

Acts to oppose insulin actions by stimulating hepatic glucose synthesis and mobilisation

Question 27

What does the pancreas release

Answer 27

Insulin and glucagon

Question 28

What is type 1 diabetes a result of

Answer 28

Result of deficiency in insulin production due to autoimmune destruction of β cells in the pancreas
Onset in childhood

Question 29

What is type 2 diabetes a result of

Answer 29

Result of a lack of sensitivity to insulin
Insufficient insulin production from β cells after period of insulin resistance