Motivation

Question 1

What is motivation?

Answer 1

• Driving force
• Physical need
• Wanting,liking

Question 2

What does the hypothalamus maintain?

Answer 2

Maintains homeostasis by regulating three interrelated functions:

• Endocrine secretions
• ANS
• Emotions and drive/behaviour

Question 3

What is parabiosis and its effect?

Answer 3

Parabiosis is the sharing of blood circulation between animals
This means blood borne signals are shared and can effect the hypothalamus

Question 4

What is the effect of parabiosis?

EXAMPLE

Answer 4

• A genetically obese mouse ob/ob fat cells do not produce leptin
• When connected to a normal mouse of whoms fat cells do produce leptin, this will lead to a reduction of obesity in the ob/ob mouse

Question 5

What is the feedback mechanism of fatty tissues?

Answer 5

• Fatty tissue produce leptin when satisfied

- Leptin travels to the brain and signals to the arcuate nucleus to stop eating

Question 6

What are the VMN and LH important for the regulation of?

Answer 6

VMN and LH important for the regulation of:

• Body weight/food intake
• Blood volume/osmolarity

Question 7

What does a VMH lesion cause?

Answer 7

Causes a dramatic increase in food intake and body weight

Question 8

What role does VMH play in?

Answer 8

VMH plays a role in controlling the cessation of eating

Question 9

What does a LH lesion cause?

Answer 9

Causes a decrease in food intake

Question 10

What signalling are both VMH and LH related to?

Answer 10

VMH and LH both are related to leptin signalling

Question 11

What is the arcuate nucleus important for?

Answer 11

It’s important for control of feeding

Question 12

What is the response to elevated leptin levels?

Answer 12

• Leptin activates arcuate neurons that release alphaMSH and CART peptides
• Neurons then project to regions that orchestrate coordinated responses of humoral, visceromotor and somatic responses
  
  • PVN
  • Intermediolateral grey matter of spinal cord
  • Lh

Question 13

Why are alphaMSH and CART anorectic peptides?

Answer 13

Are anorectic peptides because they diminish appetite

Question 14

What is the response to decreased leptin levels?

Answer 14

-NPY/AgRP neuron of the arcuate nucleus are activated
-These neurons inhibit neurons in the PVN that control the release of TSH and ACTH from the pituitary
-The neurons in the LH are then activated that stimulate feeding behaviour
-Some of the activated LH neurons contain the peptide
MCH

Question 15

What receptor do both alpha MSH and AgRP act on?

Answer 15

Both act on the MC4 receptor

Question 16

What do alphaMSH and AgRP do to the MC4 receptor?

Answer 16

• alphaMSH stimulates MC4 receptor

- AgRP inhibits MC4 receptor

Question 17

What does the MC4 receptor do when activated?

Answer 17

Activation of MC4 receptor inhibits feeding behaviour

Question 18

What do LH neurons stimulating feeding behaviour contain?

Answer 18

Contain MCH and Orexin

Question 19

What does MCH do?

Answer 19

Prolongs consumption

Question 20

What does Orexin do?

Answer 20

Orexin promotes meal initiation

Question 21

What are the 3 phases of digestion?

Answer 21

• Cephalic
• Gastric
• Substrate

Question 22

What happens in the cephalic phase?

Answer 22

• Ghrelin is released when stomach is empty

- Ghrelin then activates NPY/AgRP containing neurons in arcuate nucleus

Question 23

What does the removal of ghrelin secreting cells do?

Answer 23

Removal of ghrelin secreting cells of stomach are thought to cause loss of appetite

Question 24

What happens in the gastric phase?

Answer 24

• Gastric distension
• CCK release in intestines
• Insulin also released by beta cells of the pancreas

Question 25

What signals does gastric distension and CCK release send and what does this cause?

Answer 25

Gastric distention and CCK release signals the nucleus of the solitary tract via the vagus nerve to cause satiety

Question 26

What happens to levels of 5HT in the hypothalamus in the anticipation of food or a meal?

Answer 26

They rise

Question 27

What is 5HT levels associated with?

Answer 27

Associated with anorexia nervosa and bulimia with depression

Question 28

What are examples of natural rewards?

Answer 28

• Food
• Water
• Sex
• Nurturing

Question 29

What are the stages in the addiction cycle?

Answer 29

Acute reinforcement/social drug taking –>Escalating and compulsive use–>Dependence–>Withdrawal–>Protracted withdrawal–>Recovery

Question 30

What is positive reinforcement?

Answer 30

It is anything added that follows a behaviour that makes it more likely that the behaviour will occur again in the future

Question 31

What is negative reinforcement?

Answer 31

It is a response or behaviour that is strengthened by stopping, removing or avoiding a negative outcome or aversive stimulus