lecture 13 - regulation of energy metabolism by the nervous system Flashcards
what does the hypothalamus regulate?
several energy related processes including sleep, arousal, fatigue, thermoregulation, hunger and thirst.
what is an orexigenic signal?
when we are hungry - drives our hunger forward
- NPY/AgRP neurons
what is a satiety signal?
peaks as chews meal and then drops – supresses our intake after eating
what does hypophagia mean?
reduced appetite
what does hyperphagia mean?
increased appetite
what are some of the neural and hormonal mechanisms to promote or cease eating behaviour
pancreatic hormones, GI tract signalling, the amygdala etc
what does the hypothalamus do relating to hormones and nutrients?
relays them as signals
what are anorexigenic signals?
inhibit appetite and promote energy expenditure – POMC/CART neurons
why is a balance between PVN and LHA neurons highly crucial?
if disrupted can lead to obesity
what does the melanocortin system do? (POMC/CART)
Release stimulating hormones onto the pre synaptic membrane
Reduces our food intake and increases our energy expenditure
what does the melanocortin system do? (AgRP/NPY)
Prevent weight loss
Work antagonistically
what is ghrelin?
Peptide hormone that is primarily secreted form the stomach associated with appetite
- Prevents the POMC neurons supressing our appetite
- Stimulates the AgRP neurons – increases appetite
when does ghrelin increase?
when we have an empty stomach
when does ghrelin decrease?
when we have a full stomach
what is leptin?
Peptide hormone secreted by adipocytes which decreases metabolic activity
what does GABA do in relation to the melanocortin system?
contacts the POMC neurons to promote overfeeding
what is the Paraventricular nucleus? (PVN)
synthesise and secrete various catabolic hormones (vasopressin, oxytocin etc) - it plays inhibitory role in food intake and weight gain
what is the Ventromedial Hypothalamus? (VMH)
increases activity of POMC neurons to reduce feeding
what is the Lateral Hypothalamus? (LH)
feeding centre, regulated by hormones like leptin and ghrelin.
- Orexin neurons activated by fasting, inhibited by glucose. Also associated with hedonic reward system.
- beh adapts in response to energy states
what is the Dorsomedial Hypothalamus? (DMN)
involved in glucocorticoid secretion, body temperature, arousal, and circadian rhythms of locomotor activity.
- All areas are connected in regulation of neurons they produce
Circadian activity – promotes activity when it believes we should be awake and searching for food
what does the brain stem do?
Regulates nutrient supply
- enables locomotive activity
- tells you to spit out food because you don’t like it
what is the mesolimbic reward system in the midbrain?
Intake of palatable foods elicits dopamine release from the midbrain ventral tegmental area (VTA).
- promotes feeding (dopamine)
- supresses feeding (leptin)
what is brown adipose tissue?
The role of basal metabolism and adaptive thermogenesis.
