Motivation Flashcards
What are the three components in homeostasis?
- Humoral response - pituitary hormones
- Visceromotor response - sympathetic and parasympathetic
- Somatic Motor Response - behavioural response
Define motivated behaviour
Behaviour that is incited to achieve a goal
What is the prandial state?
Blood is filled with nutrients
During and immediately after a meal
How is energy stored?
Glycogen and triglycerides
Define anabolism
The biosynthesis of organic molecules from nutritive precursors
Define catabolism
The breaking down of complex nutrient molecules into simpler molecules
When is the energy reserves balanced?
When the energy reserves are replenished at the same average rate that they are expended.
What happens when the intake and storage of energy consistently exceed the usage?
Obesity
How does starvation occur?
When the intake of energy consistently fails to meet the body’s demand.
What neurons incite feeding behaviour?
Hypothalamic cells in the periventricular zone in the lateral hypothalamus
What is the lipostatic hypothesis?
A hypothesis proposing that body fat is maintained homeostatically at a specific level
What is the purpose of leptin?
To regulate body mass by acting directly on neurons of the hypothalamus that decreases appetite and increase energy expenditure.
What does leptin deficiency stimulate?
Hunger and feeding
Suppresses energy expenditure
Inhibits reproductive competence
What causes anorexia?
Bilateral lesions on the lateral hypothalamus
What causes animals to overeat and become obese?
Bilateral lesions on the ventromedial hypothalamus
Define lateral hypothalamic syndrome
Anorexia associated with lesions of the lateral hypothalamic area
Define ventromedial hypothalamic syndrome
Obesity associated with lesions of the ventromedial hypothalamic area
What does leptin activate?
Leptin receptors on neurons of the arcuate nucleus
When leptin levels begin to rise, what do the neurons of the arcuate nucleus release?
aMSH - alpha-melanocyte-stimulating hormone
CART - cocaine- and amphetamine-regulated transcript
What is the body’s integrated response to excessive adiposity, high leptin levels, and activation of the aMSH/CART neurons of the arcuate nucleus?
- Humoral response: increased secretion of TSH and ACTH to raise the metabolic rate of cells throughout the body
- Visceromotor response: increase the sympathetic division of the ANS to further raise the metabolic rate, in part by raising the body temperature
- Somatic motor response: decreases feeding behaviour
How do aMSH/CART neurons trigger the Humoral response?
Activating neurons in the paraventricular nucleus of the hypothalamus which in turn causes the release of the hypophysiotropic hormones that regulate the secretion of TSH and ACTH from the anterior pituitary.
Define anorectic peptides
Diminish appetite
How does a fall in leptin affect the arcuate nucleus?
Turn off responses mediated by aMSH/CART neurons
Stimulate NPY/AgRP neurons
What connections do the NYP/AgRP have?
PVN and the lateral hypothalamus