Chapter 16: Motivation Flashcards
Probability and direction of behavior vary with the () needed to perform
the behavior
driving force (i.e. motivation)
process of maintaining the body’s internal environment within a narrow physiological range
homeostasis
plays a key role in regulating body temperature, fluid balance, and energy balance
hypothalamus
three components of neuronal response
- humoral response (hormones)
- visceromotor response (ANS)
- somatic motor response
3 functional zones of the hypothalamus
- lateral
- medial
- periventricular
energy balance state wherein energy is stored as glycogen and triglycerides
prandial state (anabolism)
types of energy storage in body
glycogen (liver and muscle, limited capacity)
triglycerides (adipose tissue, unlimited capacity)
energy balance state where in complex macromolecules are broken down for energy
postabsorptive state (catabolism)
Long-term regulation: Feeding is stimulated when hypothalamic neurons detect a ()
drop in the level of a hormone released by fat cells.
the idea that the brain monitors and acts to maintain the amount of body fat
Lipostatic hypothesis
hormone released by body fat; tells the brain that fat (energy) reserves are normal and sufficient
leptin
actions of leptin that allow it to help regulate body mass
- decreases appetite
- increases enegy expenditure
Incites adaptive responses to fight starvation (stimulates hunger and feeding, suppresses energy expenditure, and inhibits reproductive competence)
leptin depletion
severely diminished appetite, caused by lesion in lateral hypothalamus -> lateral hypothalamic syndrome
anorexia
overly active appetite, caused by lesion in ventromedial hypothalamus -> ventral hypothalamic syndrome
obesity
() of hypothalamus important for the control of feeding
arcuate nucleus
LH (1): stop feeding; LH (2): triggers feeding
- lesions
- stimulation
LH neurons stimulating feeding behavior contain:
- melanin-concentrating hormone (MCH)
- orexin
compound in LH neuron that makes widespread connections in the brain; involved in prolonging meal consumption
MCH
compound in LH neurons that promote meal initiation
orexin (hypocretin)
3 phases of eating
- cephalic
- gastric
- substrate (intestinal)
() phase: the sight and smell of food trigger a number of physiological processes that anticipate the arrival of food (e.g., secretion of saliva and digestive juices)
Cephalic
() phase: these responses grow much more intense, when you start chewing, swallowing, and filling your stomach with food.
Gastric
() phase: as your stomach fills and digested food moves into your intestine, nutrients begin to be absorbed into your blood stream.
Substrate (intestinal)
() released when stomach is empty
(hunger is not merely the absence of satiety) -> Activates NPY/AgRP-containing (orexigenic) neurons in arcuate nucleus
Ghrelin
Gastric distention signals brain via vagus nerve. Vagal axons activate neurons in the ().
nucleus of the solitary tract
() released in intestines in response to certain foods (esp fatty foods); acts on vagal sensory axons.
CCK (cholecystokinin)
insulin acts directly on the () of the hypothalamus (like leptin)
arcuate and ventromedial nuclei
Trajectory of () projecting to the forebrain are effective sites for self stimulation
dopaminergic axons in the ventral-tegmental area
the () neurotransmitter was found to play a powerful role in motivation -> inhibiting it caused a decrease in driving force to do something or satisfy a craving
dopamine
new understanding of dopamine role in motivation -> Dopamine-depleted animals () food.
“like” food but do not “want” -> lack motivation to find food, but still enjoy it when it is available
explain the idea that Dopamine neurons signal reward prediction error
changes in dopamine release occur when rewards are either better or worse than expected
describe serotonin levels between and during meals
- low in postabsorptive (between meals)
- rise in anticipation of food
- spike during meal (esp in response to carbs)
Drugs that elevate serotonin (activate/suppress) appetite
suppress
disorders in serotonin regulation: anorexia, bulimia, are often accompanied by ()
depression (treatment may include drugs that increase serotonin)
The transduction of physiological stimuli in the blood occurs in specialized regions of the hypothalamus
- Humoral and visceromotor responses: by the ()
- Behavioral actions: by the ()
- periventricular and medial hypothalamus
- lateral hypothalamus
thirst in reponse to hypovolemia
volumetric thirst
responses to volumetric thirst
humoral: (1)
visceromotor: (2)
somatic motor: (3)
- ADH release
- sympathetic activation
- motivates drinking
acts on kidneys to increase water retention; inhibits urine production
vasopressin (ADH)
thirst in response to hypertonicity
osmometric
responses to osmometric thirst
ADH release, motivation for drinking
neurons for temperature homeostasis are clustered in ()
anterior hypothalamus
humoral and visceromotor responses to change in temp -> activation of () in the hypothalamus
medial preoptic area
somatic motor responses to changes in temp -> activation of () hypothalamus
lateral
humoral response to fall in temp
stimulate release of TSH and consequently thyroxin (increase cell metab)
visceromotor response to fall in temp
vasoconstriction in skin (retain heat)
somatic motor response to fall in temp
shivering, seek warmth
