Lesson 7 (Hunger)
What are the different (genetic & psychological) causes of obesity?
*Psychological* causes: emotional disturbances. When a person feels unhappy or anxious, they overeat, which leads to more unhappiness, which in turn causes more overeating. *Genetic* causes: Leptin (a protein produced by fat cells). Some people could lack leptin receptors in their VMH, which causes overeating. Others could lack leptin altogether. The genetic cause is *extremely* rare in humans.
What distinguishes anorexia nervosa from bulimia nervosa? What do these disorders have in common?
*Similarities* include purging, possibility of excessive exercise. For *differences*, anorexics are often underweight and avoid eating food as much as possible. Bulimics binge on food, and subsequently purge the food. They also tend to normal weight or overweight.
What are some potential causes of anorexia and bulimia?
Exact cause in unknown. Believed to be combination of biological, psychological, and environmental factors. Certain type of estrogen may make women more susceptible. High serotonin is linked with anorexia, low serotonin is linked with bulimia
What role do the following structures play in our eating behavior: lateral hypothalamus (LH), ventromedial hypothalamus (VMH), & paraventricular nucleus of the hypothalamus?
The *lateral hypothalamus* acts as a feeding center that initiates eating behavior. The *ventromedial hypothalamus* acts as the satiety center, or "stop" eating center. The *paraventricular nucleus* helps regulate eating behavior by both starting and stopping eating behavior.
What is the relationship between leptin, the VMH, and eating behavior? What are the two types of genetic obesity in mice and what are their causal factors?
The relationship is that leptin circulates throughout the bloodstream, and if it isn't present, then the VMH never receives the signal to reduce eating. Also, if the VMH lacks leptin receptors, then the VMH never knows when to reduce eating.
What treatments are available for people suffering from eating disorders?
Treatments include low doses of antipsychotic medication and psychotherapy. Psychotherapy is more effective now that it focuses on patient's self-worth instead of gaining weight.
Who is at greatest risk for developing eating disorders?
Westerners, teen/young girls, and athletes.
What occurs when the LH and VMH are selectively stimulated (activated) or destroyed?
When the *LH* is destroyed, a person starves to death because they never feel hungry. When the *VMH* is destroyed, a person dramatically overeats because they never feel full.
