Y (NPY), and agouti-related peptide (AgRP). They inhibit the PVN and the satiety-sensitive cells of the arcuate nucleus to increase hunger and stimulate eating behaviors. NPY cells also have a pathway to the orexin- producing cells of the lateral hypothalamus. Orexin stimulates activity and the onset of meals but has a minor overall effect on feeding behavior. The lateral hypothalamus controls insulin secretion, alters taste responsiveness, and facilitates feeding in other ways. Damage to the lateral hypothalamus causes an animal to refuse food and water. The ventromedial hypothalamus (VHM) regulates eating. And stimulates overeating and weight gain. Response Feedback: that is only part of the process Question 3 0.4 out of 0.52 points Describe the different causes and mechanisms of osmotic and hypovolemic thirst. Correct Answer: Hypovolemic thirst is thirst associated with low volume of body fluids such as too much sweating, bleeding or diarrhea. It is triggered by the release of the hormones vasopressin and angiotensin II, which constrict blood vessels to compensate for a drop in blood pressure. Angiotensin II stimulates neurons in areas adjoining the third ventricle. Neurons in the third ventricle send axons to the hypothalamus where angiotensin II is also released as a neurotransmitter. Animals with hypovolemic thirst have a preference for slightly salty water as pure water dilutes body fluids and
changes osmotic pressure. Sodium-specific hunger, a strong craving for salty foods which develops automatically to restore solute levels in the blood when individuals or animals eat salty food. Osmotic thirst occurs when solutes are more concentrated on the outside of the cell. This causes water to move from high concentration inside the cell to the outside that has a lot of solutes. For example if a person eats a salty meal, the stomach will detect high levels of sodium. The high levels of salt outside the cells increases osmotic pressure causing the cells to shrink as water leaves from inside the cell. This change is pressure is detected by cells in the hypothalamus (OVLT and SFO). The OVLT and SFO also stimulates the supraoptic nucleus and paraventricular nucleus of the hypothalamus. The PVN also stimulates the lateral preoptic area that causes individuals to feel thirsty and go to get a drink of water. The PVN of the hypothalamus also signals the release of vasopressin from the posterior pituitary. Vasopressin increases blood pressure by constricting blood vessels to compensate for decreased water volume in cells. Vasopressin also causes the kidneys to reabsorb water and excrete very concentrated urine. When an individual feels thirsty with osmotic thirst, they will drink pure water. Response Feedback: [None Given] Question 4 0.52 out of 0.52 points Describe how bulimia nervosa resembles drug addiction.
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- Fall '16
- Dr. Tulloch
- Biological Psychology