Section 3 - Quiz On Eating And Drinking

Leptin is a hormone that regulates body weight and appetite. It signals the brain to reduce food intake and increase energy expenditure. When the ob mouse lacks the gene that produces leptin, it leads to a deficiency of this hormone. This deficiency disrupts the normal regulation of body weight, resulting in obesity. Therefore, the absence of leptin in the ob mouse is the reason for its obesity.

Osmoreceptors are specialized neurons that detect changes in solute concentration of the interstitial fluid. These receptors are responsible for monitoring the osmotic balance in the body by detecting any changes in solute concentration. This information is then relayed to the brain, which triggers appropriate responses such as thirst or the release of antidiuretic hormone (ADH) to maintain the body's fluid balance. By detecting changes in solute concentration of the interstitial fluid, osmoreceptors play a crucial role in regulating osmotic pressure and ensuring proper functioning of the body's cells.

Ghrelin is a hormone that stimulates appetite and is primarily secreted by the stomach. It plays a key role in initiating the process of eating by signaling hunger to the brain. Insulin, on the other hand, is a hormone secreted by the pancreas that helps regulate blood sugar levels and has no direct role in initiating eating. The hypothalamus is a region in the brain that controls various bodily functions, including appetite regulation, but it does not directly secrete ghrelin or insulin. CCK, another hormone, is involved in regulating digestion but does not play a primary role in initiating eating. Therefore, the correct answer is Ghrelin; stomach.

The correct answer is liver and muscles. The liver and muscles store glycogen, which is a form of glucose, as a short-term fuel reservoir. When the body needs energy, glycogen is broken down into glucose and released into the bloodstream to be used by the cells. This allows the body to maintain a steady supply of fuel for immediate energy needs. The liver and muscles are the primary storage sites for glycogen, making them essential for short-term fuel storage.

CCK, or cholecystokinin, is a hormone that is involved in the regulation of digestion and appetite. It is released by the small intestine in response to the presence of fat and protein in the digestive system. CCK stimulates the contraction of the gallbladder and pylorus, which helps with the digestion and absorption of nutrients. It also inhibits gastric contractions, which slows down the emptying of the stomach. Additionally, CCK inhibits eating by acting on the brain to reduce appetite. The blood level of CCK is indeed related to the fat content of a meal, as it is released in response to the presence of fat in the digestive system. However, the site of action of CCK is not directly on neurons of the ventromedial hypothalamus.

Ingestion of a bag of salted potato chips is a strong stimulus for producing osmometric thirst because the high salt content in the chips increases the osmolarity of the blood. This increase in osmolarity is detected by osmoreceptors in the hypothalamus, which then trigger the thirst response to restore the body's fluid balance.

An aqueous solution whose solute concentration is less than that of the intracellular fluid is termed hypotonic. In a hypotonic solution, there is a lower concentration of solutes outside the cell compared to inside the cell. This causes water to move into the cell through osmosis, leading to cell swelling or potentially bursting if the solution is extremely hypotonic.

The correct answer is "Reduced blood flow to the kidneys; reduced stimulation of atrial baroreceptors." When there is reduced blood flow to the kidneys, it can lead to decreased filtration and increased reabsorption of water, which triggers the sensation of thirst. Additionally, reduced stimulation of atrial baroreceptors, which are pressure-sensitive cells in the heart, can also contribute to hypovolemic thirst. These baroreceptors detect changes in blood volume and pressure, and when they are not adequately stimulated, it can trigger the release of hormones that signal thirst.

Angiotensin II is a hormone that plays a role in regulating blood pressure and fluid balance in the body. The subfornical organ is a region in the brain that lacks a blood-brain barrier and is sensitive to changes in blood composition. It has been shown that angiotensin II can stimulate neurons in the subfornical organ, leading to increased drinking behavior. Therefore, the correct answer is the subfornical organ.

Damage to the Area postrema and the Nucleus of the solitary tract abolishes glucoprovic and lipoprivic eating.