internal regulation ii: energy (3.3)

Question 1

gastrointestinal tract (GIT)

Answer 1

a part of the physiological system involved in the regulation of the body’s energy homeostasis; takes in food (mouth), digests it (mouth, stomach, small intestines) to extract and absorb energy and nutrients (small and large intestines), and expels the remaining waste as feces (rectum)

Question 2

prandial vs fasting state

Answer 2

prandial: food has been consumed; glucose is stored (via anabolism) in the form of glycogen (in liver) and triglycerides (in fat)
fasting: stored molecules are broken down (via catabolism) to provide nutrients

Question 3

lipostatic hypothesis

Answer 3

the brain monitors the level of body fat and “defends” this source against perturbation; asymmetric body weight (more sensitive to weight loss than weight gain)

Question 4

leptin

Answer 4

hormone released by fat cells to communicate the level of fat to the brain (coded by ob gene in mice)

Question 5

stomach hunger/satiety

Answer 5

hormone ghrelin = hunger; distention (vagus nerve) = satiety

Question 6

intestine satiety hormone

Answer 6

cholecystokinin (CKK)

Question 7

insulin

Answer 7

low = hunger; high = satiety

Question 8

lateral vs ventromedial hypothalamic syndrome

Answer 8

lateral: lesions cause severely reduced appetite and reduced fat stores (issues with hunger signals)
ventromedial: lesions cause severe overeating and weight gain (arcuate nucleus)

Question 9

arcuate nucleus

Answer 9

considered to be the “master area” (sensor) for control of appetite

Question 10

sets of neurons in arcuate nucleus (2)

Answer 10

AgRP: sensitive to hunger signals
NPY: sensitive to satiety signals

Question 11

hedonic hunger

Answer 11

incorporates motivational (reward) and emotional influences on eating (dopamine and serotonin)

Question 12

nigrostriatal vs mesocorticolimbic pathway (dopamine reward circuit)

Answer 12

nigrostriatal: substantia nigra to the striatum (motor selection)
mesocorticolimbic: ventral tegmental area (VTA) to cortex and limbic sites (i.e. nucleus accumbens (NA))

Question 13

ventral tegmental area (VTA)

Answer 13

can incite feeding behavior if the body does or does not have energy needs (see notes for description)

Question 14

tryptophan

Answer 14

the amino acid from which serotonin is derived; must be consumed (found in proteins); levels vary with the amount of carbohydrates in the diet

Question 15

obesity (definition, causes (3), and treatment (2))

Answer 15

definition: a medical condition in which excess body fat has accumulated, with adverse health effects (i.e. heart disease, diabetes)
causes: excessive food intake, lack of physical activity, genetic susceptibility
treatment: dieting and exercising; weight-loss drugs or surgery

Question 16

anorexia nervosa vs bulimia nervosa and risk factors

Answer 16

anorexia: a condition in which people refuse to eat or fear to eat as much as they need
bulimia: characterized by binge eating followed by purging
risk factors: psychological stress, cultural pressure to attain a certain body type, genetic predisposition