chapter 12 Flashcards
homeostasis
the process by which the body’s substances and characteristics are maintained at their optimal level
ingestive behavior
eating or drinking
system variable
a variable that is controlled by a regulatory mechanism for example, temperature in a heating system
set point
the optimal value of the system variable in a regulatory mechanism
detector
in a regulatory process, a mechanism that signals when the system variable deviates from its set point
correctional mechanism
in a regulatory process, the mechanism that is capable of changing the value of the system variable
negative feedback
a process whereby the effect produced by an action serves to diminish or terminate that action; a characteristic of regulatory system
satiety mechanism
a brain mechanism that causes cessation of hunger or thirst produced by adequate and available supplied of nutrients or water
intracellular fluid
the fluid contained within cells; monitored by receptors measuring cell volume
extracellular fluid
all body fluids outside the cells; interstitial fluid, blood plasma, and cerebrospinal fluid
intravascular fluid
the fluid found within the blood vessels; monitored by receptors measuring blood volume
interstitial fluid
the fluid that bathes the cells, filling the space between the cells of the body
hypovolemia
reduction in the volume of the intravascular fluid
osmometric thirst
thirst produced by an increase in the osmotic pressure of the interstitial fluid relative to the intracellular fluid, thus producing cellular dehydration
osmoreceptor
a neuron that detects changes in the solute concentration of the interstitial fluid that surrounds it
volumetric thirst
thirst produced by hypovolemia
angiotensin
a peptide hormone that constricts blood vessels, causes the retention of sodium and water, and produces thirst and a salt appetite
glycogen
a polysaccharide often referred to as animal starch; stored in the liver and muscle; constitutes the short-term store of nutrients
insulin
a pancreatic hormone that facilitates entry of glucose and amino acids into the cell, conversion of glucose into glycogen and transport of fats into adipose tissue
glucagon
a pancreatic hormone that promotes the conversion of liver glycogen into glucose
triglycerides
the form of fat storage in adipose cells; consists of a molecule of glycerol joined with three fatty acids
glycerol
a substance derived from the break down of triglycerides
fatty acid
a substance derived from the breakdown of triglycerides along with glycerol; can be metabolized by most cells of the body except for the brain
fasting phase
the phase of metabolism during which nutrients are not available from the digestive system; glucose, amino acids, and fatty acids are derived from glycogen, protein, and adipose tissue
absorptive phase
the phase of metabolism during which nutrients are absorbed from the digestive system; glucose and amino acids constitute the principal source of energy for cells during this phase, and excess nutrients are stored in adipose tissue in the form of triglycerides
ghrelin
a peptide hormone released by the stomach that increases eating; also produced by neurons in the brain
duodenum
the first portion of the small intestine, attached directly to the stomach
glucoprivation
a dramatic fall in the level of glucose available to cells; can be caused by a fall in the blood level of glucose or by drugs that inhibit glucose metabolism
lipoprivation
a dramatic fall in the level of fatty acids available to cells; usually caused by drugs that inhibit fatty acid metabolism
cholecystokinin (CCK)
a hormone secreted by the duodenum that regulates gastric motility and causes the gallbladder to contract; appears to provide a satiety signal transmitted to the brain through the vagus nerve
peptide YY 3-36 (PYY)
a chemical produced by cells in the gastrointestinal tract and released by the small intestine after a meal in amounts proportional to the calories that were just ingested; serves as a satiety signal
hepatic portal vein
the vein that transports blood from the digestive system to the liver
ob mouse
a strain of mice whose obesity and low metabolic rate are caused by a mutation that prevents the production of leptin
leptin
a hormone secreted by adipose tissue; decreases food intake and increases metabolic rate, primarily by inhibiting NPY-secreting neurons in the arcuate nucleus
decerebration
a surgical procedure that severs the brain stem, disconnecting the hindbrain from the forebrain
melanin-concentrating hormone (MCH)
one of two peptide neurotransmitters found in a system of lateral hypothalamic neurons that stimulate appetite and reduce metabolic rate
orexin
one of two peptide neurotransmitters found in a system of lateral hypothalamic neurons that stimulate appetite and reduce metabolic rate. also called hypocretin
neuropeptide Y (NPY)
a peptide neurotransmitter found in a system of neurons of the arcuate nucleus that stimulate feeding and insulin and glucocorticoid secretion; decreases the breakdown of triglycerides; and decreases body temperature
agouti-related protein
a neuropeptide that acts as an antagonist at MC4Rs and increases eating
arcuate nucleus
a nucleus in the base of the hypothalamus that controls secretion of the anterior pituitary gland; contains NPY-secreting neurons involved in feeding and control of metabolism
paraventricular nucleus
a nucleus of the hypothalamus located adjacent to the dorsal third ventricle contains neurons involved in the control of the autonomic nervous system and the posterior pituitary gland
CART
cocaine and amphetamine-regulated transcript; a peptide neurotransmitter found in a system of neurons of the arcuate nucleus that inhibit feeding
a-melanocyte-stimulating hormone (a-MSH)
a neuropeptide that act as an agonist at MC4Rs and inhibits eating
melanocortin-4 receptor (MC4R)
a receptor found in the brain that binds with a-MSH and agouti-related protein; plays a role in the control of appetite
anorexia nervosa
a disorder that most frequently afflicts young women; exaggerated concern with overweight that leads to excessive dieting and often compulsive exercising; can lead to starvation
bulimia nervosa
bouts of excessive hunger and eating often followed by forced vomiting or purging with laxatives; sometimes seen in people with anorexia nervosa
binge eating disorder
a disorder that includes bouts of excessive eating
