Chapter 6 Motivation and Regulation of Internal States

glucoprivic hunger

1st signal for hunger - tells brain of low supply of glucose

lipoprivic hunger

2nd signal for hunger - indicates deficit in fatty acids

ghrelin

3rd signal for hunger. A hormone that is synthesized in the stomach and released into the bloodstream as the stomach empties during fasting.

glycerol

A breakdown product of fats, which is converted to glucose for the brain during the fasting period.

instinct

A complex behavior that is automatic and unlearned and occurs in all the members of a species.

obesity gene

A gene on chromosome 6 that causes obesity; in mice it results in an inability to produce leptin.

glucagon

A hormone that causes the liver to transform stored glycogen back into glucose.

insulin

A hormone that enables body cells to take up glucose for energy and certain cells to store excess nutrients.

angiotensin II

A hormone that signals lowered blood volume and, thus, volemic thirst to the brain. Stimulates SFO.

Orexin

A neuropeptide that increases appetite and induces eating.

median preoptic nucleus

A nucleus of the hypothalamus that initiates drinking in response to osmotic and volumetric deficits.

lateral hypothalamus

A nucleus of the hypothalamus with roles in feeding and metabolism, aggression, and waking arousal. (initiates eating, )

nucleus of the solitary tract (NST)

A part of the medulla that monitors several signals involved in the regulation of eating.

paraventricular nucleus (PVN)

A structure in the hypothalamus that monitors several signals involved in the regulation of eating, including input from the NST.

neuropeptide Y (NPY)

A transmitter released by NPY/AgRP neurons in the arcuate nucleus of the hypothalamus when nutrient levels diminish; it is a powerful stimulant for eating and conserves energy. excites the PVN and lateral hypothalamus to increase eating and reduces metabolism Also see agouti-related protein

agouti-related protein (AgRP)

A transmitter released by NPY/AgRP neurons in the arcuate nucleus of the hypothalamus when nutrients diminish, which stimulates feeding. excites the PVN and lateral hypothalamus to increase eating and reduces metabolism Also see neuropeptide (NPY)

arcuate nucleus

A vital hypothalamic structure for monitoring the body's nutrient condition - sends neurons to the PVN and lateral hypothalamus to regulate bothe feeding and metabolism

peptide YY3-36 (PYY)

An appetite-suppressing peptide hormone released in the intestines in response to food. Inhibits NPY releasing neurons.

drive

An aroused condition that impels the individual to engage in appropriate action such as eating, drinking, or seeking warmth. departure from homeostasis. Temporary state: is a state of brain (i.e. sexual behavior)

fatty acids

Breakdown product of fat, which supplies the muscles and organs of the body (except for the brain).

body mass index (BMI)

Calculated by dividing the person's weight in kilograms by the squared height in meters.

homeostasis

Condition in which any particular body system is in balance or equilibrium.

amino acids

Converted from proteins

binge eating disorder

Disorder in which an individual frequently eats large amounts of food during a short period of time, and they feels they cannot control what or how much they eat.

basal metabolism

Energy required to fuel the brain and other organs and to maintain body temperature;

glycogen

Form in which glucose is stored in the liver and muscles during the absorptive phase; converted back to glucose for the brain during the fasting phase.

diabetes gene

Forty years ago, it was known as one of the genes that causes obesity in mice on chormosome 4

bulimia nervosa

Involves weight control, but the behavior is limited to bingeing and purging.

anorexia nervosa

Known as the "starving disease" because the individual restricts food intake to maintain weight at a level so low that it is threatening to health. two types: Restrictors and binge-purgers

motivation

Literally means "to set in motion." Refers to the set of factors that initiate, sustain, and direct behaviors.

hypovolemic thirst

Occurs when the blood volume drops due to a loss of extracellular water. (vomiting, diarrhea, sweating) drinking induceed by median preoptic nucleus (see vagus nerve, NST, renin, angiotensin II and SFO)

osmotic thirst

Occurs when the fluid content decreases inside the cells. Salty meal results in blood more concentrated - drinking initiated by the medial preoptic nucleus of the hopothalamus (see OVLT)

area postrema

One of the places in the brain that is outside the blood-brain barrier, so toxins can activate it to induce vomiting. part of digestive process

subfornical organ (SFO)

One of the structures bordering the third ventricle that increases drinking when stimulated by angiotensin II. Not protected by the blood-brain barrier.

Glucose

One of the sugars; the body's main source of energy, reserved for the nervous system during the fasting phase; a major signal for hunger and satiation.

absorptive phase

Period for a few hours following a meal when the body lives off the nutrients arriving from the digestive system (see: insulin, insulin receptors, diabetes I and II, glucose, glycogen, adipose tissue)

learned taste preference

Preference for a food containing a needed nutrient (identified by the food's taste), learned, presumably, because the nutrient makes the individual feel better.

incentive theory

Recognizes that people are motivated by external stimuli, not just internal needs

diabetes

Results when the pancreas is unable to produce enough insulin or the body's tissues are relatively unresponsive to insulin.

preoptic area

Structure in the hypothalamus that contains warmth-sensitive cells and cold-sensitive cells and participates in the control of body temperature. See medial preoptic area regarding regulation of sexual behavior.

fasting phase

Sympathetic activity. The period following the absorptive phase, when the glucose level in the blood drops and the body must rely on its energy stores. (See glucagon, glycerol, glycogen)

learned taste aversion

The avoidance of foods associated with illness or poor nutrition. can be used as predator control

cholecystokinin (CCK)

The best known of satiety signals. A peptide hormone released as food passes into the duodenum.

drive theory

The body maintains a condition of homeostasis, in which any particular system is in balance or equilibrium

duodenum

The initial 25 cm of the small intestine where digestions occurs

sensory-specific satiety

The more of a particular food an individual eats, the less appealing the food becomes. takes place in NST and prevents deficiencies in diet

set point

The point of equilibrium the system returns to.

organum vasculosum lamina terminalis (OVLT)

The reduced water content of cells that contributes to osmotic thirst is detected primarily in areas bordering the third ventricle, particularly in the organum vasculosum lamina terminalis (OVLT; see Figure 6.3). See. Osmotic thirst

satiety

The satisfaction of appetite.

arousal theory

Theory which says that people behave in ways that keep them at their preferred level of arousal - sensation seeking

epigenetic

Types of characteristics that are inheritable traits that result from modifications of gene expression rather than changes in the individual's DNA sequence.

umami taste receptor

aid in selection of protein - three types one is for distinguishing amino acids two are for distinguishing glutamate (found in meats, cheese, soy and MSG)

flavor

combinations of taste and smell

taste

experience from taste receptors

temperature regulation

homeostatic drive Ecothermic and endothermic

renin

hormone triggered by kidneys in response to lowered blood volume in hypovolemia which then increases hormone angiotensin II

Endothermic

mammals: preoptic area (thermostat) info from warm sensitive and cold sensitive cells internal - panting, sweating and shivering

carnivores

meat eaters - depend on prey for balanced diet

methylation

mechanism of epigenetic change where the attachment of molecules called methyl groups to a gene, which makes it more difficult for the gene to function.

agouti gne

methylation of the agouti-related peptide - mutation produces obesity and a atypical yellow coat. See hunger winter

hepatic portal vein

part of the digestive system where the products of digestion are absorbed through the intestinal wall into the blood and transported to the liver by this vein

omnivores

plant and meat eaters - need to distinguish sources, must be varied

herbivores

planting eating animals - all nutrients from a single source (Koalas and giant pandas)

homeostatic drives

require a control system and a set point

Ecothermic

snake and lizards external temperature regulation

primaries

taste sensations sour (likely to be spoiled), sweet (fruit and carbs), bitter (likely to be toxic), salty, umami