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Brain&Behavior ch.9

Homeostasis: active regulation of the internal environment

TermDefinition
Homeostasis self-regulation to maintain a stable internal environment despite changes in external environment
What are five things homeostasis regulates? Temperature, Water and pH levels, Blood pressure, Glucose concentration, and Nutrition
Changes in the internal environment can affect _________ – process that induces or sustains a behavior motivation
Temperature: There are two types of thermo regulators endotherms, ectotherms
Temperature: Endotherms GENERATE most of their own heat through INTERNAL processes
Temperature: Ectotherms GET most of their heat from the ENVIRONMENT
Temperature: Both actively regulate body temperature, but ectotherms do so by ________ behavior
Behavioral regulation of temperature occurs in three ways: • Changing exposure of the body surface • Changing external insulation (feathers, fur, blubber, clothes) • Changing surroundings
Temperature: Why are behavioral methods of thermoregulation especially important to ectotherms (like iguanas)? because they generate little heat through metabolism
Temperature: how does the iguana control its body temperature? by moving toward or away from a heat source (lamp)
Temperature: when the iguana was injected with bacteria, how did it react? it moved closer to the lamp to produce a “Behavioral fever” to fight infection
Temperature: in most endothermic animals body temperature is tightly regulated by the body's thermostat. The ____________ hypothalamus (POA: preoptic area of hypothalamus, brain stem, and spinal chord too)
Temperature: these neural regions (hypothalamus/POA, brain stem, and spinal cord) initiate what? physiological and behavioral responses to return temperature to the set zone
Temperature: What are some examples of behavior responses? shivering, heat-seeking/avoiding behaviors
Temperature: What are some examples of physiological responses? constriction/dilation of blood vessels, sweating, respiration, thyroid hormone secretion
Thermoregulation can occur at different levels of the nervous system (redundancy). Narrower set zones are at ______ levels and broader (less precise) at ______ levels higher levels (brain) and broader (less precise) at lower levels
______ studies show separate regulatory systems in the hypothalamus Lesion
Anterior damage lose__________ response, but not ________; Lateral damage opposite effect physiological, behavioral
what are the primary homeostatic mechanisms? negative feedback systems
If a desired value, the set point, is deviated from, ____________ action begins compensatory
The set zone refers to what? the range of tolerance in a system
fluid regulation: Water in the Human Body Shuttles between Two Major Compartments. What are they? Intracellular compartment and extracellular compartment
Most water in our body is ___cellular intra
Intracellular compartment fluid contained within cells
Extracellular compartment fluid space outside cells
what fluids does extracellular compartment contain? (2) interstitial fluid (between cells) and blood plasma
What are two forces driving water movement in our bodies? osmosis and diffusion
Diffusion – molecules of a substance (_____) dissolved in another substance (______) will move until a uniform concentration is achieved solute, solvent
Osmosis is the movement of water across a ____________ membrane that separates solutions of two different concentrations of a solute semipermeable
Osmotic pressure force that pushes or pulls water across the membrane
The extracellular fluid indicates the state of the intracellular space, and is monitored by the _______ system nervous
Two states signal a need for water: Low extracellular volume from a loss of bodily fluids stimulates what? hypovolemic thirst
Two states signal a need for water: High extracellular solute concentration, or very salty fluids, stimulate what? osmotic thirst
Hypovolemic thirst is triggered by a loss of ______ volume water (the saline concentration is not changed)
Hypovolemic thirst: ___________ in blood vessels and the heart detect the initial drop in pressure due to extracellular fluid loss Baroreceptors
Hypovolemic thirst: a neural response: The brain activates responses such as _____ or salt ________ thirst, hunger
Hypovolemic thirst: a neural reponse: The _________ nervous system causes arteries to constrict and several _______ systems are activated sympathetic, hormone
Hypovolemic thirst: Physiological response 1: Heart decreases secretion of ______ _________ _______ atrial natriuretic peptide (ANP)
Hypovolemic thirst: Physiological response 1: atrial natriuretic peptide (ANP) does what? (3)` inhibits drinking, reduces blood pressure and promotes excretion of water and salt at the kidneys
Hypovolemic thirst: Physiological response 2: Posterior pituitary releases ________ vasopressin
Hypovolemic thirst: Physiological response 2: What does vasopressin do? (1) Acts on kidneys to slow urine productions
Hypovolemic thirst: Physiological response 3: Kidneys trigger production of __________ __ angiotensin II (AII)
AII has several water-conserving actions: Conserves water by constricting ______ _________, in turn increasing blood pressure blood vessels
AII has several water-conserving actions: Stimulates release of v__________ and a___________ vasopressin and aldosterone
AII has several water-conserving actions: we already know that vasopressin acts on kidneys to slow urine productions. What does aldosterone do? promotes conservation of sodium by the kidneys
AII has several water-conserving actions: AII acts directly on the brain, at the _______ area, and areas called ___________ organs to stimulate drinking behavior preoptic area (POA, circumventricular organs (CV organs)
AII has several water-conserving actions: CV organs in wall of ventricular system can directly monitor salt in the _______ blood
Osmotic thirst occurs when the extracellular fluid becomes too _______ salty (water loss or salt increase)
osmotic thirst: Water is pulled out of the cells through osmosis. Volume ________ and solute concentration ________ decreases, increases
osmotic thirst: _________ neurons in the hypothalamus specifically monitor changes in concentration of the extracellular fluid Osmosensory
osmotic thirst: These neurons are also found in the ____ (abr), a circumventricular organ OVLT
osmotic thirst: Too much extracellular salt triggers osmosis into or out of the cell? out of the cell
The amount of water that the body can retained depends on the number of ____ ions in the body. Na+
When water is scarce Na+ ions must be conserved: Angiotensin II also stimulates adrenal glands to release a_________ aldosterone
aldosterone is a steroid hormone that stimulates the ________ to conserve Na+, aiding water retention kidneys
Drinks that are slightly salinated can quench thirst faster, because of why? they add Na+ ions back into the extracellular fluid
Too much salt in your drink (drinking seawater) would only cause more _______ thirst. osmotic
The regulation of eating and body energy involves redundant mechanisms and complex homeostatic mechanisms.________ Regulation Helps Prepare for Future Needs Nutrient
Nutrients are chemicals required for what three things? function, maintenance, and growth of the body
There are _#_ amino acids (9 essential ones not synthesized by body), Fatty acids,_#_ vitamins, Minerals, and Carbohydrates 20, 15
_________ is converted glucose stored in the liver and skeletal muscles for the ____-term storage Glycogen, short
This process of conversion is regulated by the pancreatic hormone _______ insulin
When glucose levels drop, the hormone ________converts glycogen back into glucose glucagon
For ____-term storage, lipid (fat) molecules from fats or excess sugars are stored in ______ tissue long, adipose (fat)
Under prolonged food deprivation ___ can be converted into glucose and ketones, which can be used as fuel fat
______ _________ – comsumption of energy used for heat production, membrane potential maintenance, and life-sustaining processes Basal metabolism
Only __-__% of food energy is used for active behavior… the majority of food energy is spent on basal metabolism. 10-20
Metabolism is under homeostatic control and can be adjusted, so dietary changes will not always produce changes in ______ weight
The body needs insulin to help glucose transporters do what? import glucose from the blood into most cells (except neurons)
________ _________ results from lack of or ineffective insulin Diabetes mellitus
Diabetes mellitus: In Type I (juvenile-onset) diabetes, what happens? the pancreas stops producing insulin
Diabetes mellitus: Type II (adult-onset) diabetes is caused by what? decreased sensitivity to insulin or decreased insulin production
Insulin release is important at mealtimes and is triggered by several mechanisms: What three phases? cephalic phase, digestive phase, absorptive phase
The cephalic phase of insulin release is mediated by the brain in response to ______, _______, or _______ food seeing, smelling, or tasting
In the digestive phase, insulin is released when what? food enters the digestive tract
In the absorptive phase specialized liver cells called ________ signal the pancreas to release even more insulin glucodetectors
The brain integrates ________ and _______ levels with other information to monitor appetite glucose and insulin
The hypothalamus coordinates multiple systems that control _______ hunger
Ventromedial hypothalamus (VMH) lesions caused what? obesity—it was identified as a satiety center
Lateral hypothalamus (LH) lesions caused what? a refusal to eat and weight loss – it was identified as a hunger center
The dual-center hypothesis proposed... that the two areas work in opposition
Later research showed that the lesioned animals did in fact experience satiety or hunger and _______, so neither center was in sole control stabilize
Lesion Study: What was the hypothesis? the hypothalamus contains discrete systems for controlling hunger and satiety
Lesion Study: What was the test? place small lesions in target areas within the hypothalamus
Lesion Study: What happened to the lesioned animals? lesioned animals stabilize at new body weight, return to that weight after deprivation and gain weight with rich food
________ from the body drive hypothalamic appetite controller Hormones
The digestive organs and fat tissue release hormonal signals about ______ balance energy
A circuit within the ________ ________ of the hypothalamus is key in integrating peptide hormone signals from the body arcuate nucleus
Fat cells are endocrine cells and release the hormone _____ into the blood stream leptin
the release of leptin into the blood stream provides information about what to the brain? long-term fat reserves
Mice deficient in leptin or with nonfunctional leptin receptors become _______ obese; brain not triggered satiate
Shorter-term energy balance—presence or absence of food in the gut—is reported by hormones from the _________ organs digestive organs
Two hormones important for _________ _________ are released and synthesized by endocrine cells of the stomach: appetite control
G_____ reaches high levels before eating and drops off after eating. This works as an appetite _________ stimulant
______ reaches high levels after eating and works as an appetite ________ PYY3-36, suppressant
How do these hormones affect the appetite control center in the hypothalamus: the ______ nucleus? arcuate
2 types of neurons with opposite effects: NPY neuron and POMC neuron
NPY neurons – act as _____ neurons, stimulating appetite and reducing metabolism when activated hunger
POMC neurons – act as _____neurons when activated, inhibiting appetite and increasing metabolism satiety
p_______ hormones also interact with this appetite center Peripheral
Visceral (gut) and somatosensory (stomach and sight, smell, taste…) information travels via what? the vagus and spinal/facial nerves
______ hormones from the gut are carried to the brain, where they help regulate appetite Peptide
Leptin (and insulin) signal current state of energy store; ________ NPY and ________ POMC inhibiting, stimulating
______ and ____ have opposing effects on NPY: stimulating versus inhibiting appetite Ghrelin and PYY
The peripheral hormone leptin affects arcuate neurons in opposite ways: explain High levels of leptin activate the POMC satiety neurons but inhibit the NPY hunger neurons, working to suppress appetite
Ghrelin and PYY3-36 act on NPY hunger neurons in opposition: • ______ stimulates them and increases appetite • ______ inhibits them and reduces appetite Ghrelin, PYY3-36´
Orexin from the lateral hypothalamus participates in control of ______ behavior feeding
Appetite signals converge on the what in the brainstem?—a common pathway for feeding behavior nucleus of the solitary tract (NST)
__________ is a peptide released by the gut after feeding and acts on the vagus nerve to inhibit appetite Cholecystokinin (CCK)
The ___________ system is a major regulator of appetite and feeding endocannabinoid
Obesity, based on body mass index (BMI), is an epidemic in the United States: __% overweight and 1/3 obese 61
Several emerging strategies for treatment: (6) Appetite control, Increased metabolism, Inhibition of fat tissue, Reduced absorption, Reduced reward, and Anti-obesity surgery
Appetite control—drugs to dampen the what? (PYY nasal spray) hypothalamic appetite controller
increased metabolism—cause the body’s metabolic rate to increase and burn more ______ (thyroid) calories
Inhibition of fat tissue does what? interfere with the formation of new fat tissue
Reduced absorption–an obesity medication Orlistat works by doing what? interfering with the digestion of fat
Reduced reward—use ____ to reduce the brain’s reward circuitry drugs
Anti-obesity surgery: Liposuction the surgical removal of fat tissue
Anti-obesity surgery: ______ procedures bypass part of the stomach or intestinal tract to reduce absorptive capacity Bariatric
_______ _______ is a disorder in which the patients have no appetite (anorexia) and it originates in the nervous system (nervosa) Anorexia nervosa
Treatments include family-based treatment (FBT), also called Maudsley therapy—focuses on “________” of the anorexic person instead of identifying causal factors refeeding
Created by: cmccartney2