Term | Definition |
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 |