Unit 2 - Chapter 9 Reading Flashcards
What is homeostasis?
the maintenance of a relatively constant internal physiological environment
9.1
the psychological process that induces or sustains a particular behavior
motivation
yes, and: effect can escalate as deviation worsens from minor distraction (urge to sip water) to a major distraction (raging thirst of person lost in desert)
9.1
active process of maintaining a relative constant internal temperature through behavioral and physiological adjustments
thermoregulation
9.1
General concepts of homeostasis:
- negative feedback
- redundancy
- behavioral compensation
- concept of allostasis
9.1
an animal whose body temperature is regulated chiefly by internal metabolic processes
examples: mammals, birds
endotherm
make heat inside our bodies using metabolism, muscle activity
9.1
animal whose body temperature is regulated by, and whose heat comes mainly from, the environment
examples: snakes and bees
endotherms
get heat from outside our bodies using metabolism, muscle activity
advantages endotherms have over ectotherms
- we can roam more widely, ectotherms need to stay near sources of warmth
- enhanced capacity for oxygen utilization, so muscles will work for longer periods of time in endotherms
Negative feedback allows ———————-
precise control
Name some primarily negative feedback systems.
homeostatic mechanisms that regulate temperature, body fluids and metabolism
the process whereby a system monitors its own output and reduces its activity when a set point is reached
negative feedback
What is a “set point”?
the point of reference in a feedback system
ex. temperature at which a thermostat is set
9.1
What is a set zone?
optimal range of a variable that a negative feedback system tries to maintain
9.1
What does redundancy ensure?
that critical needs are met
9.1
the —————– senses and controls body tempurature
hypothalamus
9.1
How is the hypothalamus an example of homeostatic reduncancy (i.e., two different systems for regulating the same variable)?
lesion experiments showed different hypothalamic sites control 2 separate thermoregulatory systems:
- lesions in preoptic area (POA) of rats impair physiological responses to cold, like shivering and constriction of blood vessels but did not intervere with behaviors like pressing levers to control heating lamps or cooling lamps
- lesions in lateral hypothalamus of rats abolished behavioral regulation of temp but did not affect physiological responses (e.g., they still shivered)
9.1
Animals use behavioral compensation to adjust to ———————– ———————–.
environmental changes
9.1
In general, both ectotherms and endotherms use 3 kinds of temp-regulating behaviors:
Behaviors that change….
1. exposure to the body surface (huddling or extending limbs)
2. external insulation (using clothes or nests)
3. behaviors that change surroundings (move into sun, shade, burrow)
9.1
Why are behavioral methods of thermoregulation especially important to ectotherms?
Since they cannot generate much heat through metabolism, they need to rely more on behavioral methods to preserve warmth or stay cool (lizards move closer to a heat lamp)
yes, and: lizards can develop “behavioral fevers” caused by moving closer to a heat source during bacterial infection
9.1
How could endothermics’ use of internal processes to regulate temperature have a negative effect?
when fighting an infection, we often generate a fever to boost our immune system response. However, sometimes it heats up too much and causes harm
9.1
Name the components of the basic mammalian thermoregulatory system.
receptors in the skin, body core, and hypothalamus detect and transmit information to three neural regions:
- spinal cord
- brainstem
- hypothalamus
9.1
Where are receptors for mammalian thermoregulatory systems?
body core, skin surface, and hypothalamus/POA
9.1
Which neural regions are involved in the thermoregulatory system?
spinal cord, brain stem, and hypothalamus/POA
9.1
What physiological and behavioral responses can thermoregulation cause?
Behavioral: shivering; heat-seeking or avoiding behaviors
Physiological: constriction/dilation of blood vessels; sweating; respiration; thyroid hormone secretion
9.1
the varying behavioral and physiological adjustments that an individual makes in order to maintain optimal (rather than static) functioning of a regulated system in the face of changing environmental stressors
allostasis
9.1
unavoidable expenditures of bodily resources that must then be regained from the external environment
obligatory losses
ex. we lose water when we pee to get ride of waste molecules
these challenge our homeostatic mechanisms
9.2
Even minor deviation from optimal ——— and ——– balance can be lethal.
water; salt
the ———– of the extracellular fluid, resembling dilute ————-, is consistent across different species of animals.
only a few exceptions across hundreds of millions of years of evolution
saltiness; seawater
water contained within our cells is collectively referred to as the
intracellular compartment
fluid that is outside of our cells
extracellular compartment
the fluid outside of our cells (or extracellular compartment) is divided between the —————– and —————–
interstitial fluid; blood plasma
the fluid between cells
interstitial fluid
protein-rich fluid that carries red and white blood cells
blood plasma
———- is continually moving back and forth between intracellular and extracellular compartments.
water
a membrane that is permeable to some molecules but not others is referred to as ——————————
semipermeable (or selectively permeable)
—————- is the movement of water molecules that occurs so as to equalize the concentration of two solutions separated by a semipermeable membrane
osmosis
physical force that pushes or pulls water across a membrane
osmotic pressure
———- ———– occurs when the extracellular fluid becomes too salty
osmotic thirst
a desire to ingest fluids that is stimulated by high concentration of solute (like salt) in the extracellular compartment
osmotic thirst
What could cause ostmotic thirst?
- obligatory water losses (through repiration, urination, etc.) decrease the volume of extracellular fluid and increase the solute concentration of the EC fluid; bc of EC saltiness, water is pulled out of cells through osmosis
- eating a lot of salty food
a solution with a normal concentration of salt in EC fluid (approx. .9%) is called:
physiological saline (or is described as isotonic)
the extracellular fluid serves as a ————, a reservoir of isotonic fluid that provides and acceptw water molecules so cells can maintain proper internal conditions and prevent damage
buffer
neurons that specifically monitor the concentration of extracellular fluid
osmosensory neurons
Where are numerous osmosensory neurons found?
- several regions of the hypothalamus (including preoptic area, anterior hypothalamus, and supraopitc nucleus)
- organum vasculosum of the lamina terminalis (OVLT) which is one of a set of specialized brain structures monitoring fluid balance of body
any of multiple distinct sites that lie in the wall of a cerebral ventricle and monitor the composition of the cerebrospinal fluid
circumventricular organs
outputs from the circumventricular organs project to multiple cortical regions, including ———- and —————, leading to the conscious perception of thirst
insula; anterior cingulate cortex
a peptide hormone from the posterior pituitary that promotes water conservation and increases blood pressure; acts on the kidneys to slow the production of urine by increasing the reabsorption of water
vasopressin (aka arginine vasopressin or antidiuretic hormone)
the production of urine
diuresis
a mineralcorticoid hormone, secreted by adrenal cortex, that promotes the conservation of sodium by the kidneys
aldosterone
thirst is triggered not by salt balance or osmosis but by a decrease in the overall volume of the extracellular fluid
hypovolemia
literally “low volume”
the loss of body fluids and resulting decrease in extracellular volume can cause an individual to experience:
hypovolemic thirst
a decrease in fluid volume in the body does not necessarily change the ———— of the cellular fluid
concentration
a pressure receptor in the heart or a major artery that detects a change in blood pressure
baroreceptor
a word meaning “less salty than normal”
hypotonic
a cardiac hormone that regulates salt-water balance and blood pressure by promoting renal sodium and water excretion and stimulating vasodilation;
in hypovolemic thirst, the heart decreases its secretion of this hormone, which normally reduces blood pressure, inhibits drinking, and promotes excretion of water and salt at the kidnes
atrial natriuretic peptide (ANP)
a hormone produced in the blood by the action of renin and that may play a role in the control of thirst
angiotensin II (AII)
hypovolemic thirst is triggered by —-
loss of fluid volume
Cranial nerve X, which transmits informaiton between the brain and the viscera; the fagus both regulates visceral activity and transmits signals from the viscera to the brain
vagus nerve
a circumventricular organ that possesses neurons governing drinking behavior; stops drinking in anticipation of correcting the extracellular volume and/or concentration of solutes
subfornical organ
what are the two types of thirst
osmotic and hypovolemic
chemicals required for the effective functioning, growth, and maintenance of the body
nutrients
a simple sugar that is obtained through the breakdown of more complex molecules
glucose
the principle fuel for the cells of the body
for shorter-term storage, glucose can be converted into a more complex molecule called ——— and stored as reserve fuel in several locations (espcially the liver and skeletal muscles)
glycogen
the process of converting glucose to glycogen
glycogenesis
a hormone, synthesized and released by the pancreas, that promotes glycogenesis
insulin
a pancreatic hormone that lowers blood glucose, promotes energy storage, and facilitates glucose utilization by cells
insulin
when blood glucose levels drop too low, a second pancreatic hormone called ———, converts glycogen back into glucose
glucagon
the process of converting glycogen back into glucose
glycogenolysis
a peptide gut hormone believed to act on the hypothalamic appetite system to suppress appetite
glucagon
a large molecule, frequently a fat, that consists of fatty acits and glyeral; insoluble in water
lipid
molecules from dietary sources that are stored in adipose tissue for long-term storage
lipids
tissue made up as fat cells
adipose tissue
aka fat tissue
under conditions of prolonged food deprivation, body fat can be converted into ——– and ———-
glucose; ketones
the process of converting body fat into glucose
gluconeogenesis
an organic molecule, derived from the breakdown of fat, that can be used be cells as an energy source
a secondary form of fuel that can be used by the body and brain
ketones
9.3
the brain uses only ——– but it can do so without the aid of ————-
glucose; insulin
9.3 Figure 9.10 The Role of Insulin in Energy Utilization
they body can make use of either ——— or ———- for energy but it requires ———– in order to use glucose.
glucose; fatty acits; insulin
9.3 Figure 9.10 The Role of Insulin in Energy Utilization
Only about —— to ——-% of the energy in food is used for active behavioral processes
10-20%
9.3
What is the majority of food energy spent on?
basal metabolism
9.3
the use of energy for processes such as heat production, maintenance of membrane potentials, and all the other basic life-sustaining functions of the body
basal metabolism
9.3
Metabolism is under homeostatic control and can be adjusted to a surprising extent, but it is outside ——————————-
our conscious control
9.3
a dramatic decrease in basal metabolism following weight loss
metabolic adaptation
9.3
———– is essential for obtaining, storing, and using food energy
insulin
9.3
the membrane-spanning proteins that most cells use to import glucose from the blood
glucose transporters
9.3
a condition, characterized by excessive glucose in the blood and urine and by reduced glucose utilization by body cells, that is caused by the failure of insulin to induce glucose absorption
diabetes mellitus
9.3
disease results from lack of insulin production
type 1 diabetes (juvenile onset)
9.3
disease results from greatly reduced tissue sensitivity to insulin
type 2 diabetes (adult onset)
9.3
Phases of insulin release
cephalic phase
digestive phase
absorptive phase
9.3
phase of insulin release that is triggered by sights, smells, and tastes we have learned to associate with food
cephalic phase
9.3
phase of insulin release during which food entering the digestive tract prompts an additional release of insulin
digestive phase
9.3
phase of insulin release during which, as digested food is absorbed into the bloodstream, glucodetectors detect the increase in circulating glucose and signal the pancrease to release more insulin
absorptive phase
9.3
a specialized type of liver cell taht detects and informs the nervous system about levels of circulating glucose
glucodetectors
9.3
the liver communicates with the pancreas via the ————–
nervous system
9.3
information from glucodetectors in the liver travels via the vagus nerve to the ——————— in the brainstem and is relayed to the ———————-.
nucleus of the solitary tract (NST);
hypothalamus
system informs brain of circulating glucose levels, involved in hunger
9.3
high insulin levels direct for of the blood glucose into storage, which means there is ——– glucose in circulation
less
9.3
when there is less glucose in circulation, it is called
hypoglycemia
9.3
Brain learns of hypoglycemia directly via ————-, leading to a hunger response
glucodetectors
9.3
somehow, the brain integrates ——— and ———– levels with other sources of information to decide whether to initiate eating
insulin; glucose
9.3
a central theme in research on appetite control is that the brain ————— rather than —————– to trigger hunger
integrates many different signals; relying exclusively on any single trigger
9.3
the ————– is important for regulating metabolic rate, food intake, and body weight
hypothalamus
9.4
How did researchers show that the hypothalamus is crucial for appetite?
Lesion studies
EXPLAIN MORE
9.4
What did researchers learn about the hypothalamus through lesion studies?
the hypothalamic system conrolling feeding must involve multiple components coordinating to establish a set point for metabolic fuels, monitor energy balance in the body, and trigger behavioral responses to meet the established energy goals with a collective effect on body weight
9.4
Following glucose ingestion, changes in activity in the ————- are evident in fMRI images.
hypothalamus
9.4
——— from the body drive the hypothalamus’s role in appetite control.
Hormones
9.4
an arc-shaped hypothalamic nucleus implicated in appetite control
arcuate nucleus
9.4
a circuit within —————————— is the key element in a highly specialized appetite network integrating peptide hormone signals from several sites in the body.
arcuate nucleus of the hypothalamus
9.4
one important source of information about energy stores is the ————
pancreas
9.4
fat cells that make up adipose tissue are ——— and release a hormone called ———— into the bloodstream
endocrine; leptin
9.4
What is leptin?
A peptide hormone released by fat cells
9.4
What do experiments with leptin signalling tell us?
that the brain monitors circulating leptin levels as an indicator of the body’s longer-term energy reserves in the form of fat
9.4
———- or ————- causes a false unerreporting of body fat and leads to overeating
defective leptin production or impaired leptin sensitivity
9.4
a peptide gut hormone believed to act on the hypothalamic appetite system to increase hunger
——- is synthesized and released into bloodstream by endocrine cells of the stomach. It reaches high concentrations during fasting and stimulates appetite, then drops sharply after meal is eaten
ghrelin
stimulates food intage
9.4
an intestinal peptide that spiles to higher levels on ingestion of a meal and provides an appetite-suppressing signal
PYY3-36
9.4
a peptide intestingal hormone believed to act on the hypothalamic appetite system to suppress appetite
glucagon-like peptide 1 (GLP-1)
9.4
——————— shows a rapid increase in secretion during a meal, especially if meal is high in fats and carbs;
the release of ————- is initially governed by rapid autonomic neural mechanism and then by the presence of nutrients in the intestinal tract
glucadon-like peptide 1 (GLP-1)
9.4
GLP-1 activity directly blocks the effects of ————- on metabolism and appetite
ghrelin
9.4
Where are GLP-1 receptors found?
in brain regions implicated in:
- food intake
- mediating reductions in appetite and feeding
- changes in the system that signals the rewarding aspects of food
9.4
within the arcuate nucleus, the system relies on two types of neurons with opposite effects. What are these to neurons?
POMC neurons and NPY neurons
9.4
———– act as satiety neurons when activated, inhibiting appetite and increasing metabolism
POMC Neurons
9.4
————- act as hunger neurons when activated, stimulating appetite directly and inhibiting the POMC neurons (thereby blocking satiety signals) and reducing metabolism
NPY Neurons
9.4
What are the neural and hormonal inputs to the hypothalamus?
Neural inputs: visceral and somatosensory info travels via the vagus nerve and spinal nerves
Hormonal inputs: peptide hormones from the gut – or in the case of leptin, from body fat cells – are carried to the brain, where they help regulate appetite
9.4
———- provides information about current energy stores, decreasing feeding behaviors by inhibitting ———- and stimulating ————-.
Leptin; NYP neurons; POMC neurons
9.4
———-, ———–, and ————- are thought to exert ongoing minute-to-minute control on appetite, and they have opposing effects on NPY neurons: ———— stimulates eating and ———– appears to inhibit appetite
Ghrelin, PYY3-36, and GLP-1
Ghrelin; PYY-3-36
9.4
neurons of the hypothalamic appetite system that promote feeding behavior
located principally in the lateral hypothalamus, coordinate increased appetite and food intake signals
orexigenic neurons
9.4
neurons of the hypothalamic appetite system that inhibit feeding behavior
in the paraventricular nucleus (PVN), coordinate signals that decrease appetite and feeding
anorexigenic
9.4
a complicated brainstem nucleus that receives visceral and taste information via several cranial nerves
where appetite signals from the hypothalamus converge
can be viewed as part of a common pathway for feeding behavior, receving appetite signals from a variety of sources in addition to the hypothalamus
nucleus of the solitary tract (NST)
9.4
sensation of hunger is affected by variety of peripheral sensory inputs, like oral stimulation and feeling of stomach distention, transmitted via ——– and ———- nerves.
cranial; spinal
9.4
info about ————- levels is conveyed directly from the body to the NST via the vagus nerve
nutrient
9.4
a peptide hormone that is released by the gut after ingestion of food that is high in protein and/or fat
among other gut peptides, it acts directon on receptors of the vagus nerve to alter appetite
cholecystokinin (CKK)
9.4
neurons of the hypothalamic appetite system that promote feeding behavior
orexin
9.4
brain’s ———- system is initmately involved with feeding
reward
9.4
activity of a circuit including the ———— and —————mediated reawrd system of the —————————- is hypothesized to mediate pleasurable aspects of feeding
amygdala; dopamine; nucleus accumbens
9.4
an endogenous ligand of cannabinoid receptors, thus an analog of cannabis that is produced by the brain
endocannabinoid
9.4
endocannabinoids might stimulate feeding by affecting the ——————— reward system
mesolimbic dopamine
9.4
————- drugs may be useful for stimulating appetite and weight gain in people who are having troule maintaining weight because of cancer or other diseases
cannabinoid
9.4
microorganisms that normally inhabit the digestive system
gut microbiota
9.4
collective term for a population of microorganisms that inhabit the body
microbiome
9.4
Each one of us possesses a distinct microbial enterotype. What is an enterotype?
personal combination of different species of microbiota;
researchers increasingly believe to be in extensive two-way communication with our brain via the vagus nerve and chemical signals
9.4
a medical procedure in which gut microbiota, via fecal matter, are transplanted from a donor to a host
fecal transplantation
9.4
What might fecal transplantation help with?
obesity, severe infection, neurological conditions, etc.
9.4
the passage from one individual to another of changes in the expression of targeted genes, without altering the sequence of nucleotides in the gene
epigenetic transmission
9.5
Researchers now believe that ————————————————– is a leading cause of obesity.
replacement of fat calories with carbohydrates, especially sugar
This is thought to be a result from medical recommendations to avoid dietary fats after 1980.
9.5
In the span of 35 years, the prevalence of obesity in the USA has ————.
tripled
9.5
List some scientific targets for addressing obesity.
7
- appetite control
- increased metabolism
- inhibition of fat tissue
- reduced absorption
- reduced reward
- anti-obesity surgery
- lifestyle changes
9.5
Name the medical procedure
by reducing the stomach to a narrow tube, its ability to absorb nutrients is reduced, and secretion of the appetite hormone ghrelin is reduced
sleeve gastronomy
9.5
Name the medical procedure
a reduced stomach is reconnected so as to bypass the initial stretch of the small intestine
gastrointestingal bypass (specifically Roux-en-Y bypass)
9.5
Name the medical procedure
a less invasive option is a surgically implanted intestinal liner that can act as a barrier to prevent absorption of nutrients
gut liner
9.5
a syndrome in which individuals severely deprive themselves of food
anorexia nervosa
anorexia = have no appetite
nervosa = originates in the nervous system
9.5
What is one approach to treating anorexia nervosa that has been successful in some cases?
family-based treatment that de-emphasizes the identification of causal factors and instead focuses on intensive, parent-led “refeeding” of the anorexic person
9.5
a syndrome in which individuals periodically gorge themselves, usually with junk food, and then either vomit or take laxatives to avoid weight gain
bulimia (or bulimia nervosa)
9.5
the rapid intake of large quantities of food, often poor in nutritional value and high in calories
binge eating
9.5
