Psych 280 FInal Flashcards
Motivation
A drive state that initiates homeostatic behaviour
Homeostasis
Active process of maintaining a more or less stable, balanced environment in the body
Obligatory losses
Unavoidable loss of a regulated variable (energy/water/temp) as a consequence of processes necessary for life
Are humans endotherms or ectotherms?
Endotherms, bc we make our own heat inside our bodies like all mammals
Ectotherms get their heat from outside their body (lizards and snakes) and need to be close to hear sources
What do ectotherms rely on for oxygen?
Bursts of intense anaerobic muscular activity (activity initiated by chemical reactions that postpone the requirement for oxygen) so after a bit they need rest and regain the oxygen that was lost
What evolutionary trait has helped endotherms with generating heat?
A greater capacity for oxygen utilization to generate heat through metabolism (no oxygen debt)
The homeostatic mechanisms that regulate temperature/body fluids/metabolism are what type of systems?
Negative feedback systems=deviation from desired value (set point) triggers a compensatory action of the system
Negative bc restoring desired value stops the response
Set zone for body temp of mammals
36-38 C
When does a mammals body temp go up or down?
Down during sleep
Up to produce a fever to fight infection
Dangers of a high fever?
Proteins lose their correct shape, link together and malfunction (denaturing)
Eventually it can cause brain centres that regulate heart rate and breathing to die killing the person
Dangers of body temp too low?
Chemical reactions in body occur too slowly and ice crystals can disrupt cell membranes, killing the cell
“Antifreeze” of some fishes and beetles consists of what?
Special protein molecules that suppress the formation of ice crystals/prevent damage to membranes
Hypothalamus’ role (hint: lesions)
Sense and controls body temp
Lesion experiments eventually showed that diff hypothalamic sites controlled two diff thermoregulatory systems
Lesions in POA (preoptic area) = no physiological responses to cold (shivering/constriction) but didn’t interfere with behaviours like pressing levers to control heating lamps
Lesions in lateral hypothalamus = no behavioural regulation of temp but didn’t interfere with physiological responses
EXAMPLE OF REDUNDANCY
Describe 3 levels of hierarchy of thermoregulatory circuits
Spinal level
Brainstem
Hypothalamus
Endotherms and ectotherms both behaviourally regulate body temp in 3 ways
1-Changing exposure of body surface (huddling/extending limbs)
2-changing external insulation
3-changing surroundings
What are the three basic elements of mammalian thermoregulatory systems?
Afferents (skin surface/body core/hypothalamus or POA) Neural regions (spinal cord/brainstem/hypothalamus or POA) Effectors (behavioural responses and automatic responses)
Which homeostatic system is the most complex?
Food intake/energy balance bc food supplies not only energy but nutrients
What are nutrients? Which can we only get thru diet?
Chemicals required for the effective functioning/growth/maintenance of the body
We don’t know all nutritional requirements for humans
We have 20 amino acids but 9 only found in diet (essential amino acids)
Also need some fatty acids and 15 vitamins and lots of minerals
How is energy made in the body?
Released when chemical bonds if complex molecules are broken and smaller, simpler compounds form as a result
Basal metabolism
Consumption of energy to fuel processes such as heat production, maintenance of membrane potentials and other basic life-sustaining functions of the body
Consumes 55% of food energy in a meal
Metabolic studies show that animals lose what percent of energy from a meal in what
33% of energy in food: digestion
55%: basal metabolism
12%: active behavioural processes
Basal metabolism rule (relates energy expenditure to body weight)
Kcal/day=70 x weight0.75
Food deprivation affects what even more than body weight?
Metabolic rate
What part of the cell is responsible for basal metabolic rate?
Mitochondria
Benefit of calorie reduction in diet of animals
Slowing aging of body and brain bc pair of genes for transcription factors (substances that control other genes) that are involved in food deprivation and control production of hormones and trophic factors (substances that promote cell growth/survival) important for longevity
What happens to the body during caloric restriction?
Ubiquitous protein called SIRT1 (marker for increased longevity in diff animals) is increased
20 years of this has shown slower aging and prevented disease and early death in rhesus monkeys
What is the most immediate source of energy in the body?
Complex carbohydrates that are rapidly broken down into simple sugars that cell can use
Principle sugar used by body for energy
Glucose
Describe short-term storage of glucose
Glucose converted into more complicated molecule called glycogen and stored as reserve fuel (liver and skeletal muscles) = GLYCOGENESIS promoted by pancreatic hormone INSULIN
Second pancreatic hormone GLUCAGON turns glycogen back into glucose = GLYCOGENOLYSIS (triggered when concentrations of glucose drop too low)
Describe long-term storage of glucose
Fats (lipids=large molecules consisting of fatty acids and glycerol that are insoluble in water) deposited in fat-storing cells that form adipose tissue
Some come from food and others synthesized in body from surplus sugars/other nutrients
During prolonged food deprivation, fat converted to glucose (=GLUCONEOGENESIS) and secondary form of fuel called ketones as well which is used by body/brain
Best way to lose weight
Diet low in carbs and high in proteins/fats which ups good cholesterols while decreasing fats
Questionable as high fat diets are shown as bad
Diet + exercise
2 things insulin is important for
1- converting glucose into glycogen
2- enabling the body to use glucose
What are glucose transporters and what do they do?
Specialized proteins that span the cell membrane and transport glucose molecules into the cell for use
Interact with insulin in order to function
What are the three diff mechanisms that stimulate insulin release?
1- sensory stimuli from food evokes a conditioned release of insulin in anticipation of glucose arrival in the blood (=cephalic phase of insulin release)
Cephalic means coming from the head
2- DIGESTIVE PHASE: Food entering stomach/intestines makes them release gut hormones, and some of those stimulate the pancreas to release insulin. Also digestive tract’s taste-receptive cells stimulate insulin release too
3- ABSORPTIVE PHASE: glucodetectors (special cells found in liver) detect glucose entering bloodstream and signal pancreas to release insulin
Once insulin is released, two things can happen
Body makes use of some of the glories immediately
Extra glucose is converted into glycogen which is stored in liver/muscles
Describe system that informs the brain of circulating glucose levels and contributes to hunger
1- liver communicated with pancreas via nervous system
2- info from glucodetectors in liver travels via vagus nerve to the nucleus of the solitary tract (NST) in the brainstem
3- then info relayed to hypothalamus
What causes diabetes mellitus? Describe
Cause: lack of insulin
It’s excessive glucose in the urine caused by failure of insulin to signal to body to absorb the glucose
Type 1 diabetes
Juvenile-onset diabetes
Pancreas stops producing insulin
Brain can still make use of glucose from food, the rest of the body can’t
Forced to use energy from fatty acids which means lots of leftover glucose in bloodstream (some of which is secreted in urine)
What’s happens if person with type 1 diabetes untreated?
Eats a lot
Loses weight bc body can’t make efficient use of digested food
Reliance on fatty acids causes damage to tissues
Drink and urinate a lot to get rid of extra glucose
Missing insulin replaced by injections
What’s the cause of type 2 diabetes? Describe
Adult-onset diabetes
Reduced sensitivity to insulin
Usually associated with obesity
Leads to further health problems
What are the signals for satiety or hunger?
High or low levels of insulin secreted by amount of food in pipeline
Glucose levels
Both integrated with other sources of info to decide whether to initiate hunger
Hypoglycemia
High insulin levels directing much of the glucose out of circulation and into storage
What three things is the hypothalamus vital for
Regulation of metabolic rate
Food intake
Body weight
Describe lesions in rats that created extreme satiety or hunger
Bilateral regions of ventromedial hypothalamus (VMH) = WEIGHT GAIN/HYPERPHAGIA
Legions of the lateral hypothalamus (LH) = WEIGHT LOSS/APHAGIA
Describe inconsistencies in dual-centre hypothesis for appetite
VMH lesioned animals = period of rapid weight gain but then stabilized at new, higher body weight and would only eat amount of food necessary to maintain that weight
LH lesioned animals = first kept alive via feeding tube soon resumed spontaneous eating to maintain new, lower body weight
Arcuate nucleus
Arc-shaped hypothalamic nucleus implicated in appetite control
What happens when mice receive two copies of the gene called obese (ob)?
They regulate their body weight at a high level
They have larger and more fat cells compared to ob/+ (normal) mice
They maintain their obesity even when given a gross diet or when required to work hard for their food
They have defective genes for the peptide leptin
Leptin
Peptide hormone released by fat cells then protein secreted into bloodstream; ob gene product
Where are leptin receptors found?
ObR found in choroid plexus, the cortex, and several hypothalamic nuclei
What happens when animals have defects in the gene that encodes ObR?
Become obese
Describe ghrelin (where it comes from, and what it’s named for)
Endrocrine cells of the stomach release ghrelin into the bloodstream
Named after it’s effects in growth hormone secretion (GH-releasing)
Appetite STIMULANT
How are ghrelin levels affected by fasting and eating a meal?
RISE during fasting
DROP after eating a meal
Oddity of an obese person’s ghrelin levels?
Obese subjects have lower baseline levels of ghrelin before eating but after a meal they never go down (as well as their leptin levels)
Ghrelin mechanism unresponsive to feeding and always slightly elevated = constant hunger
Describe PYY3-36
Peptide hormone
Comes from intestines
Acts on hypothalamic appetite control mechanisms to lessen appetite
Describe levels of PYY3-36 before and after eating
Low levels in the blood before eating
Levels rise quickly after eating
What do injections of PYY3-36 do to appetite?
Systematic injections lessen appetite (also injections directly into Arcuate nucleus of hypothalamus in rats)
What levels of PYY3-36 are associated with obesity?
Lower than normal levels
Post meal increases in this peptide linked to feeling full in normal weight people
How does PYY3-36 interact with ghrelin?
Acts in opposition to ghrelin = acts as an appetite stopper for hypothalamus, working together on the arcuate appetite
Describe the Arcuate appetite system
Has TWO SETS of ARCUATE NEURONS with OPPOSITE EFFECTS (named accordingly to types of hormones/nuerotransmitters they produce)
Set 1- produce peptide NEUROPEPTIDE Y (NPY) and AGOUTI-RELATED PEPTIDE (AgRP) thus known as NPY/AgRP neurons which STIMULATE APPETITE while REDUCING METABOLISM = WEIGHT GAIN
Set 2- POMC/CART neurons bc they produce pro-opiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript (CART) which INHIBIT APPETITE and INCREASE METABOLISM = WEIGHT LOSS
Two main functions of projections from the POMC/CART neurons and NPY/AgRP neurons
Some projections stay within Arcuate = 2 sets of neurons INFLUENCE each other’s ACTIVITY thru RECIPROCAL CONNECTIONS
Some projections leave the Arcuate = MAKE CONTACT with other NEURONS in other HYPOTHALAMIC SITES
This is how FOOD INTAKE is MODULATED by the Arcuate system
What’s the diff between what ghrelin/PYY3-36 do to appetite and what leptin/insulin do?
Ghrelin and PYY3-36 provide faster, hour to hour hunger signals from the gut
Act primarily on the appetite-stimulating NPY/AgRP neurons of the Arcuate
More specifically:
Ghrelin STIMULATES the cells = INCREASE in appetite
PYY3-36 INHIBITS cells = REDUCES appetite
Describe the two hypothalamic sites that are the primary targets of the projections of the Arcuate
1- OREXIGENIC neurons of the LATERAL HYPOTHALAMUS act to INCREASE appetite/food intake
2- ANOREXIGENIC neurons of the PARAVENTRICULAR NUCLEUS (PVN) act to DECREASE appetite/food intake
What is released when appetite-suppressing POMC/CART neurons of the Arcuate go to the LH?
- They release a-melanocyte-stimulating hormone (a-MSH) which is a PEPTIDE HORMONE belonging to a small family of substances called MELANOCORTINS (derived from POMC)
- Acts on specific MELANOCORTIN TYPE 4 RECEPTORS (MC4Rs) located on LH neurons
- decreases the LH’s appetite stimulating activity = net decrease in feeding
Describe how NPY/AgRP neurons are essential for increases in feeding (thru PVN and LH)
- Via INHIBITORY ACTION on ANOREXIGENIC PVN NEURONS, NPY released by the NPY/AgRP neurons = INCREASED appetite
- AgRP competes with a-MSH for MC4R binding and when the a-MSH signal is blocked, AgRP COUNTERS the appetite-suppressing effects of a-MSH and instead produces an INCREASE in feeding behaviour via LH
What is Orexin and what does it do
- Peptide produced by hormones in LH
- participates in control of feeding
- direct injection into hypothalamus of rats causes 6x feeding
- regulated by circulating leptin
- involved in sleep disorder narcolepsy
Describe the nucleus of the solitary tract (NST) and what it does with feeding
- Appetite signals from the hypothalamus converge here
- part of the common pathway for feeding behaviour
- reviews/integrates appetite signals from diff sources (including hypothalamus)
- info about nutrient levels is conveyed thru body to NST via vagus nerve (thanks to peptide cholecystokinin (CCK) which inhibits appetite by acting on vagus nerve after eating)
Describe endocannabinoid system
- regulator for appetite/feeding
- can stimulate hunger
- act in brain and periphery
- could affect mesolimbic dopamine reward system
- act directly on hypothalamic appetite mechanisms while inhibiting satiety signals from gut
What is epigenetic transmission
Passage of epigenetic modifications of a gene from one generation to the next
Is alteration of leptin signals an effective strategy for appetite control?
No, bc only a tiny amount of obese people have abnormal leptin levels or MORE than thin people
How could cannabinoid antagonist drugs effectively suppress appetite? Name an example of a drug
-By causing “anti-munchies” (reverse of hunger experienced by marijuana users
-example: RIMONABANT interferes with signalling via CB1 cannabinoid receptors, effectively lessens appetite/feeding behaviour = weight loss
BUT causes mood problems
Describe two types of drugs that can be designed to target some of the signalling systems that have to do with the Arcuate appetite controller
- a-MSH activity effectively reduces hunger so drugs that activate the MC4R MELANOCORTIN receptor could be effective appetite suppressants
- treatment with PYY3-36 (via nasal spray) or something that mimics it can act directly on Arcuate neurons to reduce appetite
Describe metabolic rate and how it affects obesity
- Metabolic rate increases = extra calories expended in the form of heat
- controlled by thyroid hormones (thyroxine specifically) but treating people with thyroxine has cardiovascular side effects
Two ways that metabolic rate can be increased by drugs
- drugs that increase energy utilization by selectively activating TRB thyroid hormone receptors (which avoids side effects cause by TRa receptors)
- drugs that increase activity of mitochondrion-rich brown fat which burns energy faster to generate heat (possible to make regular “white” fat tissue to behave like brown fat and start burning stored energy at a high rate)
Describe how inhibition of fat tissue could happen in weight loss
-You can interfere with the formation of new fat tissue (needs to add new blood vessels which is a process called angiogenesis, so blocking this process could lessen fat formation)
Describe reduced absorption treatment
One of the only approved weight loss meds out there, ortlistat (Xenical) works by interfering with the digestion of fat
Bad side effect: intestinal discomfort
Describe 3 types of anti-obesity surgery
- liposuction: popular, but only kinda successful and usually temporary results
- bariatric procedures: bypass part f intestinal tract or stomach in order to reduce volume/absorption capacity of digestive system, changes appetite control hormones indirectly, no bad side effects except for surgery risks
- less invasive surgical procedures: user study, includes use of gastric stimulators that activate feelings of fullness to reduce appetite, inserting weights into stomachs of mice works as well
Anorexia nerviosa
Anorexia- no appetite
Nerviosa- nervous system related
-their insulin levels go up higher in the presence of food than regular, which shows that they could have exaggerated hunger but not consciously be able to perceive it
-mismatch between physiological and cognition
-abnormal levels of agouti-related peptide (AgRP) = abnormal hypothalamic appetite system
-hereditary
-abnormalities in serotonergic neurotransmission and weird functioning of dopamine reward system = predisposition
Bulimia (bulimia nerviosa)
gorge themselves then vomit/take laxatives to avoid weight gain
Might not look emancipated
Binge eating
- Strong pleasure associated with food activates opiate and dopaminergic reward mechanisms = like drug addiction
- associated with mutation of gene encoding in the MC4R receptor (failing to receive a-MSH message to feel full)
Electroencephalography (EEG)
Recording and study of gross electrical activity in the brain recorded by large electrodes placed on the scalp
Electro-oculography (EOG)
Electrical recording of eye movements
Electromyography (EMG)
Electrical recording of muscle activity
What are the three measurements (“graphy”s) used in studying sleep
EEG
EOG
EMG
Describe the two classes of sleep
Slow-wave sleep (SWS): sleep which is defined in stage 1 to 3 and defined by presence of slow wave EEG activity
+
Rapid eye movement (REM) sleep: also called paradoxical sleep; characterized by small amplitude, fast EEG waves, no postural tension
What is desynchronized EEG?
AKA beta activity; pattern of EEG activity that is a mix of many diff high frequencies with low amplitude
What’s your EEG rhythm when you close your eyes and relax?
Regular oscillation at frequency of 8-12 hertz = ALPHA RHYTHM
What happens when you go from relaxed mode into sleep?
Time spent in alpha rhythm decreases, EEG shows events of much smaller amplitude and irregular frequency, as well as sharp waves called VERTEX SPIKES (leads into stage 1 sleep)
Stage 1 sleep
- heart rate slows
- muscular tension lessens
- eyes may roll about slowly
- lasts only several mins
Stage 2 sleep
- SLEEP SPINDLES (waves of 12-14 hertz occurring in periodic bursts)
- K COMPLEXES (sharp negative EEG potential)
Stage 3 sleep
- large amplitude, slow waves (DELTA WAVES)
- divided into early and late (late when delta waves are present more than half the time)
After about an hour (progression thru all stages with a brief return to stage 2) what happens?
You see pattern of small amplitude, high frequency activity similar to pattern of someone who’s awake but skeletal muscles are totally relaxed/limp
REM SLEEP
Breathing/pulse rates irregular
Vivid dreams
Why are muscles flaccid during REM sleep?
Brainstem regions stop motoneurons
Describe average sleep time for adults and what it’s made up of
- 7 to 8 hours
- half in stage 2
- REM 20%
- repeat cycles of 90 to 110 minutes about four or five times each night
What’s the diff between REM stage dreams and other stage dreams?
REM stage: visual imagery, story with odd perceptions
Other stages: just thinking
Diff between night terror and nightmare?
Nightmare: long scary dream that makes you wake up from REM sleep
Night terror: sudden arousal from stage 3 SWS w/ intense fear and autonomic activation, can’t remember it, only remember crushing feeling on chest
Symptoms of sleep deprivation
- hallucinations (like schizophrenia)
- irritability
- difficulty concentrating
- episodes of disorientation
Fatal familial insomnia
- Inherited disorder in which humans sleep normally at the beginning of life but later stop sleeping
- damage is not to single organ system but diffuse bacterial infections
- degeneration of thalamus
Describe sleep recovery
First night: biggest diff found in stage 3 sleep (increased, which leads to decrease of stage 2)
NEVER COMPLETELY MAKES UP FOR SLEEP LOSS
Second night: REM sleep shows greatest recovery, more intense with greater number of rapid eye movements
What are the four main functions of sleep
Conservation
Niche adaptation
Body restoration
Memory consolidation
How does sleep conserve energy?
Reduces activity thus metabolic rate
How does sleep enforce niche adaptation?
Makes creatures nocturnal or diurnal to help them survive according to ecological niche
How does sleep restore the body?
Wards off illness/diseases by restoration/building of materials used during time awake such as proteins; growth hormone released
Describe sleep aiding memory consolidation
SWS aids in consolidation of memory, specifically declarative memory (that can be stated or described)
REM sleep may help consolidation of non declarative memory
Patterns of neuronal activity seen while task is being learned awake, recreated during SWS where brain “rehearses” the material
Sleep is an active state mediated by which four interacting neural systems?
1- FOREBRAIN system (displays SWS by itself)
2- BRAINSTEM system (activates the forebrain into wakefulness)
3- PONTINE system (triggers REM sleep)
4- HYPOTHALAMIC system (affects the other 3 brain regions to determine whether brain will be awake or asleep)
How do general anaesthetics work?
Barbiturates and anesthetic gases that make people unconscious
Produce slow waves in EEG that resemble SWS
Some are glutamate antagonists which block neuronal excitation in brain
All are noncompetitive agonists at GABA A receptors and boost their inhibitory effect on neurons
= brain system normally uses GABA to inhibit neural activity and promote SWS
Isolated brain
Experimental preparation where animals brainstem is separated from the spinal cord from a cut below the medulla; has helped show that the forebrain promotes slow wave sleep (SWS) and also that wakefulness/SWS/rem sleep are all controlled within the brain
Isolated forebrain
Cut in the midbrain (higher on the brainstem than isolated brain)
Does not show REM sleep so proves that forebrain can generate SWS with no contributions by lower brain regions
Where is the constant SWS seen in the cortex of the isolated forebrain generated?
By the basal forebrain in the ventral frontal lobe and anterior hypothalamus
At sleep onset, what do neurons of the basal forebrain do?
Become active and release GABA To stimulate GABA A receptors in the nearby tuberomammillary nucleus in the posterior hypothalamus and if left alone, this system could keep the cortex asleep forever but brainstem system eventually wakes the forebrain up
What part of the brain awakes the forebrain and how?
Reticular formation=diffuse group of cells whose axons and dendrites go in mang directions (extending from medulla to thalamus)
Electrical stimulation awakes animals rapidly
What is the pons role in sleep?
- triggers REM sleep
- region ventral to the locus coeruleus stop REM sleep and with electrical/pharmacological stimulation of this region with cholinergic agonists can induce or prolong REM sleep
- some neurons here only active during REM sleep
What are the jobs of the pontine REM sleep center?
-stop motoneurons to keep them from firing (GABA and glycine, both inhibitory transmitters, make powerful inhibitory post synaptic potentials in spinal motoneurons that stop them from reaching threshold/producing an action potential = dreamer has flaccid muscles
What part of the pons disables the motor system during sleep?
Small lesions ventral to locus coeruleus
Narcolepsy
Disorder that involves frequent, intense episodes of sleep, which can last from 5-30 minutes every 90 minutes and occur at anytime during usual waking hours, have normal nighttime sleep, enter REM within first few minutes of sleep
Cataplexy
Sudden loss of muscle tone, leading to collapse of the body without losing consciousness
Triggered by intense emotional stimuli like anger or laughter
What’s the mutant gene responsible for cataplexy and what parts of the brain are affected?
Receptors for NEUROPEPTIDE hypocretin lost 90% which causes inappropriate activation of cataplexy pathway that should only happen during REM sleep
Neural degeneration of amygdala and close by forebrain structures
Neurons that produce hypocretin are found where? And where do they send their axons to release the hypocretin?
Found in the hypothalamus
Send their axons to 3 parts of the brain involved in sleep: basal forebrain, reticular formation and locus coeruleus
Also project axons to hypothalamic tuberomammillary nucleus (inhibited by basal forebrain to induce SWS)
Treatments for narcolepsy (3)
GHB (xyrem; concerns about abuse)
Modafilin (provigil; good for narcoleptic attacks and people with ADHD for attention)
Modafinil (debated but studies show it’s no more effective than caffeine)
Sleep paralysis
- common symptom of narcolepsy
- inability to move or talk just before falling asleep or just after waking up
- only lasts a short time
- hypothesis: results when pontine center continues to impose paralysis for a short time after waking from REM period
What are 2 children sleep disorders?
Night terrors
Sleep enuresis (bed wetting)
-associated with SWS, treatment is reducing amount of stage 3 sleep/rem time and increasing stage 2 sleep or nasal spray of hormone vasopressin which decreases urine production
What is the scientific name for sleepwalking and what stage of sleep?
Somnambulism
Occurs during stage 3 SWS and more common during first half of night
REM behavioural disorder (RBD)
- Characterized by acting out organized behaviour while asleep
- begins after age 50 and more common in men
- lesion near locus coeruleus so not paralyzed during REM
- early symptom of dementia and Parkinson’s disease
- can be controlled by anti anxiety drugs (benzodiazepines)
What’s it called when you’re sleeping and you don’t think you ever slept?
Sleep state misconception
Scientific name for having a hard time falling asleep
Sleep-onset insomnia
Scientific name for difficulty staying asleep due to drugs/neurological/psychiatric factors?
Sleep-maintenance
What are the two types of sleep apnea?
Obstructive apnea: progressive relaxation of muscles of chest, diaphragm, throat cavity
Central apnea: changes in the pacemaker respiratory neurons of brainstem
How does apnea lead to brain damage?
Interruptions in oxygen kill neurons in the hippocampus and impair learning ability
What’s the machine used to treat sleep apnea?
Continuous positive airway pressure (CPAP) machine that maintains air pressure in airways and prevents collapse of those airways
Cause of sudden infant death syndrome (SIDS)
Sleep apnea as a result of immaturity of systems that pace respiration
Abnormalities in brainstem serotonin systems
Drugs used to treat sleep disorders
Scopolamine and atropine in the past
Barbiturates developed by bayer
Benzodiazepine triazolam (halcion, ambien, sonata, lunesta) bind to GABA receptors which inhibit broad regions of brain
How do current sleeping pills fall short of being a suitable remedy?
- continued use causes non effectiveness
- persistent drowsiness
What is an organ specialized to receive certain stimuli called?
Sensory receptor organ
What do the receptor cells in sensory receptor organs do?
Detect certain kinds of stimuli and concert them into the language of the nervous system aka electrical signals
How does info from sensory receptors travel?
Sensory receptor organs to brain via action potentials that travel along axons
Scientific name for the type of stimulus to which a given sensory organ is particularly adapted to
Adequate stimulus
What frequency can’t humans hear?
Frequencies above 20,000 cycles per second aka ultrasonic sound
Describe specific nerve energies
Doctrine that receptors and neural channels for the different senses are independent and operate in their own special ways, producing one particular sensation each
Ex: no matter how eye is stimulated (light, electrical shock, etc) result is always visual
Describe the concept of labeled lines (senses)
Particular neurons are labeled for distinctive sensory experiences; actions potentials travel along separate nerve tracts depending on what sense they correspond with
Describe sensory transduction
- detection of energy in receptor cells
- receptor cell converts that energy into change in electrical potential across it’s membrane
What are the six main receptors in the skin and what do they do?
Free nerve endings: pain/temp Merkel's disk: touch Meissner's corpuscule: touch Hair follicle receptor: touch Pacinian (or lamellated) corpuscule; vibration/pressure Ruffini's ending: stretch
Receptor potential
Aka generator potential; local change in resting potential of a receptor cell that mediates between the impact of stimuli and the initiation of nerve impulses
Describe Pacinian corpuscule
- Detects vibration
- found in skin/muscle
- axon surrounded by structure that looks like a tiny onion because it has layers of tissue