final exam new material Flashcards
what is a stressor
stimuli/circumstance that triggers a stress response
what is a stress response
physiological/psychological response to stress
what is stress
situation in which there is both a stressor and a stress response
what are the two main physiological stress response systems
sympathetic nervous system
hypothalamic pituitary-adrenal axis
who is the historical proponent of the SNS
walter cannon
who is the historical proponent of the HPA axis
hans selye
what is the function of the SNS
supports fight or flight response
what is the function of the HPA axis
general adaptation syndrome
what is the effector hormone of the SNS
adrenaline (epi and NE)
what is the effector hormone of the HPA axis
cortisol
what is the speed of onset and duration of action of the SNS
rapid
short lasting
what is the speed of onset and duration of action of the HPA axis
slow
long lasting
the speed of onset and duration of hormone effects are largely determined by
hormone receptor signal transduction mechanisms
what is the purpose of the emotional aspect of stress
motivates coping behavior to avoid and/or escape the stressor
why is the general stress response not stressor specific
because it is adaptive for dealing with a wide range of physical stressors
why are psychological stressors as effective as physical stressors at triggering a stress response
because psychological stressors are potentially cues associated with impending physical stress
what does psychological stress serve as a warning sign of
motivate coping behavior to avoid the physical stressor
prepare the body to combat/avoid a physical stressor
what are the three main conditions that are effective psychological stressors
lack of controllability
lack of predictability of stressor onset/offset
social relationships
what is the psychological stress “detector” or stress “generator”
the brain
what is the greatest ill effect of stress on our health
not efficiently turning off a stress response after it has been triggered
what is the ANS
autonomic nervous system
motor neural system that innervates periphery organs and is not under voluntary control
what are the two branches of the ANS
SNS- fight or flight
PSNS- return to calm state
where does the synapse between the preganglionic and postganglionic neurons take place
in ganglia
what is a ganglia
large cluster of neuronal synapses
where are the sympathetic chain ganglia located
close to the spinal cord
where are the cell bodies of the SNS preganglionic neurons located
thoracic and lumbar portion of the spinal cord
are the axons of SNS preganglionic neurons short or long
short
where are the axon terminals of SNS preganglionic neurons located
sympathetic chain ganglia
where are the cell bodies of the SNS postganglionic neurons located
sympathetic chain ganglia
are the axons of SNS postganglionic neurons short or long
long
where are the axon terminals of SNS postganglionic neurons located
target organs
where are the cell bodies of PSNS preganglionic neurons located
brain stem and sacral portion of spinal cord
what kind of sensory info does the vagus nerve send to the brain
visceral sensory info
what are the two main types of cholinergic receptors
nicotinic
muscarinic
are the axons of PSNS preganglionic neurons short or long
long
where is the axon terminal of a PSNS preganglionic neuron located
ganglion close to target organ
where is the cell body of a PSNS postganglionic neuron located
near target organ
is the PSNS postganglionic axon short or long
short
where is the location of the axon terminal in a PSNS postganglionic neuron
target organs
what NT is released from the SNS preganglionic neuron
ACh
what NT is released from the SNS postganglionic neuron
NE
what NT is released from the PSNS preganglionic neuron
ACh
what NT is released from the PSNS postganglionic neuron
ACh
what is the target receptor type of the SNS preganglionic neuron
nicotinic cholinergic receptor
what is the target receptor type of the SNS postganglionic neuron
adrenergic receptors
(alpha 1, alpha 2, beta 1, beta 2, beta 3)
what is the target receptor type of the PSNS preganglionic neuron
nicotinic cholinergic receptor
what is the target receptor type of the PSNS postganglionic neuron
muscarinic cholinergic receptor
where does the specificity in the response occur
at the receptor on the target organ
what is one target organ that provides the same response in both the SNS and PSNS
salivary (both secrete saliva)
what is found in the plant called belladonna
atropine
what role does PSNS activation play in male orgasm
erection
what role does SNS activation play in male orgasm
ejeculation
what kind of sexual dysfunction can stress lead to
too much SNS activation can inhibit erection or lead to premature ejaculation
what is the hormonal (endocrine structure) component of the SNS
adrenal medulla
where is the adrenal gland located
on top of the kidney
what neuron directly innervated the adrenal medulla
SNS preganglionic neuron
what kind of endocrine cells contain epi and NE
chromaffin cells
is epi and NE located in the adrenal medulla or adrenal cortex
adrenal medulla
is more epi or NE produced and released
3-10 times more epi
what controls the secretion of epi and NE
SNS preganglionic neurons
what kind of NT is epi/NE
monoamine
are monoamines stored in vesicles
yes
where are the cell bodies of the SNS neurons that innervate the adrenal medulla located
thoracic spinal cord
what kind of receptors are on the surface of chromaffin cells
nicotinic cholinergic receptors
is there a RH controlling epi/NE secretion
no
it is not an effector hormone of a third order neuroendocrine arrangement
how do epi and NE have different effects in the body
they interact with different combinations of adrenergic receptor subtypes
what receptors does NE bind to
alpha 1
alpha 2
beta 1
what receptors does epi bind to
alpha 1
alpha 2
beta 1
beta 2
beta 3
what kind of receptors are found more in the heart
beta 1
what kind of receptors are found more in the lung
beta 2
what is primatene mist
an effective bronchodilator (active ingredient is epi) but has a side effect of increased heart rate
what is the james lange theory of emotion
we “feel” stressed because of the physiological changes in our body
our physiological response to stress can increase our emotional stress response
do epi and NE cross the BBB
no because they are monoamines and therefore are not lipid soluble and can be in vesicles
what does the bottom up component of psychological stress refer to
we can suppress emotional stress response by suppressing the SNS response
what is one pharmacological way that we can suppress emotional stress response by suppressing the SNS response
beta adrenergic receptor blockers that will inhibit many of the actions of epi and NE on target organs
what is one behavioral way that we can suppress emotional stress response by suppressing the SNS response
relaxation techniques: designed to suppress SNS and PSNS activity
what is an example of a glucocorticoid
cortisol
what is the molecular structure of cortisol
steroid hormone
(lipid soluble, crosses BBB, no vesicles)
what neuroendocrine circuit is cortisol the effector hormone of
hypothalamic pituitary adrenal axis
who was kurt vonnegut
an author
what was hans selyes most famous discovery
HPA axis
general adaptation syndrome
what is the general adaptation syndrome triad of chronic stress effects
- adrenal hypertrophy
- involution (shrinkage) of the thymus gland
- ulcers
how does chronic stress cause adrenal hypertrophy
chronic activation of the HPA axis causes increased CRH > increased ACTH
ACTH is a trophic factor for the adrenal cortex so the adrenal cortex will increase in size
where do CRH neurons receive input from
the BNST, other hypothalamic subnuclei and some brainstem nuclei
do not receive direct sensory and cortical input
do CRH neurons receive information in order to determine if an event is “stressful” or not
no
what happens in the thymus gland
T lymphocytes mature
what are T lymphocytes involved in
specific immunity
why does cortisol cause the thymus to shrink
cortisol can kill T cells
what can T cells in the body discriminate against
infected cells and healthy cells
what kind of T cells does cortisol kill
the autoreactive (bad) T cells but too much cortisol can cause the good T cells to get killed off as well
how does chronic stress cause ulcers
we dont know
could be more of an effect of adrenaline than cortisol
what is helicobacter pylori
the bacterium responsible for causing ulcers
does chronic stress cause ulcers
not directly
stress can cause microbiome changes that can contribute to more helicobacter pylori but ulcers are not directly modulated by stress
what are the targets for glucocorticoids
any cell that expresses a glucocorticoid receptor (most cells in the body)
where in the body does not have receptors for glucocorticoids
suprachiasmatic nucleus (circadian rhythms)
what are the two subtypes of receptors for cortisol
mineralocorticoid receptor
glucocorticoid receptor
what is the difference between the two subtypes of cortisol receptors
MR: high affinity for cortisol; more sensitive to changes in cortisol
GR: lower affinity for cortisol
is cortisol a glucocorticoid
yes
what is the difference in distribution between MR and GR
GR is widely distributed throughout the body
MR has restricted distribution and is high in the hippocampus and the kidney
what does survival of granule neurons in the hippocampus (memory) require
daily cortisol activation of MR
what do MRs in the kidney primarily respond to
aldosterone
what does aldosterone regulate
sodium retention
what are some pharmacological uses of glucocorticoids
based on the immunosuppressive and anti-inflammatory effects
what is dexamethasone
potent glucocorticoid receptor agonist
(used in covid treatment)
what is cushings syndrome
excessive chronic glucocorticoid levels that is sometimes the result of an adrenal or pituitary tumor
can glucocorticoid levels be measured in the blood and saliva
yes
because cortisol is a steroid, a saliva sample will contain what
the CBG unbound “free” levels of cortisol
what are two factors that regulate HPA axis activity
strong circadian rhythm
stress
what is the nadir
trough (low-point) during behavioral inactive period
humans: night
nocturnal animals: day
when is the peak in HPA axis activity
right at the time of awakening
what are three examples of stressors that can interfere with HPA axis activity
physical stressors: hemorrhage, pain, fasting, etc
alcohol: increases cortisol/decreases vasopressin, stimulates HPA axis
cytokines
what are cytokines
immune system derived hormone that potently activate the HPA axis
why should the immune system activate the HPA axis
HPA axis may serve as a negative feedback modulator for the immune system (help keep the immune system in check)
why is glucocorticoid negative feedback of the HPA axis important
too much glucocorticoid exposure produces too many of the pathological consequences of chronic stress
how do glucocorticoids provide direct negative feedback on the HPA axis
cortisol acts directly on PVN neurons and/or corticotrophs
is cortisol a glucocorticoid
yes
how do glucocorticoids provide indirect negative feedback on the HPA axis
cortisol acts on other brain areas that indirectly inhibits PVN neurons
what is fast feedback (in relation to glucocorticoids and the HPA axis)
glucocorticoids can rapidly attenuate the HPA axis response to stress (mechanism is too rapid to require gene transcription)
what is delayed feedback (in relation to glucocorticoids and the HPA axis)
kicks in after stress onset (30-60 min) and only partially suppresses subsequent HPA axis activity
what is biological psychiatry
study of biologic basis of psychiatric disorders to find a physiological biomarker/indicator of psychiatric disorder
what is the difference between a trait marker and a state marker
trait marker: life-long symptom of someone predisposed to a particular disorder (ex. genes)
state disorder: symptom that is present only during the expression of the disorder (ex. hormones)
what are two examples of HPA axis dysregulation in major depression
- hypercortisolemia: elevated basal cortisol especially through circadian trough
- impaired DST result
what is DST
dexamethasone test
- a potent synthetic glucocorticoid receptor agonist
what is the procedure for the dexamethasone supression test
at bedtime, subject takes 1mg DST tablet
following morning and afternoon, blood samples are obtained and cortisol levels are measured
what is the normal response to a DST
suppressed basal cortisol levels because of increased negative feedback
what is a possible implication of an abnormal DST response in depressed individuals
these individuals may have impaired glucocorticoid negative feedback function
what are two other disorders that are found to be associated with hypocortisolemia
PTSD
chronic fatigue syndrome
what is the relationship between depression and stress
stress may exacerbate and/or trigger depressive episodes but does not CAUSE depression
what is the period
time duration to complete one cycle
what is the peak/zenith
maximum; value of high point
what is the trough/nadir
minimum; value of low point
what is the amplitude
absolute value of the difference between peak or nadir and the mid-point
what is the frequency
number of cycles per given amount of time (inverse of period) (ex. 1 cycle per day)
what is the mesor
average value (midpoint of the waves)
what is the phase
synchronization of 1 cycle with another cycle or some other temporal event
how many degrees is 1 cycle
360 degrees
what is it called when 2 cycles are 180 degrees out of phase with each other
antiphasic
what is circadian
around the day
24 hr period
what is the difference between diurnal, nocturnal, and crepuscular
diurnal: active during the day
nocturnal: active during the night
crepuscular: active at dawn and dusk
what is circalunar
approx 28 day cycle
(menstrual cycle)
what is circatidal
approx 12 hr cycle - tides
(fiddler crab activity)
what is circannual
approx 1 yr cycle
(breeding, hibernation, body weight, fur growth, migration)
what is the difference between ultradian and infradian
ultradian: period less than 24 hrs
infradian: period greater than 24 hrs
what does “zeitgeber” mean
“time giver”
what is chronobiology
study of the timing of biological rhythms
in hamsters, if the time of lights off is shifted to three hrs later, will the hamster shift their wheel running time to 3 hrs later
yes
if a hamster is kept in constant darkness, what will happen to its running patterns
they will keep a regular running schedule indefinitely
what kind of rhythm do hamsters running on wheels have
endogenous circadian activity rhythm
(doesn’t need environmental cue to maintain rhythm but can be entrained by the light/dark pattern)
what does entrainment of biological rhythms mean
environmental periodic cue that synchronized endogenous rhythm
what is a free running biological rhythm
expression of an endogenous rhythm in the absence of entraining cues
why is the definition of stress circular
we only know what the stress response is by observing the response to stressors and we only know what a stressor is by observing a stress response
do stressors have a physical dimension of “stressfulness”
no
what is a possible reason for the fact that some people are morning people and some are not
implies that some people may have an endogenous period greater than 24hrs
what is the relationship between winter and seasonal affective disorder
in the winter the lack of morning light may lead to free running rhythms and desynchronization of rhythms that will contribute to SAD
what part of endogenous rhythms shows inheritance patterns
the period of the endogenous rhythms
what are the six biological clock characteristics
inheritance
temperature independence
resistance to chemical intervention
limits of entrainment
independence of behavioral feedback
ubiquity of clocks
what are the five mammalian clock genes
[+] clock
[+] bmall
[-] per1, per2, per3
[-] cry1, cry2, cry3
casein kinase 1e
what clock genes are on the positive arm
clock
bmall
what clock genes are on the negative arm
period (per)
cryptochrome (cry)
what is FASPS
familial advanced sleep-phase syndrome
is the endogenous rhythm resistant to temperature fluctuations
yes
what drugs can lengthen the endogenous circadian period
lithium
alcohol
how much can a phase shift in one day
approx 1 hr per day
what is the maximum length the human endogenous clock can be lengthened or shortened (period)
2-3 hours
is the endogenous biological rhythm dependent on behavior
no, endogenous rhythm will continue regardless of behavior
what organisms have endogenous clocks
all organisms including single celled
what brain region is responsible for the endogenous clock
suprachiasmatic nucleus of the hypothalamus (SCN)
where is the SCN located
just above the optic chiasm
what happens when the SCN is lesioned
expression of endogenous biological rhythms is abolished
what input do SCN afferents receive
direct input from retina
what kind of activity do SCN neurons in a culture dish show
rhythmic activity pattern with a period very close to 24 hours
what happens when SCN cells are transplanted from a fetal donor hamster to a brain of a hamster whose SCN has been lesioned
transplant restores biological rhythm
when the rhythm of the lesioned hamster was restored, was the period the same as the donor cells or the pre-lesioned host
period was the same as the donor cells
T or F: the SCN functions as a light entertainable master pacemaker for the body
true
how does the SCN talk to the rest of the body
cortisol
melatonin
when are cortisol levels high in humans and what does cortisol signal
levels are high in the morning and it is the wake up signal in all mammals
when are melatonin levels high in humans and what does melatonin signal
levels are high at night (even in nocturnal animals) and it is the sleep signal in humans
where is melatonin produced
pineal gland
where is the pineal gland located
attached to dorsal surface of brainstem right above the superior colliculus
what is the chemical structure of melatonin
related to serotonin (monoamine) but is lipid soluble
what are the targets of melatonin
high density of MT1 and MT2 receptors in the hypothalamus
how does melatonin secretion change over the lifetime
highest during childhood
declines around puberty
low in old age
what kind of neurons innervate the pineal gland
special postganglionic neurons of the SNS
SNS postganglionic neurons that innervate the pineal gland stimulate the production and release of melatonin by stimulating what receptors
adrenergic receptors in the pineal gland
what stimulates serotonin conversion to melatonin in pineal cells
norepinephrine
how much light is sufficient to shut down melatonin secretion in hamsters
single light pulse (0.1 lux)
how much light is thought to turn off human melatonin secretion
exposure to bright sunlight (1500 lux)
are clock genes only found in the SCN
no, whole body
what causes retinal ganglion cells to be able to directly sense light
protein called melanopsin
where do retinal ganglion cells containing melanopsin project to
directly to the SCN
what kind of light are the intrinsic photosensitive retinal ganglion cells (ipRGCs) most activated by
short (blue) wavelength light
what causes jet lag
consequences of suddenly having endogenous circadian rhythms out of phase with light/dark cycle
what does subjective day and night refer to
individuals circadian night and day
what happens during phase advance
subjective night and day begins earlier
what happens during phase delay
subjective night and day begins later
to produce a phase advance when would the individual need light and melatonin exposure
light during the second half of their subjective night
melatonin in late afternoon/early evening
to produce a phase delay when would the individual need light and melatonin exposure
light during first half of subjective night
melatonin in early morning
what are physiological changes that occur in hamsters as winter approaches
decrease eating
fur thickens
decreased HPG activity
hibernation
what are physiological changes that occur in hamsters as spring approaches
increased HPG activity
shedding of fur
mating and child rearing
what is the zeitgeber for hamsters switching behavior for the seasons
environmental cues: temp, humidity, weather patterns, amount of sunlight
photoperiod: daylight length
what behavior is seen when hamsters are maintained on a long day photoperiod
hamsters behave as if its summer indefinitely
what behavior is seen when hamsters are maintained on a short day photoperiod
hamsters behave as if its winter but after 20-30 weeks, summer behavior and physiology spontaneously emerges
what is the refractory to short-day photoperiod
after 20-30 weeks of short-day photoperiod, hamsters no longer respond to short-day photoperiod
is the refractory period to photoperiods permanent
no
if hamsters are exposed to long day photoperiod for approx. 10 weeks they will become sensitive to short day photoperiod
what environmental cue does the secretion of melatonin depend on
the duration of darkness
mammals are exposed to more melatonin each day in what season
winter
during a long day (summer) photoperiod, what happens if the hamster is treated with a winter-time melatonin secretion pattern
hamster goes into winter mode
hamster will become refractory to the additional melatonin treatment after 20-30 weeks
hamsters have greater HPG activity in which season
in the summer
what is the relationship between photoperiod and gonadal steroid negative feedback
during the winter, HPG axis exhibits greater negative feedback sensitivity to gonadal steroids
what is the relationship between melatonin and gonadal steroid negative feedback
melatonin increases negative feedback sensitivity of GnRH neurons to gonadal steroids
what are some symptoms of seasonal affective disorder that are atypical for depression
hypersomnia
carbohydrate cravings
excessive weight gain
when during the day will bright light most benefit those with SAD
in the morning
what is the implication of bright light helping with SAD more in the morning
benefit is not just a general effect of bright light but depends on bright light adjusting (advancing) the circadian phase
what is the circumstantial evidence for the role of gonadal steroids to modulate mood in women
women note changes in mood:
around time of menstruation
shortly after child birth
around the period of menopause
starting/ending oral contraceptive use
when does premenstrual dysphoric disorder occur during menstrual cycle
symptoms occur during last week of luteal phase and remitted within a few days after onset of the follicular phase
is PMS a result of changing activational effects of hormones
there are no clear differences in progesterone and estrogen profiles of women with PMDD vs women without PMDD
where is there a high concentration of estrogen receptor alpha
ovary, uterus, mammary glands, hypothalamus
where is there a high concentration of estrogen receptor beta
kidney, bone, heart, cerebral cortex
what are three treatments of PMDD
- block luteal phase with a progesterone antagonist (no benefit)
- prevent entire cycle with GnRH agonist (was effective)
- progesterone and thyroid hormone treatment (was effective in many cases)
how much input do CRH neurons in the PVN of the hypothalamus receive
no direct input but get indirect input from other brain structures
what in biochemical terms oscillated in order to generate a molecular clock
positive arm drives expression of negative arm
negative arm inhibits expression of positive arm
how can an SCN be transplanted from one hamster into another
SCN cells from fetus are injected into the 3rd ventricle, attach to wall of third ventricle and makes synaptic contact with brain
is melatonin a neurohormone
no because it is not produced by a neuron
what is a neurohormone
a hormone produced by a neuron
how is melatonin secretion controlled
SCN (suprachiasmatic nucleus) projects to the PVN (paraventricular nucleus) which controls the HPA axis ; the PVN projects to the SCG (superior cervical ganglion) and the SCG directly innervates the pineal gland
what is the circadian pattern of melatonin secretion in rodents and humans
high at night for all mammals
sleep signal in humans but not sleep signal for rodents
