W3: Measuring Hormones Flashcards
The negative feedback loop is responsible for
Regulating hormones
Controlling hormone - NE Feedback loop
Circulating hormones are monitored
By the brain (hypothalamus)
In the negative feedback loop
If levels of hormones below setpoint/threshold
Increases the release of hormones
In the negative feedback loop
If levels of hormones are above setpoint/threshold
Decreased release of hormones
There is fluctuation of HPA activity
throughout the day
Fluctuation of HPA activity throughout the day provides energy to body regardless of
stress
Fluctuation in HPA activity throughout the day
Increased cortisol in the morning and then
traila off throughout the day
Fluctuations in HPA axis throughout the day
Natural release of cortisol is regulated by the
superchiasmatic nucleus
Superchiamastic nucleus (SCN) is located in
hypothalamus
The superchaismatic nucleus is responsible for
Controlling the circadian rhythm/biological clock
HPA axis increases activity during stress which disrupts the
diurnal (daily) cortisol curve
Physiological influence of stress
Inital stress response engages the SAM axis which… (3)
- Increases heart rate
- Releases epinephrine/norepinephrine (i.e., adrenaline)
- This is a short-term stress response
Physiological influence of stress
What if the SAM activity does not fade? (2)
- The stressor is more intense than atnicipated
- Body needs to engage in long-term stress response (HPA axis)
During early stress response, HPA is excited by (2) - hormones
- Epinephrine
- Norepinephrine
Once HPA axis is engaged, hormones such as cortisol , epinephrine and norepinephrine have
inhibitory effects on HPA axis to maintain setpoint for stress response
Norepinephrine is excitatory and inhibitory? (2)
- Different effects on glutamate (excitation) and GABA (inhibition) neurons in the hypothalamus
- Norepinephrine effects differ based on the presence of cortisol
Issues with measuring hormones
Since hormones are constantly fluctuating, how do we know if our
Manipulations are responsible for this fluctuation
Since hormones are constantly fluctuating, how do we know if our manipulations are responsible?
Overcome? (2)
Possibly control for confounding variables
Be aware of constant potential influences
Addressing an issue that hormones fluctuate constantly
(2)
- Record and control for time of study
- Run studies at consistent time each day
Run studies at a consistent time each day to address issue of hormones fluctuating
When is it best to run study? (4)
- Studies run in the afternoon have stronger effect
- Since hormone at physiological ceiling in the morning
- There is individual differences affect morning hormone levels
- So best to run in the afternoon
Issue with measuring hormones
Biological influences on hormones problem (3)
- Sex hormones flctuate based on menstrual cycle
- Presence of these hormone vary based on phase of menstrual cycle
- Estrogen has downstream effects on other hormones
Biological influences on hormones problem - menstrual cycle
How to overcome? (4)
- Record and control for menstrual cycle
- Ask of date of last menstruation
- Ask for the average cycle length
- Test women only in one particular stage of the cycle
Issues with measuring hormones
Other factors that influence hormones levels are (4)
- Prescription drugs (e.g., contraception)
- Anti-inflammatory medications
- Antidepressants
- Etc..
How do we assess hormones (3)
- Saliva
- Blood
- Brain (Cerebrospinal fluid)
What are the two types of hormones? (2)
- Steriod hormones
- Non-steriod hormones
Steroid hormones are produced in
- adrenals, ovaries (in women) and testes (in men)
Steriod hormones propertieis
Cross cell membrane, effiectiveness (2)
- Cross cell membrane freely without resistence
- More effective, very robust than non-steriod hormones
Non-steriod hormone are
Peptide or protein-like hormones ; short chains of amino acids
Non-steriod hormone
Crossing cell membrane and effectiveness (2)
Cannot cross cell membrane, indirect effects on cell activity
Less effective
Steriod hormones are
stable, hard to break down
Steriod hormones are detectable in blood and saliva!
Which means.. (2)
- Steriod hormones are relatively consistent across these collection methods
- Saliva methods are preferred due to ease
Example of a steriod hormone (3)
- Cortisol
- Testosterone
- Progesterone
Non-steriod hormones (peptides)
breakdown (2) + stability in samples
- Break down easily so they are quickly metabolised in the body
- Because of this they are difficult to stabilise when they are sampled
Nonsteroid hormones are not detectable in saliva (2)
- Inconsistent across collection methods
- Need to measure via blood :(
Example of non-steriod hormones (peptides) - (3)
- Epinephrine
- Melatonin
- Insulin
Assessing salivary hormones
Sample collections requires
pure sample with no contaiminants (e.g blood, food)
Assessing salivary hormones
it is refrain from
eating, brushing teeth 1 hour before the study
Assessing salivary hormones
Pps given several samples throughout the study such as (3)
- Baseline
- After task
- Recovery
Method to collect and assess salivry hormones
Passive drool collection
the saliva is allowed to pool at the bottom of the mouth and then eased into the collection device
When do you assess salivary hormones? (2)
- Several intervals throughout study to track fluctations
- Endocrine system is slow so takes 15-20 minutes to detect salivary hormones - delayed assessment of them
Storing salivary hormones (3)
- After sealing the tube
- Place in freezer
- Samples kept in -20 degrees celsius and last to up to a year
Processing salivary hormones (3)
- Repeatedly thaw and freeze samples to break down saliva
- Spin in centrifuge to separate watery bits from coarse bits
- Separated bits tested with an assay - measures amount of chemical present in the saliva sample
Evaluating salivary hormones
Advantage as the steriod hormones are
easy to access via saliva
Evaluating salivary hormones
Limited to
hormones (steriods) which make to saliva
Alternative methods to saliva (3)
- Metabolites of nonsteroid/peptide hormones in urine
- Experimental manipulations of hormones via nasal spray
- Assess hormone levels in blood (ethical issue)
Evaluating salivary hormones - disadvantage
Delayed response in detection of hormones (3)
- Assesses that biological stress occured but not sure when
- There is also individual differences in the endocrine system
Delayed response in detection of hormones - more efficient and immediate way to assess HPA axis is through
- Cardiovascular system
