HSCI 216 Lecture Notes - Energy Flux, Endometrium, Cortisol
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Lecture 8: Friday June 1st
Proximate explanation for variations in female fecundity
o We don’t have to reproduce today
o An adaptation does not have to be plesant, it has to get the job done
o Stress is not always bad (ie: running away from someone who wants to beat you up)
If you keep getting stressed you will stop your immune system from working
It will kill you slowly
Allocation of energy!
o Understand this graph!!
o Energy flux: energy turnover analogy of bank account, deposit a dollar everyday and
take out a dollar everyday, or deposit 100$ everyday and take out $100 everyday.
The flow is different
Energetic challenges can affect the chances of conceiving a pregnancy
o Ovarian suppression: your ovaries are not making enough hormones for menstrual cycle to
o If energy expenditure affect reproductive function then it would have happened before?
Therefore… seasons are a good predictor of energy availability and expenditure
If this is tied to seasons, peak energy expenditure tied with (?)
Having a baby in the spring so during summer you can eat and relax
o Experiment in poland:
Women work hard during the summer for harvesting, and have winters off
Therefore energy expenditure was 1/3 higher during summer
During summer progesterone levels were low than in winter indicating
Progesterone is produced from the luteal follicle hormone that promotes
of growth and thickening of the endometrium (inner lining of uterus where
baby will grow, and important for vacuolization)
If the levels are low then the endometrium wont grow well
o Not enough blood supply etc.
Therefore energy expenditure is a modulator of reproductive function**
o Energy: burning a chip burns slowly, which is how your body will burn it
o What happens when the requirements aren’t met
Stress-triggered reproductive suppression
o How does a women’s body regulate fertility
o “Inauspicious” times not good for the body
o stress is the physiological alarm
it affects ovarian function
“stress should lead to reproductive suppression”