Mod 4. L29

Question 1

How is breeding generally timed

Answer 1

it is timed so offspring emerge when food is abundent to support its growth and development

Question 2

Environmental cues to breeding time

Answer 2

photoperiod
temperature
salinity
rainfall
etc…

Question 3

what is the primary cue for reproduction

Answer 3

photoperiod

Question 4

how is photoperiodic information transduced?

Answer 4

melatonin!

Question 5

melatonin

Answer 5

synthesized by the pineal gland
synthesized in response to darkness (less in long days than short days)

inhibits GnRH release or responsiveness

Question 6

pathway leading to sex steroid hormone synthesis

Answer 6

hypothalamus (gonadotropin releasing hormones GnRH)

-> Anterior pituitary gland (Luteinizing hormone (LH) & follicular-stimulating hormone (FSH))

-> Gonads (Sex steroid hormones)

Question 7

how does melatonin affect GnRH- synthesizing neurons in the hypothalamus?

Answer 7

It inhibits GnRH release of responsiveness

(but not in all species i.e in red deers melatonin promotes GnRH!! )