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PSL300H1 Lecture Notes - Carnitine, Negative Feedback, Gamete

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Michelle French

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Repro: Lecture 1: male
1:15 PM
Common between males and females
Formation of gametes (spermo/ocytes)
Hypothalamic/pituitray control of reproduciotn
Gametes withb 23 chromosomes are produced from cells in the gonads with 46
Precess involves meiosis
oDNA replicated once
oCells undergo division twice
In contrast : mitosis = normal cell division
oDNA replicated once
oCells undergo division once
Mitosis vs. Meiosis (crossing over also happens, mixing of DNA)
Hypothalamic/pituitary control of reproduction
Internal and environmental stimuli in CNS _> GnRH
GnRH (gonadotropin releasing hormone) in hypothalamus ->anterior pituitary
-GnRh in anterior pituitray -> LH and FSH
LH -> endocrine cells -> steroid and peptide hormones, gamete produciton in females
FSH-> gamete prduction
LH is the main regulator of endocrine secetion from the gonads
Steroid hormones long loop feedback either positive or negative on GnRH
GnRH in ant. Short loop Negatively feedbacks GnRH in hyp
GnRH secreted in pulses from neuroendocrine cells in hypothalamus
Pulsatility critical for reproductive function
Regulated by hormonal feedback and higherbrain centres
Pulse frequency/amplitude changes during brain development
If pulsatility is absent, no reproduction
When hyp neurons fire, gnrh is released (triggered by electrical activity)
Male reproductive system
Same passage for semen and urine
oSphincter that prevents urine form being released with semen
Testes in scrotum
Sperm starts at the scrotum, goes through vas deferens to get to seminal vesicle and
then out through utrethra
Sperm produciton
Produced in testis
Optimal at 2-3 degrees lower than body temperature
Takes ~64 days
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