Hypothalamic control Flashcards
Reproductive function is controlled by which organ?
The brain
How must GnRH pulses be for normal reproductive function?
Need to have enough pulses that vary in frequency
What does the GnRH pulse generator drive?
Production of hormones from the anterior pituitary
What is puberty?
The acquisition of reproductive competence - occurs over time
How is puberty defined in males and females?
Males = Age when ejaculate contains sufficient spermatozoa to fertilise Females = Age at which female can support a pregnancy without deleterious effects
Which hormone provides an indication of sexual maturity?
Increase in GnRH pulsatility
Which factors need to be considered when there is onset of puberty?
- size and body fat important in the female
- season of birth and photoperiod
- social cues e.g. presence of a male
Which factors influence the GnRH pulsatility/hypothalamus?
- weight
- age
- metabolic status
- photoperiod
- social conditions
Give examples of when GnRH pulsatility is suppressed and ovarian cycles stop
- Lactation
- photoperiod
- pregnancy
What factors may cause cycles to stop in a newly calved dairy heifer?
- weight loss
- stress/bullying
- lactating
- still growing
Which two hormones induce development of the mammary glands at the onset of puberty?
- Oestrogen
- Progesterone
How does the microanatomy of of mammary glands/teats differ in a cow, mare and bitch?
Cow = 1 canal per teat Mare = 2-3 ducts per teat Bitch = 5-6 ducts per teat
Where is milk synthesised?
Across the apical surface of highly metabolically active cells
What type of immunity is provided by colostrum?
Passive immunity
What are the two stages of lactogenesis? (onset of milk secretion)
- acquisition of secretory capability pre-partum
2. onset of copious secretion at/around parturition
