Basic Physiology - Quines Flashcards
What are the steps of a developing ovarian follicle in the Ovary?
Stroma
- > Primordial Follicle
- > Growing Follicle
- > Vesicular Follicle
- > Mature Grafiaan Follicle containing Antrum (antrum surrounds oocyte)
- > Oocyte (Egg) is then released aka ovulation
- > Follicle becomes a Corpus Luteum (Young then mature)
- > Corpus luteum then regresses and becomes an ovarian scar known as a Corpus Albicans
When do Oocytes become haploid?
The primary (Diploid) Oocyte undergoes mitosis and begins meiosis in utero, it pauses and only completes meiosis just before ovulation.
Secondary (Haploid) Oocyte is then released in ovulation. It starts its second meiotic division which only completes after the sperm has reached the 2* oocyte.
What triggers ovulation?
The LH (Luteinising Hormone) Surge which occurs due to high levels of oestrogen.
How do oestrogen and Progesterone affect LH and therefore ovulation?
Low levels of oestrogen have a -ve feedback effect on the hypothalamus and Ant Pit so low levels of LH.
But then around day 12-14 of the menstrual cycle the levels reach a threshold where they trigger a +ve feedback –> LH surge and ovulation
Major female reproductive hormones and where are they produced?
- GnRH (Hypothalamus)
- LH (Ant Pit)
- FSH (Ant Pit)
- Oestradiol (Granulosa cells)
- Progesterone (Corpus Luteum aka CL)
What does GnRH do?
Stimulates LH and FSH from Ant Pit
What does LH do?
Induces follicle maturation and ovulation
Stimulates CL function
What does FSH do?
Stimulates Follicle recruitment and development
What does Oestradiol do?
Support 2* female sex characteristics as well as reproductive organs
-ve feedback on LH and GnRH until late follicular stage –> +ve feedback for LH surge
Stimulates endometrial proliferation
-ve control of FSH
What does Progesterone do?
Maintains secretory endometrium
-ve feedback on HPO (Hypothalamic-Pituitary-Ovarian Axis)
How does oocyte number change over time?
7 million sa foetus down to roughly 500000 by puberty
Quickly summarive the effects of Oestrogen outside of reproductive organs?
- Protein/carb/lipid metabolism
- Water/electrolyte balance
- Clotting
- Fat Distribution
- Mammary gland development
- Bone maturation and turnover
- CNS effects
What produces progesterone?
Corpus luteum
What is estradiol and what produces it?
- Produced by the granulosa cells
* One of the 3 most strong steroid hormones of oestrogen
Histological differences between the different types of follicles?
1- Primordial follicle: Oocyte
2- Primary follicle: Zona pellucida and granulosa cells begin to develop
3- Matura Graafian follicle : Theca cells and antrum
After ovulation
• Theca cells and granulosa cells converted into corpus luteum
• Corpus luteum develops into corpus albicans
