L30 The Female Reproductive System Flashcards
What are the functions of the female reproductive system? (4)
- Produce haploid gametes
- Facilitate fertilisation with spermatozoan
- Site for implantation of the embryo
- Provide physical and nutritional needs to nurture neonate after birth (mammary glands)
What are the sections of the ovaries? And what are in each sections?
- Medulla (inner) - blood vessels + lymphatic vessels
- Cortex (outer) - contains developing eggs (oocytes)
What are oocytes?
Oocytes are immature egg cells produced during a process called oogenesis and are crucial for reproduction as they contain the genetic material
What are the 2 follicles and the distinct structure that arises from a follicle after ovulation?
Primordial follicle (premature) and graafin follicle (mature)
Corpus luteum
What does the ovarian follicular cells secrete?
They secrete steroid hormones:
- Granulosa - 17β- estradiol
- Theca- progesterone
What is the role of the Fallopian tubes?
Transport egg from ovary to uterus (10cm)
What are the different sections of the fallopian tubes? (3)
Infundibulum - fimbriae
Ampulla
Isthmus
What is peristalsis?
A coordinated series of muscle contractions and relaxations that create a wave-like motion
What adaptations do the ampulla of the fallopian tube have that enables it to transport the egg to the uterus? (3)
- Highly folded mucosa - ciliated and filled with secretory cells
- Longitudinal smooth muscle layer
- Circular smooth muscle layer
What are the 3 distinct layers of the uterine wall?
- Perimetrium
- Myometrium
- Endometrium
What are the adaptations of the endometrium? (4)
- Simple columnar epithelial cells, with leukocytes + macrophages
- Lamina propria - cell- rich connective tissue
- Compound tubular glands
- Spiral arteries
What is the role of the cervix?
- Gatekeeper: Acts as a barrier between the vagina and the uterus, helping to prevent the entry of bacteria
- Sperm transport: During ovulation, the cervix produces mucus that changes in consistency to allow sperm to pass through more easily on their way to fertilise an egg in the fallopian tubes
Where are the internal and external Os located?
Internal Os - Opening between cervix and lower part of the uterus
External Os - Opening between cervix and vagina
How does the cervix ensure that no microbes reach the uterus?
Cervical glands secrete mucus preventing microbes reaching uterus
What are the 3 layers of the vaginal wall?
Thin distensible wall of:
1. Adventitia
2. Muscularis
3. Mucosa
What are the vaginal natural defences?
- Stratified squamous epithelium rich in glycogen:
Ferments glycogen to lactic acid by bacteria, producing pH 3.5-4 which inhibits pathogens - Antigen-presenting dendritic cells.
What are the two female cycles?
Ovarian + endometrial (menstrual)
What is HPGA?
Hypothalamic-pituitary-gonadal axis which is responsible for promoting the menstrual cycle
What does the hypothalamic neurones release within the menstrual cycles?
Releases Gonadotropin - releasing hormone (GnRH)
What does Hypophyseal portal system do?
It’s a system which has a crucial network of blood vessels that connects the hypothalamus to the anterior pituitary.
How are FSH and LH released?
The G-protein coupled GnRH receptors on the anterior pituitary endocrine cells (gonadotrophs) release gonadotropins: FSH and LH
What does FSH and LH stand for?
Follicular stimulating hormone
Luteinising hormone
What does the FSH + LH do together?
They stimulate ovarian follicular cells to secrete steroid hormones
What does Thece cells secrete?
Progesterone
What does Granulosa cells secrete?
17β - estradiol (estrogen)
How does HPGA produce gonadotropins?
- CNS sends signals to the hypothalamus
- Hypothalamus releases Gonadotropin - releasing hormones (GnRH)
- Anterior pituitary stimulates the release of two key gonadotropins - LH and FSH
Is HGPA a cycle?
Yes. It has positive and negative feedback (inhibiting hormone release)
Describe how the HGPA acts in the follicular phase
Hypothalamic-pituitary-gonadal axis
1) Hypothalamus begins by releasing GnRH
2) This stimulates the anterior pituitary gland to release FSH and LH
3) FSH acts on mulitple follicles within the ovaries and as they grow, the begin to produce increasing amounts of estradiol
4) Rising estradiol levels exert negative feedback on the hypothalamus and pituitary gland which suppresses the further release of GnRH and FSH
Gonadotropin-Releasing Hormone
Describe how the HGPA acts in the midcycle phase
1) Hypothalamus begins by releasing GnRH
2) This stimulates the anterior pituitary gland to release FSH and LH
3) FSH acts on mulitple follicles within the ovaries and as they grow, the begin to produce increasing amounts of estradiol
4) High levels of estradiol now exerts a positive feedback on the hypothalaums and pituitary gland which releases more GnRH and LH
5) The LH surge is the trigger for ovulation. It causes the mature follicle to rupture, releasing the egg from the ovary
( Basically same as follicular phase but positive feedback instead of negative feedback)
Describe how the HGPA acts in the luteal phase
1) Hypothalamus begins by releasing GnRH
2) This stimulates the anterior pituitary gland to release FSH and LH
3) FSH acts on mulitple follicles within the ovaries and as they grow, the begin to produce increasing amounts of progesterone
4) Progesterone exerts a negative feedback on the hypothalamus and anterior pituitary gland that inhibits the release of GnRH, LH and FSH. This helps to prevent the premature release of another egg
What are the two phases of the ovarian cycle?
Follicular phase (First)
Luteal phase
Midcycle is a transition between the two
What is the name given to a ruptured follicle after ovulation?
Corpus luteum
What is the difference between the ovarian cycle and endometrial cycle?
- Ovarian cycle - primarily focuses on events occuring within the ovaries
- Endometrial cycle - primarily focuses on changes occuring within the endometrium (lining of the uterus)
Ovarian cycle - steroid hormone levels
Endometrial cycle - physical changes within the lining of the uterus (endometrium)
Order these from smallest to biggest: ng/mL, mU/mL, pg/mL
Smallest - pg/mL
ng/mL
mU/mL
What happens during the follicular phase in the ovarian cycle? (Talk about steroidal hormones)
- Multiple follicle begins to grow which contains immature eggs
- Estradiol, LH and FSH begin to increase slowly
- Progesterone and inhibin remains the same
What happens during the midcycle phase of the ovarian cycle? (Talk about steroidal hormones)
- Estradiol increase
- LH massive surge due to positive feedback of the HGPA
- LH surge triggers ovulation so the mature follicle ruptures, releasing the egg from the ovary
What happens during the luteal phase of the ovarian cycle?
- Corpus Luteum formation: After ovulation, the ruptured follicle transforms into the corpus luteum
- ## Think about the HGPA …. progesterone surge, and negative feedback of the release of LH and FSH so they decrease
What happens to the endometrial functional layer during the ovarian phases?
1) Follicular phase: levels of estrogen (estradiol) and progesterone are low which the top layers of the thickened lining of the endometrium breaks down and are shed, menstrual bleeding occurs (13-14 days)
2) Luteal phase: Corpus luteum forms and produces increasing quantities of progesterone which causes endometrium to thicken
Menses - 1-5 days - endometrium breaks down
Proliferative phase - 6-14 days - Endometrium regenerates
Secretory phase - 15-28 days - further thickening
What happens in the cervical mucus in the follicular phase and the secretory phase?
- Follicular phase (17β - oestradiol) - watery mucus forms channels to propel sperm
- Secretory phase - mucus becomes thick
What does the secretion of 17β-oestradiol stimulate the growth of? (4)
- Endometrium (lining of uterus thickens)
- Glands
- Stroma (supporting connective tissue of endometrium)
- Spiral arteries elongate
Does the thickness of the endometrium decrease when endometrial proliferation slows down?
Yes
What does the hormonal contraceptives do ?
They alter hormonal balance to prevent pregnancy
What is the mechanism behind hormonal contraceptives?
- Hypothalamus decrease GnRH secretion
- Anterior pituitary gonadotrophs - inhibit FSH/LH + prevent ovulation
- Low FSH insufficient to make follicles (stimulate folliculogenesis)
- Low LH (no surge) inhibits ovulation
What is progestin?
Synthetic (human - made) form of progesterone
Describe the mechanism behind Progestin (key component of hormonal contraceptives) (3)
- Cervical mucus thickens, making it difficult for sperm to reach eggs
- Decreases contractions in uterus and fallopian tube to decrease its motility
- Decrease endometrial glycogen
What does the hormonal ‘morning after’ pill do?
It has higher dose preparation of oestrogen and progesterone so it can:
- Inhibit ovulation
- Interfere with implantation
