Lecture 46: Female reproductive system II

Question 1

What is menarche?

What is menopause?

Answer 1

Menarche = the commencement of cyclic menstrual function
- at approx at 14 and is stimulated by increase in estradiol associated with puberty

Menopause = cessation of menstruation
- at approx age 45 - 50 and is associated with decreased estradiol and progesterone as the body becomes less sensitive to gonadotrophic hormones (LH and FSH)

Question 2

What are breasts located?

What is their function?

What is the structure of breasts?

Answer 2

• Breasts lie on top of the pectoralis major muscles
• function to nourish infants
• estradiol and progesterone prepare the breast tissue
  Lobes –> lobules —-> alveoli —-> lactiferous ducts —-> lactiferous sinuses that open at nipple pores
• suspensory ligaments support the glands

Question 3

Describe the structure and function of breast;

- what happens after birth?

Answer 3

• decreased estradiol
• increased prolactin secretion from anterior pituitary
• increases oxytocin secretion from posterior pituitary

Question 4

What is oogenesis ?

Describe the process of oogenesis?

How many oogonium are generated?

Answer 4

= generating the ovum
- oogonium is formed by mitosis from a primary oocyte
- Primary oocyte completes meiosis I to from secondary oocyte and first polar body
- secondary oocyte halts at metaphase II of meiosis II
- Meiosis II resumes when the sperm penetrates plasma membrane of ovum at fertilisation
= one oogonium will form from one oocyte and 3 polar bodies which undergo atresia (die)

Question 5

What are some of the female reproductive hormones?

Answer 5

• GnRH (hypothalamus) = Release of FSH and LH
• FSH (anterior pituitary) = Stimulates the growth of ovarian follicles
• LH (anterior pituitary) = Surge of LH involved in ovulation
• Estradiol (developing follicles) = - Assists folic growth (w/FSH);
• Inhibin (granulosa cells) = Negatively feeds back to anterior pituitary to suppress FSH
• Progesterone (theca cells) = - Negatively feeds back to suppress GnRH(therefore LH and FSH)

Question 6

What is the ovarian cycle?

What is the menstrual/endometrial cycle?

Answer 6

Ovarian cycle: to produce ovum each month to regulate the menstrual cycle

Menstrual/Endometrial cycle: To ensure lining of uterus is suitable for implantation

Question 7

Describe the two phases of the menstrual cycle ?

- proliferative phase

Answer 7

Proliferative phase day 1 - 14

• endometrium is shed in menstruation
• triggered by low progesterone levels
• it involves contraction of the endometrial arteries and the sloughing of the endometrium
• the post menstrual phase occurs on day 4-14 and is triggered by rising estradiol levels which stimulates the thickening of the endometrium as well as development of glands and coiled arteries

Question 8

Describe the two phases of the menstrual cycle?

- secretory phase

Answer 8

Secretory phase day 15-28

• progesterone stimulates further thickening of the endometrium and endometrial gland growth
• the secretory phase is associated with an increase in core body temperature

Question 9

Describe the two phases of the ovarian cycle?

- follicular phase

Answer 9

Follicular phase day 1 - 14 includes menstrual cycle and preovulatory phase

• rising levels of FSH from the ant.pituitary
• Mature follicle protrudes on surface of ovary
• Last day preovulatory estradiol is very high
• Estradiol stimulates LH and GnRH —> increases FSH and LH
• Follicle ruptures —> oocyte enters peritoneal space/collected into uterine tube

Question 10

Describe the two phases of the ovarian cycle?

- lucteal phase

Answer 10

Lucteal phase day 12 - 28 includes postovulatory phase and premenstrual phase

• corpus luteum produces progesterone and inhibin which inhibits FSH and LH secretion
• if fertilisation does not occur the corpus luteum will involute to become corpus albicans and progesterone will decline