Physiology of the reproductive system - female

Question 1

Interplay between ovarian and menstrual cycle

Answer 1

• h

Question 2

Menstrual cycle

Answer 2

• Process of thickening and increased vascularisation of the uterine wall ready for implantation

Question 3

Decidualisation

Answer 3

• Oestrogen → causes thickening to the endometrium
• Progestogen → increased vascularisation of the endometrium

Question 4

Ovarian cycle

Answer 4

• Follicular phase → FSH from anterior pituitary causes follicle to mature and produce oestrogen (inhibits development of other follicles)
• Ovulation → rising oestrogen causes positive feedback causing LH surge (follicle ruptures and releases secondary oocyte)
• Luteal phase → ruptured follicle becomes corpus luteum and secretes progesterone (and some oestrogen)
• Menstruation → corpus luteum degenerates in corpus albicans (endometrial lining sheds and new ovarian cycle begins)
  

Question 5

Ovaries

Answer 5

• Oogenesis
  
  • Production of one oocyte per menstrual cycle
  • Majority eggs perish
  • Finite number and declines with age
• Steroid hormone production
  
  • Estrogen → secondary female sexual characteristics
  • Progestogen → endometrial changes for implantation
  • ½ of testosterone production before menopause §

Question 6

Fallopian tubes

Answer 6

• Site of fertilisation by sperm
• Maturation of the egg before implantation
  *

Question 7

Uterus

Answer 7

• Site of implantation and foetal growth

Question 8

Structure of the ovary

Answer 8

• Surface → capsule of connective tissue covered in simple cuboidal epithelium
• Cortex → peripheral part of the ovary, contains the ovarian follicle (one oocyte surrounded by single layer of cells)
• Medulla → central part, connective tissue with blood vessels
  

Question 9

Oogenesis

Answer 9

1. Primordial germ cell mitosis in feta life, arrest at first meiotic stage of division until puberty
2. During puberty: second meiotic division start → primary follicle → secondary follicle (capable of fertilisation)
3. Second meiotic division occurs after of fertilisation of oocyte with sperm

Question 10

Why does cell division in oogenesis occur in multiple separate stages

Answer 10

• Allows for diploid cells of the mother to be halved from 46 chromosomes to 23 to become haploid
• This forms the female gamete ready to be fertilised by the male gamete (sperm) → full 46 chromosomal complement

Question 11

Stages of follicular development

Answer 11

• Primordial follicle → primary oocyte arrested at first stage of meiosis and surrounded by squamous pre granulosa cells
• Primary follicle → oocyte surrounded by zone and cuboidal granulosa cells
• Secondary follicle → increased oocyte diameter and multiple layer of granulosa cells, resumption of meiotic division
• Tertiary/ graffian follicle → fluid forms between cells to form the antrum, first meiotic stage complete and forms secondary oocyte (start of second meiotic stage)

Question 12

Hypothalamic-pituitary-ovarian axis

Answer 12

• GnRH → Secreted by hypothalamus to stimulates release of FSH and LH from the anterior pituitary gland
• FSH → Secreted by anterior pituitary and stimulates follicular recruitment and development in ovaries
• LH → Also secreted by anterior pituitary and maintains dominant follicle, induces follicular maturation and ovulation and corpus luteum function
• Oestrodiol → secondary sexual characteristics (feedbacks to anterior pituitary + hypothalamus )
• Progestogen → maintenance of secretory endometrium (feedbacks to anterior pituitary + hypothalamus )