Uterine/Menstrual Cycle

Question 1

How long can the menstrual cycle be?

Answer 1

21-35 days

Question 2

What are the 3 phases of the menstrual cycle?

Answer 2

Menses
Proliferative phase
(both occur during follicular phase of ovarian cycle)
Secretory phase
(occurs during luteal phase)

Question 3

Describe menses

Answer 3

• degeneration of functional zone of endometrium
• caused by constriction of spiral arteries + deprivation of O2 + nutrients
• weakened arterial walls rupture, blood pours into CT of FZ
• break away + enter uterine lumen, travel through cervical os + into vagina
• degeneration occurs in patches + repair begins almost immediately
• lasts 1 to 7 days
• 35 - 50 ml blood lost

Question 4

What is painful menstruation called and caused by?

Answer 4

Dysmenorrhoea

• can result from uterine inflammation + contraction
• problems involving adjacent pelvic structures

Question 5

Describe the proliferative phase and relate it to ovarian cycle

Answer 5

• epithelial cells of glands in basilar zone multiply + spread across endometrial surface, restoring integrity
• further growth + vascularisation completely restore functional zone
• happens at same time as enlargement of primary and secondary follicles in ovary
• stimulated by oestrogens
• when ovulation occurs, FZ is few mm thick, glands secreting mucus rich in glycogen

Question 6

Describe the secretory phase

Answer 6

• endometrial glands enlarge, accelerating rates of secretion
• arteries elongate + spiral through FZ
• stimulated by progesterone + oestrogen from corpus luteum
• this phase begins at ovulation + persists as long as corpus luteum intact
• peak 12 days after ovulation
• 1/2 days after, glandular activity declines, corpus luteum stops producing stimulatory hormones
• lasts 14 days