Menstrual cycle, Sexual response cycle (SLRC)

Question 1

Three cycles of the feedback system that controls menstruation

Answer 1

In order:

1. Hypothalamic-pituitary
2. Ovarian
3. Endometrial

Question 2

Hypothalamic-pituitary cycle

a. Site
b. Trigger
c. Organs involved

Answer 2

a. CNS and the anterior pituitary area
b. Low levels of estrogen and progesterone in the bloodstream
c. Hypothalamus and the anterior pituitary gland (APG)

Question 3

Hypothalamic-pituitary cycle

d. Phases (2)

Answer 3

Phase 1: Follicular (days 1 to 12-13)

• Release of GnRH by hypothalamus
• GnRH stimulates APG to release FSH
• FSH targets ovarian cortex to produce Graafian follicles; estrogen production increases

Phase 2: Luteal (days 13 to 28)

• Estrogen decreases on day 12
• Hypothalamus then releases GnRH
• GnRH stimulates APG to release LH
• LH stimulates ovaries to produce progesterone

Question 4

Ovarian cycle

a. Site
b. Trigger (2)
C. Organs involved (3)

Answer 4

a. Adnexa (internal reproductive tract)
b. Low levels of estrogen and progesterone in the bloodstream, and recession of the corpus luteum
c. Ovaries, fallopian tubes (oviducts), and the uterus

Question 5

Ovarian cycle

d. Phases (3)

Answer 5

Phase 1: Pre-ovulatory (days 1 to 12-13)
One to 30 immature Graafian follicles start to mature under the influence of FSH and estrogen

Phase 2: Ovulatory (day 14)

• Surge of LH occurs
• One or more than one ovum will be released (other term: ovulation)
• This ovum is viable only within 24 hours

Phase 3: Post-ovulatory (days 14 to 28)

• Estrogen decreases
• LH continues to stimulate the empty follicle called the corpus luteum to produce progesterone

Question 6

Endometrial cycle

a. Site
b. Trigger
C. Organs involved

Answer 6

a. Endometrium (innermost layer of the
uterus)
b. Low levels of estrogen and progesterone in the bloodstream
c. Uterus

Question 7

Endometrial cycle

d. Phases (4)

Answer 7

Phase 1: Menstrual (days 1 to 3-5)
- Shedding of the functional two thirds of the endometrium (the compact & spongy layers) is initiated by periodic vasoconstriction in the upper layers

Phase 2: Proliferative (days 4-6 to 14)
- Influenced by the increased levels of estrogen, an eight- to ten-fold thickening of the endometrium occurs, with a leveling off of growth at ovulation

Phase 3: Secretory (days 15-25)

• Larger amounts of progesterone are produced by corpus luteum
• An edematous, vascular, functional endometrium becomes apparent

Phase 4: Ischemic (days 26-28)

• Spiral arteries spasm due to the rapid decrease in progesterone and estrogen levels
• The blood supply to the functional endometrium is blocked —> necrosis develops —> bleeding follows

Question 8

Average length of a menstrual cycle

Answer 8

28 days

Question 9

Average duration of a menstrual cycle (with range)

Answer 9

5 days (3-6 days)

Question 10

Average blood loss (with range)

Answer 10

50 mL (20-80 mL)

Question 11

Components of a complete menstrual history/ What to ask a client when taking their menstrual history (5 answers)

Answer 11

1. Menarche (when)
2. Duration of menses
3. Interval between menses
4. Date of onset of last menstrual period
5. Date of past/previous menstrual period (menstrual period before the last)

Question 12

a. Average age of a menarche
b. Before what age is it considered an early menarche?
c. After what age is it considered a late menarche?

Answer 12

a. 12 to 13 years
b. Early menarche – before age 12
c. Late menarche – after age 18

Question 13

Four phases of the sexual response cycle

Answer 13

In order:

1. Excitement phase
2. Plateau phase
3. Orgasmic phase
4. Resolution phase