Puberty and Disorders of Development and Menstrual Disorders Flashcards
How does the menstrual cycle occur?
- GnRH from the hypothalamus stimulates the follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary, which stimulates estrogen and progesterone from the ovarian follicle
Where is the pituitary gland located?
- Below the hypothalamus at the base of the brain within a bony cavity and is separated from the cranial cavity by a condensation of dura matter covering the sella turcica
What are the two divisions of the pituitary? What does each produce?
- Anterior lobe: FSH, LH, TSH, prolactin, growth hormone, and ACTH
- Posterior lobe: Vasopressin and Oxytocin
What are the phases of the normal ovarian cycle?
- Follicular phase: begins with the onset of menstruation and culminates in the preovulatory surge of LH
- Luteal phase: begins with the onset of the preovulatory LH surge and ends with the first day of menses
What do decreasing levels of estradiol and progesterone from the regressing corpus luteum of the preceding cycle do?
- Initiate an increase in FSH by a negative feedback mechanism, which stimulates follicular growth and estradiol secretion
What is a major characteristic of follicular growth and estradiol secretion?
- Is explained by the 2 gonadotropin (LH and FSH)
- 2 cell theory of ovarian follicular development
What is the 2 cell theory of ovarian follicular development and estrogen production?
- Separate ovarian functions in the ovarian follicle
- LH stimulates the theca cells to produce androgens
- FSH stimulates the granulosa cells to convert these androgens into estrogen
What happens during the luteal phase?
- LH and FSH are significantly suppressed at the start of the phase through the negative feedback effect of the elevated circulating estradiol and progesterone
What happens if conception does not occur during the luteal phase?
- Progesterone and estradiol levels decline near the end of the luteal phase as a result of corpus luteal regression
- Then FSH will rise which initiates new follicular growth for the next cycle
What are the 5 peptides that affect the reproductive cycle that are isolated from the hypothalamus?
- GnRH
- TRH
- SRIF or somatostatin
- CRF
- PIF
- All exert specific effects on the hormonal secretion of the anterior pituitary gland
What is GnRH responsible for?
- Synthesis and release of LH and FSH
- Reaches the anterior pituitary and stimulates the synthesis and release of FSH and LH into the circulation
What does estradiol do in regards to GnRH and LH?
- Enhance the hypothalamic release of GnRH and induce the midcycle LH surge
What do gonadotropins do on GnRH release?
- Inhibitory effect
When do estradiol levels begin to rise?
- Approximately 1 week before ovulation, they begin to rise
- Rise to a maximum 5 to 7 days after ovulation and returns to baseline before menstruation
When are estrogen levels at a maximum?
- 1 day before the midcycle LH peak
What happens with progestin during follicular development?
- Ovary secretes only a very small amount of progesterone
- Prior to ovulation the unruptured luteinizing graafian follicle begins to produce increasing amounts of progesterone
Where does a bulk of progesterone come from during follicular development?
- The peripheral conversion of the adrenal pregnenolone and pregnenolone sulfate
When does secretion of progesterone reach a maximum?
- Reaches a maximum 5-7 days after ovulation and returns to baseline before menstruation
What happens to primordial follicles during follicular development?
- Undergoes sequential development, differentiation and maturation until a mature graafian follicle is produced
- Follicle then ruptures and releases an ovum
- Subsequent luteinization of the ruptured follicle produces the corpus luteum
What happens about 8 to 10 weeks of fetal development?
- Oocytes become surrounded by precursor granulosa cells
- This complex is called the primordial follicle
What is the cumulus oophorus?
- The innermost 3 to 4 layers of multiplying granulosa cells become cuboidal and adherent to the ovum
How does the antrum and corona radiata form among the granulosa cells?
- Antrum enlarges and centrally located primary oocyte migrates to the wall of the follicle
- Innermost layer of the granulosa cells of the cumulus become elongated and form the corona radiata
- Corona radiata is release with the ootyce at ovulation
How does ovulation start?
- Preovulatory LH surge initiates a sequence of biochemical and structural changes that result in ovulation
- Cells on the follicular wall surface degenerate and a stigma forms, follicular basement membrane bulges through the stigma
- When this ruptures, the oocyte is expelled into the peritoneal cavity
What makes of the corpus luteum?
- Luteinized granulosa cells, theca cells, capillaries, and connective tissue
What does the corpus luteum do?
- Produced copious amounts of progesterone and some estradiol
- If pregnancy doesn’t occur, menses does causing the corpus luteum to be replaced by avascular scar tissue called corpus albicans
What is the normal life span of the corpus luteum?
- 9 to 10 days
What is the endometrium responsive to?
- Circulating progestins, androgens, and estrogens
What are the two zones of the endometrium?
- Outer portion or functionalis
2. Inner portion or basalis
What does the functionalis zone of the endometrium do?
- Undergoes cyclic changes in morphology during the menstrual cycle and is sloughed off at menstruation
- Contains spiral arteries
What does the basalis zone of the endometrium do?
- Remains relatively unchanged during each cycle and after menstruation provides stem cells for the renewal of the functionalis
- Contains basal arteries
What are the three stages of histopathology of the endometirum?
- Menstrual phase
- Proliferative or estrogenic phase
- Secretory or progestional phase
What occurs during the menstrual phase?
- First day of menstruation is known as day 1
- Disruption and disintegration of the endothelial glands and stroma, leukocyte infiltration, and red blood cell extravasation
- Sloughing of the functionalis layer and compression of the basalis layer
What occurs during the proliferative phase?
- Endometrial growth secondary to estrogenic stimulation
- Increase in length of spiral arteries and numerous mitoses can be seen in these tissues
What occurs during the secretory phase?
- Following ovulation, progesterone secretion by the corpus luteum stimulates the glandular cells to secrete mucus, glycogen and other substances
- Glands become tortuous and lumens are dilated and filled with these substances
- Stroma become edematous
- Spiral arteries extend into superficial layer of the endometrium and become convoluted
What happens if conception does not happen by day 23?
- Corpus luteum begins to regress, secretion of progesterone and estradiol decline, and endometrium undergoes involution
What happens the day before menstruation during the secretory phase?
- Marked constriction of the spiral arteries occurs resulting in ischemia of the endometrium, leukocyte infiltration and RBC extravasation
What is important in regulating menstruation?
- Intact coagulation pathway
How does coagulation affect menstruation?
- Menstruation disrupts blood vessels, but with normal hemostasis, they are repaired
- Restoration of the vessels requires successful interaction of platelets and clotting factors
- Anticoagulants impair the coagulation system and are associated with heavy bleeding
When does menarche occur?
- 12.43 is median age
- Occurs within 2-3 years after thelarche at Tanner stage IV, rare before tanner stage III
- By age 15, 98% of females have had menarche
What is primary amenorrhea?
- No menstruation by 13 without secondary sexual development OR by the age of 15 with secondary sexual characteristics
What is the average length of the first cycle and how many days do they bleed?
- Length is 34 days
- Bleed for 2-7 days
What is the mean blood loss per menstrual period?
- 30cc
- Most report changing a pad 3 to 6 times a day
What is blood loss of greater than 80cc associated with?
- Anemia
- Changing a pad every 1-2 hours is considered excessive especially if bleeding is lasting >7 days
What is the usual age of puberty?
- 10-16 years old
What is the onset of puberty determined by?
- Genetic factors including race
- Geographic location (metro areas and near sea level begin puberty early)
- Obese children have earlier puberty
- Malnourished, chronically ill with weight loss will have later onset
What mean weight is essential to start menarche?
- 106 lbs
When do females have the peak number of oocytes?
- 6-7 million by mid-gestation (16-20 weeks)
What happens during ages 4-10?
- Hypothalamic-pituitary-ovary axis is suppressed
What 2 mechanisms do low levels of gonadotropins and sex steroids affect?
- Gonadostat sensitivity to the negative feedback of low circulating estradiol
- Intrinsic central nervous system inhibition of the hypothalamic GnRH secretion
What happens during ages 8-11?
- Is an increase in serum concentration of DHEA, DHEA-S, and androstenedione
What are the initial endocrine changes associated with puberty?
- Adrenal androgen production and differentiation by the zona reticularis of the adrenal cortex
What happens a result to a rise in adrenal androgens?
- Growth of axillary and pubic hair
How does puberty start?
- Around 11, there is a gradual loss of sensitivity by the gonadostat to the negative feedback of sex steroids. In combo with the intrinsic loss of central nervous system inhibition of hypothalamic GnRH release
What does an increase in GnRH promote?
- Ovarian follicular maturation and sex steroid production, which leads to the development of secondary characteristics