Physiology Flashcards
Number of oocytes at birth
1-2 million
Number of oocytes at puberty
400,000 oocytes
Number of eggs ovulated in a lifetime
500
Primary oocyte - formed when?
By 5 months ovulation
Only cell that undergoes mitosis
Primordial germ cell
Primary oocyte arrested at?
Prophase of Meiosis I
From 5 months ovulation until onset of puberty/ menses
When is the first meiotic division completed?
Onset of puberty/ menses
When is the secondary oocyte formed?
After completion of meiosis I at the onset of puberty/ menses
Secondary oocyte arrested at?
Metaphase of Meiosis II (until fertilization occurs)
When is the first polar body released?
During ovulation, with secondary oocyte
When is 2nd Meiotic division completed?
Fertilization
Ovum?
Fertilized secondary oocyte
When is the second polar body formed?
If there is fertilization
What is released every menstruation?
Secondary oocyte with 1st polar body
Stratum functionale
Action of LH? What cell?
LH stimulates activation of DESMOLASE in THECA CELLS which converts CHOLESTEROL to PREGNENOLONE, forming ANDROSTEINEDIONE
Effect of menopause on FSH, estrogen, inhibin, granulosa cells?
Decreased granny cells –> low estradiol and low inhibin –> high FSH (because of low inhibin)
Fate of androsteinedione in Theca cells?
80% crosses BM to granulosa cells
20% goes to periphery for conversion to testosterone
Effect of inhibin
Inhibits FSH secretion from anterior pituitary
Effects of estrogen on uterus and cervix?
Uterus: increase rate of mitotic division (proliferation)
Cervix: cause cervical mucus to be thin and watery - easier for sperm to traverse; causes FERNING of cervical mucus
Peak of LH secretion?
10-12 hrs before ovulation
Spinnbarket?
Thin and watery cervical mucus produced, as triggered by estrogen
Main provider of progesterone before placenta in pregnancy?
Corpus luteum
Effects of progesterone on uterus and cervix?
Uterus: endometrium becomes secretory, providing a source of nutrients for the blastocyst; subnucleolar vacuoles, stroma becomes edematous
Cervix: mucus becomes THICK
Origin of corpus luteum?
Remains of the dominant or Graffian follicle - leutinization
When will the corpus luteum regress if fertilization does not occur?
9-11 days after ovulation
Chemotactic activating factor for neutrophils in the pre-menstrual endometrium?
IL-8
Key event in endometrium pre-menstruation
Infiltration of stroma by PMNs, giving a pseudoinflammatory appearance to the tissue
Most striking and constant event the precedes the onset of menstruation
Period of vasoconstriction (of spiral arteries –> hypoxia of functionalis layer)
When is the endometrium restored completely after onset of menses
Day 5 of menses
Most important factor in recovery of endometrium after menses
Estrogen increase in the early follicular phase
Earliest histological evidence of progesterone action in the endometrium
Basal vacuolization
When is endometrial secretion at its maximum?
At the time of blastocyst implantation
Most appropriate endometrium for implantation
Predecidual reaction (day 20-24 of cycle)
Most ripe for implantation
When does leukocyte infiltration begin?
1-2 days before onset of menses
Trigger for endometrial leukocyte infiltration?
IL-8
Source of hormones in the preovulatory phase
Follicular granulosa cells
What happens to the endometrium in pregnancy?
Decidualization - transformation of secretory endometrium to decidua
Highly modified endometrium of pregnancy
Decidua
Layers of the decidua
Basalis
Parietalis
Capsularis
First necessary event in fertilization
Acrosome reaction (remove cap to release enzymes)
When is meiosis II completed?
At fertilization
Product of completion of the second meiotic division?
Ovum
Fusion the the male and female pronuclei forms?
Zygote
What reaction renders the secondary oocyte impermeable to other sperm?
Cortical reaction
Endometrium of pregnancy?
Decidua
Process that establishes the 3 primary germ layers
Gastrulation
What is formed during gastrulation?
Trilaminar embryonic disk - ectoderm, endoderm, mesoderm
First organ to develop during the embryonic period?
CNS
Cardiac activity via TVS can be appreciated by – weeks AOG?
6 weeks
Derivatives of the endoderm?
Lining of GIT, pancreas, respiratory tract, thyroid
Derivatives of the ectoderm?
CNS, PNS
Sensory organs of seeing and hearing
Integument layer
Heart - completed by how many weeks?
8 weeks
Limbs completed by how many weeks?
8 weeks
CNS - completed by how many weeks?
Continues post-natally
External genetalia - completed by how many weeks?
9 weeks
Number one cause of preterm labor
Breaking of amnion
Fetal urine production at – weeks AOG?
9-12 weeks AOG
Membranes - fetal to maternal
Amnion Chorion Decidua parietalis (endometrium) Myometrium Serosa
Hemoglobin at 6 months AOG?
90% HgF
Hemoglobin at near-term?
70% HgF
Medication that induces formation of Hemoglobin F?
Hydroxyurea - given to patients with sickle cell anemia
Breast sebaceous glands are called?
Montgomery glands - increase in size starting 2nd month of pregnancy
Number of oocytes in fetal period
6-7 million at 5 months AOG