Pregnancy and Development Lab 18 Flashcards
menstrual cycle
Series of changes that occur in the endometrium of a non-pregnant female. There is no blastocyst, fertilization, and implantation so endometrium is shed
What does the endometrium prepare for
prepared to receive a blastocyst which is the early form of an embryo that is implanted into the surface of the uterus.
ovarian cycle
monthly series of events associated with the formation and release of the female gamete.
what initiates the uterine cycle, ovarian cycle,
and other changes associated with puberty in the female.
Gonadotropic hormones: FSH, LH
fsh - females
stimulates the initial development of the ovarian follicles and the secretion of estrogens and inhibin
by the follicles.
LH - females
stimulates
-further development of ovarian follicles
- ovulation
-readies the mammary glands for milk secretion.
-Causes follicle to rupture
Also stimulates the corpus luteum to secrete progesterone, estrogens, relaxin, and inhibin
LH males
LH stimulates cells in the testes to secrete testosterone.
FSH on Males
Stimulate testes for sperm production
estrogens
1) They promote the development and maintenance of
female reproductive organs, the secondary sex characteristics, and the breasts.
2) They control fluid and electrolyte balance. 3) increase protein anabolism.
4) They are believed
to contribute to the female sex drive.
5) Moderate levels of estrogens in the blood inhibit the
secretion of FSH by the anterior pituitary gland. This inhibition provides the basis for the
action of one kind of contraceptive pill. Also GnRH, LH
-stimulate proliferation of basal layer to form new functional layer after menstruation
-lowers blood cholesterol
-
Progesterone
works with estrogens to prepare the endometrium for implantation and to
prepare the breasts for milk secretion.
High level inhibit release of GnRH, FSH, LH
Relaxin
during labour, increase the flexibility of the pubic symphasis
4 phases of the uterine cycle
- menstruation
- preovulatory phase
- ovulation
- postovulatory
menstruation
-uterine cycle:
periodic discharge
of blood, tissue fluid, mucus, and epithelial cells from the endometrium of the uterus. Lasts the first 5 days of the cycle.
-Functional layer sheds resulting in bleeding and uterine glands discharging their contents.
-only the basal layer remains
-ovarian cycle:
Several primordial ovarian follicles in each ovary start developing into primary and then secondary ovarian follicles due to FSH
Granulosa cells
Granulosa cells are cells inside the ovaries that surround and support the developing oocyte (egg cell). They produce hormones like estrogen and inhibin, which are crucial for the ovarian and uterine cycles
primordial ovarian
follicles
develop into primary and secondary follicles. Multiple ovarian follicles begin development but usually only one becomes mature.
What happens to the secondary ovarian follicles that don’t finish maturation?
follicle degenerates and is reabsorbed
What happens if more than one mature ovarian follicle is ovulated?
Can lead to the development of multiple fetuses.
THE PREOVULATORY PHASE /follicular phase
-between the end of menstruation and ovulation.
-lasts from day 6 to 13 in a 28-day cycle.
Ovarian cycle
-secondary follicle matures into a mature ovarian follicle, ready for ovulation.
-During
the maturation process, the granulosa cells increase their production of estrogens.
Uterine cycle
-FSH and LH stimulate ovarian follicle to secrete estrogens. this increase in estrogens stimulates the repair of the endometrium in
the uterus. During the process of repair, basilar cells (stratum basale) undergo mitosis and
produce a new functional layer.
ovulation
-rupture of the mature follicle with the release of the secondary oocyte into the pelvic cavity.
- occurs on
day 14 in a 28-day cycle
-high estrogen levels in the preovulatory phase inhibit fsh and LH levels
-As LH and estrogens secretion
increase and FSH secretion is inhibited, ovulation occurs
-
What happens if the secondary oocyte is not swept into the uterine tube as it usually is?
degenerate or ectopic pregnancy (fertilized egg developing outside the uterus)
postovulatory phase/luteal phase/ secretory phase
-15 to 28 in a 28-day cycle
-between ovulation and the onset of the next menses
-FSH secretion gradually increases and LH
secretion decreases. The functionally dominant hormone during this phase is progesterone.
ovarian cycle:
-luteal phase: mature follicle collapses,
and the blood within it forms a clot.
-corpus hemorrhagicum becomes corpus luteum. Corpus luteum increasing estrogen and progesterone levels
-uterine cycle:
- secretory phase of the uterine cycle prepares the endometrium for implantation of blastocyst. Maximum one week:
1. filling of endometrial glands
2. vascularization of the superficial endometrium (new blood vessels form and grow into the functional layer)
3. thickening of the
endometrium
4. increase in the amount of tissue fluid
phases of the ovarian cycle
Follicular phase
ovulation
-luteal phase
ruptures follicle is called
corpus hemorrhagicum
what does the corpus hemorrhagicum turn into?
corpus luteum