Flashcards in Module 9: Reproductive System Deck (224)
• cAMP mechanism
• Secreted by the anterior pituitary
FSH AND LH
FSH AND LH: Actions
– Steroidogenesis in the ovarian follicle and corpus luteum
– Follicular development beyond the antralstage
• Stimulates ovulation, formation of corpus luteum, and synthesis of estrogen and progesterone (ovary)
• produce progesterone to maintain the endometrium (from proliferative to secretory phase)
LH (Luteinizing Hormone)
• Belong to the same glycoprotein family.
• Each has an α subunit and a β subunit.
• α subunits = identical
• β subunits = Unique
FSH, LH and TSH
Phases of Testosterone
• can become Estradiol via CYP 19 (aromatase) - AROMATIZATION
• can become Dihydrotestosterone (DHT) via 5-alpha reductase - REDUCTION
Estrogen: Actions (1)
– Has both negative and positive feedback effects on FSH and LH secretion.
– Causes maturation and maintenance of the fallopian tubes, uterus, cervix, and vagina.
– Causes the development of female secondary sex characteristics at puberty.
– Causes the development of the breasts.
– Up-regulates estrogen, LH, and progesterone receptors.
Estrogen: Actions (2)
– Causes proliferation and development of ovarian granulosa cells.
– Maintains pregnancy.
– Lowers the uterine threshold to contractile stimuli during pregnancy.
– Stimulates prolactin secretion (but then blocks its action on the breast).
– Ovary: estradiol (during reproductive stage)
– Placenta: estriol (during pregnancy)
– Adipose tissue: estrone (via aromatization) (when the ovaries are not functioning/menopause/ovaries are taken out)
estradiol > estriol > estrone
– Has negative feedback effects on FSH and LH secretion during luteal phase.
– Maintains secretory activity of the uterus during the luteal phase.
– Maintains pregnancy.
– Raises the uterine threshold to contractile stimuli during pregnancy.
– Participates in development of the breasts.
Facts about Females’ Egg
- 2 million Primary oocytes at birth
- 400,000 follicles at onset of puberty
- Remaining follicles are depleted at a rate of 1000 follicles per month until age 35
- After 35 yo, the rate becomes FASTER
- 400 follicles are normally released during female reproductive life = 400 opportunities for pregnancy (assuming no contraception)
- 99.9% of follicles undergo atresia via apoptosis
Fetus >> Puberty >> Fertilization
Primary oocytes begin Meiosis I during fetal life and complete meiosis I just before ovulation Meiosis begins but
levels of proteins required for completion of meiosis are too low – oocyte arrests at prophase I. This happens for years, until __
What is the event that happens in Prophase I?
- formation of chiasmata
- crossing over of the genetic material between homologous chromosome
As the oocyte grows, it synthesizes enough proteins (CDK 1, cyclin) to complete meiosis but HIGH cAMP levels actively maintain arrest. Therefore: Primary oocyte is __
MEIOTICALLY COMPETENT but ARRESTED
A few hours after OVULATION, oocyte completes meiosis I, and Meiosis II is arrested at metaphase II until FERTILIZATION. If fertilization does not occur within 1 day >> secondary oocyte __
What happens in Metaphase II?
- alignment of the chromosomes at the center
• dominant hormone during preovulatory phase
• dominant hormone during the post ovulatory phase
• the ovary in the follicular phase it produces estrogen. in response to estrogen, what happens in the endometrium?
- it proliferates
- during the follicular phase of the ovarian phase, it coincides with the proliferative phase of the endometrial cycle
Ovarian Cycle and Endometrial Cycle
1. Follicular (Ovary) or Proliferative (Uterus) - increase in estrogen (ovary) will cause the uterus to proliferate
2. Ovulation - triggered by the LH surge; estradiol declines and progesterone increase because of the corpus luteum
3. Luteal (Ovary) or Secretory (Uterus) - increase progesterone will cause the endometrium to increase its nutrition and secretion (glands and vessel)
• produced by the syncitiotropoblast; hormone that will rescue the corpus luteum from dying
HcG (Human chorionic gonadotrophin)
The __ (also called the uterine tubes and the fallopian tubes) are muscular tubes with the distal ends close to the surface of each ovary and the proximal ends traversing the wall of the uterus.
Oviducts: 4 sections (distal to proximal)
1. Infundibulum + fimbriae
4. intramural or uterine segment - junction where it meets the uterus
- where fertilization occurs; most common site for ectopic pregnancy
- Site for sperm storage
- Secrete fluids that provide nutritional support to preimplantation embryo
The __ is a single organ that sits in the midline of the pelvic cavity between the bladder and the rectum
Layers of the Uterus:
– Innermost: endometrium (mucosa); reactive to ovarian changes
– Middle: myometrium (three-‐layered, thick muscularis layer)
– Outermost: perimetrium (outer connective tissue and serosa)
Parts of the Uterus:
1. FUNDUS, which is the portion that rises superiorly from the entrance of the oviducts
2. the BODY OF THE UTERUS, which makes up most of the uterus
3. the ISTHMUS, a short narrowed part of the body at its inferior end
About two thirds of the luminal side of the endometrium is lost during menstruation and is called the __ (also called the stratum functionalis)