REPRODUCTIVE SYSTEM Flashcards
(36 cards)
Explain the layers of the uterus
Perimetrium
Myometrium: muscular layer
Endometrium: mucosal inner layer, 2 part
- Strata functionalists: changes in response to ovarian hormones, undergoes menstruation
- Strata basialis: un response to ovarian hormones
Define the ovarian cycle and its phases
series of changes where a follicle and ovum mature.
Follicular phase: ovulation occurs
Luteal phase: period of corpus lute activity
Explain the steps of the ovarian cycle regarding follicle growth
Primordial follicle: oocyte surrounded by granulosa cells
Primary follicle activated at puberty: cells become cuboidal, zone pellucida forms and oocyte fully grown
Preantral phase: Granulosa cells proliferate and form layers of early theca (produce oestrogen).
Early astral follicle: Antrum starts to form
Explain the dominant follicle formation
1-25 of the preantral follicles continue to develop
only one dominant follicle.
The non dominant follicles undergo atresia (apoptosis) at any stage of follicular growth.
Explain the physical process of ovulation
Mature follicle has a large antrum where the oocyte projects into cavity.
Ballooning of follicle walls cause ovary to rupture
Lutenising hormone allow ovulation to occur
Left over follicle closes around antrum and granulosa cells enlarge
Granulosa + internal theca cells form corpus luteum
What happens to the corpus luteum
Secretes progesterone and some oestrogen until the placenta can take over
If the egg is not fertilised the corpus lute degenerates into the corpus albicans (a scar)
Explain the hormone levels during the ovarian cycle
FSH: early part of follicular phase
LH: Spike 18 hours before ovulation
Estrogen: Increases as dominant follicle grows. second peak due to corpus luteum
Progesterone: Low until just before ovulation. Increases after due to corpus luteum
Inhibin B: inverse to FSH in follicular phase as produced by earlier follicles
Inhibin A: Produced by older follicles to stop FSH secretion
Explain the function of GnRH in the ovarian cycle
released by hypothalamus to cause FSH and LH release from anterior pituitary
FSH acts on granulosa cells
LH acts on theca cells
Explain the functions of the LH surge
Causing primary oocyte to complete first meiotic division
Antrum size and blood flow to follicle increases
Granulosa cells produce enzymes that break the follicular-ovarian membrane for release
Transforms ruptured follicle into the corpus luteum
Explain the menstrual phase
Day 1-5: menses
Estrogen and progesterone are low because corpus luteum is degrading
- endometrial lining sloughs
- secretion of FSH and LH is released to cause follicles to mature
Explain the proliferative phase
Day 6-14: Prevovulatory
Proliferation of glandular epithelial cells, stroma and blood vessels with enlargement of glands to rebuild endometrium
Thins mucus to allow sperm into uterus at ovulation
Ovulation occurs at end of this phase
Explain the secretory phase
Day 15-28: Postovulatory
Progesterone rises rapidly to prepare for implantation
Glands and stroma enlarge, arteries elongate and glycogen is secreted
Progesterone stops mutometrium contraction
If fertilisation does not occur luteum degenerates and menses phase begins
What are the bodies response to oestrogen rising in puberty
Growth of ovary and early follicle
Increased genitalia, breast and bone growth (Ca uptake)
Widening and lightening of pelvis (feminisation)
Na reabsorption in renal tubule
Female libido
What are the main functions of progesterone
Promotes secretory phase
Stimulates mucus production
decrease fallopian tube and myometrium contraction
-ve feedback reduces FSH and LH
What are the main functions of androgens
Stimulate pubic hair and axillary hair growth
Maintains sex drive
Stimulate skeletal muscle growth
How is an erection caused
Parasympathetic release of NO
relaxes smooth muscle so vessels dilate
Vascular channels enlarge with blood causing erection
Explain the steps of spermatogenesis
Stem cells in basal compartment undergo mitosis to produce 2 1º spermatocytes
Move into adluminal compartment and undergo first meiotic division to form 2 2º spermatocytes
Second meiotic division to form 4 spermatids
Spermatids undergo spermiogenesis into spermatozoa
How is the blood testes barrier maintained
As the 1º spermatocyte moves into the adluminal compartment tight junctions in front degrade and new junctions form behind them
Explain spermiogenesis
Golgi packing acrosomal enzymes into acrosome
MTs elongate to form the flagellum
Mitochondria multiply and move to surround inner part of flagellum
Sperm released into lumen and matures in epididymis.
Explain the function of GnRH in males
Secreted from hypothalamus once every 90 minutes to cause release of FSH and LH from anterior pituitary
LH acts on Leydig cells causing testosterone synthesis
FSH acts on sertoli cells to stimulate secretion of paracrine factors like ABP which bind to testosterone to keep concentration high and stimulate spermiogenesis
Testosterone -ve feedback stops GnRH and LH release and Inhibin from sertoli cells stops FSH release
What are the other body functions of testosterone
Spermatogenesis (via sertoli cells)
Male accessory organs and secondary sex characteristics
Stimulates protein anabolism, bone growth, erythroprotein in kidneys
Explain the travel of the effects through the fallopian tube
Fimbriae sweep oocyte into fallopian tube
Beating cilia move egg along fallopian tube
Takes 4 days to reach uterus
Why do only 1000 sperm reach the fallopian tube
leaking from vagina
Acidic vaginal environment
Energy requirements for trip
Explain capacitation
Changes in the sperms membrane so that it is fragile and acrosomal enzymes can be released
epididymis: membrane coated with proteins and cholesterol to keep tough
ejaculation: additional seminal plasma proteins to strengthen
Secretions of female tract cause capacitation
