Reproductive system Flashcards
Name the hormone axis for reproduction
Hypothalamus= GnRH
APG= LH/FSH
Stimulate follicle development in ovaries
Theca granulosa secrete oestrogen
Negative feedback
What does oestrogen act on?
tissues w/ oestrogen receptors to promote 2r female sexual characteristics: breast tissue development, growth and development of female sex organs at puberty (vulva, vagina, uterus), blood vessel development in uterus, endometrium development
What is progesterone produced by?
CL after ovulation
Placenta after 10 wks pregnancy
What is function of progesterone?
Thicken/maintain endometrium
Thicken cervical mucus
increase body temp
When is average age of puberty?
8-14 girls
9-15 boys
4 years start to finish
Why do overweight children enter puberty at an earlier age?
Aromatase enzyme found in adipose tissue important in creating oestrogen.
so, delayed puberty in low birth weight girls, chronic disease, eating disorders, athletes.
Why dont girls have puberty earlier?
They have relatively little GnRH/LH/FSH and progesterone and oestrogen in their system in childhood, in puberty it increases a lot leading to the 2ry characteristics
Describe the pubertal changes in girls
Breast buds, pubic hair (light thin, coarse and curly, adult like, reaching medial thigh), menstrual periods, Growth spurty usually before boy (due to GH increase in initial phases of puberty)
Describe the hormonal changes during puberty
The hypothalamus starts to secrete GnRH, initially during sleep, then throughout the day in the later stages of puberty. GnRH stimulates the release of FSH and LH from the pituitary gland. FSH and LH stimulate the ovaries to produce oestrogen and progesterone. FSH levels plateau about a year before menarche. LH levels continue to rise, and spike just before they induce menarche.
Two phases of menstrual cycle
Follicular- start menstruation to ovulation 1-14 days
Luteal- ovulation to start of menstruation final 14 days
Describe the follicular phase
Follicle= granulosa cells surrounding oocyte
Primordial follicles mature into 1ry/2r follicles at any time independent of cycle-
2rydevelop FSH receptors and need stimulation from FSH to develop further.
Menstrual cycle starts, FSH stimulates 2ry development, as they grow granulosa cells secrete lots of oestrogen which negative feedback on pituitary reducing LH/FSH producton. also makes mucus more penetrable for sperm around ovulation time
One follicle becomes dominant, LH spikes before ovulation so DF releases ovum from ovary. Ovulation= 14 days before end of menstrual cycle so 14/28 or 16/30.
Describe the luteal phase
Follicle that releases ovum collapses becomes CL- secretes progesterone which maintains lining of endometrium, causes mucus to thicken, also CL secretes some oestrogen.
Fertilisation- Syncytiotrophoblast of embryo secretes HCG which maintains CL.
No fertilisation- no HCG, CL degenerates, fall in oestrogen/progesterone= breakdown of endometrium and menstruation occurs. Stromal cells of endometrium produces PG’s, which encourange endometrium breakdown and contraction of uterus. Negative feedback ceases so LH/FSH can rise again.
What is day 1 of menstrual cycle
Menstruation- breakdown of superficial/middle endometrium layers separating from basal layer. broken down in uterus and released over 1-8 days.
What is a primordial follicle?
Contains primary oocyte- germ cells that eventually undergo meiosis to become mature ovum.
develops into primary follicle
Rest inside ovaries, waiting for their time to develop.
Primary oocyte, pregranulosa cell and basal lamina layer on the outside
What is the primary follicle layers?
Primary oocyte, zona pellucida (secreted content by graulosa sells, and oestrogen), granulosa cells.
As they grow larger they get an outer layer called theca folliculi (interna- secretes androgens and externa contains connective tissue cells such as SM/collagen)
Which type of follicle develops receptors for FSH
2ry follicle
Antral follicle? what is that
2ry follicle develops further gets antrum within granulosa cell (fills w/ fluid)
Also has corona radiate mad eof granulosa cells, surrounds zona pellucida and oocyte within the antrum.
What is the dominant follicle?
One of the follicles becomes the dominant follicle. The other follicles start to degrade, while the dominant follicle grows to become a mature follicle. This follicle bulges through the wall of the ovary.
What is the process of ovulation?
LH surge= SM of theca externa to squeeze, folllicle bursts, follicular cells release digestive enzymes to puncture hole in ovary wall to let ovum pass. oocyte rleased into surround area and floating in peritoneal cavity, swept up by fimbriae of follopoion tubes