The Reproductive System Flashcards
What is seminal fluid made of?
- Fructose
- Citric acid
- Bicarbonate
- Fibrinogen
- Fibrinolytic enzymes
What is the HPG axis?
hypothalamus
pituitary
Gonad organs axis
What is the spermatic cord?
-Formed at deep inguinal ring
-Contains several structures including:
Testicular artery
Pampiniform plexus (v)
Autonomic & GF nerves
Lymph vessels
Vas deferens
Do remember most of this diagram.
Y or N
What causes erection and what causes ejaculation?
- Erection due Parasympathetic stim
- Ejaculation due Sympathetic stim
Point and Shoot
What is the penis made of?
2 x Corpora Cavernosa
1 x Corpora Spongiosum
What is the male gonad?
the testes
What is the lymphatic drainage of the testes?
para-aortic lymph nodes
Are you happy with this diagram?
Y or N
What is the lymphatic drainage of the female reproductive tract?
Ovaries -> Para-aortic LNs
Uterus/Vagina -> Iliac, sacral, aortic and inguinal LNs
Are you happy with this diagram?
Y or N
Where are ovaries?
Ovaries inside peritoneal cavity (remainder outside)
What do fallopian tubes have?
cilia and spiral muscle
Where does fertilisation occur?
ampulla (wider part of Fallopian tube)
What supports the uterus?
Uterus supported by tone of pelvic floor (levator ani & coccygeus) and ligaments (broad, round, uterosacral)
Where is the endometrium shed and why?
shed at menses due to vasoconstriction of arterioles
What is 1cm lateral to cervix?
ureter
What areas are sterile of the female reproductive tract?
All areas superior to cervix are sterile (shedding, thick mucus, narrows, pH<4.5)
What are the functions of the gonads in both males and females?
Gametogenesis
Reproductive hormone production
Is a man always fertile?
yes, throughout his life
What are spermatogonia?
Undifferentiated male germ cell
Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testis
What happens to number of germ cells for both men and women across their lifetime?
What happens to spermatogonia throughout life?
- Gametogenesis begins at puberty
- Spermatogonia undergo differentiation and self-renewal -> pool available for subsequent spermatogenic cycles throughout life (continuous fertility)
How many mature sperm are formed per second?
-Produce ~1,500 mature sperm/second
What happens to oogonia throughout a woman’s life?
BEFORE BIRTH
-Multiplication of Oogonia to ~ 6 million/ovary
-Form 10 Oocytes within ovarian follicles (= primordial follicle) -These begin meiosis (halted in prophase)
-Some primordial follicles degenerate (atresia).
At birth ~2 million/ovary remain
PUBERTY
-By puberty <0.5 million/ovary remain (due further atresia)
What is gametogenesis for males?
spermatogenesis (produce mature spermatozoa)
How does spermatogenesis work?
Who determines the sex of a child?
Men
What is this?
seminiferous tubules
coiled tubes, the walls of which contain cells that produce sperm
Do you remember this diagram of the seminiferous tubules?
Y or N
What do sertoli cells do (google)?
support process of spermatogenesis
What are leydig cells (google)?
the primary source of testosterone or androgens in males
What are the reproductive hormones produced in the male gonads?
Androgens
-Testosterone
-Dihydrotestosterone
-Androstenedione
Inhibin + Activin
Oestrogens
-(from androgen aromatisation)
What does oestrogen do in males?
preserves role in bone mass and roles in sexual behaviours
What do activins and inhibins do?
inhibin inhibit FSH
activin activate FSH
What does FSH do in males (google)?
control production of sperm
What are sertoli cells?
Within seminiferous tubules
Have FSH receptors
FUNCTION:
- Support developing germ cells
- Assist movement of germ cells to tubular lumen
- Transfer nutrients from capillaries to developing germ cells
- Phagocytosis of damaged germ cells
- Hormone synthesis
- Inhibin & Activin (-ve or +ve on FSH)
- Anti-Mullerian Hormone (AMH)
- Androgen-Binding Protein (ABP)
What are leydig cells?
Between seminiferous tubules
Pale cytoplasm as cholesterol-rich
LH receptors
FUNCTION:
- Hormone synthesis…
On LH stimulation, secrete androgens: - Testosterone (oestrogens)
- Androstenedione
- Dehydroepiandrosterone (DHEA) (can be aromatised to oestrogens)
What converts testosterone to oestrogen?
androgens and aromatisation
What is gametogenesis in females?
oogenesis (produce mature oocytes)
How does oogenesis work?
What happens during the 2nd trimester of pregnancy?
In 2nd trimester of pregnancy, all Oogonia in foetus develop into 1ary Oocytes (forming primordial follicles)
What is menarche?
the first occurrence of menstruation.
What is folliculogenesis?
Follicle development
Describe folliculogenesis.
- Primordial follicle (1ary Oocyte at birth)
- Primary (=Preantral) follicle
- 1ary Oocyte and layers of granulosa cells and outer theca cells - Secondary (=Antral) follicle
- Fluid-filled cavity (antrum) develops
- FSH and LH receptors - Mature (=Graafian/Preovulatory) follicle
- Forms due to LH surge
- 2ary Oocyte formed - Ruptures surface of ovary
6-7. Corpus Luteum
- Progesterone & oestrogen (stim by LH/HCG)
- In pregnancy, progesterone & oestrogen
production taken over by placenta
What is corpus albicans?
a scar on the surface of the ovary that is a remnant of ovulation
When is menarche?
between the primary and secondary follicles
What is a mature follicle called?
Ovary
What is in an ovary?
Ovum
Follicular fluid
Remnants of last corpus luteum
Ovarian stroma
Follicles undergoing atresia
What is another way to say mature follicle?
(Sac that contain ovum)
Graafian follicle
Preovulatory follicle
What are the reproductive hormones produced by female gonads?
Oestrogens
-Oestradiol
-Oestrone
-Oestriol
Progestogens
-Progesterone
Androgens
-Testosterone
-Androstenedione
-DHEA (but not DHEAS which is made in adrenals)
Relaxin
Inhibin
What is a theca cell in the ovary?
Associated with outer part of ovarian follicles
FUNCTION:
Support folliculogenesis
Structural & nutritional support of growing follicle
Hormone synthesis
- LH stimulates synthesis of androgens
- Overactivity -> high androgen levels
hat are granulosa cells in the ovary?
Associated with inner part of ovarian follicle
FUNCTION:
Hormone synthesis
- FSH stimulates granulosa cells to convert androgens to oestrogens (by aromatase)
- Secrete Inhibin & Activin (effects on FSH)
After ovulation…
- Turn into granulosa lutein cells that produce:
Progesterone (-ve feedback, promote pregnancy by maintaining endometrium)
Relaxin (helps endometrium prepare for pregnancy and softens pelvic ligaments/cervix)
What are the gonadal/ sex steroid hormones?
Oestradiol and testosterone
Where does steroidogenesis occur?
all of steroidogenesis occurs in leydig cells
Where does steroidogenesis occur for women?
Theca and granulosa cells
Adrenals
Theca only
Granulosa only
within those they can happen in the mitochondria or SER
What is the hypothalamic-Pituitary-’Gland’ Axis for reproduction?
What is the hypothalamic-Pituitary-’Gland’ Axis for metabolism?
hypo-> pituitary-> glands/ target-> target hormones
What is the hypothalamic-Pituitary-’Gland’ Axis for lactation?
hypo-> pituitary-> glands/ target-> target hormones
What is the hypothalamic-Pituitary-’Gland’ Axis for growth?
hypo-> pituitary-> glands/ target-> target hormones
What is the hypothalamic-Pituitary-’Gland’ Axis for stress?
hypo-> pituitary-> glands/ target-> target hormones
What is the hypothalamic-Pituitary-’Gland’ Axis for water balance?
Hypothalamus-> gland/ target
What is the hypothalamic-Pituitary-’Gland’ Axis for lactation parturition?
Hypothalamus-> gland/ target
Diagram for HPG axis.
hypophyseal portal circulation
systemic circulation
How does the HPG axis work?
Prolactin binds to prolactin receptors on kisspeptin neurons in hypothalamus->
Inhibits kisspeptin release->
Decreases in downstream GnRH/LH/FSH/T/Oest->
Oligo (>35d menses) or amenorrhoea (3-6m no menses)/Low libido/Infertility/Osteoporosis
What inhibits kisspeptin?
hyperprolactinaemia (lots of prolactin)
What are the hormones of the menstrual cycle?
LH
FSH
Oestrogen
Progesterone
What does the female reproductive system prepare for?
possible fertilisation of 2ary oocyte
What is the ovarian cycle?
What causes tubular fluid reabsorption in the male reproductive tract and why does it happen?
Oestrogen
More concentrated and less volume?? (I think)
What causes nutrients (e.g., fructose) and glycoprotein secretion into epididymal fluid?
androgens
What is the voyage of the spermatozoa?
Travels 100,000 x its length from Testes to Fallopian tube
How many semen ejaculate into the cervix?
1/100
How many spermatozoa make it from cervix to ovum?
1/10000
Overall how many reach ovum?
1/1,000,000
What is carried in ejaculation?
Leukocytes
potentially viruses e.g., hep B, HIV
Spermatozoa 15-120 million/ml
seminal fluid 2-5 ml
Where does seminal fluid come from?
Small contribution from:
Epididymis/testis
Mainly from accessory sex glands:
Seminal vesicles
Prostate
Bulbourethral glands
Why is there bicarbonate in seminal fluid?
to neutralise pH in cervix
What is capacitation of sperm?
= Achieve fertilising capability in the female repro tract
- Loss of glycoprotein ‘coat’
- Change in surface membrane characteristics
- Develop whiplash movements of tail
Takes place in ionic & proteolytic environment of the Fallopian tube
- Oestrogen-dependent
- Ca2+-dependent
What is the structure of a sperm?
Head
Mid piece
Tail
acrosome (has lots of enzymes to break into egg)
nucleus
mitochondria
proximal centriole
axial filament
end piece
What is the acrosome reaction?
Sperm binds to ZP3
(= sperm receptor)
- Ca2+ influx into sperm (stimulated by progesterone)
- Release of hyaluronidase & proteolytic enzymes (from acrosome)
Spermatozoon penetrates the Zona Pellucida
What is in the oocyte during the acrosome reaction?
Where does fertilisation occur?
fallopian tube (ampulla)
What does fertilisation trigger?
Cortical reaction
Cortical granules release molecules which degrade Zona Pellucida (e.g. ZP2 & 3)
- Therefore prevents further sperm binding as no receptors
- Haploid -> Diploid
What is conceptus?
the embryo in the uterus, especially during the early stages of pregnancy.
What is the development of conceptus?
Continues to divide as it moves down Fallopian tube to uterus (3-4 days)
Receives nutrients from uterine secretions
This free-living phase can last for ~ 9-10 days
What are the phases of implantation?
attachment phase then decidualization phase
Requries progesterone domination in the presence of oestrogen
What is the attachment phase of implantation?
Attachment phase: outer trophoblast cells contact uterine surface epithelium
What is the decidualization phase of implantation?
changes in underlying uterine stromal tissue (within a few hours)
What happens if there is no pregnancy?
corpus luteum shrinks
hCG works on LH receptors to maintain corpus luteum
What does attachment need?
Leukaemia inhibitory factor (LIF) from endometrial cells stimulates adhesion of blastocyst to endometrial cells
Interleukin-11 (IL11) also from endometrial cells is released into uterine fluid, and may be involved
Many other molecules involved in process (e.g. HB-EGF)
What is decidualization?
Endometrial changes due to progesterone
- Glandular epithelial secretion
- Glycogen accumulation in stromal cell cytoplasm
- Growth of capillaries
- Increased vascular permeability (→oedema)
Factors involved:
Interleukin-11 (IL11), histamine, certain prostaglandins & TGFb (TGFb promotes angiogenesis)
What are the hormone changes and effects during pregnancy?
What is progesterone and oestrogen production like during pregnancy?
First 40 days
- Produced in corpus luteum (in maternal ovary)
- stimulated by hCG (produced by trophoblasts) which acts on LH receptors
- Essential for developing fetoplacental unit
- Inhibits maternal LH & FSH (-ve feedback)
From day 40
– Placenta starts to take over
What are the physiological increases in maternal hormones during pregnancy?
ACTH
Adrenal steroids
Prolactin
IGF 1 (stimulated by placental GH-variant)
Iodothyronines
PTH related peptides (mobilise calcium for foetus)
What are the physiological decrease in maternal hormones during pregnancy?
Gonadotrophins
Pituitary GH
TSH
Other than TSH, what in pregnancy can stimulate T3 and T4?
hCG
What is parturition?
labour
What is the endocrine control of partruition?
oxytocin
- uterine contraction
- cervical dilation
- milk ejection
myometrium and endometrial cells involved
Endocrine control of lactation.
What stimulates ejection of milk and what stimulates production of milk?
oxytocin= ejection of milk
prolactin= production of milk
