The Reproductive System Flashcards
Male germ cell levels
Gametogenesis begins at puberty
Constantly fertile as spermatogonia occurs
1500 sperm made per second d
Female gamete changes
- Before birth, multiplication of oogonia to 6 mil/ovary
- Form primary oocytes within ovarian follicles which begin meiosis (halted in prophase)
- Some primordial follicles degenerate (atresia) leaving 2 million/ovary at birth
- Due to further atresia, by puberty 0.5 mil/ovary remain
Spermatogenesis
Spermatogonium (diploid) → Primary Spermatocyte (diploid) → Secondary Spermatocyte (haploid) → Spermatids (haploid) → Spermatozoa (haploid)
Where does spermatogenesis occurr
Seminiferous tubules
These are made of tunica propria which are several layers of flattened cells
Why hormones are replaced by testes
- Androgens
- Testosterone
- Dihydrotestosterone (DHT)
- Androstenedione
- Inhibin + Activin (for FSH production regulation)
- Oestrogens
Aromatherapy converts androgen too estrogen
Sertoli cells
FSH receptors in seminiferous tubules
Makes inhibin and activin
Anti mullerian hormone which aid regression of mullerian ducts
Androgen binding proteins direct testosterone from leydig cells
How do Sertoli cells support developing germ cells
Assist in movement of germ cells to tubular lumen
Transfer nutrients from capillaries to developing germ cells
Phagocytosis of damaged germ cells
Leydig cells
Found between seminiferous tubules
LH receptors
Have a pale cytoplasm because it’s cholesterol rich
Releases testosterone androstenedione and dehydroepiandrosterone
What makes up semen
- 15-120 mil/ml spematozoa
- 2-5ml seminal fluid
- leukocytes
- potentially viruses like hep B, HIV
What path do spermatozoa take after the testis?
Into efferent ducts where tubular fluid is reabsorbed induced via estrogen
Then Exeter epididymis where nutrients and glycoproteins are this is induced by androgen
Oogenesis
Oogonium (diploid) → Primary Oocyte (diploid) → Secondary Oocyte (haploid) → Ootids (haploid) → Ova (Ovum singular) (haploid)
Polar bodies
Small haploid cells with virtually no cytoplasm as oocyte cytoplasm doesn’t divide evenly- they undergo apoptosi
Describe the steps involved in folliculogenesis
1) Primordial follicle (primary oocyte at birth)
2) Primary (aka preantral) follicle → primary oocyte and layers of granulosa and outer theca cells
3) Secondary (aka antral) follicle → fluid-filled cavity (antrum) develops
4) Mature (aka Graafian/preovulatory) follicle → secondary oocyte formed
5) Ruptured follicle, ruptures surface of ovary
6) Corpus Luteum → produces progesterone and oestrogen (stimulated by LH/hCG) and in pregnancy, production of these is taken over by placenta
When does mature follicle for
During LH surge
- What reproductive hormones are produced by the ovaries?
Oestrogens
Oestradiol
Oestrone
Oestriol
Progestogens
Progesterone
Androgens
Testosterone
Androstenedione
DHEA (not the DHEAS made in adrenals)
Relaxin
Inhibin
Granulosa cells
Associated with inner ovarian follicles
FSH receptors
Stimulates androgen conversion into oestrogen
After ovulation turn into granulosa lutein cells which. Make progesterone and relaxin
What does progesterone do
(-ve feedback, promote pregnancy by maintaining endometrium)
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What does relaxin do
helps endometrium prepare for pregnancy and softens pelvic ligaments/cervix)
Theca cells
Outer part of ovarian follicles
LH receptors
Support folliculogenesis by structural and nutritional support
Overactivity of theca cells
Hyperadrogenism due to PCOS
What are two made gonadal hormones
Oestradiol
Testosterone
Hypothalamic pituitary gonadal axis
Kisspeptin neurones release kisspeptin→ GnRH (Gonadotrophin releasing hormone) (travels down Hypophyseal-Portal Circulation to the Anterior Pituitary)→ LH/FSH (released from Gonadotrophs of anterior pituitary)→ Gonads (target glands)→ oestrogen/progesterone/androgen (target hormones)
How does hyperprolactinaemia affect the pathway
Prolactin binds to prolactin receptors on kisspeptin inhibiting it’s release
Leads to oligomenorrhoea or amenorrhea low libido infertility or osteoporosis
What kind of release does GnRH and FSH + LH have
Pulsatile release
Can GnRH be detected in blood tests?
No, because it is only released locally into the hypophyseal circulation and not the systemic circulation
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Capacitation of sperm
Loss of glycoprotein coat
Change in surface membrane characteristics
Develop whiplash movements of tails
Oestrogen dependent
Ca2+ dependent
Acrosome reaction
Sperm binds to ZP3
Calcium influx into sperm stimulated by progesterone
Release of hyaluronidase and proteolytic enzymes
Spermatazoon penetrates zona pellucida
Implantation
Attachment phase where outer trophoblast cells contact uterine surface epithelium and then decidualisation phase where changes in underlying uterine stromal tissue occur
Needs progesterone domination
What promotes attachment
Leukaemia inhibitory factor from endometrial cells stimulates adhesion of blastocyst to endometrial cells
Interleukin 11 is released into uterine fluid
What is the substrate for oestrogen
DHEAS made by mother and fetus
Endocrine control of lactation
Stimulation causes hypothalamus to be activated and pituitary causes neurohypophysis which releases oxytocin and adenohypophysis releases prolactin
How does deciduoaistaion change due to progesterone
Glandular epithelial secretion
Glycogen accumulation in stromal cell cytoplasm
Growth of capillaries increases the nutrients available to a potential implanted embryo
Increased vascular permeability (→ oedema) to increase nutrients and O2 going to potential implanted embryo
What 4 factors are involved in decidualisation phase
- IL-11
- Histamine,
- Prostaglandins
TGFbbeta which promotes angiogenesis
the first 40 days how is progesterone and oestrogen produced during pregnancy?
Produced in corpus luteum
Stimulated by hCG (which is produced by trophoblasts) which act on LH receptors of corpus luteum (since hCG is similar to LH)
Essential for developing fetoplacental unit
Inhibits LH and FSH so no periods
From 40 days onwards how is progesterone and oestrogen produced
By placenta
Main substrate is DHEAS made by mother and fetus
What (6) maternal hormones increase in pregnancy?
- ACTH, meaning raised urinary free cortisol (UFC)
- Adrenal steroids
- Prolactin- suppresses HPG axis
- IGF-1 (Stimulated by placental GH)
- Iodothyronines due to increased requirement- driven by hCG which has same alpha subunit as TSH- leads to lower TSH
- PTH related peptides- produced mainly in breast tissue and can increase Ca2+ for foetal skeleton
What (3) effects does oxytocin have on pregnant women (What processes does oxytocin stimulate during parturition)?
- Uterine contraction- with increased numbers of oxytocin receptors in late pregnancy
- Milk ejection
- Cervical dilation
Name a condition related to milk production, that hyperprolactinaemia can cause?
You get excess milk production and can get galactorrhoea- leaking of milk even outside of pregnancy
Male reproductive system
Testes make sperm and testosterone
Epididymis stores and matures sperm as well as absorbing fluid to concentrate sperm
Seminal vesicles make seminal fluid which nourishes sperm
Vas deferens transports mature sperm from epididymis to urethra during ejaculation
Female reproductive
The ovaries produce eggs (ova) and hormones such as estrogen and progesterone. The fallopian tubes (oviducts) capture the released egg during ovulation and provide a site for fertilization to occur. Ovulation is indeed triggered by a surge in luteinizing hormone (LH). If fertilization does not occur, the thickened lining of the uterus (endometrium) is shed during menstruation, along with the unfertilized egg.
Human placental lactogen
Made by placenta and modulates maternal metabolism to provide nutrients for fetus eg causes insulin resistance so more insulin is circulating for fetus
