The reproductive system and sex hormones Flashcards
What does seminal fluid contain?
Bicarbonate and fructose.
What is the function of bicarbonate in seminal fluid?
Neutralise acidic environment in female vagina.
What does the spermatic cord contain?
Testicular artery, lymph vessels and vas deferens.
What is the function of vas deferens?
Carry sperm from testes to penis.
What nerves result in an erection? How does it result in an erection?
Parasympathetic. Dilates arteries in penis. More blood and less venous drainage leads to an erection.
What nerves result in ejaculation?
Sympathetic nervous system.
What lymph nodes drain lymph from testes and ovaries?
Para aortic lymph nodes.
What lymph nodes drain uterus and vagina?
Sacral and para aortic lymph nodes.
How are fallopian tubes adapted?
Contain cilia and spiral muscle. Waft egg.
Where does fertilisation occur?
Ampulla (widest part of fallopian tubes).
What causes endometrium to shed?
Vasoconstriction of arteries supplying it due to drop in progesterone.
What part of the female reproductive system is not sterile?
Vagina
What part of the female reproductive system is sterile?
Superior to cervix.
Where is sperm produced in the testes?
Seminiferous tubules.
What are the two main cells in the seminiferous tubules?
Leydig cells (between seminiferous tubules) and sertoli cells.
What are some androgens?
Testosterone, androstenedione and DHT.
What does inhibin do?
Suppresses FSH.
What does activin do?
Stimulates FSH.
What is a germ cell?
Cell that gives rise to gametes
What receptors do sertoli cells contain?
FSH receptors.
What do sertoli cells do? How do they do it?
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
What hormones do sertoli cells produce?
Inhibin and activin. Anti-mullerian hormone. Androgen binding hormone.
What receptors do leydig cells contain?
LH receptors.
What is the function of leydig cells?
Hormone synthesis.
Why are leydig cells pale?
Cholesterol rich.
What stimulates hormone synthesis in leydig cells?
LH binding to leydig cells.
What are some hormones produced by leydig cells?
Testosterone, androstenedione.
What are polar bodies?
Cytoplasmic structures shed during meiotic division during oogenesis.
What is menarche?
First menstrual period.
When does 2nd meiosis division and differentiation of oocytes occur?
After sperm fusion.
Simple pathway for folliculogenesis?
Ovarian follicle to oocyte to corpus luteum.
Describe folliculogenesis?
Primordial follicle to primary follicle. Primary follicle contains layers of granulosa and theca cells. Development of secondary follicle; contains fluid filling cavity, FSH and LH receptors. Surge of LH results in development of mature follicle. Follicle ruptures allowing ovum to leave. Formation of corpus luteum which produces progesterone and oestrogen.
What is secreted after fertilisation to keep corpus luteum alive?
hCG.
What does the female hormome relaxin do?
Relaxes muscles during pregnancy.
What do theca cells do?
Provides structural support of growing follicle. Androgen synthesis.
What stimulates theca cells?
LH stimulates theca cells to produce androgens.
What do overactive theca cells result in?
High androgen.
What occurs in granulosa cells?
Aromatisation.
What stimulates granulosa cells?
FSH.
How do granulosa cells regulate FSH?
Secretion of inhibin and activin.
What occurs to granulosa cells after ovulation?
Formation of corpus luteum. Granulosa lutein cells inside the corpus luteum produce the hormone progesterone which maintains the endometrium. They also produce relaxin.
What happens to the Hypothalamic-Pituitary-Gonadal (HPG) Axis during ovulation?
Switch to positive feedback due to rise in oestrogen.
What hormones part of Hypothalamic-Pituitary-Gonadal (HPG) Axis can you not measure in blood and why?
Kisspeptin and GNRH. Part of local circulation; present in too little concentration in systemic circulation.
Describe Hypothalamic-Pituitary-Gonadal (HPG) Axis
Kisspeptin stimulates GnRH release; this occur in the hypothalamus. GnRH acts on gonadotrophs in anterior pituitary gland to produce LH and FSH. LH and FSH target gonads. Gonads produce oestrogen, progesterone and androgens; inhibit LH/FSH and GnRH release.
How is GnRH, LH and FSH released?
Pulsatile release.
Explain Hypothalamic-Pituitary-Gonadal (HPG) Axis in hyperprolactinaemia.
Prolactin inhibits kisspeptin. Decrease in downstream hormones - GnRH, FSH, LH, Testosterone, oestrogen.
Symptoms of hyperprolactinaemia
Amenorrhoea, low libido and osteoporosis.
How do you check if a woman has ovulated?
Day 21 progesterone test (High = has ovulated). Ultrasound.
Where does seminal fluid come from?
Seminal vesicles, prostate, bulbourethral glands.
What is capacitation?
Prerequirement for fertilisation.
Process of sperm capacitation
Loss of glycoprotein coat. Develop whiplash movements of tail.
What is required for sperm capacitation?
Calcium and oestrogen.
Describe the acrosome reaction
Sperm binds to ZP3 receptor on ovum. Ca2+ influx into sperm stimulated by progesterone. Release of proteolytic enzymes from acrosome that break down glycoprotein coat around ovum. Sperm can now penetrate zona pellucida.
What occurs in fertilisation?
Haploid to diploid. Triggering of cortical reaction.
Describe the cortical reaction
Cortical granules release molecules which degrade zona pellucida. Prevents further sperm binding as no receptors.
Pregnancy that implants in fallopian tube
Ectopic pregnancy.
Describe embryo migration after fertilisation but before implantation? Describe what is occurring while it’s migrating.
Moves down fallopian tube to uterus and continues to divide. Receives nutrients from uterine secretions
What hormones are required for implantation?
Progesterone domination in presence of oestrogen.
What happens in decidualisation phase of implantation?
Changes in endometrium stromal tissue.
What factors mediate adhesion? Where are these factors released from?
Endometrial cells release leukaemia inhibitory factor and interleukin 11.
What does leukaemia inhibitory factor do?
Stimulates adhesion of blastocyst to endometrial cells.
What hormone results in decidualisation?
Progesterone.
What changes occur in the endometrium during decidualisation?
Glandular epithelial secretion. Glycogen accumulation in stromal cell cytoplasm. Growth of capillaries. Increased vascular permeability which leads to oedema.
What factor is involved in changes to endometrium?
IL11.
What does hCG stand for?
Human chorionic gonadotrophin.
In the first 40 days of pregnancy where is progesterone and oestrogen produced?
Corpus luteum.
What hormone stimulates corpus luteum to produce progesterone for the first 40 days of pregnancy? What receptors does it act on?
hCG. Acts on LH receptors.
In the first 40 days of pregnancy, production of progesterone and oestrogen inhibits what hormones?
FSH and LH.
After 40 days of pregnancy, what takes over from corpus luteum for progesterone and oestrogen production?
Placenta.
What maternal hormones are elevated during pregnancy?
ACTH, Adrenal steroids, Prolactin, IGF1, T3 and T4, PTH related peptides.
What stimulates production of T3 and T4 in pregnancy?
hCG.
What maternal hormones are lowered during pregnancy?
FSH and LH. GH and TSH.
Why may a prolactinoma increase in size during pregnancy?
Due to high oestrogen levels.
Main hormone in partruition?
Oxytocin.
Oxytocin effects for partruition?
Uterine contraction, cervical dilation and milk ejection.
What is primary amenorrhea?
Never had a period
What is secondary amenorrhea?
Had periods but stopped.
What occurs in puberty?
Production of sex steroids. Development of secondary sexual characteristics. Attain capability to reproduce.
How is puberty graded in girls?
Breast development.
How is puberty graded in boys?
Testicular volume.
What does the ‘arche’ suffix stand for?
Onset of.
What is gonadarche?
Activation of gonads by the HPG axis.
What is thelarche?
Breast development starts.
What is adrenarche?
Adrenal androgen production starts
Which sex is more dependent on adrenal androgen production?
Female
Main adrenal androgens?
Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS).
What is the main hormone result in development of secondary sexual characteristics in woman?
Oestradiol.
What is the main hormone result in development of secondary sexual characteristics in men?
Testosterone.
What is the first characteristic to develop in female puberty?
Breast development.
What is the first characteristic to develop in male puberty?
Increase in testicular volume
Onset of puberty boys vs girls?
Boys is one year later.
How is GnRH secretion through life?
High in late fetal stage. Supression of GnRH during childhood. Reactivation of GnRH secretion in puberty. Normal pulsatile GnRH secretion in adult.
Puberty range of girls?
8-13 years.
Puberty range of boys?
9-14 years.
What is oligo-menorrhoea?
Few periods.
When does the follicular phase occur in the menstrual cycle?
Before ovulation.
When does the luteal phase occur in the menstrual cycle?
After ovulation once the corpus luteum has formed.
Describe the follicular phase?
FSH rises causing growth of follicles. Follicles produce oestradiol and inhibin B. Inhibit FSH by negative feedback and only dominant follicle (the largest) survives. Smaller ones die.
Oestradiol continues to increases and there is a switch to positive feedback due to high oestradiol causing a surge in LH which causes ovulation.
Describe the luteal phase
Formation of corpus luteum after ovulation. Corpus luteum secretes progesterone and oestradiol.
Phases of endometrium cycle?
Menstrual phases, proliferative phase, secretory phase.
What occurs in the menstrual phase of the endometrium cycle?
Shedding of endometrium.
What occurs in the proliferative phase of the endometrium cycle?
Growth of epithelial cells and increase in arterioles due to high levels of oestradiol.
When is the proliferative phase of the endometrium cycle?
Just before ovulation.
What occurs in the secretory phase of the endometrium cycle?
Endometrial glands secrete glycogen. Increase volume of stromal cells produce thick lining.
What happens if you administer GnRH in a continuous non pulastile manner?
Decreased FSH/LH secretion.
Why does GnRH secretion decrease in luteal phase?
Due to progesterone and oestradiol release from corpus luteum.
What is hypogonadism in men and woman?
Reduced testosterone in men and reduced oestrogen in woman.
What does primary hypogonadism signal?
Problem with testes or ovaries.
What does secondary hypogonadism signal?
Problem with pituitary or hypothalamus.
Biomarkers of primary hypogonadism?
High LH/FSH. Low oestradiol/testosterone.
Causes of primary hypogonadism in men?
Mumps infection. Trauma to testes.
What is another name for secondary hypogonadism?
Hypogonadotrophic hypogonadism.
Causes of secondary hypogonadism?
Pituitary tumour and high prolactin.
Secondary hypogonadism biomarkers?
Low LH/FSH and low oestradiol/testosterone.
When does menopause occur?
45-55 years old.
What kind of hypogonadism if menopause?
Primary hypogonadism.
Menopause biomarkers?
Low oestradiol, High LH/FSH, Low inhibin, Low anti mullerian hormone.
Symptoms of menopause?
Skin dryness, Hot flushes, Osteoporosis, Decreased libido.
Menopause treatment?
Menopausal hormone therapy.
How does menopausal hormone therapy work? What is administered?
Oestrogen replacement to help with symptoms. Stimulates endometrium proliferation so progesterone need to be added to prevent endometrial cancer.
What is anti mullerian hormone used for?
Ovarian reserve marker.
What is premature ovarian insufficiency?
Early menopause.
Biomarkers for premature ovarian insufficiency?
High FSH.
Causes of premature ovarian insufficiency?
Autoimmune, turner syndrome, radio or chemotherapy.
Active form of testosterone?
Free testosterone (unbound).
Bioavailable form of testosterone? Why is it bioavailable?
Albumin bound testosterone. Weakly bound so testosterone can unbound.
Unavailable form of testosterone? Why is it unavailable?
Testosterone bound to sex hormone binding globulin. Strongly bound.
How do androgen levels change in older men?
Total testosterone stays constant. SHBG increases and therefore free testosterone decreases.
Why does testosterone need to be measured before 11am?
Testosterone has a diurnal rhythm. You want to measure when the hormone is meant to be secreted.
Why does testosterone need to be measured while fasting?
Increase in blood glucose causes a drop in testosterone.
Low testosterone symptoms in men?
Reduced libido, erectile dysfunction and loss of muscle mass.
What enzyme converts testosterone to DHT?
5-alpha reductase.
Where is testosterone converted to DHT?
Scalp and prostate.
Where is testosterone converted to oestrogen?
Adipose tissue.
Aromatase inhibitor example?
Anastrozole.
5-alpha reductase inhibitor example?
Finasteride.
How is DHT different to testosterone?
More potent ligand for androgen receptor and can’t be converted to oestrogen.
What is decidualisation?
Decidualization refers to the functional and morphological changes that occur within the endometrium to form the decidual lining into which the blastocyst implants.
