Reproductive System Flashcards
sperm production facts
- 300 million per day
- constant fertility post puberty, gradual decline with age
- 1500 sperm/second
oocyte production facts
- 7 million follicles at birth
- 400 ovulate
- 0 follicles at menopause
relative size of egg and sperm
sperm is the smallest cell in the body, whereas egg is the largest
hierarchal arrangement of the neurons between the pituitary and the hypothalamus allows for…
signal amplification
function of the gonads (ovaries, testes)
- produce gametes
2. produce reproductive hormones
the hypothalamus sends ____________ neurons to the posterior pituitary, where it releases _________ which is made in the __________ and affects ________ organs.
___________ neurons within the hypothalamus release ______ into _______ vessels which lead into the anterior pituitary, stimulating the release of __________ (___ and __). These hormones stimulate ___________ in males and ___________ in females.
the hypothalamus sends neurosecretory neurons to the posterior pituitary, where it releases oxytocin which is made in the hypothalamus and affects target organs.
Neuroscretory neurons within the hypothalamus release GnRH into portal vessels which lead into the anterior pituitary, stimulating the release of gonadotrophins (LH and FSH). These hormones stimulate spermatogenesis in males and oogenesis in females.
4 water soluble, peptide and protein, reproductive hormones and their sites of secretion
- GnRH - gonadotrophin releasing hormone, which is released from the hypothalamus
- FSH - follicle-stimulating hormone, which is released from the anterior pituitary
- LH - Luteinising hormone, which is released from the anterior pituitary
- Oxytocin, which is made in the hypothalamus but released at the posterior pituitary
3 lipid soluble, steroid reproductive hormones and their sites of secretion
- androgens, which are released from the testes
- Oestrogens, which are released from the ovaries
- progestagens, which are released from the ovaries
how are lipid soluble hormones transported?
transport proteins
steroid hormones made from?
cholesterol
2 androgens and their differences
- testosterone
2. 5α dihydrotestosterone (more active)
3 oestrogens and their differences
- oestradiol
- oestrone (weaker)
- oestriol
oestradiol is active during which stage of a girls life? (how does it compare to oestrone)
puberty through to menopause.
Oestradiol is a weaker oestrogen
oestriol
produced by the placenta
softens the cervix to prepare for birth
progestogens
PROGESTERONE (menstrual cycle and pregnancy)
Neurosecretory cells of the posterior pituitary
NEUROHYPOPHYSIS
- hormones synthesised in the hypothalamus
- carried down the axon
- stored in secretory vesicles in the posterior pituitary
- nerve impulse leads to exocytosis
- OXYTOCIN or ADH released into the blood from the posterior pituitary
effects of oxytocin
- smooth muscle contraction
- milk ejection
- contraction of the uterus during childbirth (used to induce labour)
ADH
water retention in the kidneys
neurosecretory cells involved with the anterior pituitary
ADENOHYPOPHYSIS
- Don’t leave the hypothalamus, release hormones (GnRH) into hypophyseal portal vessels
- Hormones act on the gonadotrophs of the anterior pituitary to release FSH and LH
somatotrophs, lactotrophs, thyrotrophs, and corticotrophs are all…
secretory cells
why does the hypothalamus release GnRH into hypophyseal portal vessels?
if it was diluted in the blood stream it wouldn’t be effective
neurosecretory neurons
can conduct a nerve impulse, synthesis and carry and release neurosecretory hormones
true/false
“the reproductive system only has single positive hormone”
TRUE
= GnRH
how do hypothalamic secretions release?
Pulsatile release.
secretions occur in discrete bursts, separated by periods of little or no secretion.
Prevents desensitisation and down-regulation
LH effect on Males vs. females
Male: stimulates production of testosterone
Female: secretion of female sex hormones and stimulate ovulation
FSH effect on Males vs. females
Male: growth of spermatozoan
Female: growth of ovarian follicles
negative feedback effect of sex hormones
inhibit hypothalamus from releasing GnRH and inhibit Anterior pituitary from releasing FSH and LH
true/false
females produce no androgens and Males produce no oestrogens
false. they produce some
key properties of androgens in males
- Male sex development
- spermatogenesis
- sexual behaviour
- muscle development
site of oestrogen production
granulosa cells of the growing follicle
key properties of oestrogens
- female sex development
- growth of the endometrium
- regulation of the menstrual cycle
- bone growth
True/false
Males make some progestagens
False. only females produce progestagens
Progesterone released by the _______ ________ and the _________. Associated with preparations for _________ and its maintenance.
Progesterone released by the corpus luteum and the placenta. Associated with preparations for pregnancy and its maintenance.
Vagina features
- 7.5-9cm elastic muscular tube
- receives the penis
- holds spermtazoa
- lower portion of the birth canal
- passageway for the elimination of menstrual fluids
uterus features
- 30-40g
- sperm transport pathway
- mechanical protection, nutritional support and waste removal for the developing embryo/fetus
- muscular wall (myometrium) for ejecting the fetus
2 zones of the uterus endometrium
- inner functional zone (stratum functionalis) - contains uterine glands
- outer basilar zone (stratum basalis) - attaches the endometrium to the myometrium
uterine (fallopian) tubes features
- fertilisation in the ampulla
- rich, nutritive environment (lipids and glycogen) for spermatozoa, oocyte and the developing embryo
- ciliated and non-ciliated secretory columnar cells
transport along the fallopian tube involves
both ciliary movement and peristaltic contractions
3 distinct regions of the ovaries
- outer ovarian cortex - contains ovarian follicles
- central ovarian medulla - ovarian stroma and steroid producing cells
- inner hilum (hilus) - point of entry for nerves and blood vessels
source of menstrual flow
endothelium
ectopic pregnancy
fertilised embryo implants into tissue other than uterine wall. Most occur in the uterine tube. Risk factors include: smoking, age, and prior tube damage
Basilar zone
where the endometrium meets the myometrium
outside of the uterus
the fundus of the uterus
primordial follicle
the oocyte, surrounded by a single layer of flat follicular cells
flat follicular cells surrounding the oocyte develop into the…
granulosa cells
primary follicle / pre-antral follicle
follicles grow.
immature primary follicles have just one layer of granulosa cells.
With FSH, some follicles get larger, producing many layers of granulosa cells.
zona peillucida
translucent, acellular layer, surrounding and secreted by the oocyte
Thecal cells
condensation of stromal cells
secondary follicle / antral follicle
granulosa cells produce a viscous follicular fluid that coalesces to form a single follicular antrum.
when a primary follicle develops into a secondary follicle, the theca develops into
- THECA INTERNA - inner glandular, highly vascular
2. THECA EXTERNA - fibrous capsule
cumulus oophorus
mass of loosely associated granulosa cells
Graafian follicle also known as…
mature follicle
mature follicle / pre-ovulatory
Antrum grows and the oocyte becomes suspended in fluid, connected to the rim of the granulosa cells by a thin stalk of cells
ovulation
- the follicle increases to the correct size and is in the correct position
- bulges out from the ovarian surface
- follicle ruptures, carrying the oocyte and the cumulus cells with it
- oocyte collected by the cilia on the fimbria
- cumulus mass swept down the uterine tubes
what happens to the antrum and the basement membrane between the granulosa and thecal layers, after ovulation?
they breakdown and blood vessels invade
lutenisation
after ovulation, granulosa cells form large lutein (yellow pigment) cells = CORPUS LUTEUM
hormones released by the corpus luteum?
progestagens
Corpus albicans
whitish scar tissue which remains after luteinisation and is absorbed back into the stromal tissue
corpus luteum lifespan without fertilisation
2 weeks
human chorionic gonadotrophin (hCG)
- released by the chorion of the embryo (8 days after fertilisation)
- rescues the corpus luteum from degeneration
- presence in urine = pregnancy test
two phases in the ovarian cycle (day 1 - ovulation)
- follicular phase (day 1 - menstruation) VARIABLE TIME
2. luteal phase ~14 days CONSTANT (ovulation - menstruation)
three phases of the endometrial cycle
- menstrual
- proliferation
- secretory
what happens when the there is a high level of oestrogen?
POSITIVE FEEDBACK EFFECT on the hypothalamus and anterior pituitary, thereby increasing secretion of GnRH and LH
10 steps of the menstrual cycle
- corpus luteum regresses, oestrogen and progesterone levels are low, increased FSH
- FSH stimulation leads to increased follicular growth
- day 6-7 there is selection of dominant follicle with increased oestrogen levels
- Oestradiol suppresses FSH and LH production in the pituitary
- Oestrogen levels rise, by day 12, a threshold concentration of oestradiol is exceeded. If this is maintained for 36 hours, there is a temporary switch from a negative to positive feedback
- Oestrogen-mediated positive feedback triggers a rise in GnRH leading to an LH surge
- LH surge induces ovulation
- corpus luteum develops, see increased progesterone
- elevated progesterone levels inhibit GnRH, lead to decreased FSH and LH
- demise of the corpus luteum
sex determining region is found on the ___ chromosome and provides a pathway for _____ to develop. Also known as the _____ gene. In the absence of the _____ gene the embryo develops into a ______ .
sex determining region is found on the Y chromosome and provides a pathway for testis to develop. Also known as the SRY gene. In the absence of the SRY gene the embryo develops into a female .
development of male internal genitals
- Presence of SRY gene
- testis form from bipotential gonad
- leydig cells release testosterone
- Wolffian duct develops into internal male genitals
- sertoli cells in the testis release Anti-mullerian hormone
- AMH causes Mullerian duct regression
development of female internal genitals
- absence of SRY gene
- Bipotential gonad becomes ovary
- oestrogens and progestagens released
- mullerian ducts develop into internal female genitals
- wolffian duct regresses (10 weeks)
epididymis, vas deferens, and seminal vesicles develop from
wolffian ducts
fallopian tubes, uterus, cervix and upper vagina develop from
mullerian ducts
_________ must be imposed against an inherent trend towards _________
musculanity must be imposed against an inherent trend towards femaleness
forming the shaft of the penis
fusion of the urethral tube
forming the scrotum
SCROTALISATION
fusion of the labioscrotal swellings
forming the glans penis
genital tubercle expands
forming labia minora and majora
urethral folds remain separate to form the labia minora and the labioscrotal swellings remain separate to form the labia majora
external genitalia formation without androgen? what can cause this?
external genitalia will appear female. Caused by a mutation in the androgen receptor gene.
reproductive system during childhood (prepuberty)
asleep. plasma levels of gonadotrophs are very low during childhood
two changes at puberty as a result of hormonal changes
- behavioural changes
2. physical changes
endocrine changes during puberty
- GnRH increase during sleep
- leads to LH and FSH increase
- sex steroid levels rise
endocrine changes in late puberty
daytime LH pulses increase
Tanner stages (what it is? why it is?)
sequence in which events of puberty should occur. Allows abnormalities to be detected.
GROWTH SPURT
stimulated by ______ hormones (________ and _______), with _______ closure (bony ends) by ________. In boys it occurs ___ years ______ girls but boys have a _______ peak.
GROWTH SPURT
stimulated by steroid hormones (androgen and oestrogen), with epiphyseal closure (bony ends) by oestrogen. In boys it occurs 2 years after girls but boys have a higher peak.
female stages of puberty
- breast development begins
- pubic hair
- height spurt
- menarche
male stages of puberty
- testicular enlargement
- pubic hair
- penile enlargement
- height spurt
menarche
- beginning of menstrual bleeds
- critical weight ~47kg must be reached (withstand pregnancy)
- first ovulation 6-9 months later
- not regular for 1-2 years
Puberty in boys aged __ and girls aged __ is too young and is alarming. Puberty is late if it has not begun by age __ in boys and __ in girls.
Puberty in boys aged 9 and girls aged 7 is too young and is alarming. Puberty is late if it has not begun by age 14 in boys and 13 in girls.
reasons puberty onset may be late / non-existant
gonadotrophin signals are inadequate
early puberty onset maybe because of…
GnRH dependant problem due to CNS lesion or injury
menopause is a consequence of? occurs at what age?
consequence of ovaries running out of follicles, occurs between age 50-52
regular menstruation - irregular menstruation period called…
pre-menopause
irregular menstruation - last bleed period called…
menopausal transition
last bleed called
menopause
no activity in the ovaries called
ovarian senescene
True/false
ovaries are inactive after menopause
false
peri-menopause
starts when irregular menstruation begins and ends when activity in the ovaries stops
activity in the ovaries stops
1-2 years after menopause
in ovary senescene, what happens to oestrogen production?
reduced to 1/10.
stromal cells of the adipose tissue produce oestrone (weaker)
vasomotor symptoms of perimenopause
- hot sweats
- night sweats
genitourinary symptoms of perimenopause
- atrophic changes
- vaginal dryness
bone metabolism symptoms of perimenopause
- osteoporosis
behavioural/psychological symptoms of perimenopause
- depression, tension, anxiety, mental confusion
- loss of libido
how are the symptoms of perimenopause combated?
oestrogen treatment
what is the main reason for the symptoms most women experience during perimenopause?
oestrogen deprivation
spermatogenesis begins
post puberty
sperm production per gram testis per second
300-600
5 phases of spermatogenesis (including chromosome numbers)
- spermatogonium stem cells (2n)
//mitosis//
[1 daughter cells remains as stem cell]
- primary spermatocyte (2n)
//meiosis I//
- 2x secondary spermatocyte (n)
//meiosis II//
- 4x spermatids (n)
//cyto-differentition//
- 4 x sperm cell (n)
another name for sperm cell
spermatazoon
excess cytoplasm from sperm cells forms the ______ ______ which is phagocytosed by ______ cells.
excess cytoplasm from sperm cells forms the residual body which is phagocytosed by sertoli cells.
leydig cells
endocrinocyte - hormone release
spermatogonia move between ______ cells from ________ _________ to the _______ ________, where they become _________ __________.
spermatogonia move between sertoli cells from basal compartment to the adluminal compartment, where they become primary speratocytes.
true/false
spermatogonia don’t develop into sperm without testosterone
true
sertoli cells secretes androgen binding protein because…
keeps testosterone levels high in the seminiferous tubules (otherwise it would diffuse away).
DHT potency vs testosterone
dihydrotestosterone is twice as potent
secondary sexual characteristics
DHT and testosterone
- libedo
- hair growth
- baldness
- agressiveness
Leydig cells found?
outside seminiferous tubules
testosterone production
- GnRH from hypothalamus to anterior pituitary
- anterior pituitary releases LH
- leydig cells bind LH
- Leydig cells stimulated to produce testosterone
spermatogenetic cells can undergo spermatogenesis when…
testosterone and FSH present
Acrosome of sperm
compartment filled with enzymes to penetrate the egg
midpiece of sperm contains
mitochondria - energy production
tail of sperm
flagellum, very long
Intracytoplasmic sperm injection
ICSI
- a single sperm is captured and injected into an oocyte using microfine pipettes
- sperm doesn’t need to be motile
- can use sperm collected by biopsy from the testes
In vitro fertilisation
IVF
- oocytes harvested and fertilised ex vito
- require 50,000 motile sperm
reason for a suction pipette in ICSI
to hold the oocytes steady when injecting the single sperm
oligospermia
reduced sperm count (less than 20 million per mL)
azoospermia
no sperm
3 things that might make a male infertile
- oligospermia
- azoospermia
- sperm may be immotile - can’t swim
Inguinal canal
connects scrotum and pelvic cavity
cremaster muscle
encases nerves, vessels, vas deferens, etc. to the testes
RAPHE
external line down the middle of the scrotum
scrotal septum
internal separation between each testis
spermatic cord
encases the cremaster muscle
cryptorchidism
testes are supposed to descend to the scrotum at ~7 months.
when they don’t descend = cryptorchidism
fertility of cryptorchid individuals
infertile
path taken by sperm, post production
- produced in the seminiferous tubules
- move to the rete testis
- move to the epididymis
- to the vas deferens
function of vas deferens
major site of storage (several months)
2 functions of the head of the epididymis
- stimulates sperm to move flagellum and become motile (10-14 days)
- absorption of fluid around sperm – concentrates sperm
peritoneum of the testis
tunica vaginalis
tunica albuginea
tough, white connective tissue which divides the testis into 200-300 lobules
1 lobule contains __ seminiferous tubules
2-3
what 4 things are present in the mucoid (sticky) substance that seminal vesicles secrete, and what do they do?
- alkaline (neutralise female acidity)
- fructose (energy source)
- prostaglandins (aid sperm motility and viabiltiy, may induce contractions of cervix)
- clotting proteins (sticky and viscous)
vas deferens over or under the bladder?
over the bladder
length of vas deferens and spongy urethra = total length travelled by sperms =
45cm vas deferens + 20cm urethra
= 65cm
where does the ejaculatory duct start from and whee does it join the urethra
starts at the end of the vas deferens and joings urethra at the prostate
swollen end of the vas deferens called
ampulla
what ‘washes’ sperm down the urethra
seminal vesicle fluid
prostatic fluid includes
- citrate (ATP)
- acidic (pH 6.5) - neutralized by alkaline seminal vesicle fluid
- milky colour (phosphates and calcium)
- PSA (prostate specific antigen) and other proteases to break down coagulum
Bulbourethral gland AKA Cowper’s gland
neutralises acidic urine
body of penis
- corpora cavernosa x2
- the main erectile tissue - corpus spongiosum penis
- surrounds penile urethra and prevents occlusion - spongy (penile) urethra
- conducts semen and urine
percentage composition of semen / ejaculated fluid
10% sperm
60% seminal vesicle fluid
30% prostatic fluid
overall pH semen
7.5
erection (following sexual stimulation ;) )
- release of NO and Prostaglandin E1
- smooth muscle of the corpora cavernosa relaxes
- blood fills cavernous spaces of the corpora cavernosa
- engorgement of the corpora cavernosa reduces venous outflow, adding to the engorgement
erect penis has __x blood volume of a flaccid penis
8
elevated levels of PSA is an indicator of
prostatic overgrowth
prostatic cancer treatments
- androgen reduction
- inhibit testosterone action
- remove prostate (prostatectomy)
relaxation of the ______ muscle of the corpora __________ requires ____________ _____________ (________) which is a secondary messenger that _______ intracellular calcium. The enzyme _____________ breaks down GMP, therefore preventing relaxation and preventing an _________.
relaxation of the smooth muscle of the corpora cavernosa requires guanosine monophoshate (cGMP) which is a secondary messenger that reduces intracellular calcium. The enzyme phosphodiesterase breaks down GMP, therefore preventing relaxation and preventing an erection.
viagra (sidenafil)
- inhibits phosphodiesterase
- cGMP levels rise
- relaxation of arteries supplying blood to the corpora cavernosa
- erection
- skux
incidence of benign prostatic hyperplasia in men over 85
90%
treatment for BPH
- 5α-reductase inhibitors
- surgery
2 5α-reductase inhibitors and what they do
- finasteride
- dutasteride
- they stop the prostate enlarging/shrink it
3 methods to reduce androgen
- 5α-reductase inhibitors - finasteride
- castration - remove testes
- inhibitors of androgen synthesis (testes)
adenohypophysis
anterior pituitary
neurohypophysis
posterior pituitary
to what, does the sperm bind during fertilisation
zona pellucida
