WH: Reproductive System + Physiology Flashcards
At how many weeks does fetal heart beat start?
6 weeks
What type of hormone is oestrogen? produced where? in response to what?
oestrogen is a steroid sex hormone produced by the ovaries in response to LH + FSH
What is the most common form of oestrogen?
17-beta oestradiol
What type of hormone is progesterone? produced where?
progesterone is steroid sex hormone produced by the corpus lute after ovulation
What type of hormone is LH? produced from where? under the influence of what? and what does it stimulate production of?
(gonadotrophin hormone)
GnRH stimulates AP to release LH => which acts on theca cells in the ovaries to produce and release androgens
What type of hormone is FSH? produced from where? under the influence of what?
(Gonadotrophin)
GnRH stimulates AP to release FSH => which acts on granulosa cells
What happens when FSH binds to granulosa cells? (3)
- Follicle growth
- Permit conversion of androgens to oestrogen
- Stimulate Inhibin secretion
Describe the negative feedback mechanisms in the HPG axis?
- Oestrogen negatively feedsback to AP and hypothalamus to decrease GnRH and gonatrophin release
- Inhibin negatively feedback to AP to reduce FSH
In males: What cells does LH act on and what does it stimulate?
LH stimulates Leydig cells to produce testosterone
L-L
What is testosterone?
main male sex steroid hormone
What does testosterone stimulate in males? (8)
- Formation of sperm (spermatogenesis
- Maintenance of libido
- development of secondary sexual characteristics
- Growth of external genitalia
- deepening of voice
- Muscle growth
- Bone growth
- promotion of anabolic creation
In males: What cells does FSH act on and what does it stimulate (2)?
FSH drives sperm production in the Sertoli cells (spermatogenesis)
(and drives synthesis of proteins)
S_S
What in the menstrual cycle? generally
menstruation occurs on a monthly cycle throughout female reproductive yrs
how long is an average menstural cycle (range)
21 - 35 day cycle
what are the words for the start and end of mesntruation ?
menarche
menopause
what is the average age for menarche ? (range)
10 - 16
What is the average age for menopause ? (range)
45 - 55
describe the HPG feedback response to:
Moderate oestrogen levels?
moderate oestrogen levels exert negative feedback on the HPG axis
Describe the HPG feedback response to: High oestrogen levels (in the absence of progesterone) ?
High oestrogen levels (in the absence of progesterone) positively feedback on the HPG axis
Describe the HPG feedback response to: Oestrogen in the presence of progesterone?
exerts negative feedback on the HPG axis
Describe the HPG feedback response to: Inhibin ?
selectively inhibits FSH at the AP
What are the general 2 phases of the menstrual cycle in terms of the ovarian cycle?
Follicular + luteal phases
When does the follicular phase start? end? how long is it?
starts at beginning of menstruation till ovulation (about 14 days)
What happens during follicular phase? generally
marks beginning of new cycle
- follicles begin to mature + prepare oocyte release
What it a follicle? structure
oocyte surrounded by stromal cells
describe the ovarian production levels at the beginning of the follicular phase? and the follicle action?
little ovarian oestrogen production (follicle begins development independate of gonadotrophines and ovarian hormones) => low steroid sex hormones
How does the lack of ovarian production at the beginning of the follicular phase affect the other hormones ?
low steroid + Inhibin levels => reduced negative feedback => rise in FSH + LH => stimulate follicle growth and oestrogen production
Describe the oestrogen levels by the end of the follicular phase? what does this cause ?
follicular oestrogen becomes high => positive feedback => increased GnRH => LH surge (ovulation)
Why does the high oestrogen levels lead to only an LH surge and not FSH surge?
gransulosa cells still secreted Inhibin which acts to reduce FSH levels
What hormone causes ovulation?
LH surge
what happens in the ovaries at ovulation?
LH surge => mature oocyte ruptures from follicle (smooth muscle in theca external contract) => assisted to fallopian tube by fimbrae
How long is the oocyte viable for after ovulation ?
24 hrs
What hormones does the corpus lute produce ?
- Progesterone
- Oestrogen
- Inhibin
What 3 phases of the mesntural cycle are there in terms of the uterine cycle? which do they run alongside compared to the ovaries)
- Proliferative (alongside follicular)
- Secretory (luteal)
- Menses
What happens to the uterus during the proliferate phase ? (4) which hormone initials this ?
Uterine cycle: proliferative phase (follicular)
- oestrogen initials fallpain tube formation
- Endometrial thickening
- increased myometrial growth and motility
- Production of thin alkaline cervical mucus
oestrogen initiates this
What happens do the uterus during the secretory phase? which hormone initiates this?
Uterine cycle: secretory phase (luteal)
- endometrial and myometrial thickening
- Decreased myometrial motility
- Thick acidic mucus
initated by progesterone
What is the purpose of the thick acidic cervical mucus? during which phase? which hormone causes this?
progesterone (during secretory/ luteal phase) => thick acidic cervical mucus => hostile environment to prevent polyspermy
How long does menses last? how much blood?
2 -7 days
10 -80 ml
Which levels of follicle development can happen independent of the stage of the menstrual cycle?
primordial follicles => primary follicles => secondary follicles
What hormone is required for further follicle development ? what kind of follicle would this be?
FSH => astral follicle development (from secondary follicles)
How does oestrogen affect cervical mucus? during which phase?
increase cervical permeability (sperm can pass) during the follicular phase
What is an ovum?
unfertilised egg
What happens to the follicle that released the oocyte after ovulation?
collapses and becomes the corpus luteum
If fertilisation occurs: what maintains the corpus luteum? which hormone?
the syncytiotrophoblast of the the embryo secretes hCG which maintains the corpus luteum
How does LH surge occur in mestrual cycle?
Oestrogen levels rise to v high, meaning that a +ve feedback is exerted on the HPG axis, rapidly increasing LH secretion bytnot FSH (Inhibin)
What is gametogenesis? overall
when haploid cells (n) are formed form a diploid cell (2n) through meiosis
what are the words for the male and female gametogenesis?
- Spermatogensis
- Oogenesis
What is spermatogenesis?
the process by which male gametes (sperm) are made
how long does spermatogenesis take?
70 days
where does spermatogenesis take place? which cells?
seminiferous tubules of the Sertoli cells
what is a spermatogonium? haploid or diploid?
diploid germ cells
(large amounts present at base of Sertoli cells in seminiferous tubules)
describe the steps from spermatogonium => spermatazoa
spermatogonium => (enter meiosis) => primary spermatocyte => secondary spermatocyte => spermatids => (spermiogenesis) => spermatozoa
Spermatogenesis: meiosis 1 is just completed. What stage of dev?
secondary spmatocyte
What are spermatids? diploid/haploid?
haploid cells not fully differentiated (correct no. chromosomes but not characteristic to survive)
Spermatogenesis: meiosis 2 is just completed. What stage of dev?
spermatids
What are the 3 components to a function spermatozoa (sperm) ? describe ?
- Nucleus (haploid genome)
- Acrosome (cap over most of nucleus)
- Flagellum ( whip like cellular appendage for locomotion)
What cell type are the seminiferous tubules lined by? function of these cells (2)?
lined with epithelial layer of sertolli cells
- Support + provide nutrients to various sperm precursors
- Protective: form blood-testes layer
What is sperm maturation ? what becomes what? where does it happen
the spermatids undergo spermiogenesis (remodelling and differentiation into spermatozoa) as they travel along the seminiferous tubules
What is sperm capacitation? which sperm stage goes through this? where does it happen? what does it allow for/why important ?
once sperm leave M + enter F body (in the uterus)
- removal of cholesterol + glycoproteins allows it to bind to soma pellucid of the egg)
Describe the structure of a primordial follicle?
oocyte surrounded by pregranulsoa cells
what is an oocyte
a germ cell which undergoes meiosis => mature ovum
What are the 3 layers to a primary oocyte?
(inner oocyte)
- Zona pellucida
- Cuboidal granuloma cells
- Theca cells
What forms the song pellucida ?
the graudlosa cells secrete material that becomes ZP
What does the theca do? 2 parts?
-Theca interna: secretes androgens
- Theca externa: made of connective tissue (smooth muscle + collagen)
Which part of the follicle is affected by the LH surge?
causes the tech external to squeeze => follicle burst
When does oocyte undergo meiosis 1? what is it now at this stage? at what stage does it stop?
at around time of ovulation, oocyte undergoes meiosis 1 up until metaphase 2
- it is now a secondary oocyte
when does meiosis II of ovum take place?
at fertilisation, creates final (3rd) polar body
What is coitus?
sexual intercourse that results in the deposition of sparm in the vagina at level of cervix
what are the 5 stages of coitus?
- Sexual arousal
- Excitement phase
- Plataue phase
- Orgasm
- Resolution phase
What happens during the Male plateau phase (4) ?
- Penile erection
- Increase size of testicles
- Increased HR
- Increased BP
What happens during the male orgasmic phase? (2)
- Emission
- Ejaculation
What happens during male emission (coitus)
orgasmic phase
- structures contract in order to mix the contents of ejaculate
what happens during male ejaculation (coitus)?
orgasmic phase
- semen is expelled form the prostate urthra due to muscle contractions
What happens during the female excitement phase of coitus?
- Increase the circumference of vagina
- Lubricate vagina
- Inner 2/3 vagina lengthen + expand
How long can sperm serve in the email reproductive tract for ?
120 hours
What is conception?
it is the union of the male sperm and the female oocyte to form a zygote
when the sperm approaches the egg, what stage of dev is the egg?
secondary oocyte
what are the 6 stages of conception?
1) sperm transport to site of fertilisation
2) Sperm capacitation
3) acrosomal reaction
4) Polyspermy block
5) Completion of meiosis II
6) Zygote formation
What helps promote sperm transport to site of fertilisation? (2)
- High female oestrogen at time of ovulation => decrease cervical mucus => allow sperm passage
- Prostaglandin in seminal fluid promote myometrial contractions to propel sperm => fallopian
What is sperm capacitation? triggered by what?
final maturation process of sperm
- Triggered by uterine secretions
What is the acrosomal reaction involved in conception?
hydrolytic + proteolytic enzymes digest ZP
On which day after fertilisation does the embryo become a blastocyst ?
Day 5
Where does conception most commonly occur? be specific?
in the ampulla of fallopian tubes
When does development of the placenta begin?
during implantation of the blastocyst
When cells for the placenta?
the outer trophoblast cells form the placenta
What happens day 6 after conception?
ZP disintegrates + blastocyst “hatches” so implantation can take place
Where does normal implantation occur?
on the anterior or posterior wall of the body of the uterus
What happens day 8 after conception ?
trophoblast differentiation into syncytiotrophblast
what is the syndcytiotrohpblast? and why is it important?
outer layer of trophoblast (of blastocyst) that is in contact in contact with the endometrium
- secrete hCG to maintain corpus luteum
what properties do the maternal blood arteries in the syncytiotrophoblast have?
low resistance, high blood flow condition to meet fetal demands
How long dies it typically take for placenta to be delivered?
30 min
Average weight of placenta at full term?
600g
at what point in pregnancy is the early utero placental circulation established?
by end of week 2
What structure in the placenta separates maternal blood from fetal tissue ?
syncytial layer
what vessel in umbilical cord? what blood? direction to/from heart?
- 2 umbilical arteries carrying deoxy blood away form heart
- 1 vein carrying oxy blood to the heart
What are the 3 layers of the fetal pole?
- endoderm (inner)
- mesoderm (middle)
- ectoderm (outer)
what does the endoderm become ?
(inner)
- Gi tract
- Lungs
- Liver
- Pancreas
- Thyroid
- Reproductive system
What does the mesoderm become?
(Middle)
- Heart
- Muscle
- Bone
- Connective tissue
- Blood
- Kidneys
What does the ectoderm become?
(outer)
- Skin
- Hair
- Nails
- Teeth
- CNS
how does maternal blood get to uterine veins?
maternal blood => uterine arteries => lucanae => uterine veins
What are the 5 main functions of the placenta?
- Respiration
- Nutrition
- Excretion
- Endocrine
- Immunity
what is the oxygen source for fetus
Placenta is the only oxygen source of the fetus
describe the fetus affinity for oxygen compared to maternal
fetal Hämoglobin has higher affinity for oxygen than adult haemoglobin
What substances are exchanged in the placenta (respiration)?
- Oxygen
- CO2
- H+
- Bicarb
- lactic acid
What can be transferred to the fetus from the placenta nutrition-wise
- mostly glucose
- harmful substances: meds, alcohol, caffeine, cigarette
What is expected from the placenta on behalf of the fetus?
acts as adult kidney (urea + kidney)
How to pregnancy levels of oestrogen and progesterone compare to normal?
Throughout pregnancy the levels of progesterone and oestrogen increase; the oestrogen being produced by the placenta and the progesterone being produced by the corpus luteum and later by the placenta.
how does oestrogen affect T3 and T4 levels? and TSH?
oestrogen increase thyroid-binding globulin => increased requirement => increased TSH => increased total T3 + T4 (but no change to free T3 + T4)
What fetal development is thyroid essential for
neural development
when does the fetal thyroid gland become functional
2nd trimester
why are pregnant women more prone to diabetes?
in pregnancy there is an increase in anti-insulin hormones (lactose, prolactin, cortisol) => ensure continuo supply of glucose to fetus
what cardiovascular changes are there in pregnancy? BP? CO? blood vol? SV? HR? PVR?
- Increased in progesterone => decrease systemic vascular resistance => decrease diastolic BP => increase CO (in response to this)
- Increase blood vol, SV, HR,
- Decrease PVR
What changes to circulating blood vol are there in pregnancy? what causes this?
increase in total blood col (due to increase sodium levels + water retention)
What respiratory changes are there in pregnancy ? TV? RR?
Increase in metabolic demand = increase oxy demand => increase TV + increase RR
what can pregnancy associated displacement of the stomach cause?
increased infra-gastric pressure => reflux (+ nausea + vomiting )
what blood gas change would be expected in pregnancy?
compensated respiratory alkalosis
Many women experience hyperventilation during pregnancy. This results in a respiratory alkalosis with a compensated increase in renal bicarbonate excretion
how does the GFR change in pregnancy ?
increase GFR because increased CO
What contributes to the increased risk of UTI in pregnancy?
progesterone => relaxation of smooth muscle (ureter)
What haematological changes are there in pregnancy?
- increased fibrinogen + increased clotting factors => thromboembolism risk
- increased RBC => increased folate, B12 + iron requirements
what is the weight of a normal and a pregnancy uterus
0.1 - 1.1 kg
What is menopause? how many months of symptoms ?
it is the end of female reproductive life
- amenorrhoea for 12 months (retrospective diagnosis)
when does perimenopause begin ?
around 45 yrs
what is classified as early menopause ?
40 - 45
Describe the oestrogen, progesterone, LH and FSH levels in menopause?
oestrogen + progesterone: LOW
FSH + LH: HIGH (in response to absence of -ve feedback from oestrogen)
what is the hormone responable for most of the symptoms (of menopause)
oestrogen (lack of)
what causes the low oestrogen levels in menopause?
low follicle numbers => reduced gonatorophin receptor sensitivity => low FSH + LH => low oestrogen
- negative feedback then drives LH and FSH up
- low follicle embers also cause low Inhibin => increased FSH
What are the main perimenopausal symptoms?
(progressing toward the menopause)
- Hot fluses
- urinary incontinence
- Increased UTIs
- Irregular vaginal bleeding
- Low mood
- PMS
- Decreased libido
Explain how dyspareunia is linked with menopause?
decrease circulating oestrogen => vaginal atrophy + myometrial thinking => vaginal wall thinning + dryness => pain during sex
What risks are associated with menopause? (5)
- Osteoporosis
- CVD
- Stroke
- POP
- Urinary incontinence
why is there an increased osteoporosis risk associated with the menopause? what cells involved?
oestrogen protect bone mass + density (by reducing osteoclast activity) => so less oestrogen => increased osteoclast action
When is it considered no longer possible for a woman to conscieve?
after 12 consecutive moths of no menstruation
What tests might you do in menopause? what might you find
FSH blood test (increase FSH)
(not worth relying oestrogen levels as they can fluctuate a lot anyway)
which mechanism stimulates the female secondary oocyte to complete meiosis II?
cortical reaction
What is congenital structural abnormalities caused by? due to?
by abnormal development of pelvic organs prior to birth
- Due to faulty genes of by chance
What is another name for the paramesonephric ducts?
mullerian ducts
what do the paramesonephric ducts develop into?
- upper vagina
- Cervix
- Uterus
- Fallopian tubes
What structure in fetus does congenital structural abnormality relate to?
mullerian ducts
why do males not develop a uterus?
Anti-mullerian hormone
- AMH supresses growth of paramesonephric ducts => causes them to disappear
give examples of congenital structural abnormalities ?
- Bicornuate uterus
- Imperforate hymen
What is androgen insensitivity syndrome?
it is a condition where cells are unable to respond to androgen hormones due to a lack of androgen receptors
- extra androgens are converted into oestrogen => female secondary characteristics
what type of inheritance is androgen insensitivity syndrome ?
x-linked recessive
describe the the genotype of phenotype of a patient with androgen insensitivity syndrome ?
- patients are genetically male (XY)
- Normal female external genitalia and breast tissue (patients have testes in abdo or inguinal canal)
describe the pathophysiology of androgen insensitivity syndrome?
patient XY (male) but the absent response to testosterone plus conversion of additional androgens to oestrogen
androgen insensitivity syndrome presentation infancy? puberty?
- Infancy: inguinal hernias
- Puberty: primary amenorrhoea
androgen insensitivity syndrome managment?
generally raised as female
- bilateral orchidectomy
- oestrogen therapy
- Vaginal dilators (to create adequate vaginal length)
in fertilisation: what prevents multiple sperm from fertilising egg?
cortical reaction
