Reproductive system Flashcards
Name the hormone axis for reproduction
Hypothalamus= GnRH
APG= LH/FSH
Stimulate follicle development in ovaries
Theca granulosa secrete oestrogen
Negative feedback
What does oestrogen act on?
tissues w/ oestrogen receptors to promote 2r female sexual characteristics: breast tissue development, growth and development of female sex organs at puberty (vulva, vagina, uterus), blood vessel development in uterus, endometrium development
What is progesterone produced by?
CL after ovulation
Placenta after 10 wks pregnancy
What is function of progesterone?
Thicken/maintain endometrium
Thicken cervical mucus
increase body temp
When is average age of puberty?
8-14 girls
9-15 boys
4 years start to finish
Why do overweight children enter puberty at an earlier age?
Aromatase enzyme found in adipose tissue important in creating oestrogen.
so, delayed puberty in low birth weight girls, chronic disease, eating disorders, athletes.
Why dont girls have puberty earlier?
They have relatively little GnRH/LH/FSH and progesterone and oestrogen in their system in childhood, in puberty it increases a lot leading to the 2ry characteristics
Describe the pubertal changes in girls
Breast buds, pubic hair (light thin, coarse and curly, adult like, reaching medial thigh), menstrual periods, Growth spurty usually before boy (due to GH increase in initial phases of puberty)
Describe the hormonal changes during puberty
The hypothalamus starts to secrete GnRH, initially during sleep, then throughout the day in the later stages of puberty. GnRH stimulates the release of FSH and LH from the pituitary gland. FSH and LH stimulate the ovaries to produce oestrogen and progesterone. FSH levels plateau about a year before menarche. LH levels continue to rise, and spike just before they induce menarche.
Two phases of menstrual cycle
Follicular- start menstruation to ovulation 1-14 days
Luteal- ovulation to start of menstruation final 14 days
Describe the follicular phase
Follicle= granulosa cells surrounding oocyte
Primordial follicles mature into 1ry/2r follicles at any time independent of cycle-
2rydevelop FSH receptors and need stimulation from FSH to develop further.
Menstrual cycle starts, FSH stimulates 2ry development, as they grow granulosa cells secrete lots of oestrogen which negative feedback on pituitary reducing LH/FSH producton. also makes mucus more penetrable for sperm around ovulation time
One follicle becomes dominant, LH spikes before ovulation so DF releases ovum from ovary. Ovulation= 14 days before end of menstrual cycle so 14/28 or 16/30.
Describe the luteal phase
Follicle that releases ovum collapses becomes CL- secretes progesterone which maintains lining of endometrium, causes mucus to thicken, also CL secretes some oestrogen.
Fertilisation- Syncytiotrophoblast of embryo secretes HCG which maintains CL.
No fertilisation- no HCG, CL degenerates, fall in oestrogen/progesterone= breakdown of endometrium and menstruation occurs. Stromal cells of endometrium produces PG’s, which encourange endometrium breakdown and contraction of uterus. Negative feedback ceases so LH/FSH can rise again.
What is day 1 of menstrual cycle
Menstruation- breakdown of superficial/middle endometrium layers separating from basal layer. broken down in uterus and released over 1-8 days.
What is a primordial follicle?
Contains primary oocyte- germ cells that eventually undergo meiosis to become mature ovum.
develops into primary follicle
Rest inside ovaries, waiting for their time to develop.
Primary oocyte, pregranulosa cell and basal lamina layer on the outside
What is the primary follicle layers?
Primary oocyte, zona pellucida (secreted content by graulosa sells, and oestrogen), granulosa cells.
As they grow larger they get an outer layer called theca folliculi (interna- secretes androgens and externa contains connective tissue cells such as SM/collagen)
Which type of follicle develops receptors for FSH
2ry follicle
Antral follicle? what is that
2ry follicle develops further gets antrum within granulosa cell (fills w/ fluid)
Also has corona radiate mad eof granulosa cells, surrounds zona pellucida and oocyte within the antrum.
What is the dominant follicle?
One of the follicles becomes the dominant follicle. The other follicles start to degrade, while the dominant follicle grows to become a mature follicle. This follicle bulges through the wall of the ovary.
What is the process of ovulation?
LH surge= SM of theca externa to squeeze, folllicle bursts, follicular cells release digestive enzymes to puncture hole in ovary wall to let ovum pass. oocyte rleased into surround area and floating in peritoneal cavity, swept up by fimbriae of follopoion tubes
What is the CL
Leftover follicle turns yellow, Granulosa/theca interna become luteral cells- secrete progesterone. HCG in pregnancy makes it persist otherwise degenerates after 10-14 days
How does fertilisation occur?
ovulation time- primary oocyte undergoes meiosis= 46 chromosomes split into 23 and a polar pody (2ry oocyte)= corona radaiata.
Sperm enters fallopian tube and tries to penetrate corona radiata. 1 sperm will usually get in and the layers shut rest out.
23 chromosomes from sperm and egg multiplies into two sets (one= diploid 46 set, and 23 other chromosomes floats to create 2nd polar body).
How does blastocyte develop?
23+ 23= zygote.
cells rapidly divides= morula. travels towards uterus
Fluid filled cavity gathers within cells= blastocyte cell whilst travelling. Main group of cells is called embryoblast, fluid cavity is called bastocele, surrounded by outer trophoblast cells. Corona radiata and zona pellucida are last. Blastocyte enters uterus
What happens during implantation?
Blastocyte arrives at uterus. 8-10 days after ovulation, reaches endometrium.
Outer trophoblast cells (synctiothrophoblast) undergo adhesion to stroma of endometrium. Forms projections into and mixes with the cells of the stroma.
Stroma cells convert into decidua tissue which specialise in providing nutrients to trophoblast. when blastocyte implants on endometrium, synchtiotrophoblast, produces HCG- maintains CL allowing production of progesterone/oestrogne
Describe the embryo production from blastocyte
A week after fertilisation, implanted blastocyte differentiates
Embryoblast splits into two: Yolk sac and amniotic cavity, split with embryonic disc- this is the fetal pole and develops into fetus.
Chorion surrounds this- cytotrophoblast inner layer and syncytiotrophoblast is outer layer.
Chorionic cavity forms surrounding yolk sac, embryonic disc and amniotic sac which are suspended from chorion by connecting stalk (which will become umbilical cord)
When does embryonic disc develop into fetal pole and what layers does it form?
5 wks gestation
Endoderm around yolk sac
mesoderm in middle
Ectoderm around amniotic sac
What happens around 6 weeks gestation
fetal heart forms and starts to beat.
Spinal cord and muscles begin to develop. 4mm fetal pole length
What happens 8 weeks gestation
major organs have started to develop
What are spiral arteries?
During the follicular phase of the menstrual cycle, the endometrium thickens and gets ready for a fertilised egg to arrive. The myometrium sends off artery branches into the endometrium. Initially, these arteries grow straight outwards like plant shoots. As they continue to grow, they coil into a spiral. These thick-walled and coiled arteries are bunched together, making the endometrial tissue highly vascular. These are known as the spiral arteries.
Placental and umbilical cord development?
Blastocyte implants, syncytiotrophoblast grows into endometrium- forms finger like projections caused chorionic villi (contain fetal blood vessels)
Chorionic villi near connecting stalk are most vascular (chorion frondosum)- proliferate and become placenta, connecting stalk becomes umbilical cord
When is placental development usually complete by?
10 wks gestation
When do lacunae form and what are they?
Trophoblast invasion of endometrium sends signals to spiral arteries, reduce vascular resistance, makes them more fragile. Blood flow increases, breakdown, pools of blood.
Maternal blood flows from uterine arteries into lacunae and back out uterine veins
20 wks gestation
Lacunae surround chorionic villi- separated by placental membrane: c02/02, other substances can diffuse across placental membrane
If formation of lacunae is inadequate what cna happen?
Pre- eclampsia
High vascular resistance in spiral arteries= increased BP/complications for fetus and mother
What is the function of the placenta?
Respiration- fetal Hb has high affinity- only source of O2. co2, bicarb/lactic acid also exchanges, acid-base balance
Nutrition- glucose, vitamins, minerals, harmful substances e.g. alcohol, caffeine, cigarette, medicines.
Excretion- filter waste e.g. U+C
HCG- synctiotrophoblast produces HCG, maintain CL, placenta takes over, can cause N/V (esp in higher HCG levels e.g. multiple pregnancy/molar).
Oestrogen- placenta produces this, helps soften tissues/make them more flexible, muscles/ligaments of uterus expands, cervix becomes soft/ready for birth, enlarges breasts for rbeast feeding
Progesterone- 5 wks, placenta takes over production. maintains pregnancy: relaxation of uterine muscles, maintains endometrium. SE: relaxes LOS= heartburn, bowel= constipation, BV= hyotension, headache, skin flushing. raises body temperature.
Immunity =Ab’s transfer, LT immunity.
Give some hormonal changes during pregnancy?
APG= more, ACTH, prolactin, melanocyte stimualting hormone= rise in steroid hormone- cortisol/aldoesterone, improves AI conditions, susceptible to diabetes and infection/ Supress FSH/LH. increased pigmentation- linea nigra, melasma
TSH normal, T3/T4 rise
HCG rise- double every 48 hours till plateau 8-12 weeks, then fall gradually
Progesterone rise
Oestrogen rises
What happens to uterus/cervix/vagina during pregnancy?
Uterus zie increases 100g to 1.1kg
Hypertrophy of myometrium/BV
Increased oestrogen= cervical ectropion/cervical discharge, hypertrophy of vaginal muscles/discharge, prepare it for delivery but make bacterial/candidial infection thrush more common
Pg break down collagen in cervix alowing it to dilate and efface during childbirth, before delivery it is released
CVD changes during pregnancy
Increased BV, plasma volume, cardiac output (sv/hr)
Decreased peripheral v\scular resistance/BP (in early/middle pregnancy
Variscose veins (peripheral vasodilation, obstruction of IVC by uterus)
Peripheral vasodilation= flushing/hot sweats
Respiratory change during pregnancy
Later pregnancy= tidal volume/resp rate increase to meet 02 demands
Renal changes in pregnancy
Increased blood flow to kidenys, GFR, aldoesterone (increased Salt/h20 reabsorption/retention), increase protein excretion from kidneys, dilatation of ureters/ collecting system, physiological hydronephrosis (right sided)
Skin/hair changes in pregnancy?
Skin pigmentation- melanocyte stimulating hormone, linea nigra
Striae gravidarum
Itchiness but can indicate obstetric cholestasis
Spider naevi
palmar erythema
Post partum hair loss- usually resolves in 6 months
Haematology/ biochemistry pregnancy changes
Increased rbc production (higher folate/iron/b12 req.)
plasma volume increases more than RBC volume= lower conc./hb conc= anaemia
Clotting factors (fibrinogen, factor v11, v111, X) increase= hyprcoagunle state. VTE/PE risk
Increased WBC
decreased platelets
Increased ESR/d dimer
Increased alkaline phosphatase (secreted by placent)
reduced albumin due to loss protein in kidneys
calcium requirements increase and gut absorption of calcium
When is a normal labour?
37-42 wks gest
What are 3 stages of labour
1= onset of labour (true contractions) until 10cm cervical dilatation
2= 10cm cervical dilatation to delivery of the baby
3= delivery of baby to delivery of placenta
What are braxton hicks contractions?
Braxton-Hicks contractions are occasional irregular contractions of the uterus. They are usually felt during the second and third trimester. Women can experience temporary and irregular tightening or mild cramping in the abdomen. These are not true contractions, and they do not indicate the onset of labour. They do not progress or become regular. Staying hydrated and relaxing can help reduce Braxton-Hicks contractions.
What do prostaglandins do in labour?
Local hormones- stimulate contraciton of uterine muscle, ripen cerxic before delivery
Pg E2= pessaries can idnuce labour
Describe first stage of labour
Cervix dilatation, effacement
Show (mucus plug) falls out, creates space for baby to pass
1= latent: 0-3cm, irregular contraction, 0.5cm per hour
2= active= 3-7, regular contraction 1cm per hour
3- transition- 7cm-10cm. 1cm per hour, strong regular contractions
Describe 2nd stage of labour
Power: strength contraciion
Passenger= size of head, attitude posture of fetus (rounded back, head and limbs flexed), lie (longitudinal, transverse, oblique), presentation: cephalic, shoulder, breech (complete breech= cannonball, frank breech- hips flexed, knees not, bottom first, footling breech= foot first)
Passage= size and shape of passageway (pelvis)
Movements of labour
Descent: compare baby head to ischial spine. -5 is high above pelvic inlet, 0 is head at ischial spine (head engaged), +5 is when head has descended out
Describe 3rd stage of labour
Physiological managment= placenta delivered by materal effort
Active management= midwife/doctor asssist in placenta. shorten 3rd stage, reduce risk of bleeding, haemorrhage/60 min+ delay in delivery of placenta= active management. can lead to nausea/ vomiting
How can you actively manage 3rd stage of labour
IM oxytocin- to help uterus contact/expel placenta
Careful cord traction to guide placenta out
