The Reproductive System Flashcards
what is GnRH? where is it released from?
- gonadotropin-releasing hormone
- hypothalamus
what does GnRH do?
stimulates the anterior pituitary to produce LH and FSH
where are LH and FSH released from? what do they do?
- anterior pituitary
- FSH: stimulates follicles to develop in the ovaries
- LH: stimulates egg maturity
which cells secrete oestrogen? where are these found?
- theca granulosa cells
- around the follicles in the ovaries
what is the role of oestrogen?
- negative feedback to the hypothalamus and anterior pituitary (suppresses GnRH, LH and FSH release)
- stimulates female secondary sexual characteristics
what stimulates oestrogen release?
LH and FSH
which changes does oestrogen cause to the body?
- breast development
- growth and development of vulva / vagina / uterus
- blood vessel development in the uterus
- development of the endometrium
where is progesterone produced in a non-pregnant person? when is it produced?
- corpus luteum
- after ovulation
where is progesterone produced in a pregnant person?
- corpus luteum and then the placenta
- placenta takes over at 10w gestation
actions of progesterone?
- thickens and maintains endometrium
- thickens cervical mucus
- increases body temp
when does puberty start in girls?
ages 8 - 14
when does puberty start in boys?
ages 9 - 15
why do overweight females enter puberty earlier?
having more adipose tissue increases oestrogen production
which children enter puberty later?
- underweight ones
- children with chronic disease
- children with eating disorders
- athletes
order of signs of puberty in girls?
- breast buds (thelarche)
- pubic hair (pubarche)
- menstruation (typically 2 years after the start of puberty)
what is the first menstruation called?
menarche
how can pubertal development be staged?
tanner staging
which characteristics does tanner staging take into account for females?
- pubic hair
- breast development
hormonal changes in puberty?
- GH increases
- hypothalamus starts secreting GnRH
- triggers HPG axis to start
what causes growth to slow down in puberty? why?
- increasing oestrogen levels
- oestrogen inhibits GH action
- this is why growth spurts stop earlier in girls
what are the 2 phases of the menstrual cycle?
- follicular phase
- luteal phase
what marks the start and end of the follicular phase of the menstrual cycle? how long does it last?
- start: first day of menstruation
- end: ovulation
- lasts 14 days
what marks the start and end of the luteal phase of the menstrual cycle? how long does it last?
- start: ovulation
- end: first day of menstruation
- lasts 14 days
which structures make up an ovarian follicle?
1 oocyte surrounded by granulosa cells
4 stages of follicular development?
- primordial follicles (contains primary oocyte)
- primary follicles
- secondary follicles
- antral follicles
what’s the other name for antral follicles?
graafian follicles
which receptors can be found on the secondary follicle surface? why is this important?
- FSH receptors
- FSH is needed for it to develop into an antral follicle
what do granulosa cells secrete? how does this impact the HPG axis?
- oestriadol (oestrogen)
- negative feedback effect on the hypothalamus and pituitary
- reduces LH and FSH production
how does oestrogen affect the cervical mucus? why is this important?
makes it more permeable to sperm
which hormone stimulates ovum release from the dominant follicle?
LH
how can the ovulation date be calculated?
length of cycle - 14
what happens in the luteal phase of the menstrual cycle if the egg is not fertilised?
- dominant follicle turns into corpus luteum
- CL secretes progesterone to maintain endometrial lining and thicken cervical mucus
- CL eventually degenerates and stops secreting oestrogen and progesterone
- endometrial lining breaks down and sheds (menstruation)
what happens in the luteal phase of the menstrual cycle if the egg is fertilised?
- embryo forms
- syncytiotrophoblast of embryo secretes hCG
- hCG maintains corpus luteum
what is actually happening when you menstruate? what causes this?
- endometrial lining is being shed
- lack of oestrogen and progesterone from CL
which cells secrete prostaglandins? what does this cause?
- stromal cells of endometrium
- causes endometrial breakdown and uterine contraction
how long does menstruation last?
1 - 8 days
where are primary oocytes found? be specific
- pregranulosa cells of primordial follicles
how does a primary oocyte develop into a mature ovum?
meiosis
what happens to the primary oocyte before ovulation? how many chromosomes does it have?
- undergoes meiosis again
- chromosomes go from 46 (diploid) to 23 (haploid)
- the other 23 chromosomes form a polar body
which layers does the sperm cell need to penetrate in order to fertilise the egg?
- corona radiata
- zona pellucida
what makes up a zygote?
23 chromosomes from the egg and 23 from the sperm
what does the zygote become? how many cells does this have? what happens at this point?
- morula (16 cells)
- moves along fallopian tube
what does the morula become? how many cells does this have when it enters the uterus?
- blastocyst
- 100-150 cells
what are the 3 layers of the embryonic disc?
- ectoderm
- mesoderm
- endoderm
what does the endoderm become?
- GI tract
- lungs
- liver
- pancreas
- thyroid
- reproductive system
what does the mesoderm become?
- heart
- muscles
- bone
- connective tissue
- blood
- kidneys
what does the ectoderm become?
- skin
- nails
- hair
- teeth
- CNS
at which gestation does the foetal heart form and start to beat?
week 6
at which gestation do major organs other than the heart start to develop?
week 8
what are the spiral arteries? where are they found?
branches of myometrial arteries that penetrate the endometrium making it highly vascular
different roles of the placenta?
- supplies oxygen + nutrition and removes CO2
- excretes urea and creatinine
- endocrine role
- transfers antibodies
describe the endocrine role of the placenta
it produces oestrogen and progesterone to prepare the mother for birth
role of oestrogen in pregnany?
- muscles of uterus and pelvic expand
- cervix softens
- breasts enlarge
role of progesterone in pregnancy?
- uterine muscles relax
important SE of progesterone in pregnancy? hint: causes common problems
relaxes muscles:
- LOS (heartburn)
- bowel (constipation)
- blood vessels (hypotension, headaches, skin flushes)
hormonal changes seen in pregnancy?
- anterior pituitary produces more ACTH, prolactin and melanocyte stimulating hormone
- T3 and T4 rise
- hCG levels double every 48h until 8-12 weeks
- oestrogen rises
what does higher ACTH cause in pregnancy?
- increased cortisol and aldosterone levels
- higher risk of diabetes and infection
what does higher melanocyte stimulating hormone cause in pregnancy?
increases skin pigmentation:
- linea nigra
- melasma
which organ produces oestrogen in pregnancy?
- placenta
changes to uterus seen in pregnancy?
- hypertrophy of myometrium and blood vessels
what might increased oestrogen in pregnancy cause?
- cervical ectropion
- increased vaginal discharge
- increased risk of bacterial infections and thrush
- vaginal muscle hypertrophy
what is the role of prostaglandins in labour?
- break down the collagen in the cervix
- allows it to dilate and efface
cardiovascular changes seen in pregnancy?
- increased blood volume
- increased plasma volume
- increased CO (BOTH SV and HR go up)
- reduced peripheral vascular resistance (causes vasodilation, flushing and hot sweats)
- BP drops then normalises
- varicose veins form
how does BP change through pregnancy?
- drops in 1st and 2nd trimesters
- normalises by full term
respiratory changes seen in pregnancy?
- increase in tidal volume
- increased RR
renal changes seen in pregnancy?
the following go up:
- blood supply
- GFR
- aldosterone
- protein excretion
ureters dilate, causing physiological R-sided hydronephrosis
why do pregnant women require increased iron, folate and B12?
there is increased RBC production
explain how haematocrit drops in pregnancy
plasma volume increases MORE than the RBC count does, making the red cells more diluted
how does a physiological anaemia occur in pregnancy?
Hb becomes diluted by the large increase in plasma volume
why does risk of VTE increase in pregnancy?
there is an increase in fibrinogen and clotting factors VII, VIII and X
changes seen on blood results in pregnancy?
- increased WCC
- reduced platelets
- increased ESR and D-dimer
- increased ALP
- reduced albumin (increased protein excretion)
how is hair affected in pregnancy?
- postpartum hair loss is normal
- should improve by 6 months
skin changes seen in pregnancy?
- linea nigra
- melasma
- striae gravidarum
- pruritus
- spider naevi
- palmar erythema
which weeks of gestation would you expect labour and delivery to happen?
37 - 42 weeks
how many stages of labour are there?
3
describe the first stage of labour
from onset of labour with true contractions until cervix is fully dilated by 10cm
describe the second stage of labour
from 10cm dilation to delivery of the baby
describe the third stage of labour
from delivery of baby to the delivery of placenta
how can a pessary be used to induce labour?
- they contain prostaglandin E2 (dinoprostone)
- used to induce dilation and effacement of the cervix
what are braxton-hicks contractions? what is their significance?
- occasional irregular contractions of the uterus
- they are not true contractions and do not progress or become regular
when are braxton-hicks contractions felt?
2nd and 3rd trimesters
presentation of braxton-hicks contractions?
- irregular tightening in abdomen
- mild cramping
how can braxton-hicks contractions be reduced?
- relaxing
- hydration
what are the 3 phases of the first stage of labour?
- latent phase
- active phase
- transition phase
first stage of labour: describe the latent phase
- cervix dilates from 0 to 3cm
- progresses at 0.5cm / hr
- contractions are irregular
first stage of labour: describe the active phase
- cervix dilates from 3 to 7cm
- progresses at 1cm / hr
- contractions become regular
first stage of labour: describe the transition phase
- cervix dilates from 7 to 10cm
- progresses at 1cm / hr
- contractions become stronger
3Ps: factors which affect second stage of labour?
- power
- passenger
- passage
what does “power” describe in the second stage of labour?
strength of uterine contractions
what does “passenger” describe in the second stage of labour?
qualities of the fetus
- size of fetal head
- attitude (posture) of fetus
- fetal lie
- fetal presentation
different types of fetal lie?
- longitudinal
- transverse
- oblique
different types of fetal presentation?
- cephalic
- shoulder
- breech
types of breech presentation?
- complete
- frank
- footling
what does “passage” describe in the second stage of labour?
size and shape of pelvis
what are the 7 cardinal movements of labour?
- engagement
- descent
- flexion
- internal rotation
- extension
- restitution and external rotation
- expulsion
how is the descent of the baby’s head measured in labour?
- measured in cm against the mother’s ischial spines
- -5cm = head is high up around the pelvic inlet
- 0cm = head is at ischial spines (“engaged”)
- +5cm = head has descended further out
what is involved in the active management of the third phase of labour? advantages of this?
- midwife / doctor assists in delivery of the placenta
- IM oxytocin used
- traction of umbilical cord
- shortens duration and reduces risk of bleeding
when is active management indicated in the third phase of labour?
when there is either haemorrhage or >60 min delay in delivery of the placenta
