Endo/Repro 3 Flashcards
STIs - high risk groups
More than half from young adults - higher rates of partner change and concurrent partners
Middle age emerging as high risk group now - experimentation and the internet
MSM
Black African/Caribbean
Inner cities
(internet allows easier access to new partners and commercial sex workers, as well as being disinhibiting, link to riskier sex)
Condoms most effective for transmission via genital secretions eg chlamydia/gonorrhoea, rather than genital warts/HIV
Chlamydia
MEN
50% no symptoms:
- urethral discharge, dysuria, urethral itch, rectal discharge/bleeding
WOMEN
70% no symptoms:
- urethral discharge, dysuria, pelvic paid, PCB/IMB, rectal discharge/bleeding
Investigate with NAAT (nucleic acid amplification test) by first catch urine for men, vaginal swab for women
Treat with doxycycline/azithryomycin
Contact tracing 4 weeks symptomatic/6 months asymptomatic
Complications of chlamydia
MEN
- prostatitis
- epididymitis
WOMEN
- pelvic inflammatory disease
- salpingitis (tubes) -> ectopic, infertility
Gonorrhoea
MEN
90% - urethral discharge, dysuria, urethral itch
7% - rectal discharge/bleeding
WOMEN
50% - vaginal discharge, dysuria, pelvic pain, IMB/PCB, rectal discharge/bleeding
More common in MSM
Investigate with NAAT (nucleic acid amplification test) by first catch urine for men, vaginal swab for women
Culture bacteria - concern about antibiotic resistance
Treat with ceftriaxone and azithromycin
Contact tracing 2 weeks symptomatic/3 months asymptomatic
Complications of gonorrhoea
MEN
- prostatitis
- urethral strictures
- epididymitis
WOMEN
- PID -> salpingitis -> ectopic/infertility
- Bartholin’s abscess
- chronic pelvic pain
- parihepatitis
can (1%) -> disseminated gonococcal infection
- arthritis
- necrotic pustules
- tenosynovitis
Genital warts
Very common - 50% those sexually active
Caused by Human papilloma virus
Transmitted by skin-skin contact - can have transmission by hands/fingers
Incubation period weeks-months
No test for infection - diagnose by visual recognition
Treat with cryotherapy/topical creams (some will resolve spontaneously)
HPV types 16 + 18 are oncogenic -> intraepithelial neoplasia
HPV vaccinations now for young girls - effective for heterosexual men by herd immunity, but still leaves MSM at risk
(pearly penile papules are not warts - normal, bumps at rim of penis head)
Molluscum contagiosum
Often mistaken for (genital) warts Caused by pox virus Transmitted skin-skin contact Common in children Treatment as for warts - eg freezing (doesn't need treating but is done for genital cases)
Why have STIs increased
Increase in duration of sex lives - younger first intercourse - emerging 'Middle youth' Number of partners increasing Increase in condom use - offset by increased partner change More testing, better tests Associated alcohol/drugs Increased overseas travel and immigration
R0
= basic reproductive rate
Number of new infections produced by an infected individual in a population with no immunity in the absence of intervention
R0 = βCD
= probability of transmission x rate of partner acquisition x duration of infectiousness
Spreading: R0>1
Maintenance: R0 = 1
Dead-end: R0<1
HIV prevention
PRIMARY PREVENTION Targeted at risk groups - post exposure prophylaxis with HAART - treatment of HIV +ve individuals - pre-exposure prophylaxis
SECONDARY PREVENTION
HIV testing - routine health care and antenatal care especially
25% of those infected in UK are unaware
Risk of transmission per episode - receptive anal sex 1/90 - insertive anal sex 1/600 - receptive vaginal sex 1/1000 - insertive vaginal sex 1/1200 (some risk with oral sex also)
Syphilis
Esp MSM and sex workers
Common in Africa and Far east
PRIMARY LESION
= chancre
- painless solitary shallow ulcer, like button under skin
- diagnosis with microscopy of ulcer exudate, blood test
- treat with penicillin
SECONDARY SYPHILIS
- polymorphic rash
- systemically unwell
- mucous patches
Foetus characteristics
- dependent on mother for nutrients for growth and survival
- independent in regulation of its development (controls own development)
- exerts effects on mother to enhance her ability to meet the metabolic demands of pregnancy
- co-ordinates with mother in preparations for birth
Foetal growth and development stages
Pre-embryonic period
- 0-3 weeks
- histiotrophic nutrition
Embryonic period
- 3-8 weeks
- haemotrophic nutrient supply from placenta
- for organ system development
Foetal period
- 9-38 weeks
- haemotrophic nutrient supply from placenta
- for maturation and growth
42 cell divisions in this time - needs regulation
Determinants of foetal growth
Pattern of growth is determined by the foetus
Modulated by: Placenta Hormones - glucocorticoids, insulin, IGFs, thyroid hormones, hPL Environment - nutrition and health Metabolic
Growth measured by
- biparietal diameter of head
- circumference of skull
- circumference of abdomen
- length of individual
Intrauterine growth retardation
IUGR
~5% all pregnancies
= birthweight more than two standard deviations below the mean for gestation age
Substantial risk of morbidity and mortality
TYPE 1 (symmetric)
- occurs early in development
- due to chromosomal abnormalities, infections (rubella), alcohol, drugs
- decreased growth all over - hypoplasia and hypotrophy
TYPE 2 (asymmetric)
- restricted growth later on in development
- due to vascular diabetes, chronic hypertension, kidney disease
- head normal size with small body - hypotrophy only
INTERMEDIATE
- combination of types I and II
Human Placental Interface
Placenta - organ of gas exchange, nutrient uptake, excretion during pregnancy
(barrier for no mixing of maternal and foetal blood, though pass very close together for facilitated exchange of materials)
Terminal villi branch into pools of maternal blood
Spiral arteries provide slow delivery of blood to the interface - unresponsive to vasoconstrictors, tend to dilate, blocked by trophoblasts
Blood flow in the placenta
Developmental changes in the villous architecture during pregnancy
1 - thick trophoblast layer around villi thins so reduced distance for exchange
2 - terminal blood vessels in villi dilate, so slows down blood flow so enough time for exchange
Foetal
Umbilical artery - DEOXYgenated blood to placenta
Umbilical vein -OXYgenated blood to foetus
Maternal
Uterine vein - deoxygenated blood out from foetus/placenta
Uterine artery - oxygenated blood into foetus/placenta
Molecules and their transport across the placenta
Amino acids
- transported intact from mother, across placenta, to foetus
Oxygen
- partially consumed in placenta as goes to foetus
Glucose
- metabolised, 2/3 crosses to foetus, 1/3 metabolised to lactate in placenta which then crosses to foetus
Bilirubin
- not transported - can only cross from foetus to be broken down in maternal liver
Oxygen transfer across the placenta
Very good - higher oxygen saturation in every vessel in foetus (uterine/umbilical artery/vein)
Due to:
- Cardiac output of foetus proportionally higher than the mother when compared to body size
- O2 trapping properties of foetal haemoglobin (higher affinity) more effective than in the mother
- Increased amount haemoglobin in foetal blood than in adult
Foetal oxygen binding curve shifted to left of maternal
- 2 gamma units instead of beta units in haemoglobin, so have lower affinity for 2,3-DPG (regulatory molecule)
-> glucocorticoids needed to regulated switch from gamma to beta chains, and to switch site of RBC production from foetal liver to spleen and bone marrow
Glucose and carbohydrates in foetus
Foetus has little capacity for gluconeogenesis
- glucose supplied by mother
Maternal glucose depends on:
- nutrition
- endocrine control mechanisms - in diabetic mother, large baby, in diabetic foetus, small baby
In early pregnancy, progesterone
- increases maternal appetite, builds fat stores
In late pregnancy, maternal tissues insulin insensitive so more glucose available to foetus (gestational diabetes mellitus)
Roles of reproductive medicine
Safety and health of mother and baby \+ assist those with difficulty conceiving \+ assist in terminating a pregnancy \+ provide information about the foetus \+ help prepare for parenthood
-> increase choice in reproduction
Four approaches to reproductive choice
PROCREATIVE AND REPRODUCTIVE AUTONOMY
- liberal
- right of adults to make own choices based on own values
- only intervene where extreme circumstances
INTERESTS OF THE CHILD
- eg in assisted reproduction, don’t have to offer if not in the best interests of the future child
INTERESTS OF SOCIETY/STATE
(choices of a couple influences the makeup of future society)
- where significant cost implications, eg selecting child for non-disability
- or where choice has undesirable social consequences, eg sex selection
RESPECT FOR LIFE
(pro-life)
- killing a foetus is immoral as foetus is person
- contraception immoral as prevents life forming
Morality of abortion
MORAL STATUS
- dictates how you can be treated
- human>hamster>chair
- foetus is only potential life, has lower moral status than existing life
BODILY INTEGRITY
- woman has no obligation to use her body to support the life of another - putting herself at risk and doing something she doesn’t want to do
Abortion act 1967 (1990)
Two medical practitioners need to have opinion that:
PRE 24 WEEKS
- continuing pregnancy poses greater risk than not terminating of injury to physical/mental health of the mother or another child in her family
POST 24 WEEKS
- termination necessary to prevent grave permanent injury to physical/mental health of woman
- continuing pregnancy poses greater risk to woman’s life than not continuing
- substantial risk that child born would suffer from serious mental or physical abnormalities (life not worth living)
Practitioner allowed to conscientiously object, but must refer on to other doctor
Abortion act 1967 (1990)
Two medical practitioners need to have opinion that:
PRE 24 WEEKS
- continuing pregnancy poses greater risk than not terminating of injury to physical/mental health of the mother or another child in her family
POST 24 WEEKS
- termination necessary to prevent grave permanent injury to physical/mental health of woman
- continuing pregnancy poses greater risk to woman’s life than not continuing
- substantial risk that child born would suffer from serious mental or physical abnormalities (life not worth living)
Practitioner allowed to conscientiously object, but must refer on to other doctor
Early pregnancy more reasons accepted (can feel pain at 32 weeks)
80% abortions at under 10 weeks
Lifestyle in pregnancy
Legally, women not held liable for damage they cause to unborn child eg by alcohol
(at time of activity, foetus not a person, changes as soon as born)
Forced caesarean sections
Invasion of bodily integrity? It is assault and battery to perform surgery without consent
But is a woman in labour fully competent?
(if a woman has carried the baby to term but would now rather it died than have a C section then can they ever be competent?)
If have capacity, cannot override decision
Interests of foetus do not take precedence - unborn foetus does not have legal status until born
Assisted reproductive technology - legal aspects
ART
Legally regulated - all embryos outside of the body, use and storage of gametes
Potential recipients now include single women, older women, same sex couples, couples with ill health - as well as heterosexual couples
ART motivated by compassion, response to medical need (infertility is a disease), having children is intrinsically important
Just use of resources? One cycle of IVF £3000
Donor insemination
- sperm/egg donated
- need to try to match physical characteristics/ethnic background, cannot select irrelevant to health characteristics
- no payment beyond reasonable expenses
- low success rate
- anonymity now removed
Surrogacy
- commercially is criminal offence
- advertising for commercial arrangements also illegal
- legal mother is gestational mother unless relevant court proceedings carried out
- only allowed where mother is unable for physical/medical reasons to carry child herself
Compliactions of In vitro fertilisation
- risk multiple pregnancies
- incidence birth defects
- incidence pre-term delivery
+ don’t know long term effects (first IVF baby born in 1978)
Ethical issues around ART
Unnatural Disposal of surplus embryos Cost/accessibility Justice and priority Risk vs benefit
Need to consider potential child, couple/woman seeking treatment, broader social interests
Posthumous conception - now not permitted without written permission from father in case of death
PGD = pre-implantation genetic diagnosis
- avoid birth of child with inherited condition
- choose non-medical traits in child
- create ‘saviour sibling’
Time-consuming, expensive, low success rate
Which diseases is it acceptable to use PGD for?
CANNOT implant embryo known to have abnormality where there is another that doesn’t (eg deaf parents selecting for deaf child)
Sex selection banned unless to avoid sex-linked abnormality
Puberty
The bodily changes that confer fertility
- activation of gonads, growth of reproductive tract, development of secondary sex characteristics
- gradual
- recognised by first (anovulatory) menstruation/(nocturnal) ejaculation
Age reaching puberty is declining - due to nutritional factors and maybe increased exposure to artificial light
Sequence of maturational change is always the same, age of onset and length of time taken to complete varies
Sequence of pubertal changes
FEMALE
Pubic hair, breast buds, growth spurt, menarche
MALE
Pubic hair, testis enlarges, penis size increases, voice breaks, growth spurt
(pubertal staging important to detect anomalies early on)
Endocrine changes in puberty
Adrenarche - weak adrenal androgens (DHEA and androstenedione)
-> growth of axillary and pubic hair
Reactivation of HPG axis
Gonadarche - nocturnal rise of gonadotrophins (diurnal rhythm) before development of adult pattern (sustained higher LH levels) - pulsatility due to GnRH release
Progressive rise in overall levels of gonadotrophins and steroids
Sex steroid upregulation of GH release and function
Adolescent growth spurt
Around age 12 in girls, age 14 in boys (hence boys ~10cm taller, as 2 years more growth)
Height gain of ~10cm per year (prev 5cm)
Increased activity of epiphyseal plates, then ossification
- due to combined effects of steroids and GH (GH due to oestrogen)
- > sexual dimorphism of body form fully established - size and shape of skeleton, amount of muscle, amount/distribution of body fat differs
- girls increase fat, hips widen, boys become leaner, shoulder widening, thickened laryngeal cartilage
Steroids action in growth spurt
OESTRADIOL
- increase secretion of GH in pulses -> differentiation and clonal expansion of chondrocytes
- release IGFs in cartilage and bone -> increased activity of chondrocytes and oesteoblasts
- directly accelerated mineralisation
Also need background levels of insulin and thyroxine hormones
Theories of mechanisms of puberty
Endogenous stimulation of GnRH release is rate-limiting step for puberty - restraint of GnRH secretion must be removed
SOMATOMETER HYPOTHESIS
- need to achieve critical body weight
- 30kg growth spurt, 47kg start menarche in girls, 55kg puberty onset in boys
- about fat mass deposition, not just weight
- leptin is fat-derived hormone, rises proportional to body mass, signals to hypothalamus to activate GnRH mechanism
MELATONIN
- melatonin restrains GnRH release
- so less melatonin in puberty
Disorders of puberty
PRECOCIOUS
- before 7 years in girls/8 years in boys
- GnRH dependent or independent
- due to endocrine cause (fault in HPG axis) or tumour
DELAYED
- no puberty by 17 years
- may be hypergonadotrophic or hypogonadotrophic (Prader Willi)
Common in female athlete triad (lean body mass)
Stages of labour
FIRST
- onset regular contractions
- effacement and dilatation of the cervix
> latent phase: onset contractions -> cervix fully effaced
> active phase: fully effaced cervix dilates
- up to 14 hours long
SECOND
- full dilatation of the cervix - delivery of baby
> propulsive phase: head descends to pelvic floor
> expulsive phase: experiencing desire to push
- up to 3 hours long
- head needs to rotate - transverse through pelvic inlet, diagonal through middle, facing down through pelvic outlet
THIRD
- after delivery of baby - delivery of the placenta
- 30mins
Cervical ripening
Thinning, softening, relaxing, dilating
- inflammatory process
- collagen fibres realigned
- collagen cross-linkages broken by proteolytic enyzmes
- uterine contractions exert pressure on cervix
Due to PROSTAGLANDINS - PGE2 mainly - increase collagen degradation - increase chemotaxis for leukocytes (draw in WBCs to increase collagen degradation) - increase interleukins OESTRADIOL REDUCED PROGESTERONE Relaxin Nitric oxide Apoptosis
Role of placenta in initiation of labour
Corticotrophin-releasing hormone
Peptide hormone released from hypothalamus, and secreted by placental trophoblasts during pregnancy
CRH receptors in myometrium and foetal membranes
Three weeks before onset spontaneous labour
- rise in plasma CRH
- abrupt fall in CRH binding proteins (so more CRH available)
- > stimulates release of prostaglandins from amnion and decidua and potentiates their actions
- > potentiate oxytocin actions
- > synthesis of glucocorticoids
- –> positive feedback loop, stimulates placental CRH secretion, drives onset labour
Role of foetus in initiation of labour
HPA activation in foetus -> production of DHEA
-> converted to oestriol in placenta
Rise in DHEA and E3 (oestriol) in last 4-6 weeks pregnancy
HPA activation also -> cortisol -> increased CRH by placenta
Cortisol -> foetal organ maturity, placental expression of uterotonic genes, increased placental production of CRH, oxytocin, prostaglandin
Progesterone withdrawal as initiator of labour
Progesterone in pregnancy
- hyperpolarises myometrial cells, inhibits contractions
- reduces oxytocin sensitivity
- stabilises decidua and membranes
- decreases gap junction formation
- NO synthesis (uterine quiescence)
- inhibits CRH expression at placenta
Anti-progesterone -> cervical ripening and initiate labour
(but exogenous progesterone doesn’t prevent spontaneous labour)
SO uncoupled action of progesterone - functional withdrawal
Uterus contraction
Intracellular calcium waves -> AP threshold, depolarisation
Transmitted between myometrial bundles by gap junctions, for coordinated contraction
Oxytocin increases the gap junctions and calcium channels
Oestrogens and labour
Increase uterine contractility
- increase actomyosin and glycogen in myometrium
- depolarises myometrial cells
- increase gap junctions
- increase oxytocin sensitivity
- destabilise decidua and membranes (so prostaglandin release)
Stimulation is dilatation of cervix by foetal head
Oxytocin and labour
Synthesised in hypothalamus, released from posterior pituitary
Potent stimulator of myometrium -> contractions
(but only works if already primed by oestrogen)
Stimulation is dilatation of cervix by foetal head
Prostaglandins and labour
Local tissue hormones - rapidly destroyed in circulation Made by all tissues of uterus Levels rise early in labour - powerful contractors of smooth muscle - can promote labour at any stage
Artificial induction of labour
1 - prostaglandins
2 - artificial rupture of membranes (allows head to drop and exert pressure on cervix and cause release of prostaglandins and oxytocin)
3 - syntocinon (artificial oxytocin)
IF
- term past 42 weeks
- baby growth compromised
- if baby too large (mother diabetic)
- preeclampsia/mother’s health compromised
- foetal demise (miscarriage)
Structure of breast
20-30 separate tubulo-alveolar glands
Each gland forms a lobe, each has single lactiferous duct to nipple
Alveoli supported by connective tissue
(before lactation, secretory tissue rudimentary, much of gland made of fat)
Pregnancy -> major growth of breast, replace fat with secretory tissue
Growth stimulated by oestrogen (ducts) and progesterone (secretory)
Prolactin released during suckling -> complete emptying of mammary gland by milk-ejection reflex (can be conditioned)
Suckling inhibits release of dopamine from hypothalamus
Lactotrophs free of dopamine inhibition, release prolactin
Composition of milk
Water - 88%
Lactulose - main carbohydrate energy source, promotes growth of lactobacillus in gut, galactose is important in myelin formation
Fat - TGs in membrane bound globules, major energy supply medium for vitamins
Protein
Guidelines to breast-feed exclusively for 6 months
Targets for contraceptives
FEMALE
- ovulation
- egg transport
- implantation
- sperm transport
MALE
(- sperm production)
- sperm transport
Efficacy of contraceptives
Perfect use/typical use
Pill - 0.3-0.5%/8% Injectables and implantations - 0.3%/3% IUDs - 0.5-0.8% Sterilisation - 0.02-0.5% Barrier - 2-5%/15-20% Natural - 2-6%/25%
Combined oral contraceptive pill
COCP (though same for contraceptive patches and vaginal ring - wear for 3 weeks, 1 week off)
Mix of progesterone and oestrogens
1 - prevent ovulation
2 - cervical mucus thickens (halt sperm transport)
Usually monophasic (same mix of hormones every day), sometimes bi/triphasic
Advantages
- effective
- easy to use
- not intercourse related
- reversible
- periods lighter and less painful
- reduction in PMS
Disadvantages
- forgetability
- needs advance planning before sex
- side effects
- risk for venous thromboembolus
Progesterone only pill
Low dose progesterone throughout cycle
1 - cervical mucus thickens (halt sperm transport)
2 - 20% prevent ovulation (cerazette)
Advantages
- effective
- easy to use
- not intercourse related
- reversible
- suitable for more - smoker/obese/older/lactating/high BP
Disadvantages
- forgetability - smaller window that COCP
- needs advance planning before sex
- side effects
Levonelle
Post-coital contraceptive
- progesterone
- one pill within 72 hours
- prevents/delays ovulation, prevents follicular rupture or cause luteal dysfunction
- no prescription needed
- no harmful effects if is pregnant
- side effects
- may not work
EllaOne
Post-coital contraceptive
- ulipristal acetate
- progesterone receptor modulator
- prevents/delays ovulation
- up to 120 hours after
- no effect if is pregnant
- side effects
- may not work
Cu-IUD
Copper bearing intrauterine device
Post-coital contraceptive
- disrupts egg transport and implantation (still get fertilisation)
- up to 120 hours after (can stay in for up to 10 years)
- side effects
- may not work
Injectables and implants
Depot of slowly releasing progesterone
- prevent ovulation
- act on cervical mucus, endometrium and fallopian tubes
(same as progesterone only pill, just don’t have to take daily)
- effective
- non-intrusive
- long-lasting
- fewer side effects (not orally taken)
- require operative procedure
- injectables cannot be immediately reversed, ~3 months
- irregular bleeding common
IUS (mirena)
Hormonal coil
- increase thickness of cervical mucus
- thinning of endometrium
- preventing ovulation
- very effective
- not user or intercourse dependent
- local hormonal action only
- reduced periods
- reduced risk endometrial cancer
- side effects, irregular bleeding
Contraindications to using hormonal contraception
OESTROGEN
- pregnancy
- focal migraines
- venous thromboemolus (risk of)
- breast cancer
PROGESTERONE
- acute porphyria
- severe liver cirrhosis
- breast cancer
Non hormonal intrauterine devices
Made of copper or plastic
Cause mild inflammatory response -> toxic environment reducing survival of gametes and embryo
AND disrupt implantation
- work long-term
- highly effective
- non-intercourse related
- no user error
- no hormones, don’t affect cycle
- need to be fitted by expert
- heavier periods
- may be expelled or displaced (at beginning)
- ? increased risk of ectopic pregnancy
Barrier methods
Male or female condoms
- no medical interference
- protective against STIs
- need planning
- user dependent
- intercourse reliant
Natural methods
Monitoring female cycle to avoid intercourse when most fertile: calculation (need to be very regular), temperature measurements, cervical mucus observations, hormone levels in urine, lactation amenhorrea, coitus interruptus (25% failure)
- no medical interference
- allowable by faith
- unreliable
- requires periods of sexual abstinence
- increased likelihood of fertilisation with aged gametes?
Sterilisation
Clip vas deferens/fallopian tubes
Permanent
Should be considered non-reversible
- effective
- no side-effects
- requires surgery
- much more invasive for women - key hole laparoscopy or new essure method via uterus, coils into tubes
- some failure rate - clipping wrong tubes, or tubes rejoining
Future of contraception
Male pill
- testosterone and progesterone
- halt sperm production
- phase III trials
RISUG - reversible inhibition of sperm under guidance
- chemical blockage and spermicide in vas deferens
- then other chemical to unblock
IVD - intra-vas device
- injectable plug to vas deferens
Factors involved in second stage of labour
3 Ps
POWERS
- uterine contractions (dehydration)
- maternal pushing (exhaustion, epidural)
PASSAGES
- bony pelvis (hip problems, previous fractures)
- soft tissues (masses, fibroids)
PASSENGER
- suboptimal head position (deflexed)
- rotational malposition of head (occipitoposterior, occipitotransverse)
- malpresentation of head (brow, face)
- size of foetus
Assisted delivery
Ventouse
- silicone cup - plugged into wall for vacuum / kiwi cup - smaller, handheld / metal cup (rare)
- head must be occipito-anterior, below spines
- requires maternal effort
- local analgesia only
- bigger bump/bruising left for baby, will go down quickly
Forceps
- Kiellands / Wrigleys / Neville Barnes / Simpsons
- head must be occipito-anterior, below spines
- no maternal effort required
- need pudendal anaesthetic or epidural
- safer for baby, but more maternal trauma
Caesarean section
Assisted delivery often done as ‘trial’ in operating theatre, if not working then -> C section
- if baby above ischial spines / brow face or shoulder presenting / pelvic tumour
Better for woman to be awake with spinal analgesia - safer for mum and baby (GA crosses placenta), nicer for families (partner can be in room)
Glycogen and fat in foetus
Glycogen stores in liver and cardiac muscle
- regulated by adrenal cortex
Fat stores
- white fat - fatty acids - all around body
- brown fat - heat generation (many mitochondria) - at specific points around body: neck, under scapulae, back, under adrenals, around kidneys
- regulated by foetal insulin
Other nutrients in foetus
Amino acids
- no increase in maternal protein intake
- progesterone increases metabolism efficiency
Fatty acids
- mother accumulates lipids in early pregnancy
- placental transfer and foetal synthesis to meet demands
Salt and water
- maternal retention stimulated by oestrogen and progesterone
Iron
- maternal absorption enhanced
- foetal blood 2-3 x higher concentration
(need to take supplements)
Calcium
- maternal absorption enhanced
- foetal ossification needs much calcium
Vitamins
- folic acid (B9) for amino acid metabolism, risk of neural tube defects if deficient
- B12 for fatty acid and amino acid metabolism
- at expense of maternal stores (so need to take supplements)
Foetal systems redundancy
Intrauterine environment relieves foetal organs of need to
- respire/digest - placenta
- weight bear - amnion makes weightless state
- control temperature - isothermal environment in utero
-> redundancy in systems
But must be developed and mature enough to sustain life immediately after birth
Foetal cardiovascular system
Adaptations
- two foetal ventricles pump in parallel (not lub dub)
- four foetal shunts to divert blood:
> placenta - foetal blood is diverted here instead of to abdominal organs/legs
> ductus venosus - through liver - best oxygenated blood needs to go straight to heart first
> foramen ovale - flap valve open between right and left atria
> ductus arteriosus - vessel joining pulmonary artery to aorta, so bypassing foetal lungs
Changes in foetal circulation at birth
Four foetal shunts need to close, replacing placental with pulmonary circulation:
- placenta stops delivering oxygenated blood, lungs open
- pulmonary vascular resistance drops as PO2 rises (with low PO2 get hypoxic vasoconstriction), increased pulmonary blood flow
- increased peripheral resistance as placenta lost, pressure on right side heart decreases, left side increases, foramen ovale physiologically and biochemically shuts
- ductus venosus stops carrying blood to heart
- ductus arteriosus contracts and closes
Foetal respiratory system
1-4hours each day spent practise breathing in utero
- rapid and irregular
- only during REM sleep
- diaphragmatic
- moving amniotic fluid in and out of lungs
Near birth, steroids increase no. type II alveolar cells, increase no. lamellae bodies
- so increased surfactant
- water reabsorption, switch from Cl- secretion to Na+ absorption - change from CFTR to ENaC salt and water channels to dry out foetal lungs
First breath needs most energy to inflate lungs, gets easier
Foetal gastrointestinal system
Foetus swallows lots amniotic fluid each day
- salt, water, small molecules absorbed in small intestine
- debris and large molecules accumulate in large intestine -> meconium
Should be no defecation in utero (distress)
- to practise
- small contribution to foetal nutrition
- control amniotic fluid volume (take in)
Foetal renal system
Placenta, not kidney is organ of excretion
- kidneys function to regulate amniotic fluid volume (water turn over at least once every day) (excrete)
Foetal endocrine system
Foetus self-sufficient in hormone requirements from early on
- foetal hormones influence mother
- maternal hormones only influence foetus in disease
Specialised functions:
- hypothalamus to co-ordinate activity of other endocrine organs
- anterior pituitary to regulate other endocrine organs
- thyroid for foetal development
- pancreas for insulin, regulating rate of glucose use
- gonads: ovaries inactive, testis essential for male sexual differentiation
