Block 11 key things to learn Flashcards
What is the polar body and when is it formed?
Second meiotic division is uneven and extrudes a polar body to get rid of chromosomes that aren’t needed.
Presence of it means fertilisation has occurred
What do foetus and placenta work together to produce?
Oestrogens- foetus make C19 androgens and placenta converts it to oestrogen
What drugs have fetotoxic effects in the 1st trimester?
Androgens- visualisation of female foetus
Oestrogen- feminisation of male foetus
Warfarin- nasal hypoplasia and skeletal defects
Retinoids- craniofacial, CVS and CNS defects
Diethylstillboestrel- uterine lesions, transplacental carcinogen
Anti-epileptics- facial defects, mental retardation, neural tube defects
What drugs have fetotoxic effects after the 1st trimester?
Anti-epileptics- mental retardation Narcotics- respiratory depression Warfarin- foetal haemorrhage, CNS abnormalities Antidepressants- neonatal withdrawal Benzodiazepines- floppy infant syndrome withdrawal, respiratory depression
What do ACE inhibitors cause in the foetus?
Oligohydraminous, growth retardation, lung and kidney hypoplasia, hypocalvaria, neonatal convulsions, hypotension and anuria
What are some issues of where foetal circulation doesn’t adapt after birth?
Duct dependent systemic circulation-
coarctation of aorta
critical aortic stenosis
hypo plastic left heart syndrome
Duct dependent pulmonary circulation- pulmonary atresia critical pulmonary stenosis tricuspid atresia teratology of ballot
Duct dependent systemic and pulmonary circulation-
transposition of great arteries
What happens in capacitation?
Needs time away from seminal fluid, led by calcium.
2 parts-
- hyperactivation- sperm starts swimming
- removal of acrosomal cap so fertilisation can occur
What happens in fertilisation?
Acrosomal head of sperm has enzyme hyaluronidase to digest through cumulus cells surrounding egg to get to zona pellucida.
Then sperm interacts with proteins ZP2 and 3 to trigger acrosome reaction and sperm gets incorporated into egg.
Then trigger hardening of zona to block polyspermy
How does the egg get activated?
Sperm contributes DNA and phospholipase C gamma.
Enzyme starts calcium signalling cascade needed to activate egg and trigger 2nd meiotic division
How does blastocyst implantation occur?
Uterine epithelium produces heparin binding epidermal growth factor and signals to embryo to produce epidermal receptor so embryos can attach to uterine epithelium.
Embryo then produces enzyme serine I theonine kinase to change the endometrium so it can implant
What are the 4 pelvis types?
Gynecoid- 50% of women, wide pubic arch- good for delivery
Android- narrower pubic arch, harder delivery
Anthropoid- wider anterior-posterior direction but narrower across so issue with rotation- baby born back to back
Platypelloid- same as above but wider across ways
What are the forces of retention in labour?
Progesterone Hypervolaemia Relaxin CRH Adrenaline Cervix
What are the forces of release in labour?
Oestrogen Oxytocin Vasopressin Prostaglandins Cortisol Uterine distension
What is looked at in the postnatal examination?
W- wound assessment O- observations M- monitor first urine void A- assess uterus N-note colour and circumference of calves
What is looked at in the newborn APGAR?
Activity Pulse Grimace Appearance Respiration
What is the UK vaccination schedule?
8 weeks- 6 in 1, pneumococcal, rotavirus, menB 12 weeks- 6 in 1, rotavirus 16 weeks- 6 in 1, menB, pneumococcal 1 year- hib/ menC, MMR, MenB, pneumococcal 2-9 yrs- Annual flu jab Preschool- 4 in 1, MMR 13 yrs girls- HPV x2 14 yrs- 3 in 1 , MenACWY
How does foetal mammogenesis occur?
Derived from ectoderm and mesoderm layers
Starts as 2 milk streaks from axilla to groin then thickens and become glandular tissue that grows into chest. Then get mammary bud branching and differentiation of smooth muscle cells of nipple cells etc.
Then have primary milk ducts by 32 weeks gestation which open up onto nipple and nipple and areola develop and become pigmented
What is the nerve and blood supply of the breasts?
Intercostal nerves
Arterial supply from internal mammary artery and 30% from lateral thoracic artery
Venous drainage from internal and external mammary and axillary veins
What are the stages of lactogenesis?
I- Mid/ late gestation- 48 hours after birth
Endocrine control
Some colostrum made in alveoli and fat droplets accumulate in lactocytes
Colostrum produced is proportional to prolactin but prolactin is inhibited by high progesterone levels
II- Triggered after labour finished and oestrogen and progesterone levels fall
Tight junctions between lactocytes close and mum feels breast fullness 2-3 days after birth
Breast milk sodium and protein levels fall but lactose and lipids rise
Change to aubocrine process
III- from day 8-9
Process is aubocrine control
Milk removal drives production
What are the theories of lactation?
Prolactin receptor theory-
Prolactin receptors in lactocytes distort shape when breast full off milk so prolactin can’t attach so less milk is produced, so prolactin can only attach when don’t have much milk made
Feedback inhibitor of lactation-
small whey protein in breast milk slows milk synthesis when breasts are full
Prolactin inhibitory theory-
Hypothalamic factor build up and suppresses prolactin secretion from anterior pituitary when breasts are not emptied to decrease milk production and vice versa
How is milk ejected?
Suckling causes release of oxytocin from posterior pituitary which travel via blood to breast to stimulate myoepithelial cells to contract and squeeze milk out of breast
What are the mediators of growth?
Growth hormone from anterior pituitary stimulates growth at epiphyseal plates.
Also have indirect actions mediated by insulin like growth factors- IGF1 which is stimulated by GH after birth.
But iGF II is independent of GH and if over expressed in foetus then get large tongue, muscles, heart liver and kidney
How is growth hormone regulated?
GH stimulates IGF1 from target tissue
IGF1 directly inhibits GH release by suppressing somatoptrophs
Also indirectly inhibits GH release by suppressing GNRH release from arcuate nucleus of hypothalamus
GH also inhibits its own release via short loop feedback on somatotropin
Describe achondroplasia?
Most common form of dwarfism
Autosomal dominant mutation in chromosome 4 coding for FGFR3
Causes decreased endochrondral ossification and inhibits proliferation of chondrocytes in growth plate cartilage and epiphyseal growth plate closes early
Average height 120-125cm
All organs normal
Large head, prominent forehead, flat bridge of nose, short hands, stubby fingers
