Embryology and Fetal screening Flashcards
Explain genetic programming and expression
Differentiation and morphogenesis of genetics
Control of cells turning on or off
Meeting of genetic material determines many external and internal characteristics of the future child
Give an overview of the first 23 days
Formation of umbilical cord and placenta happen very early
From here there will be differentiation of cells into any of the 250-300 cells needed in the body
What is blastocyst
Cells division becomes asymmetrical
Cells polarise
Loose their totipotency and begin to differentiate
Inner cell mass - fetus
Outer cell mass - the trophoblast which develops into the placenta
What occurs during week 2
Epiblast & hypoblast= bilaminar embryonic disc
Hypoblast - endoderm layer
Epiblast - ectodermal layer
Day 14 primitive streak starts to develop- threshold at which experimentation must stop
What occurs during week 3 ( gastrulation cell migration and rearrangement)
Primitive streak in the midline
Bilaminar disc is converted into trilaminar disc
3 germ layers- ectoderm, mesoderm and endoderm
2mm long
Notochord forms induces development of the neural plate
Morphogenesis
Primitive heart - heart tube
Primitive nervous system
What happens during week 4 ( organogenesis)
Folding
C shaped embryo
Constriction between embryo and yolk sac
Beating heart present
What is the function of the placenta
Pneumonic SERPENT
What does the S in SERPENT and explain
Placenta stores glycogen, metabolises this provide glucose as fetus requires until fetal liver is sufficiently developed to function
Stores iron and fat soluble vitamins
What does the E in SERPENT mean and explain
Produces steroid ( e.g. oestrogen & progesterone) and placental ( HCG, human placental lactogen, hPGH & PAPP-A and B ) protein hormones
What does the R in SERPENT mean and explain
Oxygen and carbon dioxide transferred to and from maternal circulation to and from fetus by diffusion, transfer assisted by slight maternal respiratory alkalosis in pregnancy ( fetal uptake assisted by the higher affinity to oxygen of fetal haemoglobin and high fetal haemoglobin levels in utero )
What is the P in SERPENT and explain
Acts as a filter to most bacteria- however tubercle bacilli may transfer to fetus
Many viruses can transfer- e.g. rubella, parvo virus B19, cytomegalovirus, HIV, hepatitis
Some Protozoa can transfer- e.g. malaria, toxoplasmosis
What does the E in SERPENT mean and explain
Excretion
CO2 is main product excreted from fetus
Bilirubin also excreted due to turn over of RBC
Small amounts of urea and uric acid also excreted
What is N in SERPENT and explain
Nutrition
Fetus receives simplified raw materials for growth and development
Protein in form of amino acids
Carbohydrates in form of glucose
Fats in form of fatty acids, fats and fat soluble vitamins in later pregnancy stages
Water, and minerals
What is T in SERPENT and explain
Transfer of substances
Usual cellular membrane transport systems used
Simple diffusion of lipid soluble substances
Water pores transfer water soluble substances
Facilitated diffusion of glucose using carrier proteins
Active transport against conc gradients of ions
Endocytosis of macromolecules
Describe the placenta
Diameter- 20cm
Circumference- 62.5cm
Thickness- 2.5cm at centre, tapering towards edges
Describe maternal surface of placenta
Attached to the decidua basalia in pregnancy
Dark red in colour
Divided into 10-40 cotyledons
Cotyledons made of lobules consisting of chorionic villi
Residual remains may leave grey areas on surface of placenta
Describe the fetal surface of the placenta
Shiny, greyish blue colour, cord attached here
What is the outer placental membrane and explain
Chorion
Continuous with edge of placenta
Rough, thick, fibrous, opaque
Lines decidual Vera during pregnancy- loosely attached
Friable - ruptures easily which can reduce locally produced progesterone
Produces enzymes which can reduce locally produced progesterone
Produces prostaglandins, oxytocin and platelet activating factor which stimulate uterine activity
What is the inner placental membrane and explain
Amnion
Derived from inner cell mass
Moves over chorion aided by mucous
Can rupture and therefore cause amniotic bands
Tough, smooth and translucent, continuous with outer surface of umbilical cord
Contains amniotic fluid which it also produces to some extent as it grows
Produces PGE2 involved in initiation of labour
What occurs in week 5
Facial prominences develop
Head larger than trunk
Upper limb paddle shaped
Lower limb flipper like
Crown rump length 7-9 mm
What occurs during week 6
Upper limbs bent at elbow
Palate forming
External ear and canal formed
Crown rump length 11-14 mm
What happens in week 7
Liver prominent
Rapidly growing intestine herniate into umbilical cord
Crown rump length 16-18mm
What occurs during week 8
Fetal circulation functioning
Anal membrane perforated
External genitalia present
Ossification of bones in legs begins 8 weeks
Fingers distinct but webbed
Crown rump length 27-31mm
All organs now
What occurs during week 9
The fetus is probably about an inch long and its tail has all but disappeared
Some fetuses have been shown to suck their small thumbs
The fetus has begun to make facial grimaces and even swallowing motions
What occurs during week 10
Baby’s brain is developing rapidly right now
Well formed arms and legs as well as fingers and toes
The baby will begin to kick his little feet and even open his/her mouth
The baby’s intestines may begin to move into his/her body
What occurs during week 11
Between w 10-12 the fetus heartbeat can be heard with a hand held doppler
The baby is completely developed with all the necessary major organs and systems he/she needs to survive
What occurs during week 12
The fetus may be up to 3 inches long and is very active
Hair has begun to form on the fetus head and taste buds and vocal cords have begun to develop
End of the 1st trimester
What occurs during week 13
Beginning of second trimester
Fetus looks like a tiny infant with fully formed limbs and fingers and toes
Women’s body is also beginning to swell and grow as the baby begins to take up more and more space
The uterus may even pop outside of the pelvic cavity a bit
What occurs during week 14
Fetus neck continues to get longer and the eyes move closer together
Fetus learning how to move his hands through the amniotic fluid
Fingerprints are formed
What occurs in week 15
Fetus body is covered in lanugo which protects the skin
Baby’s bones are getting harder and muscles are developing more
The fetus hearing is also getting better and may jump in response to loud noises
What occurs during week 16
Gender of baby can be determined
Baby may suck his/her thumb or grab umbilical cord
The fetus is urinating and the fetus 1st stool has been forming in the intestines over the last few weeks
What occurs during week 17
Fetus is almost 5 inches long
Body is slowly catching up to head side and fetus no longer looks so top heavy
Eyes are in their final position
Fetus is almost finished developing both sets of their teeth buds
Begins to develop vernix and brown fat stores begin to build up
What occurs during week 18
Baby’s hearing becomes better each week
Baby can distinguish between mom’s heartbeat and voice
Fetus will even respond negatively to loud noise they don’t like
Fetus eyes becoming sensitive to light and can make facial expressions
What occurs during week 19
Fetus brain develops at a rapid rate
Millions of motor neurons are forming and nerve cells are developing to serve the senses
The baby will continue to mimic the act of breathing
What occurs during week 20
Halfway
Fetus is almost 6 inches long and 10 ounces
Movements are easier
A boys fetus testes will begin to drop into his scrotum
Hair will begin to grow on baby’s scalp
Baby’s legs are most finished growing to their final length
What occurs during week 21
Baby has thin eyebrows and hair continues to develop
Mothers bone marrow will begin to make RBCs for fetus
Movements are getting more frequent and easier to feel
What occurs during week 22
Taste buds are forming on the baby’s tongue
Baby begin to feel world around
Girl fetus has already produced all the eggs her ovaries will contain throughout life
What occurs during week 23
The baby will begin to develop surfactant
Fat production is also still developing and the fetus begins to look more like a newborn
What occurs during week 24
Footprints and fingerprints are continuing to develop
Every time the baby moves through amniotic fluid they create unique grooves in feet and hands
The baby begins to get regular sleeping and waking cycle
What occurs in week 25
Baby’s eyes may still be fused shut
The baby will begin to open their eyes and look around
Baby has eyelashes on their eyes and eyebrows now ell formed
What occurs in week 26
Baby is now capable of maintaining balance and can even tell if their right side up in the uterus
Baby starts to open eyes and may begin blinking
Brain waves are strong
Bronchial tract is developed
What occurs in week 27
Baby is about 2 pounds and would have 85% chance of survival if born
Baby has tripled or even quadrupled in length during second trimester
What occurs during week 28
Baby starting running out of room
The kicks and jumps will get alter as the baby begins to lose space
Baby’s lanugo is beginning to disappear
What occurs during week 29
Baby weighs between 2 to 3 pounds
Baby will kick to stretch their arms and legs
Baby’s skin is less wrinkly
Baby will begin to gain weight quite rapidly in preparation for birth
What occurs during week 30
Until baby is born they will gain up to half a pound a week
The mother can feel if the baby gets the hiccups
What occurs during week 31
Baby weighs about 3.5 pounds and is close to 17 inches long
Baby starts dreaming
Boy baby testicles may still be descending from scrotum
Fat stores are building up rapidly
What occurs during week 32
Baby will start to move to preferred position if not already
Mother will feel the baby kicking in the ribs when the baby is in position
What occurs during week 33
The baby is 4-5 pounds
The fetus head is still very pliable and skull bones are not joined at this point
What occurs during week 34
Fetus immune system is getting stronger
The baby is still moving slowly into position and is probably head down
What occurs during week 35
Baby will begin to gain weight at half a pound a week
Some of the bay’s features may be visible to naked eye
Fat continues to build up to help maintain baby’s body temp
Soft hair is now all gone
Vernix is at it’s thickest
What occurs during week 36
The baby could weigh up to 6 pounds and about 20 inches long
Baby’s immune system continues to grow and mature
Baby is receiving valuable antiobodies fron the mother
What occurs during week 37
Mother is considered full term
Baby’s lungs are almost completely matured
Everything the baby needs to survive outside the womb is now finished
What occurs during week 38
Pasty white vernix is almost gone
Baby can turn head towards light and sound
Baby can blink and grimace
Head remains flexible to fit through birth canal properly
What occurs during week 39
Baby should weigh between 5 pounds 11 ounces and 9 pounds
Baby will begin to move less and less due to space restriction
What occurs during week 40
Baby is full term and ready to be born
Describe the preconception care
Diet - avid caffeine, certain foods that might harm pregnancy
Exercise
Supplements- folic acid
Avoid risk behaviours- smoking, substance misuse, alcohol
Stability in housing, home life, finances ( as much as possible)
Control and stabilise existing conditions
When could we give pre- conception advice
When someone is considering a baby
At childbearing age
In contact with any medical services
Sensitive conversations- private struggles with fertility, transgender men and pregnancy, previous traumatic experiences of childbirth
Conversations about health promotion can and should be considered at any contact so this could be an opportunity to improve health long term
