keeping people healthy week 1 Flashcards
Describe the hormonal changes during pregancny
oestrogen is produced by the placenta
hCG increased - produced by placenta-cytotrophoblast
hCG maintains progesterone secretion by corpus luteum
progesterone secretion taken over by placenta - relaxes smooth muscle and increases ventilation
Prolactin levels increase and change mammary glands from ductal to lobular
PTH is increased to increase calcium reuptake
adrenal hormones, cortisol and aldosterone increase
human placental lactogen (LPL) is produced by placenta and stimulates lipolysis and fatty acid metabolism by the woman, conserving blood glucose for the foetus
Describe the physical changes during the first trimester
lots of changes and symptoms extremely high levels of oestrogen and progesterone morning sickness tender and swollen breasts elevated pulse rate mood changes
What is detected in a pregnancy test?
Human chorionic gonadotropin present from time of conception and can be detected in home pregnancy test about a week after missed period
What are the physical changes during the second semester?
body adjusts to changing hormone levels and symptoms lessen or disappear more energy increased pelvic pressure back pain may feel kicking
What are the physical changes in the third trimester?
uterus pushes on diaphragm ankle, feet and face swell as fluid is retained and circulation slows hip and pelvic pain varicose veins leakage of colostrum difficulty sleeping
What can be done to keep the embryo healthy?
healthy diet avoidance of certain foods avoid alcohol smoking cessation check drugs and medications vitamin D supplements folic acid gentle exercise (if not new) avoid high risk sports
What are the causes of spina bifida?
lack of folic acid family history some epilepsy medication genetic conditions obesity diabetes
What are the effects of spina bifida?
weekness or paralysis of the legs
bowel or urinary incontinence
loss of sensation in legs or bottom
many babies will develop hydrocephalus which can cause brain damage
What are the types of spina bifida?
Myelomeningocele
meningocele
oculta
Describe myelomeningocele
most serious
spinal cord and meninges push out and create sac on baby’s back
Describe meningocele
only meninges push out
Describe oculta
most common - opening to spine is small and covered in skin
What is screened for during pregnancy ?
infectious disease
inherited conditions
Down’s, Edward’s or Patau’s syndromes
Abnormalities
What can be used for screening?
blood tests
ultrasound tests
What diagnosis tests can be carried out during pregnancy?
amniocentesis or chorionic villus sampling
Describe the placenta
connection between mother and foetus
physical attachment of embryo to uterus
bringing feel/ maternal circulations to proximity
allow exchange of gases
foetal growth and development depend on placenta
Describe the chorionic placenta
chorionic plate is covered by avascular glossy amnion
the vessels that can be seen on this plate are chorionic vessels
chorionic vessels branch from the umbilical cord
Describe the basal plate
maternal side
top layer of surface adheres to the placenta after separation from the uterus
endometrial and trophoblast cells and fibrinoid
separated by lobes which roughly shows the underlying villous tree
What is the precursor to the placenta?
cytotrophoblast
trophoblast extensions penetrate in between the uterine endometrial cells
Describe stage one of placental development
CTB layer differentiates into the inner villous CTB and a non dividing layer called the syncytiotrophoblasts
fluid filled spaces called lacunae begin to develop within the CTB mass
What happen in stage two of placental development?
some trophoblasts migrate into the endometrium around the uterine spinal arteries
initially maternal blood escapes from the spinal arteries and passes into the lacunae before the mouths of the spiral arteries become blocked by trophoblast plugs
these prevent maternal blood from entering the lacunae or intervillous space for the first 10 weeks of pregnancy
Describe stage 3 of placental development
placenta and foetus experience no oxidative stress
as the plugs dissolve oxygen tension increases and placenta produces protective antioxidants
changes occur in the endothelial lining of the uterus including cellular growth
Describe the villous tree
trophoblasts and lacunae start branching
the lacunae are precursors to intervillous space
the branches of the trophoblast become known as chorionic villi
the villous core is known as the stroma and is mostly fibroblast cells
capillaries develop within the villi
cCTB layer is only present in early pregnancy
Describe trophoblast invasion
trophoblasts begin the invade into the maternal endometrium, myometrium then spiral arteries
this remodels the arteries from being low flow, high resistance to high flow, low resistance
Describe placental transport
fatal blood flows through the umbilical arteries to the capillaries of the villi and then returns through the umbilical vein to the foetus
a very short distance separates the foetal and maternal circulations
oxygen and substances are transported or diffuse into foetal blood and waste into maternal blood
Describe nutrient transfer in uterus
O2 diffuses
glucose - facilitated diffusion
amino acids - active transport
fatty acids - highly regulated
What is the inducer?
one cell population / tissue acts on another tissue (the responder_
Describe the development of the neural tube
gastrulation week 3
ectoderm makes epidermis and nervous systems
development of noto cord
transient pattering structure
role in molecular signalling
inductive relationship with overlying ectoderm
signals from the note cord (mesoderm) induce development of neural plate in overlying ectoderm
signals involve noggin and chordin
What does noggin do?
inactivates BMP4 which causes patterning of noto cord and somites
What does chords do?
BMP antagonist - cranial mesoderm is dorsalised
Describe the formation of the neural plate
appearance of the noto cord and mesoderm induces the overlying ectoderm to thicken and form the neural plate
cells of the plate make up the neuro-ectoderm and is the initial process of neurulation - formation of the neural tube
Describe folding of the neural plate
lengthen and lateral edges elevate
form the neural folds
depressed mid region forms neural groove
the folds approach each other in the midline and fuse forming the neural tube
tube sinks in and overlying ectoderm repairs
neural tube forms brain and spinal cord
neural tube closes by day 22
Describe bending of the neural tube
cell wedging - microtubules and microfiliametns change cell shape
Hinge points - median hinge points, dorsolateral hinge pint
extrinsic forces - pushing of the surface ectoderm, adhesion point with notocord
Describe the closure of the neural tube
fusion begins in the cervical region and proceeds in cephalic and caudal directions
open ends of tubes form anterior and posterior neuropores
these connect with the overlying amniotic cavity
closure occurs in week 4
somites also form along side neural tube
Describe sonic hedgehog signalling
one of the most potent inductive signals
part
Describe signalling involved in the differentiation of the neural tube
noto cord continues to exert inductive influence
presents the SHH to neural tube
the ventral most cells respond to this signal - make the floor plate of the neural tube
floor plate then makes its own SHH - responsible for development of motor neurones on each side of the tube
Describe the role of the PAX genes
pumps from the ectoderm up regulate PAX3 and PAX7 so the roof plate forms, sensory neurons develop here
when SHH induces the floor plate, PAX3 and 7 expression is repressed. This allows cells to adopt ventral fate
Describe patched and smoothened signalling
patched inhibits smoothened - this stops downstream signalling cis Gli which would eventually traduce SHH signs
If SHH binds to patched, removes inhibition, unreguates downstream pathway and controls effector genes ub the SHH pathways
What can cause defects?
environmental
chromosomal
multifactorial genetic predisposition
most unknown
What is a teratogen?
an agent that can disturb the development of the embryo or foetus
What effects can teratogens have during weeks 1-2?
teratogens will either have no effect or conception will be aborted
What effects can teratogens have during weeks 3-8?
organs are being established
each organ has its own period of maximum sensitivity
type of defect seen depends on time
What effects can teratogens have during weeks 9-38 of pregnancy?
functional deficits and minor abnormalities depending on stage
What sorts of things can be teratogens?
environmental
drugs and chemicals
industrial pollutants
hormones
What are the effects of foetal alcohol syndrome?
facial deformities low birth weight small head developmental delay poor coordination poor socialisation poor memory
