keeping people healthy week 1 Flashcards by Emilia Summers

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

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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

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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

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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

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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

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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

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What are the causes of spina bifida?

lack of folic acid
family history
some epilepsy medication
genetic conditions
obesity
diabetes

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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

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What are the types of spina bifida?

Myelomeningocele
meningocele
oculta

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Describe myelomeningocele

most serious
spinal cord and meninges push out and create sac on baby’s back

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Describe meningocele

only meninges push out

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Describe oculta

most common - opening to spine is small and covered in skin

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What is screened for during pregnancy ?

infectious disease
inherited conditions
Down’s, Edward’s or Patau’s syndromes
Abnormalities

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What can be used for screening?

blood tests
ultrasound tests

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What diagnosis tests can be carried out during pregnancy?

amniocentesis or chorionic villus sampling

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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

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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

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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

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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