Fetal Growth and Development

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Fetal Growth and Development
2014-09-09 22:35:47

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  1. Conception/fertilization
    • Union of the egg and sperm
    • interplay of female hormones maintain pregnancy throughout the gestation
    • - estrogen- helps things to grow-mature
    • - progesterone- during pregnancy- helps to keep pregnancy- calms everything down
    • - Human chroionic gonadotropin- sex hormone/fetal development and growth hormone tells placenta to grow- marker for pregnancy test
    • - Prostagladin- this decreases. this makes mom contract later on
    • - Relaxin

    these level all have to interact to maintain the pregnancy.
  2. What is gestation?
    Full term 40 weeks

    Fetus born < 37 weeks consider premature

    Age of Viablilty- when a fetus is able to survive outside the womb- extra uterine life 20-24 weeks
  3. Trimester
    • Pregnancy is divided into 3 trimester
    • 1st trimester- 1-12 weeks Alot happens during this time

    2nd trimester- 13-27 weeks

    3rd trimester 28-40 weeks
  4. Stages of development
    • Preembryonic stage - fertilization thru 2nd week
    •  -fertilization: cleavage and morula (splits and divides)
    • - Blastocyst (embryo) and trohoblast (placenta) implantation- 

    • Embroyonic stage- end of the 2nd week to 8th week
    •  - organogenesis is complete (all the organs are form)
    • - during this time the developing organism is called an embryo 

    Fetal stage-end of the 8th until birth
  5. Preembryonic Stage
    • 200 million rush one ovum
    • hormones have to be just right
    • fertilzation- occurs typically two weeks before period. 
    • takes place in the outer third fallopian tube

    • cells divide (cleavage) into four cells and then into 16 and this is when it is called the morula- 
    • stem cells can develop into anything
  6. Implanation
    Trophoblast attaches to the fundus

    Corpus luteum all eggs sit here

    fertilized 2/3 in the fallipian tube

    implants in the uterus 7-10 days

    upper area fundus- cause it has nutrients and muscles- placenta wants to attach here 

    ovum and sperm meet- miosis-miotosis- divide (cleavage)-morula- blastocyst and implants in upper uterus- this all happens in the first two weeks
  7. Embryonic Stage
    end of the 2nd week to the 8th week

    basic structure of major body organs and main external features
  8. Embryonic Layers
    Ectoderm- forms the central nervous system, special senses, skin, and glands

    Mesoderm- forms skeletal, urinary, circulatory, and reproductive organs

    Endoderm- forms respiratory system, liver, pancreas, and digestive system

    Multi potent cells
  9. Embroyonic/ fetal structure
    yolk sac- is the first place where RBC develop and then becomes apart of the GI tract

    Corpus luteum- ovum comes from- if egg is fertilized begins to recieve HCG from embryo

    HCG tell corpus luteum to keep producing progesterone  (to maintain pregnancy)

    after approx. 10 weeks the placenta takes the job of the progesterone production thru the end of the pregnancy
  10. Embryonic/fetal structure Decidua
    • Lining of the uterus
    • endometrial lining- allows for a nice nesting place for the baby

    • Secretes hormones- prolactin- produces mike for
    • relaxin- relaxes all your external organs, symphis pubis relaxes- so everything can move and the fetus can grow
    • prostagladins
  11. embryonic and fetal structures
    Fetal Membrane; Chorion
    • outside membrane- chorion
    • Finger like projections like arteries and veins. blood from mom and baby never mix

    function is to support the sac that contains the amniotic fluid

    Diffusion- O2 comes into the baby and CO2 comes out to get rid of it.
  12. Embryonic and fetal structures
    Fetal Membrane; Amnion
    • originate from the ectoderm germ layer
    • inner membrane- closet to the fetus
    • thin protective membrane that contains amniotic fluid
    • contributes to the protection of amniotic fluid

    Amniotic fluid- baby drinks and urinate out (increase thru out the pregnancy) keeps the baby safe and warm. helps baby to grow symmertrically. promotes fetal movement
  13. Amniotic fluid
    baby drinks and urinate out (increase thru out the pregnancy)

    • amount increases during pregnancy
    • Functions (know this)
    • - maintains a constant body temperture
    • - permit symmetric growth and developments (so baby is not on one side)
    • - cushion the fetus from trauma
    • - keep umbilical cord free from compression
    • - promotes fetus movement to enhance musculoskeletal development
  14. Aminiotic Fluid Volume
    • Fluctuates thru pregnancy
    • normal is clear fluid- approx 500-1500ml

    Green is noconum? this is not good

    • Abnormal
    • - oligohydraminos- not enough fluid
    • - hydraminos/polyhydraminos- too much fluid- can cause u to go into labor early (DM)- gi problem/kidney problem with baby
  15. Embryonic and fetal structure
    Chorionic Villi
    • maternal arteries and maternal vein
    • vascular projections
    • helps with diffusion
    • blood vessels that grow in the villi become connected to the chorion in the body stalk and within the body of the embryo
    • blood becomes to flow when the baby heart starts to beat.
  16. Umbilical Cord
    • formed from the amnion 
    • lifeline from the mother to the baby
    • one large vein and two arteries
    • - vein carries the oxygenated blood just like the pul. vein carries oxy blood to heart
    • - arteries carry deoxygenated blood 
    • - Wharton's jelly surround the vein and arteries to prevent compression (protect vessels)
  17. Umbilical cord function
    Provides a circulatory pathway that connects the embryo to the chorionic villi of the placenta (osmosis diffusion good stuff coming and bad stuff going)

    transports O2 and nutrients to the fetus from the placenta

    returns waste products from the fetus to the placenta

    AVA- two arteries and one vein
  18. Placenta
    facilitates gas exchange between the maternal blood and fetal blood

    the blood itself does not mix
  19. Placenta function
    protects fetus from immune attack by the mother

    removes waste products from the fetus

    has a deal with glycogen- drops glucose so mother can bring food to the baby

    hormone producing factory- produces hormones to mature fetal organs
  20. More Placenta
    maternal and fetal blood is separated by fetal tissue called placenta barrier

    materials can be interchanged thru diffusion 

    the mother's uterine artery brings in the nutrients

    mother uterine vein takes away the waste
  21. Placenta Hormones
    p 314-315

    Hcg etc
  22. Fetal stages
    • end of 8th week till birth
    • fetus v embryo 

    all though all major systems are present in their basic form, dramatic growth and refinement of all organ systems take place during the fetal period
  23. Fetal stage week 4 22-28days
    • a tubular heart beat begins- a rhythm
    • brain starts to deficient with the closure of the neuro tube.  

    not really regular until the 5th week

    end of third week the neuro tube closes- if it doesnt call it is called NTD- neuro tubes defect (spinal cord defect)

    Folic acid during child bearing age (green leafy 
  24. Fetal development week 6
    • CNS is formed 
    • u can detect brain waves
  25. Week 8
    • heart resembles a human heart
    • babies tail goes away

    ostogenesis is complete
  26. week 9-12
    Vernix caseosa (cheesy stuff)- helps to protect babies skin from the amniotic fluid

    Brown fat is deposited- used from thermoregulation- has a lot of capilaries and blood flow in it. it keeps the baby warm-
  27. Week 13-16
    develop languogo- fine hair on the body

    end of pregnancy it goes away

    brown fat starts to really develop week 17-20
  28. Week 24
    Surfactant is starting to develop in baby alveoli- keeps the alveoli's open when the baby wants to breath. There is fluid in the aveoli at the end of their lungs. when surfactant form it goes to the aveoli and when baby takes it first breath is collapse.

    Develops at 24 and is complete at 35 weks 

    • If there is no surfactant the aveoli's wont open. 
    • made of phospholipid
  29. week 28
    week 38 Hair goes away and baby starts to put on more fat. 

    week 28 Skin is translucent- they get cold quicker
  30. Fetal Circulation
    Not using their liver and lung

    • Umblical Vein
    •  Ductus Venousos in baby liver (drops o2)
    • Inferior Vena cava
    • right atrium
    •   Right ventricle
    • or foraman ovale (connects the atrium) -L Atrium- LV and aorta
    • Pulmon. artery (some blood goes to the lungs to help it learn to work but their is major resistance to get blood in there)
    • the blood that does not go to the lungs goes thru the ductus arteriousos which goes to the aorta. 

    Two places where the blood can bypass the lungs. 

    once the blood bypasses the lungs from blood entering thru the foraman ovale goes to the upper extremities in the blood thru the ascending aorta. once it comes back down goes into the r atrium again. there is always mixed in (babies born blue bc O2 is 80- cause the blood is mixed)

    ductus arteriousus- decending aorta- lower extremities illiac arteries, internal arteries then thru umbilical artery to the placenta
  31. Teratogens- congential defects
    • substances harmful to the developing fetus
    •  - enviromental
    •  - x-rays/radiation
    •  - viruses/illness, infections
    •  - medications/drugs/alcohol
    •  - nutritional deficiencies 

    most dangerous during the period organ development (organgenesis) 2nd to 8th week

    genetic factor
  32. Nagles Rule
    a way we determine a pregnancy

    now we used ultrasound

    1st day of ur last menstrual period subtract 3 months and add 7 days

    • ex
    • first day of last period Sept 1- 3 months back June 1 plus add 7 days so due date will be June 8th