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31 Cards in this Set
- Front
- Back
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X-linked recessive disorders
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*More common than X-linked dominant disorders
*Occur more frequently in males *Female carrier -50% chance of passing to offspring Examples: hemophilia A, Duchenne muscular dystrophy |
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X-Linked Dominant
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*Altered gene on X chromosome
*X-linked dominant in father -None of sons will inherit the disorder -All of daughters will inherit the disorder *Female with X-linked dominant trait -50% chance of passing trait to daughters |
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Nursing Priority for Genetic Testing
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*Identify for referral
*Help woman decide about genetic counseling *Teach about lifestyle *Provide emotional support *Help woman and family deal with abnormal results |
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Process of Fertilization
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*Oocyte and sperm meet in fallopian tube
*Ovulation - cervical mucus changes *200 sperm reach fertilization site -Capacitation -Penetrates zona pellucida - prevents fertilization by other sperm |
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Cleavage
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Rapid cellular division
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Morula
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-Solid ball of cells
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Blastocyst
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-Inner mass of cells
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Multifetal pregnancy - monozygotic
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-Develop from one zygote; division occurs at end of first week
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Dizygotic
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Develops from two zygotes
-Separates amnion and chorions |
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Implantation
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*Zygote propelled by
-Cilia -Peristalsis *Reaches uterine cavity in 3 to 4 days *Nidation -Occurs by 10th day after fertilization -Implantation bleeding -Blastocyst is buried beneath the endometrial surface |
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Placenta
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*Develops from trophoblast cells
-Lucanae -Chorionic villi -Intervillous spaces *Provides oxygenation, nutrition, waste elimination, and hormones *Protects fetus *Placental hormones -Human chorionic gonadotrophin (hCG): tells corpus luteum to continue producing progesterone until placenta takes over -Human placental lactogen (hPL) -Progesteron: relaxation effect on smooth muscle; maintains pregnancy -Estrogen: growth hormone, growth of number & size of cells'; prepares uterine muscles for labor |
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Amazing Placenta~ functions:
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*Metabolic functions
-Glycogen, cholesterol, fatty acids *Transfer functions -Gas exchange -Nutrient transfer -Waste removal -Antibody transfer *Endocrine functions -Hormones necessary to continue pregnancy -Human placental lactogen, estrogens, progesterone |
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Substance Transport Across Placenta
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*Diffusion
*Active transport *Pinocytosis *Bulk flow and solvent drag *Accidental capillary breaks *Independent movement |
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Development of the Embryo & Fetus - Yolk Sac
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*Develops 8-9 days after conception
*Essential for transfer of nutrients during second and third weeks of gestation *Hematopoiesis - RBCs develop here *Atrophies and is incorporated into umbilical cord |
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Development of the Embryo & Fetus - Umbilical Cord
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*Usual location - center of placenta
*55 cm long (21 inc) 1-2 cm diameter *Vessels: one vein, two arteries *Wharton's jelly: protects umbilical cord from compression |
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Pre-Embryonic Period
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*First 2 weeks after conception
*Rapid cellular multiplication and differentiation *Establishment of embryonic membranes and primary germ layers -Ectoderm -Endoderm -Mesoderm |
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Embryonic Development
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*Begins third week after fertilization through end of eigth week
*Organogenesis - formation & differentation of all organs *Vulnerable to environemental insults |
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Progression of Development - Embryo
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*Cephalo-caudal (head-to-toe)
*Central to peripheral *Simple to complex *General to specific |
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Embryonic Development
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*3rd week: CNS, contractions of heart tube begin
*4th week: Neural tube closure, respiratory and GI tracts, upper limb buds; heart is beating *6th week upper limbs, fingers webbed, ears & eyes forming, kidneys *8th week eyelids fused; heart has 4 chambers, may hear beat with ultrasound *9th week begins fetal period |
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Threats to Embryonic and Fetal Development
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*Chromosomes and teratogens
*Medications and other substances -Vitamins, alcohol, tobacco, caffeine, drugs, radiation, and lead *TORCH infections -Toxoplasmosis, hepatitis, rubella, cytomegalovirus, herpes |
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Nursing Role in Minimizing Threats to Embryonic and Fetal Development
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*Assessment:
-Environmental and lifestyle risks -Knowledge -Physical and psychosocial well-being *Preconception counseling -Initial prenatal visit -Assessment: cultural, emotional, physical, and physiological factors -Education -Genetic disorders -Prental tests |
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Fetal Circulation
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*Heart beings to beat and circulate blood by end of third week
*Umbilical vein: blood from placenta to fetus *Low PO2 important to maintain fetal circulation *Three unique shunts: (1) Ductus venosus: bypasses liver and enters inferior vena cava (2) Foramen ovale: right and left atria to supply blood to head, and upper and lower extremities (3) Ducus arteriosus: returning blood bypasses lungs |
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Fetal membranes & Amniotic Fluid
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*Amnion & chorion: Two separate membranes
-Amnion - inner membranes, contains amniotic fluid -Chorion - outer membrane, forms fetal portion of placenta *Slightly adherent, form amniotic sac *Amniotic fluid - protects growing fetus |
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Purposes of Amniotic Fluid
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*Protects and cushions fetus
*Maintains normal body temperature *Symmetrical fetal growth *Room and buoyancy for fetal movement *Keeps membrane from sticking parts of fetus *Stable temperature *Essential for normal fetal lung development *Amount: 800ml at 24 weeks *Fetal urine and lung secretions primary contributors in late pregnancy; fluid from maternal blood transported across amnion *Slightly alkaline *Contains antibacterial, other protective substances |
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FDA Categories for Drugs in Pregnancy
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*Categories A: controlled studies in humans - safest
*Category B: No fetal risk in animal studies *Category C: Adverse effects found in animal studies; use only if benefit justifies possible risk to fetus *Category D: positive evidence of fetal risk; benefits may outweigh risks; e.g. phenytoin *Category X: Risks from drug outweigh any benefits |
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Fetal Period
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*Beginning ninth week until birth or termination of pregnancy
*Rapid growth and differentiation of tissues, organs, and systems *Less vulnerable stage |
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Milestones weeks 9-12
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*Ossification centers appear
*Body growth increases *Intestines leave umbilical cord, enter abdomen *External genitalia differentiated by week 12 *Urine production begins |
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Weeks 13-16 milestones
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*Movements stronger; some feel quickening
*Very rapid growth *Coordinated movements of limbs *Ossification of skeleton *Face looks human *Ovaries differentiated |
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Weeks 17-20 Milestones
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*Growth slows
*Quickening *Vernix Caseosa *Lanugo *By 20 weeks: fetus 300 g and 19cm (7.3 inc) *Fluttering movements; quickening/fetal movement felt, languo, brown fat, FHT by fetoscope |
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WEeks 21-25
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*Gains weight
*Skin pink *Rapid eye movements *Surfactant by 24 weeks *Approaching viability thin, transluscent skin, beginning surfactant |
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Later Pregnancy Milestones in FEtal Development
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*Weeks 25-28: head hair, SQ fat, eyes open 1000g (2.5#), increasing chance of survival
*Weeks 33-38: gaining weight, lungs maturing vernix and langugo recede, 2000-2500g (4-5 #), survival good *Full term infant 36-40 weeks fertilization age or weeks 38-42 gestational age, Average size: 3400g; 7.5 lbs |
