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Study of heredity
Genetics
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Organisms complete set of DNA
Genome
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Each human cell contains ____ chromosomes
46
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There are ____ homologous pairs of chromosomes and ____ sex chromosomes
22, 1 pair
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Referring to a person's genetic makeup
Genotype
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Refer to how the genes are outwardly expressed
Phenotype
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Examples of Recessive Genetic Disorders:
Cystic Fibrosis, Sickle Cell, Falacemia, Tay Sachs
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The most common genetic disease among people of African ancestry...forms rigid crystals that distort and disrupt RBC oxygen carrying capacity of the blood
Sickle Cell Anemia (recessive)
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Most common genetic disease among people of European ancestry...production of thick mucus clogs in the bronchial tree and pancreatic ducts. Most severe are chronic respiratory infections and pulmonary failure
Cystic Fibrosis (recessive)
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Most common genetic disease of the Jewish decent...Degeneration of neurons and the nervous system results in the death by age 2
Tay-Sachs Disease (recessive)
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A person that has only 1 recessive gene is considered:
Carrier
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Lack of enzyme to metabolize the amino acid phenylalanine leads to severe mental and physical retardation....These effects may be prevented by the use of a diet (beginning at birth) that limits phenylalanine
- PKU (Phenylketonuria)
- recessive
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Uncontrollable muscle contractions between the ages of 30 and 50 years, followed by a loss of memory and personality...there is not treatment to delay mental deterioration
- Huntington's Disease (Dominant)
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Lack of factor VIII impairs chemical clotting; may be controlled with factor VIII from donated blood
Hemophilia (x-linked)
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Replacement of muscle by adipose or scar tissue, with progressive loss of muscle function; often fatal before age 20 years due to involvement of cardiac muscle
Duchenne's Muscular Dystrophy (x-linked)
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13 year international collaborative research program that was completed in 2003, has provided the scientific community with valuable information that is being used in the diagnosis, treatment, and prevention of genetically linked disorders
Human Genome Project (finished in 2003)
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Type of testing used to identify individuals who carry one copy of a gene mutation that, when present in two copies, causes a genetic disorder...Used when there is a family history of a genetic disorder
Carrier Testing (better when both parents are tested to provide info about risk of child having the genetic disorder)
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Test use to detect genetic changes in embryos that are created using assisted reproductive techniques
PGD (preimplantation testing/genetic diagnosis)
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Types of Genetic Testing:
- Carrier Testing
- PGD (Preimplantation testing)
- Prenatal Testing
- Newborn Screening
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Testing that allows for the early detection of genetic disorders, such as trisomy 21, hemophilia, and Tay-Sachs disease
Prenatal Testing
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Test used to detect genetic disorders that can be treated early in life
Newborn Screening
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Couples that have a higher risk of conceiving a child at high risk for genetic disorder:
Maternal Age older than 35
Hx of prev. preg w/ genetic disorder/abnormalities
Man/Woman who has genetic disorder
Family hx of a genetic disorder
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Dx of genetic disorders during pregnancy provides parents with options to:
- -continue or terminate the pregnancy
- -prepare for a child with this genetic disorder
- -use gene therapy when available
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Nursing actions for couples who elect to terminate the pregnancy based on info from genetic testing:
-Explain the stages of grief they will experience
-Inform the couple that grief is a normal process
-Encourage the couple to communicate with each other and share their emotions
-Refer the couple to a support group if available in their community
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Nursing actions for couples who elect to continue pregnancy based on info from genetic testing:
Refer them to support groups for pts who have children with same disorder
Provide them with info about disorder
Provide a list of websites that contain accurate info about disorder
Explain that they will experience grief over the loss of the "dream baby" and this is normal
Encourage them to talk openly
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Any drugs, viruses, infections, or other exposures that can cause embryonic/fetal developmental abnormality
Teratogens
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Effect of Alcohol on pregnant moms/baby
- Increased risk of fetal alcohol syndrome occurring when the pregnant women ingest 6 or more drinks a day
- -low birth weight
- -microcephaly
- -mental retardation
- -unusual facial features due to midfacial hypoplasia
- -cardiac defects
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Effects/risks of ACE inhibitors on mother/baby
- Risk for:
- -renal tubular dysplasia that can lead to renal failure and fetal or neonatal death
- -intrauterine growth restriction
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Effects/Risks of Carbamazepine (convulsants) on mother/baby:
- IRF (increased risk for)
- -neural tubal defects
- -craniofacial defects, including cleft lip/palate
- -intrauterine growth restriction
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Effects/Risks of Cocain on mother/baby
- IRF:
- -heart, limbs, face, gastrointestinal tract, and genitourinary defects
- -cerebral infarctions
- -placental abnormalities
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Effects/Risks of Warfarin (Coumadin) on Mother/Baby
- IRF:
- -spontaneous abortion
- -fetal demise
- -fetal or newborn hemorrhage
- -central nervous system abnormalities
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Effects/Risks from Infections/Viruses (Cytomegalovirus) on Mother/Baby
- IRF:
- -Hydrocephaly
- -Microcephaly
- -Cerebral calification
- -Mental retardation
- -Hearing loss
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Effects/Risk from Chicken Pox (Herpes varicella) on Mother/Baby
- IRF:
- -Hypoplasia of hands and feet
- -Blindness/Cataracts
- -Mental Retardation
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Effects/Risk from Rubella on Mother/Baby
- Heart Defects
- Deafness/Blindness
- Mental Retardation
- Fetal Demise
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Effects/Risks from Syphilis on Mother/Baby
- Skin, Bone and teeth defects
- Fetal Demise
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Effects/Risks from Toxoplasmosis on Mother/Baby
- Fetal Demise
- Blindness
- Mental Retardation
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The developing baby is most vulnerable to the effects of teratogens during ______
Organogenesis during the first 8 weeks....
Exposure to teratogens after 13 weeks of gestation may cause fetal growth restricion/reduction of organ size
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Upper part of the uterus
Fundus
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What hormones stimulate the endometrium to thicken in preparation for implantation?
Estrogen and Progesterone
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3 phases of the ovarian cycle:
Follicular Phase- first day of menstration and last 12-14 days
Ovulatory Phase- estrogen levels peak, egg is released from folicle (ovulation)...decrease in estrogen and increase in progesterone
Luteal Phase- lasts about 14 days, corpus luteum is formed and produces high levels of progesterone/low levels of estrogen
***If pregnancy doesn't occur, the corpus luteum degenerates and results in a decrease in progesterone which begins menstration
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Phases of the endometrial cycle:
Proliferative Phase- occurs following menstruation and ends with ovulation...endometrium is preparing/thickening
Secretory Phase- begins after ovulation and ends with onset of menstruation...endometrium still preparing
Menstrual Phase- occurs in response to hormonal changes and results in the sloughing off of the endometrial tissue
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Process of Cell Division:
Single cell Zygote > Cleavage > 16 cell Morula > Blastocyst (composed of embryoblast and trophoblast)
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Unique features of the Fetal Circulation:
High levels of oxygenated blood enter the fetal circulatory system from the placenta via the umbilical vein
The Ductus Venosus connects the umbilical vein to the inferior vena cava (highly oxygenated blood goes straight to RA)
The foramen ovale is an opening between R/L Atria...(may take 3 months to close)
The Ductus Arteriosus connects the pulmonary artery with descending aorta (constricts after birth due to higher blood oxygen levels and prostaglandins)
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Connects the umbilical vein to the inferior vena cava which allows the majority of the high levels of oxygenated blood to enter the right atrium
Ductus Venosus
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Opening between the right and left atria...Blood high in oxygen is shunted to the left atrium via this...it closes after delivery.
Foramen Ovale
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Connects the primary artery with the descending aorta...the majority of the oxygenated blood is shunted to the aorta via the this with smaller amounts going to lungs
Ductus Arteriosus
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The _____ separates the maternal and fetal blood and prevents fetal blood mixing with maternal blood but allows for the exchange of gases, nutrients, and electrolytes.
Placental Membrane
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Function of Placenta:
- Nutrients to baby (glucose, amino acids, O2)
- Hormone production (progesterone, estrogen, hCG, and human chorionic somatomamotropin)
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Progesterone facilitates:
- -implantation
- -decreases uterine contractility
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Estrogen stimulates:
the enlargement of the breasts and uterus
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hCG stimulates:
-the corpus luteum so that it continues to secrete estrogen and progesterone until the placenta is mature enough to secrete these hormones
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hPL (human choionicsomatomamotropin) works by:
- -promotes fetal growth by regulating glucose available to the developing human
- -stimulates breast development in prep for lactation
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Gestational Week coorelating with development in fetus:
-RBC being produced
-Fusion of the palate is completed
-External genitalia are developed to the point that sex of fetus can be noted with ultrasound
-Eyelids are closed
-FHT can be heard by doppler
Gestational Week 12
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Gestational Week coorelating with development in fetus:
-Lanugo present on head
-Meconium is formed in intestines
-Teeth form
-Sucking motions
-Skin is transparent
Gestational Week 16
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Gestational Week coorelating with development in fetus:
-Lanuga covers entire body
-Vernix caseosa covers body
-Nails formed
-Brown fat forms
Gestational week 20
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Gestational Week coorelating with development in fetus:
-Eyes are developed
-lungs forming
-footprints/fingerprints
-respiratory movement
Gestational week 24
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Gestational Week coorelating with development in fetus:
-Eyelids open
-Adipose tissue
-Gas exchange possible in lungs, but not fully mature
Gestational Week 28
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Gestational Week coorelating with development in fetus:
-Bones fully developed, Lungs maturing
-Increased amounts of adipose tissue are present
Gestation week 32
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Gestational Week coorelating with development in fetus:
-Lanugo disappears
-Labia majora/minora equally prominent
-Testes in upper portion of scrotum
Gestational Week 36
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Gestational Week coorelating with development in fetus:
-fetus is considered full term at 38 weeks, and all organs/systems are fully developed
gestational week 37-40
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The placenta becomes fully functional during the ___ and ___ weeks of gestation
8th and 10th
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Function of the two membranes, amnion and chorion, that form the bag of waters (amniotic sac)
Stretch to accommodate the growth of the developing fetus and increase amniotic fluid to protect the baby
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Collagenous substance that surrounds the umbilical vessels
Wharton's Jelly
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Risks for Infertility
- Women:
- Autoimmune dissorders
- Diabetes
- Eating disorders/poor nutrition
- Excessive alcohol
- Excessive exercising
- Obesity
- Older age
- Sexually Transmitted Disease
- Men:
- Environmental pollutants
- Heavy alcohol, marijuana, cocaine
- Impotence
- Older Age
- Sexually Transmitted Disease
- Smoking
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