[Exam 1] Chapter 10 – Fetal Development and Genetics Flashcards
Stages of fetal development?
Preembryonic Stage: Fertilization - 2nd Week
Embryonic Stage: 2nd week - 8th week
Fetal Stage: 8th week until birth
Preembryonic Stage: When does fertizilization usually occur?
Around 2 weeks after last normal menstrual period
Preembryonic Stage: When does the primary oocyte complete its first meiotic division?
before ovulation
Preembryonic Stage: When does the secondary oocyte begin its second meiotic division ?
Just before ovulation
Preembryonic Stage: When do primary and secondary spermatocytes undergo meiotic division?
while still in the testes
Preembryonic Stage: What is a Zona Pellucida?
Is a clear protection that covers the ovum
Preembryonic Stage: When does the Zona Pellucida disappear?
After about 5 days
Preembryonic Stage: What happens when pserm reaches plasma membrane?
Ovum resumes meiosis and forms a nucleus with half of the number of chromosomes
Preembryonic Stage: XX zygote will become what?
Female
Preembryonic Stage: XY zygote will become what?
Male, which can only be determined by the father
Preembryonic Stage: What happens once mitosis or cleavage beings?
Zygote slowly transported into uterine cavity. After four cleavages, 16 cells appear as ball of cells, or morula
Preembryonic Stage: When does morula reach uterine cavity?
72 hours after fertilization
Preembryonic Stage: Outer cells surrounding the blastocyst cavity is what?
Trophoblast
Preembryonic Stage: What does a trophoblast eventually develop into?
The chorion, and helps to form the placenta
Preembryonic Stage: Where does the trophoblast attach itself?
To the surface of the endometrium . Usually occurs in the upper uterus (fundus) where rich blood supply available.
Preembryonic Stage: With development of thropoblast and implantation, further differentation of inner cell mass occurs. The three embryonic layers of cells are
Ectoderm
Mesoderm
Endoderm
Preembryonic Stage: What does Ectoderm form
CNS, special senses, skin, and glands
Preembryonic Stage: What does Mesoderm form?
skeletal, urinary, circulatory, and reproductive organs
Preembryonic Stage: Waht does endoderm form?
respiraotry system, liver, pancreas, and digestive ssytem
Embryonic Stage: When does this begin?
At day 15 afterconception and continues through week 8
Embryonic Stage: Inner cell mass is called what?
Blastocyst, which forms the embryo and amnion
Embryonic Stage: What does the chorion consist of?
Trophoblast cells and a mesodermal lining . Has fingerlike projections called chorionic villi on surface.
Embryonic Stage: Where does the amnion originate from?
The ectoderm germ layer during the early stages.
Embryonic Stage: What happens od the amnion as the embryo grows?
Expands until it touches the chorion (outer layer). Forms a fluid-filled amniotic sac
Embryonic Stage: Where is amniotic fluid derived from?
Fluid transported from the maternal blood across the amnion and fetal urine
Embryonic Stage: What is amniotic fluid composed of?
98% water and 2% organic matter. Slightly alkaline and contains albumin, urea, bile pigments, glucose, creatinine, and bilirubin and fine hair called lanugo
Embryonic Stage: Major developments in week 3?
Begin development of brain, spinal cord, heart, GI tract.
Leg and arms buds appear and grow out
Embryonic Stage: Major developments in week 4?
Brain differentiates
Limb buds grow and develop more
Stomach, pancreas, and liver form
Embryonic Stage: Major developments week 5?
Heart beats at regular rhythm, eyes and ears form. Some nerves visible
Embryonic Stage: Major developments week 6?
Lungs form. Liver produces RBCs.
Primitive skeleton / CNS forms
Embryonic Stage: Major developments week 7?
Trunk straight, nipples/hair forms.
Arm/leg move
Diaphragm formed. Fetal heartbeat heard
Embryonic Stage: Week 8 major developments
Rotation of intestines, heart development continunes
Embryonic Stage: Major developments weeks 9-12
Sex differentiation. Buds for all 20 teeth laid down. Face and neck formed.
RBCs produced along with urine
Embryonic Stage: Major developments weeks 13-16
Fine hair developments (lanugo)
Fetal Skin transparent
Fetus makes active movemenets
Embryonic Stage: Major developments weeks 17-20
Rapid brain growth
Eyebrows and head hair appear.
Brown fat deposited to maintain temp.
Embryonic Stage: Major development week 21-24
Alveoli form in lungs. Skin red.
Embryonic Stage: Major developments Weeks 25-28
Length of 15 inches. Eyelids open and close. Fingerprints set
Embryonic Stage: Major developments weeks 29-32
Rapid increase body fat.
Rhythmic breathing movements occur.
Fetus stores iron, calcium, phosphorus
Embryonic Stage: Major developments weeks 33-38
Testes in male form.
Lanugo begins to disappear
Embryonic Stage: What is too little amniotic fluid?
Oligohydramnios. <500 mL at term. Associated with uteroplacental insufficiency, fetal renal abnormalities, and higher risk of surgical births
Embryonic Stage: What is too much amniotic fluid associated with?
Polyhydramnios >2000 mL.
Associated with maternal diabetes, neural tube defects, chromsomal deviations and malformations of CNS
Embryonic Stage: What does the umbilical cord include?
One large vein and two small arteries
Embryonic Stage: What is Whartons Jelly?
Specialized connective tissue. Surrounds the three blood vessels in umbilical cord to prevent compression which would cut off fetal blood and nutrient supply
Embryonic Stage: Length for umbilical cord?
Maximum at 30 weeks. Average is 22 inches and 1 inch wide
Embryonic Stage: Precursor cells , the trophoblasts, first appar when?
First appear 4 days after fertilizationa s outer layer of cells of the blasocyst
Embryonic Stage: As early as 3 days after conception, trophoblasts make which hormone?
human chorionic gonadotropin (hCG), which ensures endometrium will eb receptive to the implanting embryo
Embryonic Stage: What is the placental barrier?
Layer of fetal tissue that always separates the maternal blood and the fetal blood.
Embryonic Stage: What do maternal uterine arteries deliver?
Nutrients to the placenta, which in turn provides nutrients ot the developing fetus
Embryonic Stage: Why is hCG necessary?
Preserves the corpus luteum and its progesterone production so that the endometrial lining is maintained. Basis for pregnancy tests
Embryonic Stage: Why is Human PLacental Lactogel (hPL) necessary?
Modulates fetal and maternal metabolism, participates in the development of maternal breasts for lactation and decreases maternal insulin sensitivity
Embryonic Stage: Why is Estrogen important?
Causes enlargement of breasts, uterus, and external genitalia. Stimulates contractility
Embryonic Stage: Why is PRogesterone (Progestin) important?
Maintains the endometrium, decreases the contractility of the uterus, stimulates maternal metabolism and breast development
Embryonic Stage: Why is Relaxin important?
Acts with progesterone to maintain pregnancy, causes relaxation of pelvic ligaments and softens cervix
Embryonic Stage: What are Teratogens?
Substances that cause birth defects, such as alcohol and drugs
Fetal Stage: When does this period begin?
From the end of the eight week until birth
Fetal Circulation: What is the function of the shunts in here?
Direct oxygen-rich venous blood to the systemic circulation and to ensure that oxygen-depleted venous blood bypasses the underdeveloped pulmonary circulation. Finish developing after birth.
Fetal Circulation: Where does oxygenation occur for the fetus?
Occurs in the placenta. Travels through a series of shunts to accomplish this.
Fetal Circulation: What three shunts present during fetal life?
Ductus Venosus: Connects umbilical vein ot the inferior vena cava
Ductus Arteriosus: Connects the main pulmonary artery to the aorta
Foramen Ovale: Anatomic opening between right and left atrium
Fetal Circulation: Where does blood flow from the ductus venosus into?
The inferior vena cava.
Foramen ovale -> Left Atrium -> Left Ventricle -> Aorta _> Then head and upper body.
Fetal Circulation: What does the ductus arteriosus do?
Shunts the blood from going into the lungs. Instead goes into the descending aortra
Fetal Circulation: What do the two umbilical arteries carry?
The unoxygenated blood from the descending aorta back to the placenta
Fetal Circulation: What happens to the shunts when baby born?
Lungs inflate. Increases pressure in left atrium causing one way flap of left side of foramen ovale to press against opening.
Fetal Circulation: When is the foramen ovale typically closed?
Within 1-2 hours of birth. Physiologically closed by 1 month. Permanently closed by six months
Fetal Circulation: When is the ductus venosus closed?
Closes with clamping of the umbilcal cor dand inhibition of blood flow through the umbilical vein
Fetal Circulation: When does the ductus arteriosus close?
Closes within 72 hours. Permanent at 3-4 weeks of age.
Genetics: What does a fetal nuchal translucency test indicate?
Presesnce of trisomy 21 or down syndrome if increased thickness found
Genetics: Examples of conditions that can be diagnosed before birth?
Open neural tube defects
Chromosomal Aneuploids
Congenital Defects
Myriad of single gene inheritable disorders
Advances in Genetics: What can gene therapy be used for?
Replace or repair defective or missing genes with normal ones
Advances in Genetics: What are some goals of the human genome project?
Identify all possible genes
Determines all sequences that make up DNA
Store information to study
Improve tool for data anlysis
Inheritance: What are genes?
Individual units of heredity of all traits and are organized into long segments of DNA that occupy a spsecific location on a chromosome and determine a specific characteristic
Inheritance: What is a genotype?
Specific genetic makeup of an individual, usually DNA, is the internally coded inheritable information. Referes to allele which is one of two versions of gene
Inheritance: Examples of genes and alleles?
Everyone has a gene that controls height, but the variations in height are teh alleles
Inheritance: What is a phenotype?
Observed, outward characteristics of an individual.
Inheritance: What is it called when alleles are the same or diferent?
Homozygous for the same or Heterozygous for different
Inheritance: What does WW stand for?
Homozygous domaint
Inheritance: What does ww stand for?
homozygous recessive
Inheritance: How is heterozygous indicated?
Ww. Domaint one wil usually be expressed
Inheritance: What chromosomes do females and males carry?
XX for FEmale
XY for Male
Inheritance: What isi a karyotype?
Pictorial analysis of the number, form, and size of an individuals chromosomes
Inheritance: Male and Female Karotypes designated as what?
Male: 46, XX
Female: 46, XY
Mendelian/Monogenic Laws of Inhereitance: If defect occurs on the autosome, disorder is named what?
Autosomal
Mendelian/Monogenic Laws of Inhereitance: If defect is on the X chromosome, genetic disorder is called
X-Linked
Mendelian/Monogenic Laws of Inhereitance: Monogenic disorders include what?
Autosomal dominant, autosomal recessive, X-Linked Dominant, and X-Linked Recessive Patterns
Autosomal Dominant Inheritance Disorders: When does this occur?
When single gene in heterozygous state is capable of producing the phenotype . Overshadows the normal gene and will display signs of disorder
Autosomal Dominant Inheritance Disorders: Are parents affected here?
Generally, one is. But there can also be history of no family member being affected.
Autosomal Dominant Inheritance Disorders: Offspring of affected parent will have what chance of having this?
50% chance of getting one nromal and one abnormal gene
Autosomal Dominant Inheritance Disorders: Affected males can pass this on to who?
Their sons
Autosomal Dominant Inheritance Disorders: MAle-to-male transmission is important in distinguihsing what?
Autosomal dominant inheritance from X-Linked inheritance
Autosomal Dominant Inheritance Disorders: What kind of genetic disorders are sseen here?
Neurofibromatosis , Huntingtons, Achondroplasia, and Polycystic Kidney Disease
Autosomal Recessive Inheritance Disorders: When does this occur?
When two copies of the mutant or abnormal gene in the homozygous state are necessary to produce the phenotype. Two abnormal genes needed to demonstrate the signs
Autosomal Recessive Inheritance Disorders: How must parents be here?
Must be heterozygous carriers of the gene .
Autosomal Recessive Inheritance Disorders: Offspring of two carriers gives child what percentages?
25% of two normal genes
50% of inheriting one bad gene
25% of inheriting two abnormal genes (disorder)
Autosomal Recessive Inheritance Disorders: Common disease types here?
Cystic fibrosis, phenylketonuria, tay-sachs, and sickle cell disease
X-Linked Inheritance Disorders: What is this?
Associated with altered genes present on the X chromosome.
X-Linked Inheritance Disorders: How is this expressed?
In males, if they inhereit it, they will have it because they only have one X chromosome. Because females carry two X chromosomes, they have options
X-Linked Recessive Disorders: What will females need to express this?
Two abnoromal X chromosomes and one normal and one abnormal X chromosome to carry the disease.
X-Linked Recessive Disorders: How do males transmit this?
They cannot because there is no male x-to-x transmission. butu can have carrier daughters.
X-Linked Recessive Disorders: Childs chance of havingt is?
25% affected son
25% carrier daughter
X-Linked Recessive Disorders: Common disorders here?
Hemophilia, Color Blindness, and Duchenne Muscular Dystrophy
X-Linked Dominant Inheritance: When does this occur?
When a male has an abnormal X chromosome or a female has one abnormal X chromosome.
X-Linked Dominant Inheritance: What disorders are caused?
Hypophosphatemic rickets and fragile X Syndrome
X-Linked Dominant Inheritance: What is Fragile X Syndrome?
Causes range of developmental problems including learning disabilities and cognitive impairments
Multifactorial Inheritance Disorders: What disorders often come from this?
Cleft lip, cleft palate, spina bifida, pyloric stenosis, clubfoot, and cardiac defects
Nontraditional Inheritance Patterns - Mitochondrial Inheritance: THis is usually passed from who?
Inherited almost exclusively from the mother. Therefore passed to both genders
Nontraditional Inheritance Patterns - Mitochondrial Inheritance: What is this often associated with?
Associated with energy defecits in cells with high energy requirements such as nerve and muscle cells. Tend to be progressive
Nontraditional Inheritance Patterns - Mitochondrial Inheritance: Examples of this?
Kearns-Sayra Syndome (Neuromuscular Disorder) and Lebers Hereditary Optic NEuropathy (Visual Impairment)
Nontraditional Inheritance Patterns - Genomic Imprinting: What is this
Occurs by which expressionof a gene is determined by its parental origin. This affected the phenotype observed.
Chromosomal Abnomalities: Can occur during what stages?
Fertilization, during mitotic cell divsion, and result in cosaicism
Chromosomal Abnomalities: What is Mosaicism?
When the chromosomal abnormalities do not show up in every cells, only some cells or tissues carry the abnormality
Chromosomal Abnomalities - Abnormalities of Chromosome Number: Why does this ususally occur?
Due to nondisjunction (failure of separation of the chromosome pair during cell divison, meiosis, or mitosis)
Chromosomal Abnomalities - Abnormalities of Chromosome Number: What chromosome abnormalities can be carried to term?
13,18, 21 or X
Chromosomal Abnomalities - Abnormalities of Chromosome Number: Two common abnormalities of chromosome number are what?
Monosomy and trisomy
Chromosomal Abnomalities - Abnormalities of Chromosome Number: What happens in m onsomy?
There is only one cope of a particulr chromosome instead of the usual pair. Fetuses abort in early pregnancy
Chromosomal Abnomalities - Abnormalities of Chromosome Number: What happens in trisomy?
There are three of a particular chromosome instead of the usual two
Chromosomal Abnomalities - Abnormalities of Chromosome Number: Most common trisomies?
Trisomy 21 (Down) , Trisomy 18, Trisomy 13
Abnormalities of Chromosome Structure: When does this usually occur?
When there is a breakage and loss of a portion of one or more chromosomes and during repair process, broken ends are rejoined incorrectly
Abnormalities of Chromosome Structure: When does deletion occur?
When portion of chromosome is missing or deleted, resulting in loss of that portion of the chromosome
Abnormalities of Chromosome Structure: When are duplications seen?
When portion of chromosome duplicated and extra chromosomal segment is present
Abnormalities of Chromosome Structure: When does inversion occur?
When a portion of the chromosome breaks off at two points and is turned upside down and reattached
Abnormalities of Chromosome Structure: When are ring chromosomes seen?
When a portion of chromosome is broken off in two places and formed a circle or ring
Abnormalities of Chromosome Structure: What is translocation?
When a portion of one chromosome is transferred to another chromosome and an abnormal rearrangement is present
Abnormalities of Chromosome Structure: What do balanced abnormalities involve?
The rearrangement of genetic material with neither an overall gain nor loss. Are at higher risk for miscarriages
Abnormalities of Chromosome Structure: What are unbalanced structural abnormalities?
Similar to onumerical abnoralities because genetic material is either gained or lost
Sex Chromosome Abnormalities: What can these abnormalities effect?
Sexual development and may cause infertility, growth abnormalities and possibly behavioral and learning problems
Genetic Evaluation and Counseling: Purpose of genetic consulation?
To confirm, diagnose, or rule out genetic conditions
Identify medical management issues
Calculate and communicate genetic risk to family
Genetic Evaluation and Counseling: Genetic counseling involves extensive information gathering about
birth history, past medical history, and current health status as well as family history if health problems
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is Alpha-Fetoprotein>
Sample of womens blood is drawn to evaluate plasma protein that is produced by the fetal liver, yolk, andn GI tract
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What would Alpha-Fetoprotein indicate?
Increased levels might be neural tube defect, Turner Syndrome,
Decreased levels indicate downs
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is Amniocentesis?
Amniotic fluis aspirated from amniotic sac
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What would Amniocentesis show?
To perform chromosome analysis, alpha-fetoprotein, DNA markers, viral studies and karotyping
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is Chorionic Villus Sampling?
Removal of small tissue specimen from fetal portion of the placenta, which reflects fetal genetic makeup
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is Percutaneous umbilical blood sampling?
Insertion of eneding directly into umbilical vessel under ultrasound guidance ;
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is Fetal Nuchal Translucency?
Intravaginal ultrasound that measures fluid collection in subcutaneous space between skin and cervical spine
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is a Level II Ultrasound/Fetal scan?
Use of high-frequency sound waves to visualzie the fetus
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is triple and quad screening test?
Triple screening includes alpha-fetoprotein, estriol, and beta HCG
Quad includes alpha-fetoprotein, estriol, and inhibin A
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is preimplantation genetic diagnosis?
Genetic testing of embryos produces through in vitro fertilziation
Genetic Evaluation and Counseling - Common Lab & Diagnostic: What is cell-free fetal DNA?
Noninvasive prenatal test using maternal plasma which hold a mixture of maternal and fetral DNA after 4 weeks gestation
After teaching a group of students about fertilization, the instructor determines that the teaching was successful when the group identifies which as the usual site of fertilization?
Fundus of the uterus Endometrium of the uterus Distal portion of fallopian tube Follicular tissue of the ovary
Distal portion of fallopian tube
A client comes to the clinic for pregnancy testing. The nurse explains that the test detects the presence of which hormone?
Human placental lactogen (hPL) Human chorionic gonadotropin (hCG Follicle stimulating hormone (FSH) Thyroid stimulating hormone (TSH)
Human Chorionic Gonadotropin (hCG)
The nurse is counseling a couple, one of whom is affected by an autosomal dominant disorder. They express concerns about the risk of transmitting the disorder. What is the best response by the nurse regarding the risk that their baby may have for the disease?
“You have a one in four (25%) chance.” “The risk is 12.5%, or a one in eight chance.” “The chance is 100%.” “Your risk is 50%, or a one in two chance.”
Your risk is 50%, or a one in two chance
What is the first step in determining a couple’s risk for a genetic disorder?
Observing the client and family over time Conducting extensive psychological testing Obtaining a thorough family health history Completing an extensive exclusionary list
Obtaining a thorough family health history
A nurse is working in a women’s health clinic. Which woman would genetic counseling be most appropriate for?
Had her first miscarriage at 10 weeks Is 30 years old and planning to conceive Has a history with a close relative with Down syndrome Is 18 weeks pregnant with a normal triple screen result
Has a history with a close relative with Down syndrome
Which of the following is an example of an autosomal dominant disorder?
Phenylketonuria Tay–Sachs disease Polycystic kidney disease Cystic fibrosis
Polycystic Kidney Disease
Which of the following is the major goal of genetic counseling?
Diagnose and determine the role of heredity Reinforce previously presented test data Emphasize good communication skills Offer referral to community support groups
Diagnose and determine the role of heredity
