Chapter 10 Fetal Development And Genetics

Question 1

Fetal development stages

Answer 1

Pre-embryonic stage: fertilization through the second week
Embryonic stage: end of the second week through the eighth week
Fetal stage: end of the eighth week until birth

Question 2

Fertilization

Answer 2

The union of ovum and sperm which is the starting point of pregnancy. Usually around two weeks after menstrual period. Takes place in outer third of ampulla of the fallopian tube

Question 3

Zona pellucid a

Answer 3

Clear protein layer to block extra sperm. Disappears in five days

Question 4

Zygote

Answer 4

The new life that is formed from the 23 chromosomes each joining making 46. XX is female XY is male. Implants in the endometrium about 7 to 10 days after conception

Question 5

Morula

Answer 5

4 sets of mitosis/cleavages, 16 Cells appear as a ball of cells. Reaches the uterine cavity in 72 hours

Question 6

Blastocyst

Answer 6

Within the morula, a hollow ball of fluid filled space or cells (inner cell mass). The inner surface will form the embryo and amnion.

Question 7

Trophoblast

Answer 7

The outer layer of cells surrounding the blastocyst. Will develop the embryonic membranes, the chorion, and helps form placenta.

Question 8

Implantation

Answer 8

Usually occurs in the upper uterus or fundus. Usually with in 7 to 10 days after conception

Question 9

Amniotic fluid

Answer 9

Surrounds the embryo and increases in volume up to 1 L at term. It comes from fluid transported from the maternal blood and fetal urine. It helps maintain constant body temperature, symmetric growth and development, and cushions the fetus, Allows the umbilical cord to be free of compression, promotes fetal movement and muscular development.

Question 10

Oligohydramnios

Answer 10

Too little amniotic fluid, less than 500 mL at term. Associated with utero placental Insufficiency and fetal renal abnormalities

Question 11

Hydramnios

Answer 11

Too much amniotic fluid, greater than 2000 mL at term. Associated with maternal diabetes, neural tube defects, chromosomal deviations, and malformations of the central nervous system and/or GI tract That prevents normal swallowing of amniotic fluid by the fetus.

Question 12

Umbilical cord

Answer 12

From amnion, Contains one large vein and two small arteries. Whartons jelly is a connective tissue that surrounds them to prevent compression. Average is 22 inches long and 1 inch wide. The vein supplies the oxygen, the arteries bring waste back to the mom

Question 13

Placenta

Answer 13

It is a gland that produces hormones. Made from trophoblasts which make hCG that ensures the endometrium will be receptive to the implanting embryo. It makes hormones to control physiology of the mother so the fetus is supplied with nutrients and oxygen. It protects from an immune attack, removes waste products from the fetus, induces the mother to bring more food, produces hormones that ready fetal organs. It’s function depends on maternal blood pressure. Completely formed within 12 weeks

Question 14

HCG

Answer 14

Preserves the corpus luteum and it’s progesterone production so tha endometrial lining of the uterus is maintained

Question 15

hPL Human placental lactogen

Answer 15

Controls fetal and maternal metabolism, develops maternal breast for lactation, decreases maternal insulin sensitivity to increase availability for fetus

Question 16

Estrogen estriol

Answer 16

Enlarges women’s breasts, uterus, and external genitalia, stimulates myometrial contractility

Question 17

Progesterone progestin

Answer 17

Maintains endometrium, decreases contractility of the uterus, stimulates maternal metabolism and breast development, provides nourishment for the early conceptus

Question 18

Relaxin

Answer 18

Synergistic with progesterone to maintain pregnancy, causes relaxation of pelvic ligaments, softens cervix in preparation for birth

Question 19

Fetal stage

Answer 19

Pregnancy is 280 days. fetal stage is the end of the eighth week until birth. Longest period of prenatal development. Conceptus is now a fetus. All major systems are present.
Dramatic growth and maturation of organ systems

Question 20

Fetal circulation

Answer 20

Carries oxygenated blood to vital areas the heart and brain while first shunting it away from the lungs and liver. The placenta takes over the functions of the lungs and liver during fetal life. As a result large volumes of oxygenated blood are not needed.

Question 21

Three shunts of fetus

Answer 21

Ductus venosus-Umbilical vein to interior vena cava
Ductus arteriosus-Main pulmonary artery to the aorta
Foramen ovale-Anatomic opening between right and left atrium

Question 22

Allele

Answer 22

Two or more alternative versions of the gene at a given position or Locus on the chromosome that imparts the same characteristic of that gene. Example an allele might be able to produce blue eyes or one for brown eyes.

Question 23

Phenotype

Answer 23

Outward characteristics of an individual

Question 24

Karyotype

Answer 24

Pictorial analysis of the number, form, and size of individuals chromosomes.

Question 25

Mendels law

Answer 25

Inheritance of single gene disorders also referred to as monogenic or sometimes Mendelian disorders

Question 26

Autosomal dominant inheritance disorder

Answer 26

When a single gene in the heterozygous state is capable of producing the phenotype. Examples include neurofibromatosis, Huntington’s disease, achondroplasia, polycystic kidney disease. Offspring have a 50% chance of being abnormal. Male can pass the disorder onto his son. Dn nn

Question 27

Autosomal recessive inherited disorders

Answer 27

Two abnormal genes in the homozygous state are needed for the individual to demonstrate signs and symptoms of a disorder. Examples are cystic fibrosis, phenylketonuria, TaySachs disease, sickle cell disease. 25% chance of inheriting normal 50% chance of being a carrier, and a 25% of being abnormal. Male Can pass disorder onto son. Nd Nd

Question 28

X-linked inheritance disorders

Answer 28

The altered gene is present on the X chromosome. If the male inherits the X-linked gene he will express the condition because he only has one X-chromosome. Females inherit 2 x chromosomes so they can be heterozygous or homozygous.

Question 29

Three embryonic layers

Answer 29

Ectoderm, mesoderm, endoderm

Question 30

Ectoderm

Answer 30

Forms the central nervous system, special senses, skin, and glands

Question 31

Mesoderm

Answer 31

Forms the skeletal, urinary, circulatory, and reproductive organs

Question 32

Endoderm

Answer 32

Forms the respiratory system, liver, pancreas, and digestive system

Question 33

X-linked recessive inheritance

Answer 33

Males are more affected than females because all the genes on a man’s X chromosome will be expressed. There is no mail to mail transmission. Examples include hemophilia, colorblindness, and Duchenne muscular dystrophy

Question 34

X linked dominant inheritance

Answer 34

Occurs when a male has abnormal X chromosome or female has one abnormal X-chromosome. All the daughters and none of the sons of an affected male will inherit the condition while both the male and female offspring of an affected woman would have a 50% chance of inheriting the condition. Males are more severely affected than females. Examples include hypophosphatemic rickets and fragile X syndrome

Question 35

Multifactorial inheritance disorders

Answer 35

Caused by multiple gene and environmental factors. Examples include cleft lip, cleft palate, spina bifida, Pyloric stenosis(More often in males), clubfoot, congenital hip dysplasia(more often in female), and cardiac defects

Question 36

Chromosomal abnormalities

Answer 36

Caused by too many or too few chromosomes or also due to an error in the structure of the chromosome. Some pieces of the chromosome maybe deleted, duplicated, inverted, misplaced, or exchanged with part of another chromosome. Mosaicism Is when chromosomal abnormalities do not show up in every cell.

Question 37

Monosomies

Answer 37

Only one copy of a particular chromosome instead of two. All fetuses spontaneously abort in early pregnancy.

Question 38

Trisomies

Answer 38

Three chromosomes instead of two. Down syndrome is chromosome 21, trisomy 18 and trisomy 13.

Question 39

AutoSome

Answer 39

Nonsex chromosomes. We have 22 pairs

Question 40

Mutation

Answer 40

Change in gene structure or location, may alter the type and amount of protein produced.

Question 41

Amnion

Answer 41

Originates from the ectoderm germ layer during the early stages of embryonic development. Thin protective membrane that contains the amniotic fluid.

Question 42

Chromosomes

Answer 42

Long, continuous strands of DNA that carry genetic information.

Question 43

Polyploidy

Answer 43

Causes an increase in the number of haploid sets, 23, of chromosomes in a cell

Question 44

Triploidy

Answer 44

Three whole sets of chromosomes in a single cell.

Question 45

Mosaicism

Answer 45

Chromosomal abnormalities that do not show up in every cell.

Question 46

Maternal serum Alpha/fetoprotein. MSAFP

Answer 46

Usually between 15 and 18 weeks gestation.

Increased levels indicate open neural tube defects, Turner syndrome, tetralogy of fallot, multiple gestation, hydrocephaly, omphalocele gastrochisis
16-18 weeks
Decreased level might indicate down syndrome or trisomy 18

Question 47

Chorionic villus sampling

Answer 47

Removal of a small tissue specimen of the fetal portion of the placenta and shows genetic makeup. Complications include limb defects and pregnancy loss. Can detect sickle cell anemia, phenyl ketone urea, down syndrome, Duchenne muscular dystrophy, and other genetic disorders. Usually between 10 to 12 weeks just station