[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.