Chapter 29: Development and Inheritance

Define differentiation

formation of different types of cells during development

Define inheritance

transfer of genetically determined characteristics from generation to generation

Define fertilization

fusion of two haploid gametes, each containing 23 chromosomes which produces a zygote that contains 46 chromosomes

What enzyme is released from the acrosome that is used to penetrate the corona radiata?

hyaluronidase

After sperm binds to sperm receptors in the zona pellucida, two enzymes are released. State their names and their collective function

acrosin and hyaluronidase - digest a path through the zona pellucida toward the surface of the oocyte

In general, what is oocyte activation?

series of changes in the metabolic activity of the oocyte

What is polyspermy?

the fertilization of an egg by more than one sperm, resulting in a zygote with multiple sets of chromosomes

What is amphimixis?

the combining of the male and female chromosomes

Define gestation

time spend in prenatal development, period of intrauterine devlopment

What are two general processes that occur in the pre-embryonic period of the first trimester?

cleavage and implantation

What are two general processes that occur in the embryonic period of the first trimester?

cellular differentiation and embryogenesis

Define placenta

temporary structure in the uterine wall that permits diffusion between the fetal and maternal circulatory systems

Define cleavage

sequence of cell divisions that begins immediately after fertilized

What is a morula?

after three days of cleavage the pre-embryo is a solid ball of blastomere(cells)

What is a blastocyst?

an early stage in the developing embryo, consisting of an outer trophoblast and an inner cavity

What is a blastocoele?

fluid filler center cavity of a blastocyte

What is the trophoblast?

the outer layer of cells of a blastocyst (early embryo) that forms four to five days after fertilization that provide nutrients

What does the inner cell mass of a blastocyte become?

will form the embryo

Define ectopic pregnancy

implantation occurs somewhere other than within the uterus

What hormone does the trophoblast and chorion produce?

human chorionic gonadotropin

What hormones do the corpus luteum and placenta produce?

progesterone and estrogen

What occurs during gastrulation?

when a third layer of cells begins to form between the superficial and deep layers pf the inner cell mass through a cell migration process

Name the three germ layers

ectoderm, mesoderm, and endoderm

What are the two main functions of the yolk sac?

primary nutrient source for early embryonic development and becomes an important site for blood cell formation

What does the amnion produce?

amniotic fluid which cushions the developing embryo

What organ does the chorion develop into?

placenta

What is the function of the umbilical cord?

connects the fetus and the placenta, facilitates the exchange of oxygen and nutrients while removing fetal waste products

What vessels carry blood from the fetus to the placenta?

umbilical arteries

What is the function of the chorionic villi?

provide surface area for active and passive exchanges of gases, nutrients, and wastes between the fetal and maternal bloodstreams

Which trimester is the most critical for fetal development?

first trimester

During which trimester is the most weight gained by the fetus?

third trimester

Which pregnancy hormone is detected in the urine when performing a home pregnancy test?

human chorionic gonadotropin (hCG)

What is the function of human chorionic gonadotropin?

maintains the corpus luteum and promotes the continued secretion of progesterone

What is the function of human placental lactogen(hPL)?

stimulatory effect helps prepare the mammary glands for milk production

Which hormone produced by the placenta and corpus luteum suppresses the release of oxytocin by the hypothalamus and delays the onset of labor contractions?

relaxin

Define parturition

childbirth, forcible expulsion of the fetus from the uterus through the cervix and vagina

Define labor

series of strong, rhythmic uterine contractions

What are Braxton Hicks contractions?

false labor, occasional spasm in the uterine musculature that are not regular or persistent

List the three stages of labor in the order they occur

dilation, expulsion, and placental

What membrane ruptures when a birthing person’s water breaks?

amniochorionic membrane

What does the Apgar score indicate?

assessment of the newborns health of heart rate rate, breathing, skin color, muscle tone, and reflex response, each scored 0-2, total score of 8-10 is a healthy baby

What is a breech birth?

the legs or buttocks enter the vaginal canal first

What is the difference between dizygotic and monozygotic twins?

dizygotic - fraternal twins develop from two separate oocytes that were ovulated and fertilized

monozygotic - identical twins either from separation of blastomeres early in cleavage or from the splitting of the inner cell mass before gastrulation

When does the neonatal period occur?

from birth to one month of age

List two proteins contained in colostrum. What are their functions?

immunoglobins(antibodies) -

lactoferrin