CHAPTER 29

what happens during prenatal development

a fertilized ovum differentiates to form an individual

what happens during postnatal development

individual comes to maturity

differentiation

the process by which cells become specialized in structure and function during development.

inheritance

the transmission of genetic traits from parents to offspring.

fertilization

fusion of a secondary oocyte and a sperm to form a zygote

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 collective function

acrosin and hyaluronidase, which facilitate the penetration of the zona pellucida during fertilization.

what is oocyte activation

series of changes in the metabolic activity of the oocyte

what is polyspermy

the condition in which an oocyte is fertilized by multiple sperm, leading to developmental abnormalities.

what is amphimixis

sperm supplies the paternal member of each pair, and the ovum supplies the maternal member

gestation consists of what three stages

the pre-embryonic, embryonic, and fetal stages.

what is gestation

the period of development of a fetus from conception to birth.

first trimester includes

pre embryonic and embryonic development, involving the processes of cleavage, implantation, placentation, and embryogenesis

what are the two processes that occur in the pre embryonic period of the first trimester

cleavage and implantation.

placenta

an organ that develops in the uterus during pregnancy, providing oxygen and nutrients to the fetus while removing waste products.

cleavage

sequence of cell divisions that begins immediately after fertilization and leads to the formation of a blastocyst.

morula

a solid ball of cells formed from the division of the zygote before it develops into a blastocyst.

blastocyst

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

blastocoele

the fluid-filled cavity inside a blastocyst.

trophoblast

the outer layer of cells in a blastocyst that contributes to the formation of the placenta.

what does the inner cell mass of a blastocyte become

the embryo proper and additional structures such as the yolk sac.

define ectopic pregnancy

A condition where a fertilized egg implants outside the uterus, commonly in a fallopian tube, leading to potential complications.

what hormone does the trophoblast and chorion produce

Human chorionic gonadotropin (hCG), which helps maintain the corpus luteum and supports early pregnancy.

what hormones do the corpus luteum and placenta produce

Progesterone and estrogen, which are crucial for maintaining pregnancy and supporting the development of the fetus.

what occurs during gastrulation

around day 15, a third layer of cells forms between the superficial and deep layers of the inner cell mass

three layers of germs

ectoderm, mesoderm, and endoderm.

two main functions of the yolk sacs

primary nutrient source for early embryonic development; important site for blood cell formation

what does the amnion produce

amniotic fluid, which cushions and protects the embryo.

what organ does the chorion develop into

the placenta, which provides nutrients and oxygen to the developing embryo.

what is the function of the umbilical cord

supplies fetus with life sustaining substances and removes wastes

what vessels carry blood from the fetus to the placenta

The umbilical arteries

function of the chorionic villi

intricate network within the endometrium that facilitates nutrient and gas exchange between the mother and fetus.

which trimester is the most critical for fetal development

The first trimester is the most critical for fetal development as it is a time of major organ formation and growth.

during which trimester is the most weight gained by the fetus

The third trimester is when the fetus gains the most weight as it undergoes significant growth in preparation for birth.

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

Human chorionic gonadotropin (hCG) is the pregnancy hormone detected in urine during a home pregnancy test.

function of human chorionic gonadotropin

placental hormone that maintains the corpus luteum for the first 3 months of pregnancy

function of human placental lactogen

(hPL) stimulates the functional development of the mammary glands

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

Progesterone

3 stages of labor

dilation, expulsion, and placental

parturition

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

labor

strong rhythmic uterine contractions

braxton hicks contraction

occasional spasms in the uterine musculature, but these contractions are not regular or persistant (false labor)

what membrane ruptures when a birthing persons water breaks

The amniotic sac

what does the apgar score indicate

how healthy a newborn is by determining heart rate, breathing, skin color, muscle tone, and reflex

what is breech birth

a delivery where the baby is positioned feet or buttocks first rather than head first.

dizygotic twins

twins who develop from two separate eggs fertilized by two different sperm.

monozygotic twins

twins that develop from a single fertilized egg, resulting in identical siblings.

when does the neonatal period occur

occurs during the first 28 days of a newborn's life, marking a critical stage for development and adaptation outside the womb.

two proteins contained in colostrum and their functions

Immunoglobulins (provide antibodies) and lactoferrin (binds iron, has antimicrobial properties).

what enzyme is found in breast milk and what properties does it have

Lipase (aids in fat digestion and absorption; protects against gastrointestinal infections).

which hormone stimulates the milk ejection reflex

Oxytocin

when does adolescence begin

begins with the onset of puberty, typically around ages 10 to 12 for girls and 12 to 14 for boys.

in general why are boys taller than girls

period of skeletal growth ends earlier for females due to earlier onset of puberty.

why do premenopausal women have a lower incidence of arterial plaque formation

Estrogen is believed to have a protective effect on the cardiovascular system, promoting healthy blood vessel function and reducing inflammation.

senescence

aging

gene

portion of a dna strand that functions as a hereditary unit

genotype

genetic makeup of an organism

phenotype

physical characteristics that are genetically determined

homologous chromosomes

chromosome pairs that are similar in shape, size, and genetic content, with one inherited from each parent.

sex chromosomes

Chromosomes that determine the sex of an organism, typically referred to as X and Y chromosomes in humans.

karyotype

A karyotype is a visual representation of an individual's chromosomal abnormalities.

locus

the specific location of a gene or a genetic marker on a chromosome.

alleles

different versions of a gene that may produce distinct traits in an organism.

when referring to gene traits what is homozygous

When an organism has two identical alleles for a particular gene

heterozygous

When an organism has two different alleles for a particular gene.

simple inheritance

phenotypic traits are determined by a single pair of alleles

polygenic inheritance

interactions among alleles on several genes

strict dominance

allele that is dominant will be expressed in phenotype, regardless of any conflicting instructions

codominance

individual who is heterozygous for a given trait exhibits both phenotypes for that trait

incomplete dominance

heterozygous alleles produce a phenotype that is intermediate to phenotypes of the homozygous individuals.

what are punnett squares used for

draw conclusions about the identity and genotype of a biological parent

what are x linked genes

genes found of the x chromosome but not y

why are men more likely to be affected by recessive x linked traits

Because men have only one X chromosome, any recessive trait on that chromosome will be expressed.

3 conditions that occur with recessive x linked traits

hemophilia, diabetes insipidus, and muscular dystrophy

genetic recombination

gene reshuffling that occurs during meiosis, resulting in new combinations of alleles.

why do you think that only 0.5% of newborns have chromosomal abnormalities when -10% of zygotes have chromosomal abnormalities

Most chromosomal abnormalities lead to miscarriage, so only a small percentage survive to birth.

what of clinical significance can the analysis of amniotic fluid detect

It can detect chromosomal abnormalities, genetic disorders, and fetal infections.

what is translocation defect

an exchange occurs between different chromosome pairs

what genetic abnormality is the cause of down syndrome

resulting from the presence of three copies of chromosome 21

what direct correlation has been observed that increases the risk of having a baby with down syndrome

females delaying childbearing until mid 30s or later

epigenetics

study of inherited traits that are not due to changes in a person’s genotype of dna sequences

spontaneous mutations

result from errors in dna replication

teratogens

factors that result in abnormal development

what is gene therapy

medical approach aimed at treating disorders or diseases caused by genetic defects