Chapter 29 Development and Inheritance

Comprehensive vocabulary flashcards covering development, inheritance, fertilization, fetal growth, and genetics based on Chapter 29 lecture notes.

Differentiation

The process by which a cell becomes specialized to perform a specific function

Inheritance

The transmission of characteristics from generation to generation through inherited genes

Fertilization

The fusion of a secondary oocyte and a sperm, forming a zygote

Hyaluronidase

An enzyme released from the acrosome used to break down bonds between follicle cells surrounding the oocyte

Acrosin

A protein-digesting enzyme that helps digest a path through the zona pellucida during fertilization

Oocyte activation

A series of processes including membrane depolarization, calcium release, and cortical reaction following sperm-oocyte fusion

Membrane Depolarization

An increase in sodium ion permeability that occurs when sperm and oocyte membranes fuse during fertilization

Smooth Endoplasmic Reticulum

The organelle that releases calcium ions into the cytoplasm during oocyte activation

Cortical Reaction

The exocytosis of vesicles releasing zonal inhibiting proteins ($ZIPs$) to prevent polyspermy

Zonal inhibiting proteins ($ZIPs$)

Proteins released during the cortical reaction that inactivate sperm receptors and harden the zona pellucida

Completion of Meiosis II

Occurs after oocyte activation, resulting in the formation of a mature ovum

Metabolic Rate Increase

An effect of oocyte activation where enzymes activate $mRNA$ strands for rapid protein synthesis

Polyspermy

Occurs when more than one sperm fertilizes an egg, leading to a non-viable zygote with excess genetic material

Amphimixis

The process during fertilization where the male and female pronuclei fuse together

Male pronucleus

The nucleus of the sperm during the process of amphimixis

Female pronucleus

The nucleus of the egg during the process of amphimixis

Gestation

The period of prenatal development, typically divided into three trimesters

First Trimester

The period of prenatal development including pre-embryonic and embryonic stages, cleavage, implantation, placentation, and embryogenesis

Second Trimester

The middle phase of prenatal development involving significant fetal growth and organ function

Third Trimester

The final phase of prenatal development during which the fetus gains the most weight

Pre-Embryonic Period

The early phase of the first trimester characterized by cleavage and implantation

Cleavage

A series of rapid mitotic cell divisions transforming a zygote into a multicellular blastocyst

Implantation

The attachment of the blastocyst to the uterine wall to receive nutrients

Embryonic Period

A stage in the first trimester involving placentation and embryogenesis

Placentation

The formation of the placenta to facilitate nutrient and waste exchange

Embryogenesis

The formation of the embryo's body and internal organs, including the differentiation of tissues

Placenta

A vital organ connecting the fetus to the uterine wall for nutrient uptake, waste elimination, and gas exchange

Blastomeres

Smaller cells created by the rapid mitotic divisions of the zygote during cleavage

Pre-embryo

A multicellular structure formed from the zygote during the process of cleavage

Morula

A solid ball of blastomeres shaped like a mulberry, typically formed by day $3$ post-fertilization

Blastocyst

A hollow ball of cells formed from the morula, typically around day $6$ post-fertilization

Blastocoele

The fluid-filled cavity within the blastocyst providing space for cell differentiation

Trophoblast

The outer cell layer of the blastocyst that provides nutrients to the developing embryo

Inner cell mass

The cluster of cells inside a blastocyst that will eventually form the embryo

Ectopic pregnancy

A condition where implantation occurs outside the uterus, most commonly in the uterine tubes

Uterine tubes

The most common site for an ectopic pregnancy to occur

Human chorionic gonadotropin ($hCG$)

A hormone produced by the trophoblast and chorion that maintains the corpus luteum

Progesterone

A hormone produced by the corpus luteum and placenta crucial for maintaining the endometrial lining

Human Placental Lactogen ($hPL$)

A placental hormone that prepares mammary glands for milk production and ensures nutrient availability for the fetus

Placental Prolactin

A hormone from the placenta that helps prepare mammary glands for milk production

Relaxin

A hormone that increases pelvic flexibility, dilates the cervix, and suppresses oxytocin release

Placental Estrogens

Hormones that maintain the endometrial lining and stimulate labor as levels rise in the third trimester

Gastrulation

A critical phase around day $15$ where cells migrate to form three distinct germ layers

Primitive streak

A central line on the embryonic disc toward which cells migrate during gastrulation

Germ layers

The three distinct layers ($ectoderm$, $mesoderm$, and $endoderm$) formed during gastrulation

Ectoderm

The germ layer composed of superficial cells that remain on the surface of the embryonic disc

Mesoderm

An intermediate germ layer formed by migrating cells between the ectoderm and endoderm

Endoderm

The germ layer consisting of cells facing the yolk sac

Yolk sac

The primary nutrient source for the early embryo and an important site for blood cell formation

Amnion

The extra-embryonic membrane that produces amniotic fluid to surround the developing embryo

Amniotic fluid

The fluid produced by the amnion that fills the amniotic cavity

Chorion

The outer extra-embryonic membrane that develops into the functional placenta by the third week

Umbilical cord

A structure that delivers nutrients and oxygen while removing fetal waste without mixing maternal and fetal blood

Umbilical arteries

The two vessels that carry blood from the fetus to the placenta

Chorionic villi

Structures containing fetal blood vessels that anchor the placenta and facilitate gas and nutrient exchange

Ruptured maternal arteries

The source of maternal blood that surrounds chorionic villi for nutrient uptake

Home pregnancy test

A test that detects the presence of human chorionic gonadotropin ($hCG$) in urine

Prevention of Menstruation

The function of $hCG$ achieved by maintaining progesterone levels through the corpus luteum

Growth hormone-like effects

Effects produced by human placental lactogen ($hPL$) to stimulate maternal tissues

Parturition

The formal term for childbirth, the process of expelling the fetus from the uterus

Labor

The rhythmic uterine contractions and processes consisting of dilation, expulsion, and placental stages

Braxton Hicks contractions

Irregular and non-persistent uterine spasms often referred to as false labor

True labor

Persistent uterine contractions that help expel the fetus through the cervix and vagina

Dilation Stage

The first stage of labor ending when the cervix is fully dilated, often lasting $8$ or more hours

Expulsion Stage

The stage of labor involving intense contractions every $2-3$ minutes until the baby is delivered

Placental Stage

The final stage of labor involving the detachment and expulsion of the placenta within an hour of birth

Amniochorionic membrane

The membrane that ruptures when a birthing person's water breaks

Apgar score

A test at $1$ and $5$ minutes after birth measuring appearance, pulse, reflexes, muscle tone, and respiration

$1$-minute Apgar score

A score determining how well the baby tolerated the birthing process

$5$-minute Apgar score

A score indicating how well a baby is doing outside the mother's womb

Breech birth

A birth where the fetus's legs or buttocks enter the vaginal canal first

Dizygotic Twins

Fraternal twins developing from two separate oocytes fertilized by two different sperm

$50$ percent

The approximate amount of DNA shared by dizygotic twins, similar to regular siblings

Monozygotic Twins

Identical twins originating from a single fertilized egg that splits into two embryos

Neonatal period

The postnatal stage occurring immediately after birth and lasting for the first $28$ days of life

Colostrum

The initial milk produced after birth containing high concentrations of antibodies and mucins

Antibodies

Proteins in colostrum that provide passive immunity to newborns until their own immune system functions

Mucins

Proteins in breast milk that inhibit the replication of rotaviruses in infants

Rotaviruses

Viruses that can cause severe gastroenteritis and diarrhea in infants, inhibited by mucins

Lysozyme

An enzyme in breast milk with antibiotic properties that breaks down bacterial cell walls

Milk ejection reflex

Also known as the milk let-down reflex, stimulated by the hormone oxytocin

Oxytocin

The hormone responsible for stimulating the milk ejection reflex during breastfeeding

Infancy

The postnatal period following the neonatal stage that continues until childhood

Adolescence

The postnatal stage that begins at puberty and involves sexual maturation

Puberty

The period of sexual maturation marking the start of adolescence

Testosterone

A male sex hormone that stimulates bone growth and muscle development more significantly than estrogen

Arterial plaque formation

A condition occurring at a lower incidence in premenopausal women due to the protective effects of estrogen

Senescence

The process of aging that begins at maturity and continues until death

Gene

A specific segment of $DNA$ that codes for particular proteins, either structural or enzymes

Genotype

The genetic makeup of an individual inherited from both parents acting as a set of construction plans

Phenotype

The observable physical and physiological traits resulting from genotype and environmental interaction

Homologous Chromosomes

Pairs of chromosomes containing the same types of genes, including the first $22$ pairs in humans

Autosomes

The first $22$ pairs of homologous chromosomes in humans

Sex Chromosomes

The $23rd$ pair of chromosomes ($X$ and $Y$) that determine an individual's genetic sex

$X$ and $Y$

The non-identical sex chromosomes that determine genetic sex in humans

Karyotype

A visual display of the complete set of $23$ pairs of chromosomes in an organism

Locus

The specific position on a chromosome where a particular gene is located

Alleles

Different forms of a gene that can exist at a particular locus

Homozygous

Having two identical alleles at a specific locus on homologous chromosomes

Heterozygous

Possessing two different alleles at a particular locus on homologous chromosomes