zzz Watson Development Flashcards
weeks 3 - 8
embryonic period
weeks 1 -2
pre-embryonic period
weeks 9 - 38
fetal period
during the pre-embryonic period, the conceptus divides into hundreds of cells called ___ and becomes a ___ which implants in the uterine wall
cleavage, blastocyst
__ in semen may assist with movement of sperm by causing uterine contractions
prostaglandins
secondary oocytes are covered with a layer of cells called the __ __
corona radiata
the __ reaction prevents additional sperm cells from binding to the oocyte
cortical reaction
the blastocyst has 2 distinct cell populations: large flat cells called the ___ and a cluster of round cells called the ___ __ __
trophblast
inner cell mass
forms part of the digestive tract and is the first extraembryonic membrane to form
yolk sac
forms the base for the umbilical cord and later becomes part of the urinary bladder
allantois
encloses the embryo and secretes fluid to fill the sac
amnion
forms the outgrowths that blend with the stratum functionalis layer of the uterus
chorion
what are the 2 types of embryonic folding
cephalocaudal and lateral
what month- downy hair called lanugo develops
5
what month- organs specialize and grow
8 and 9
what month- lungs begin to produce surfactant
6
what month- the heartbeat can be heard with a stethoscope
4
what month- fetus turns to the vertex position
7
what month- ossification begins in most bones
3
the __ secretes hCG
trophoblast
which hormone secreted during pregnancy assists with increasing the mothers blood volume
aldosterone
___ stage is the time from the onset of labor until the cervix is fully open
dilation
the dilation stage is usually ___ compared to the expulsion or placental stages
longer
The first __ weeks after birth are the neonatal period
4
__ are segments of DNA that code for a specific protein, and the human __ includes over 20,000 of these segments
genes, genome
which pattern of inheritance includes examples of codominance
multiple allele traits
science that studies changes in form and function from fertilized egg through old age
Developmental biology
study of events that occur during approximately 38 weeks of development inside mother’s womb
Embryology
developmental stage that occurs during approximately 38 weeks duration within mother’s womb; period people usually refer to as pregnancy
Prenatal period
Postnatal period begins at ___ and continues through all of life’s stages
Birth
Three stages of prenatal development that occur during 38-week time period include:
Pre-embryonic period
Embryonic period
fetal period
Pre-embryonic period – lasts for first 2 weeks after
Fertilization
Pre-embryonic period – zygote divides mitotically many times to produce a multicellular structure (____); implants in (attaches to) endometrium of uterus
Blastocyst
Embryonic period – extends from week 3 through 8 of gestation; conceptus grows, folds, and forms rudimentary organ systems; called an
embryo
Final stage, fetal period, lasts from week _ through 38 of gestation, or until birth
9
continues development through two years of age
Infancy
lasts until period of sexual maturation, or puberty, begins
Childhood
finishes when individual is capable of sexual reproduction
adolescence
extends from end of adolescence until death
Adulthood
stage at which development ends and degeneration of tissues and organs, called
senescence
Some cells of blastocyst begin to form ____ membranes; help support developing embryo
Extraembryonic
An ovulated secondary oocyte is viable for only __ hours after it is released from ovary
24
sperm can remain viable in female’s reproductive tract for up to __ days
5
Before it can fertilize an oocyte, a sperm must undergo ___; series of functional changes that make it fully motile and modify its plasma membrane so it can fuse with plasma membrane of oocyte
Capacitation
Sperm undergo capacitation as they migrate to the
Oocyte
____ in semen are thought to stimulate uterine contractions; assist with moving sperm farther into female reproductive tract
Prostaglandins
Although female orgasm is not required for fertilization, it also results in uterine contractions and may help in moving sperm; all of these processes together are called
sperm migration
___ reaction – releases enzymes from head of sperm
Acrosomal
An ovulated secondary oocyte is surrounded by a layer of granulosa cells called ___ ___
corona radiata
Sperm must penetrate this cell layer by a combination of sperm movements and _____, an enzyme released from membrane-bound sac on head of sperm called acrosome
Hyaluronidase
Deep to oocyte’s corona radiata is zona ____
Pellucida
zona pellucida; layer of extracellular matrix secreted by oocyte that contains
sperm-binding receptors
When a sperm cell binds to a sperm-binding receptor in zona pellucida, ____ ion channels in sperm’s plasma membrane open
Calcium
Increased intracellular calcium ion level triggers ___ reaction
Acrosomal
Numerous sperm cells are needed to release enough hyaluronidase and ___ to break through corona radiata and zona pellucida
Acrosin
Sperm entry stimulates ____ reaction; destroys sperm-binding receptors
Cortical
Specialized secretory vesicles called cortical granules are present in oocyte; contain enzymes that catalyze reactions to destroy ___-___ receptors
sperm-binding receptors
Sperm entry triggers release of enzymes from cortical granules; a process termed cortical
reaction
cortical reaction prevents additional ___ cells from binding
sperm
Sperm nucleus swells to form a male
Pronucleus
Oocyte completes ___ __, and resulting ovum swells to form a female pronucleus
Meiosis 2
____ fibers form between male and female pronuclei; pronuclear membranes break down, allowing chromosomes to mingle
Spindle
inability to produce a pregnancy after 1 year of unprotected sexual intercourse
Infertility
Approximately 30 hours after fertilization occurs, zygote begins cleavage; series of rapid mitotic divisions that produce small, genetically identical cells called
blastomeres
Divisions occur too quickly for cells to grow; so cell number increases, but cell size becomes
smaller
cells start to differentiate; will be building blocks of all future tissues of developing conceptus; known as a ____ and remains covered by zona pellucida
morula
By time blastocyst is ready for implantation, it has two distinct cell populations: An outer layer of large, flattened cells, called ____ cells. An inner cluster of rounded cells (inner cell mass, or ____)
trophoblast , Embryoblasts
_____ cells, surround fluid-filled cavity, participate in forming placenta
Trophoblast
An inner cluster of rounded cells (inner cell mass, or ____) form embryo proper—developing body
Embryoblasts
Implantation occurs approximately __ to __ days after fertilization when blastocyst begins to attach to endometrium of uterus
4–7 days
____ invades stratum functionalis layer of endometrium by secreting digestive enzymes that catalyze reactions to degrade endometrial lining
Trophoblast
Trophoblast cells divide into two layers:
Inner- cytotrophoblast
Outer- syncytiotrophoblast
Trophoblast cells divide into two layers: part where cells’ plasma membranes disappear and their cytoplasmic contents merge to form a functionally single, large, multinucleated cell; begins to secrete enzymes to digest uterine cells almost immediately after formation
Syncytiotrophoblast
Syncytiotrophoblast is also responsible for secreting hormone
hCG
hCG stimulates corpus luteum in ovary to secrete estrogen and progesterone and helps promote _____ development
placental development
___ suppresses menstruation by maintaining endometrium of uterus and prolonging secretory phase of uterine cycle
Progesterone
produced only during pregnancy making it basis for urine pregnancy tests
hCG
hCG level rises in mother’s blood until end of second month of development, when a membrane called ___ takes over role of corpus luteum in secreting estrogen and progesterone
chorion
On rare occasions, blastocyst implants in a site different from uterus; if pregnancy continues, result is an ____ pregnancy
Ectopic
inner cell mass (developing offspring) separates from trophoblast and differentiates into two layers:
epiblast and hypoblast
Superior epiblast and inferior hypoblast together form a flat ___ embryonic disc
Bilaminar embryonic disc
A small cavity appears within epiblast and will enlarge to become ___ cavity
Amniotic
amniotic cavity will surround ___ and fill with fluid
embryo
____ embryonic disc will eventually become three primary germ layers that differentiate to produce all tissues in body (ectoderm, mesoderm, and endoderm); blueprint for future organ development
Bilaminar
Bilaminar embryonic disc and trophoblast together produce ____ membranes
Extraembryonic membranes
___ membranes include yolk sac, amnion, allantois, and chorion
extraembryonic membranes
arises from hypoblast cells; first extraembryonic membrane to develop
Yolk sac
cells from yolk sac form part of ____ tract and are source of first blood cells and vessels
digestive
Yolk sac also produces first ___ cells, precursors of gametes; will eventually migrate into developing ovaries and testes
Germ
transparent membrane that develops from epiblast
Amnion
The amnion eventually encloses embryo in fluid-filled amniotic cavity; penetrated only by the
umbilical cord
amniotic fluid is formed by filtering mother’s ___, but embryo’s own urine contributes to amniotic fluid volume once its kidneys become functional toward end of eighth or ninth week of development
blood
___ fluid protects embryo from trauma and drying out; helps maintain a constant temperature; also allows freedom of movement; important for muscle development, and prevents body parts from adhering to each other
Amniotic fluid
small outpocketing of caudal wall of yolk sac; forms base for umbilical cord and ultimately will become part of urinary bladder
Allantois
outermost extraembryonic membrane
Chorion
develops from cytotrophoblast and syncytiotrophoblast; encloses all other membranes and embryo
Chorion
Forms outgrowths called chorionic ___; initially found around entire surface of chorion
Villi
By late week four of development, chorionic villi are blended with stratum ___ layer and begin to form principal embryonic part of placenta
Functionalis
Embryonic period starts with a process called
Gastrulation
Gastrulation: rearrangement and migration of cells of bilaminar embryonic disc to form ___ embryonic disc
Trilaminar
Placenta forms during the ____ period
Embryonic period
In week 3, bilaminar embryonic disc contains two cell layers:
epiblast and hypoblast
A thin groove on dorsal surface of epiblast develops; called
primitive streak
elongates along cephalic-caudal (head-tail) line of embryo, establishing head and tail regions, right and left sides, and dorsal and ventral (posterior and anterior) surfaces of embryo
Primitive streak
begins after primitive streak has completed its development
Gastrulation
Gastrulation starts as cells detach from epiblast layer and move into primitive streak, a process called
ingression
during ingression, the first cells that migrate in this way become inner germ layer, or endoderm; replaces
hypoblast
Next cells migrate to a position between epiblast and endoderm; becomes middle layer aka
(mesoderm)
Remaining cells of epiblast form outer layer aka
(ectoderm)
____ folding occurs in head and tail regions of embryo; creates future head and buttocks regions of embryo
Cephalocaudal folding
____ or lateral, folding occurs when left and right sides of embryo curve and fold toward midline
Transverse
Transverse folding creates future trunk region and almost immediately forms primitive gut; later becomes ___ tract
digestive
When embryonic period ends at end of week __, embryo will have recognizable organ systems; although not all organs will be functional, some will begin to work
8
First major event of organogenesis is
neurulation
Mesodermal cells underneath primitive streak form a structure called ___; serves to support and organize embryo around a central axis
Notochord
During Embryonic period (weeks 3–8), embryo is especially sensitive to
teratogens
placenta is fully formed at about week
12
Placentation begins during ___, but majority of placental growth occurs in fetal period
Implantation
Umbilical cord contains two umbilical ___ that carry deoxygenated fetal blood away from fetal heart to placenta, and one umbilical ___ that carries oxygen and nutrients toward fetal heart
Arteries, vein
Umbilical cord also contains a soft connective tissue with a jelly-like consistency, called ____ jelly
Wharton’s
When embryonic period begins, blastocyst has implanted in uterus and chorionic villi have penetrated uterine blood vessels to form ___ filled with maternal blood
Lacunae
lacunae filled with maternal blood; merge into a single blood-filled cavity called placental
sinus
Once placentation has begun, stratum functionalis of uterus is known as
decidua
Placenta – unique organ because it develops from both ___ (chorionic villi) and maternal (decidua basalis) structures
Fetal
In addition to its nutritive functions, placenta also functions as an endocrine organ; assumes production of hCG as it grows and results in subsequent reduction of
Syncytiotrophoblast
Blood flow between mother and fetus through placenta takes following pathway: Oxygenated maternal blood flows to decidua ___ layer of uterus and then through maternal arteries into placental sinus
basalis
Blood flow between mother and fetus through placenta takes following pathway: Maternal blood touches placental barrier; allows diffusion of substances, but not passage of
blood cells
Blood flow between mother and fetus through placenta takes following pathway: Once diffusion has taken place, maternal blood which is deoxygenated and carrying waste, flows into maternal ___ and back to mother’s cardiovascular system
Veins
Oxygenated blood leaves placenta and flows back to fetus through a single umbilical
vein
Fetal hemoglobin has a greater affinity for oxygen than ___ hemoglobin, so it pulls oxygen away from mother’s hemoglobin at placental barrier
Maternal
Deoxygenated fetal blood leaves fetus and enters two umbilical ___ where it then flows into placenta and moves into fetal capillaries in chorionic villi, on fetal side of placental barrier
Arteries
Fetal blood then picks up oxygen and nutrients and delivers waste by diffusion, but again, no __ cells move through barrier
blood
Genitals are distinguishable as male or female; by end of month __
3
Hair grows on head, and skin is covered by a downy hair called
Lanugo
Mother can feel movements, a phenomenon referred to as ____, as skeletal muscles begin to contract
Quickening
Month 7: Fetus usually turns upside down, assuming ___ position
Vertex
Fetal circulation and cardiovascular system change rapidly soon after
Birth
Unique cardiovascular structures present during prenatal development include umbilical arteries and umbilical vein and three circulatory “shortcuts” called vascular
shunts
Blood from umbilical vein bypasses liver via ductus ___; connected to inferior vena cava and flows into right atrium of heart
Venosus
hole in interatrial septum that directly connects right and left atria; allows blood to “skip” ahead and avoid pulmonary circulation by moving directly from right to left side of heart and systemic circulation
Foramen ovale
short passage that connects pulmonary trunk to aorta; allows blood to move from pulmonary trunk directly into aorta
Ductus arteriosus
most critical stage of development- ___ trimester
1st trimester
After blastocyst implants in uterine lining, ____ begins secreting hCG; maintains corpus luteum so that it continues secreting estrogen and progesterone
Syncytiotrophoblast
___ and relaxin secreted from corpus luteum suppress uterine contractions until birth process begins
Progesterone
Hormone from adrenal cortex promotes reabsorption of sodium ions from kidney tubules; causes water to follow by osmosis; leads to an overall increase in blood volume during pregnancy
Aldosterone
Hormone helps to maintain a high concentration of maternal blood calcium ions because fetal demand for calcium ions is high to support bone development
Parathyroid hormone
Hormone secreted from anterior pituitary stimulates milk production by mammary glands
Prolactin
Hormone from fetal and maternal hypothalamus is secreted during second and third trimesters and peaks during labor to stimulate uterine contractions and allow milk release from mammary glands
Oxytocin
In last few weeks of pregnancy, ____ promote formation of gap junctions between uterine muscle cells to facilitate coordinated contractions during childbirth
Estrogens
Changes during Pregnancy: Glandular tissue grows and additional ___ (structures of breast that produce milk) develop under influence of prolactin
Alveoli
Changes during Pregnancy: Mother’s blood volume and cardiac output ___; blood pressure may rise to some extent
Increase
Typically, pregnant women have a ____ hematocrit (number of erythrocytes) than nonpregnant women
Lower
Fetal adrenal cortex produces cortisol; binds to receptors on placenta and stimulates it to produce large amounts of
estrogen
High estrogen level stimulates uterus to form ____ receptors on myometrium
Oxytocin
High estrogen levels also override quieting influence of progesterone on myometrium; becomes “irritable”, leading to irregular contractions called Braxton-Hicks contractions; referred to as ___ labor because they do not result in three stages of labor
False
_____s dilate cervix and, along with oxytocin, increase strength of uterine contractions
Prostaglandins
Labor can be subdivided into three stages—
Dilation, Expulsion, Placental
___ stage – time from onset of labor until cervix is fully dilated (expanded) to 10 cm (3.9 in.) in diameter
Dilation
____ stage – time from full dilation to delivery of newborn; may take up to a few hours, but typically ranges from 30 minutes to 1 hour:
Expulsion
____ stage – time after delivery of newborn when placenta and attached fetal extraembryonic membranes, collectively called afterbirth, are delivered; takes about 30 minutes without assistance
Placental
calculated to evaluate whether a newborn is adjusting appropriately; physical status is evaluated at 1 minute and 5 minutes after birth; based on five criteria: skin color, pulse rate, respiratory level, muscle activity, and grimace (which assesses reflexes)
Apgar score
Neonatal heart rates are significantly ___ than those of adults
Higher
Newborns are born with ____ fat; a special adipose tissue deposited during fifth month of fetal development that produces heat rather than storing energy
Brown
newborns have a ____ rate of water loss and require more fluid intake
higher
a bloody, yellowish discharge; expelled from uterus for up to 6 weeks after birth
Lochia
is responsible for actual ejection of milk from alveoli of mammary glands, a process called let-down reflex
Oxytocin
Genes – segments of DNA that code for a specific
Protein
genes are not necessarily identical – they may have slightly different sequences of nucleotides; variants of a gene are called
alleles
