Development Flashcards
Growth
Increase in size and entails increases in cell numbers and cell sizes
Pregnancy
Presence of a developing offspring in the uterus
Development
The continuous process by which an individual changes from one life phase to another
Fertilization
Union of an egg cell and a sperm cell
Where do eggs mature
In the ovary
Eggs ovulate to
The fallopian tube
Where is the zygote formed
In the fallopian tube
Implantation happens in
The uterine wall
Zygote
Fertilized egg
Sperm cell reaches which part during fertilization?
Corona radiata
Acrosome
Releases enzymes that penetrates the zona pellucida
Sperm size in comparison to egg
Sperm is much smaller than egg
Corona radiata
Outer portion of egg
Tip of sperm
Acrosome
Zona pellucida
Covering of egg surface deep to Corona radiata
After entering the zona pellucida
1.The head of the sperm enters the secondary oocyte
2. The zona pellucida hardens
Why does the zona pellucida harden?
So only one sperm can enter the egg
Sperms main function is to
Donate DNA
When does the egg complete second meiosis and make the large egg and second polar body
When the sperm nucleus enters the oocyte cytoplasm
Pronuclei
Nuclei from both sex cells unite and fertilization completes
Egg is released from the ovary to the
Uterine tube (LH)
Sperm travels to the uterine tube towards the
Egg
Acrosome releases enzymes that penetrate the
Zona pellucida
Egg hardens and goes through
2nd meiosis
Pronuclei
DNA joins together
Summary of stages of development from zygote to gastrula
Zygote,
Cleavage,
morula,
blastocyst,
gastrula,
Clevage
- Mitosis really fast
- From day 1 to day 3
30 hrs to 3rd day
Morula
-Third to fourth day
-solid ball of identical cells (unlike blastocyst which is hollow)
Blastocyst
-5th day to second week
-cells start to differentiate
-start to turn on DNA to make them a specific type of cell
Gastrula
-End of the second week
-primary germ layers are formed.
-skin cells and muscle cells are differentiated
-certain genes are turned on
Layers formed in gastrula
- Ectoderm
- Mesoderm
- Endoderm
Blastomeres
Cells produced as a result of cleavage
Blastomeres
Cells produced as a result of cleavage
Product of protonucleiuniting
Zygote
Blastomeres
Cells produced as a result of cleavage
Solid ball of cells produced within 3 days of fertilization about 16 cells
Morula
Blastocyte
Hollow ball that embeds into the endometrium
Change in size from day 0 to day 4 are
Mimimal
Implantation
Blastocyte nestles into uterine lining
When does implantation begin
About the 6th day of development
Trophoblast
Helps form the placenta
Trophoblast secretes
hCG which helps maintain the pregnancy
When does the trophoblast begin to work
Implantation
When does the trophoblast begin to work
Implantation
The location of the placenta can
Vary. The placenta chooses where it is
Dangerous location for placenta
Down by cervix
How can you detect hCG
Urine pregnancy test
Fertilized ovum
-12-24 hours after ovulation
-zygote forms
-30 hours to third day
-mitosis increases cell number
Cleavage
-third to fourth day
-solid ball of cell
Morula
-5th day to second week
-trophoblast and inner cell mass form
Blastocyst
-End of second week
-primary germ layers form
Gastrula
Which hormones are not released during pregnancy
FSH, LH
Corpus luteum
Secretes estrogens and progesterone to maintain uterine wall and promote growth and development
Hormones present during pregnancy
Estrogen, progesterone, hCG
hCG over time of pregnancy
High during first two months, then begins to decline
Which hormones rise throughout the pregnancy
-Estrogen
-Progesterone
Human chorionic gonadotropin
hCG
What maintains the corpus luteum?
hCG
Placenta secretes large amounts of
Estrogens and progesterone
Functions of estrogens and progesterone
-stimulate and maintain uterine lining,
-inhibit FSH and LH
-inhibit uterine contractions
-enlarge reproductive organs
Relaxin comes from
Corpus luteum
What is the function of relaxin
-inhibits uterine contractions and relaxes pelvic ligaments
Placental lactogen
Stimulates breast development
Promotes sodium retention
Aldosterone
PTH
maintains calcium concentrations in blood
Causes water retention
Aldosterone
Why is PTH important?
Prevents excessive loss of calcium from the mom
List 3 hormones involved in pregnancy
-estrogen and progesterone
-PTH
-hCG
-Inhibit FSH, LH
-Prevent contraction
Estrogen and progesterone
Ectoderm
Brain and spinal cord
Mesoderm
-muscles
-kidneys
Endoderm
-innermost part,
-intestines
Gastrula starts to spread out t/f?
True
What happens as the amnion develops
It surrounds the embryo and the umbilical cord.
Starts to form from structures in the collecting stalk
From where does the umbilical cord form
The umbilical cord forms from structures in the connecting stalk
The placenta is formed from
Chorion
Placenta function
-Gives nutrients and food to baby
The placental membrane consists of
- Epithelial wall of an embryonic capillary
- Epithelial wall of a chorionic villus
- portions of the maternal uterine wall
Oxygen and water go to the baby through the
Placenta
Portions of the placenta
Embryonic portion and maternal portion
Umbilical cord is attached to
Placenta
Blood vessels in placenta
-embryonic blood vessels
-maternal blood vessels
In umbilical cord’s blood vessel there’s
-Two veins and one artery
Umbilical cord function
-connects placenta to fetus
What does the placenta do at 7 weeks?
-synthesizes progesterone
-cells of the developing adrenal glands use progesterone to produce estrogen
- Estrogen causes changes in uterus, breasts, maternal metabolism, fetal organ development
Discuss formation of placenta
-formed from the chorion placental membrane
-has embryonic capillaries and maternal capillaries
-attached to umbilical cord
End of embryonic period
End of eighth week
When is the embryo called a fetus
After the end of the eighth week
Teratogens
Factors that cause congenital malformations during embryonic development
Structures in developing embryo are sensitive to teratogens are different times
True
Examples of teratogens
Radiation
Infections
Chemicals
Drugs
During the fetal stage the body proportions
Change considerably during development
Begins at the 8th week of prenatal development
Fetal stage
During the development of external reproductive organs
You differentiate from precursor structures
Position of full term fetus
Head down
9th-12th week of fetal development
-ossification centers appear
-sex organs differentiate
-fetal limbs begin to move
13th-16th week of fetal development
-body grows rapidly
-ossification continues, cartilage hardens
17th-20th week of fetal development
-muscle movements stronger
-skin is covered with lanugo
-skin is covered with vernix caseosa
21st-38th week
-body gains weight
-subcutaneous fat deposited
-eyebrows and eyelashes appear
-eyelids open
-testes descend
Lanugo
soft, fine, downy hair that can cover the body of a fetus or newborn
Vernix caseosa
a white, waxy, and creamy substance that coats a fetus’s skin during the third trimester of pregnancy
Helps protect from abrasions
Describe the flow of oxygen and nutrients to the fetus
Oxygen and nutrients diffuse into the fetal blood from the maternal blood
How does the fetus get rid of wastes
Waste diffuses into the maternal blood from the fetal blood
Has greater oxygen carrying capacity
Fetal blood
Umbilical vein
Carries oxygenated blood from the placenta to the fetus- half enters liver
Ductus venosus
Conducts other half of the blood to inferior vena cava; liver is bypassed
Foramen ovale
Conveys blood from right atrium to left atrium; lungs are bypassed
Some blood from the superior vena cava enters
Right ventricle and pulmonary trunk. Most bypasses lungs and instead enters the ductus arteriosis.
Ductus arteriosis
Conducts some blood from the pulmonary trunk to aorta; lungs are bypassed
Blood from the abdominal aorta is branched into
The umbilical arteries
Umbilical arteries
Carry blood from internal iliac arteries to the placenta
Where is fetal blood reoxygenated
Placenta
Birth process
-progesterone levels decrease
-prostaglandins may initiate labor
-stretching uterus stimulates the release of oxytocin from the posterior pituitary gland
Oxytocin stimulates
Uterine contractions
What happens when the fetal head stretches uterus
Greater release of oxytocin that results in stronger and stronger contractions
Stages of birth
-fetal position before labor
-dilation of the cervix
-expulsion of the fetus
-expulsion of the placenta
Stimulates further breast development
Placental estrogen and progesterone cause breasts to develop even more
Causes ductile system to grow
Estrogen
Causes alveolar glands to develop
Progesterone
Placental lactogen
Also produces changes in breast
When is prolactin first released
Prolactin is released about the 5th week of pregnancy
When does milk production begin
Until after birth
Myoepithelial cells
Contract release milk from an alveolar gland
The release of prolactin is controlled by which feedback mechanism
Positive feedback. the more you breastfeed the more milk you produce
When does the neonatal period occur
Birth to end the fourth week
What happens during the neonatal period
Carry-on respiration
obtain nutrients
Digest nutrients
excrete wastes
regulate body temperature
make cardiovascular adjustments
When does infancy occur
End of the fourth week to 1 year
What happens during infancy
-growth rate is high
- teeth begin to erupt
-muscular& nervous systems mature
-communication begins
Childhood
-1 year to puberty
-growth rate is high
-permanent teeth appear
-muscular control is achieved
-potty training
-intellectual abilities mature
Adolescence
-puberty to adulthood -person becomes reproductively functional and emotionally more mature
-growth spurts
-motor skills
-intellectual abilities continue to mature
Adulthood
Adolescence to old age
-degenerative changes can begin
Senescence
-old age to death
-degenerative changes continue
-body becomes less able to cope with demands placed on it
-death results from various conditions and diseases
Leading cause of death
Heart disease
Trophoblast forms during which stage?
Blastocyst
30 hours to day 3
Cleavage
Day 3 to day 4
Morula
Day 5 to 2 weeks
Blastocyst
After 2 weeks
Gastrula
