Unit B - Contraception and Embryonic Development Flashcards
What are the contraception options available to males?
- Vasectomy
- Ca2+ blocker → inhibition of the maturation of sperm in the epididymis.
- Condoms
- Abstinence
What are the contraception options available to females?
- Birth control pills (estrogen and progesterone)
- Barrier methods
- IUD
- Chemical → spermicides
- Abstinence
- Tubal ligation → clamp fallopian tube
What is Vitro Fertilization (IVF)?
Eggs are retrieved from the ovaries and fertilized with sperm in a laboratory setting. The resulting embryos are then transferred into the uterus.
What happens in the Embryonic Period of Development? When is it?
- Cells divide and become redistributed
- Tissues and organs form
- Structures that support and nourish the embryo form
First 8 weeks
What happens in the Fetal Period of Development? When is it?
- Body grows rapidly
- Organs begin to function and coordinate to form organ systems
9th → birth
What is a zygote?
When sperm and ovum unite in the fallopian tube to form a single fertilized cell.
How does the sperm find the egg?
Because sperm are chemically attracted to the ovum, it follows its attraction.
If not close enough, it will just wonder forward until atraction
Define copulation.
Intercourse.
How many sperm fertilize an egg?
Only one.
What does the process Cleavage do?
Process of cellular division without the enlargement of cells.
What is a morula?
A 16-cell zygote, found before implantation
What is a Blastocyst?
A morula that has absorbed fluid from the endometrium BUT doesn’t have to be IMPLANTED
What is the Trophoblast?
The outer layer of the blastocyst.
What does the trophoblast develop into?
A chorion
What helps embed the blastocyst into the endometrium?
Enzymes from the trophoblast.
What helps maintain the corpus luteum? Where is this chemical produced?
HCG produced by the Trophoblast?
What is the Inner cell mass?
The cells of the morula forming the inner cell mass.
What happens to hCG production over the three trimesters?
It diminishes over time.
What does the inner cell mass turn into?
It develops into the embryo.
What produces Estrogen and progesterone in the third trimester?
Only the placenta.
in what trimester is progesterone and estrogen production shared with the placenta and ovary
Second Trimester However, the placenta now takes the dominant role in producing the hormones.
How long is the journey for the fertilized ovum to reach the uterus?
3-5 days
What happens in implantation in embryonic development?
The embedding of the blastocyst into the endometrium.
Enzymes secreted by the trophoblast digest tissues and blood vessels of the endometrium.
Trophoblast secretes HCG to maintain the corpus luteum (helps to make progesterone and estrogen.
In the second trimester, what takes over the secretion of estrogen and progesterone?
mostly the placenta
What is the Gastrulation process?
Turning the blastocyst into a gastrula through the formation of the Ectoderm, Endoderm, and Mesoderm.
During the Gastrulation process, what is the embryo called?
A gastrula
What are the names of the different stages of egg development in order?
Zygote → morula → blastocyst → gastrula →embryo, fetus
What is morphogenesis? When does this start?
A series of events that form distinct structures of the developing organism. Starts at gastrulation.
What is differentiation in embryonic development?
Embryonic cells ability to become different types of cells.
The ectoderm helps to create what part of the body?
Brain, spinal cord, & epidermis.
The mesoderm helps to create what part of the body?
Muscles, Skeleton, and reproductive organs.
The Endoderm helps to create what part of the body?
Endocrine glands, the lining of digestive and respiratory systems.
What cells create the notochord?
Mesoderm cells.
What is the notochord?
A bundle of cells that serve as the basic framework of the skeleton.
What is the neural tube? What will it eventually form?
Ectoderm cells that thicken above the notochord.
Eventually develops into the brain and spinal cord.
What is the process of forming the Neural tube called?
Or the nervous system in general
Neurulation
what process marks the beginning of organ formation?
Neurulation
When does the heart start beating?
~ day 18
What happens in week 4 of prenatal development?
Evidence of body structures
The mother may now suspect that she is pregnant.
What happens in week 5 of prenatal development?
development of large head
Brain cells differentiate quickly
What happens in week 6 of prenatal development?
The rapid development of brain
Gonads produce hormones impacting genitalia formation
What happens in week 7/8 of prenatal development?
Organs and skeleton are ~90 formed by the end of week 8
Genitalia are still forming (sex not apparent)
What is the embryo called after week 8 of development?
A fetus.
What is the Amnion? What does it do?
A transparent sac filled with fluid.
Protects embryo from trauma and temperature fluctuations.
What is the Yolk Sac? What does it do?
A sac next to the umbilical cord.
Contributes to formation of the digestive tract and produces first red blood cells and egg/sperm cells
THERE IS NO NUTRITIVE FUNCTION
What is the Allantois? What does it do?
Foundation for the Umbilical cord
After it degenerates the remainder becomes part of urinary bladder
To lable, it is always closer to the baby on the Umbilical Cord
What is the Chorion? What does it do?
Outermost membrane
Some of it will form the fetal portion of the placenta
What is the placenta? What does it do?
An organ formed by the chorion and the endometrium
Helps facilitate metabolic exchange.
Nutrients diffuse to the fetal portion of placenta
Are the fetus and the mothers blood systems attached?
No, they are separate, but lie very close to allow for diffusion of nutrients and wastes.
What way do wastes and nutrients enter and leave the fetus and mother?
Nutrients: Mother → Fetus
Wastes: Fetus → Mother
Is the placenta a filter for drugs and diseases?
No, they can still diffuse across which can lead to birth defects.
What is the Umbilical cord? How many veins and arteries does it have?
site for transporation of nutrient and wastes in and out of baby.
Made of 2 artieries and 1 vein
What is the gestation period?
The time between fertilization and birth.
What are teratogens?
Any agents that cause a structural abnormality in the baby due to exposure during pregnancy
When is the period for severe congenital abnormalities caused by teratogens?
The first 8 weeks of pregnancy
What happens in the first trimester? What is its sensitivity to teratogens? What is an important thing that happens in the last week of the first trimester?
Cleavage, germ layers, cell differentiation. As well as the foundations of organs and skeleton.
High sensitivity to teratogens.
External genitalia are distinguisable.
What happens in the second trimester?
large portions of the brain/nervous system, legs, and Lanugo develop.
What happens in the third trimester? This is the most important trimester for…
most brain growth, testes drop, and digestive and respiratory systems.
Nutrition
What is the parturition phase?
Delivery of the baby
A series of hormonal changes that will trigger contractions
What happens in the delivery of a baby (parturition)?
The cervix thins and dilates
The amniotic membrane is forced into the birth canal
Amniotic membrane bursts (water breaking)
Cervical contractions push the baby out of the vagina.
What are the Three Stages of Labour?
Dialation (contractions and cervix dialation) → Expulsion(baby is delivered) → Placental Stage (placenta expelled)
What Hormones are involved in parturition?
Relaxin, Progesterone, Oxytocin, and Prostaglandin
Where is Relaxin produced? What does it do in parturition?
Produced by the placenta before labour, it loosens ligaments within the pelvis.
Do progesterone levels increase or decrease during parturition? What does the increase/decrease do in this process?
Progesterone decreases
Inhibits uterine contractions and enables the shedding of endometrium.
Do Oxytocin levels increase or decrease during parturition? What does the increase/decrease do in this process?
Oxytocin increases
Helps stimulate uterine contractions.
Do Prostaglandin levels increase or decrease during parturition? What does the increase/decrease do in this process?
Prostaglandin increases
constricts blood vessels
Look at the hormonal changes in the parturition diagram and label the feedback loops.
Did you do it?
What is Lactation?
The secretion and formation of breast milk in the mother.
What prepares a mother’s breast to start developing the structures to produce milk?
large amounts of estrogen and progesterone.
What hormone stimulates milk production after birth?
Prolactin
What are the steps of Suckling and breastfeeding?
- Suckling stimulates nerve endings in the nipple
- Neural pathways stimulate hypothalamus
- hypothalamus produces oxytocin
- Oxytocin causes mammary lobules to contract
- Milk letdown occurs
Oxytocin as the love hormone also helps create a bond with the baby
What is the first breast fluid a mom delivers called?
Colostrum
What are the important features of colostrum?
low fat, and contains the mother’s antibodies to protect the baby until their immune system kicks in.
What are the last body systems to develop in a fetus?
Respiratory and digestive systems.
