pregnancy and development, exam #4 a&p II

What is a zygote?

The fertilized egg

Is a zygote haploid or dipoloid?

diploid

What is fertilizaiton?

During fertilization, the sperm and egg unite in one of the fallopian tubes to form a zygote. Then the zygote travels down the fallopian tube, where it becomes a morula. Once it reaches the uterus, the morula becomes a blastocyst. The blastocyst then burrows into the uterine wall — a process called implantation.

Where does fertilization happen?

Upper third of fallopian tube 

When does feritlization happen? 

within 24 hrs of ovulation

• At ovulation, this secondary oocyte will be released and travel toward the uterus through the oviduct. If the secondary oocyte is fertilized, the cell continues through the meiosis II, completing meiosis, producing a second polar body and a fertilized egg containing all 46 chromosomes of a human being, half of them coming from the sperm.

Blastocyst:

• Implants in the endometrium abt 6 days after fertilization

• Outer layer is the trophoblast and becomes part of the placenta

• Inner part is the embryoblast and develops into the embryo

What is the trophoblast?

The outer layer of  blastocyst and becomes the placenta

What is the is the embryoblast?

Inner part of blastocyst and develops into the embryo

What is the time frame on the blastocyst, trophoblasr, and embryoblast?

6 days after fertilization

What is the morula?

• reaches the uterus around day four and during the next two days, it develops into a hollow ball of cells called the blastocyst.

• Solid ball of cells that develops from the blastomere

What is the series of cellular subdivisions after the oocyte is fertilized?

cleavage

cleavage

When the secondary oocyte is fertilized it becomes a single cell that is called the zygote. The zygote then undergoes a series of subdivisions. These subdivisions reduce the amount of cytoplasm in the cells, which are called blastomeres. The blastomeres subdivide for about three days to form a solid ball of cells called the morula. The morula reaches the uterus around day four and during the next two days, it develops into a hollow ball of cells called the blastocyst. The blastocyst is composed of two cell layers. The outer layer develops into the placenta. The cells of the inner layer are clustered at one end of the blastocyst, and eventually develop into the embryo.

What is being described here? Ectopic pregnancy, also known as tubal pregnancy

• a pregnancy that happens outside of your uterus. 

• This occurs when a fertilized egg implants in a location that can’t support its growth.

•  most often happens in your fallopian tube (a structure that connects your ovaries and uterus).

Identify this: a problem during pregnancy when the placenta completely or partially covers the opening of the uterus (cervix).

Placenta previa

HCG:

• Human chorionic gonadotropid hormone

• Released by embryo

• Helps maintain the corpus luteum in the ovary (which releases progesterone and prevents the next menstrual cycle)

• Detected in urine by pregnancy tests 

How is HCG useful in diagnosis:

In pregnancy tests, so tells you if pregnant 

What are the three germ layers in gasturation?

Ectoderm

Endoderm 

Mesoderm 

What germ layer is this?

• Epidermis of skin and its derivatives (includins sweat glands, hair follicles)

• Epithelial lining of mouth and anus

• Cornea and lens of eye

• Nervous system

• Sensory receptors in epidermis

• Adrenal medulla

• Tooth enamel 

• Epithelium of pineal and pituitary glands

ectoderm

What germ layer is this?

• Notochord

• Skeletal system

• Muscular system

• Muscular layer of stomach and intestine 

• Exretory system 

• Circulatory and lumnphatic systems

• Reproductive system (except germ cells)

• Dermis of skin

• Lining of body cavity

• Adrenal cortex

Mesoderm

What germ layer is this?

• Epithelial lining of digestive tract

• Epithelial lining of respiratory system

• Lining urethra, urinary bladder, and reproductive system

• Liver

• Pancreas

• Thymus

• Thyroid and parathyroid glands 

Endoderm

What is the early development stage, and goes to 2 months after conception?

Embryo

What looks like a human, and it occurs 2 months to 9 months after conception?

fetus

All vertebraes go through similar

embryonic stages

What is the color of the umbilical vein?

 Red, carries O₂, carries nutrients 

What color are umbilical arteries?

Blue, does not carry O₂, carries wastes

What is the placenta?

• a temporary organ that connects the fetus to your uterus during pregnancy. The umbilical cord connects the fetus to the placenta. 

• It attaches to your uterine wall and provides nutrients and oxygen to the fetus through the umbilical cord.

What is fetal circulation?

• Oxygenated, nutrient-rich blood from the placenta is carried to the fetus by the umbilical vein. 

• This blood enters through the inferior vena cava (the large vein that carries blood from the lower and middle body into the right atrium of the fetal heart). 

• After oxygenated blood arrives at the right atrium, it flows through the foramen ovale (an opening between the right and left atrium) to the left ventricle, then into the aorta (the main vessel, which carries blood from the heart to the rest of the body and the brain).

• Some blood from the aorta flows to the two umbilical arteries and re-enters the placenta, where carbon dioxide and other waste products from the fetus are taken up and enter the maternal circulation. 

• The placenta accepts the blood without oxygen from the fetus through the umbilical arteries. In the placenta the blood picks up oxygen and returns to the fetus via a third vessel in the umbilical cord (umbilical vein). The oxygen-rich blood that enters the fetus passes through the fetal liver and enters the right side of the heart.

• Blood coming back from the fetus also enters the right atrium through the superior vena cava and coronary arteries. This doesn’t shunt through the foramen ovale, but the fetus is able to send this oxygen-poor blood from the right atrium to the right ventricle (the chamber that normally pumps blood to the lungs). Most of the blood that leaves the right ventricle in the fetus bypasses the lungs through the second of the two extra fetal connections, known as the ductus arteriosus.

• The ductus arteriosus sends the oxygen-poor blood to the organs in the lower half of the fetal body. This allows for the oxygen-poor blood to leave the fetus through the umbilical arteries and get back to the placenta to pick up oxygen.

• Since the foramen ovale and ductus arteriosus are normal findings in the fetus, it is impossible to predict whether these connections will close normally after birth in a normal fetal heart. These two bypass pathways in the fetal circulation make it possible for most fetuses to survive pregnancy even when there are complex heart problems and not be affected until after birth, when these pathways begin to close.

What two adaptations in the fetus help skip the lungs?

• Ductus arteriosus 

  • Between pulmonary trunk and aortic arch 

  • Should close at birth to become ligamentum arteriosum

• Foramen ovale 

  • Hole in interatrial septum

  • Should close at birth to become the fossa ovalis 

What is:

• Between pulmonary trunk and aortic arch 

• Should close at birth to become ligamentum arteriosus

Ductus arteriosus 

What is

• Hole in interatrial septum

• Should close at birth to become the fossa ovalis

Foramen ovale 

What do the  two adaptations in the fetus help skip the lungs, become when a baby starts breathing?

• Ductus arteriosus → Ligamentum arteriosum

• Foramen ovale → fodda ovalis 

A patent foramen ovale may lead to an

ischemic stroke

Pregnancy split into trimesters:

1. Orangogenesis: all organ systems begin to develop, the first nervous system at 2 weeks after conceptions

2. Development continues

3. Fetus increases in size a lot the last month, gains abt a pound a week in the last month

What is this: all organ systems begin to develop, the first nervous system at 2 weeks after conceptions?

 Organogenesis, 1st trimester of pregnancy

What happens during second trimester of pregnancy?

Development continues

What happens during the third trimester of pregnacny?

Fetus increases in size a lot the last month, gains about a pound a week in the last month

Which system develops first in pregnancy?

the nervous system

when do all the systems develop in pregnancy?

within 2-8 wks after conception

Two safe physical activities when pregnant?

walking and swimming

Bad activities when pregnant?

 Heavy duty activities ex: lifting weights

Best sleep position when pregnant?

left side

are you eating for two? (pregnancy)

First trimester: no increase in calories are required

Second trimester: increase calories by 340 daily 

Third trimester: increase calories by 450 daily

Is a pregnant woman eating for two? 

• Not in the first trimester, because no increase in calories are required 

• You do not need to double the amount you eat during pregnancy, eat high nutritional foods instead not

• First trimester: no increase in calories are required

• Second trimester: increase calories by 340 daily 

• Third trimester: increase calories by 450 daily
  

Why is dieting during pregnancy to lose weight never a good idea:

• Normal weight women should gain about 25-35 lbs

• Overweight women should gain about 15-25 lbs

• Obese women should gain about 15 lbs

Problems with low birth weight baby? 

higher death risk

Development of systems after conceptions:

• All systems start within 2-8 wks after conception

• First system to develop is the nervous system

  • Why is this a problem? Its sensinstive, mother may have been exposed to something that is harmful and then it causes damage

Special needs:

• Increase folic acid

  • Prevents neural tube defects like spina bifida (spinal cord not encased in the bones and protected arrangements, it is exposed in the back, basically an open area)

• Increase iron

  • Needed for increased hemoglobin (two extra liters of blood are produced)

Why do pregnant women need iron?

Needed for increased hemoglobin (two extra liters of blood are produced)

What is linked with a deficiency of folic acid?

spina bifida

Folic acid facts:

• A vitamin B that our body uses to make new cells 

• Multivitamins are great sources of a folic acid

• Recommended that women take 400 micrograms of folic acid every day

• To meet daily reccommended amount of folic acid, women can eat a bowl of fortified breakfast cereal

What are things that cause birth defects that you are exposed to?

teratogens

What are some teratogens:

• High temps 

• Radiation

• Smoke 

• Alcohol

  • Fetal alcohol syndrome

  • Fetal alchol effect

• High mecury fish- avoided completely 

  • Shark, swordfish, goldensnapper= tilefish

• Medications

  • Tetracycline

  • Accutane 

• Some microbes

  • Listeria

  • Rubella

  • CMV

  • Toxoplasma

which trimester are teratogens most important to avoid?

The first trimester because all the baby’s major organs and strucutures are forming

 The effect is related to type of agent, dose and duration and time of exposure.

Aminocentesis:

• a prenatal test that can diagnose genetic disorders (like Down syndrome and spina bifida) and other health issues in a fetus. A provider uses a needle to remove a small amount of amniotic fluid from inside your uterus.

• Taking some of amniotic fluid to detect(with needle), later in pregancy for surfactant levels and then early they usually look for chromosome mistakes, like trisomy 21 down syndrome or other chromosome issues 

• Done 14-20 wks of pregnancy

Chrorionic villi sampling

After about 8 wks this is done normally vaginally, they suction off some fluid and ultrasound. This is done to look for genetic problems, so chromosome issues

Why might amniocentesis and chorionic villi sampling be done? 

• Detects chromosomal abnormalities like down syndrome (trisomy of a small chromosome)

• Detects surfactant levels if delivery is early

What is dizygotic twins?

• fraternal twins

•  two siblings who come from separate ova, or eggs, that are released at the same time from an ovary and are fertilized by separate sperm.

• They have their own placenta

What is monozygotic twins?

• Identical twins 

• one egg, one sperm, and then somewhere along development, the cells split. And so these are identical, lot of the time they share the same placenta 

• Sometimes they compete for nutrients 

Stages of labor:

1. Dilation of cervix, mucus plug is released

2. Expulsion of fetus (oxytocin)

3. Expulsion of placenta (withing 30 mins of fetus)

What is:

• The babys first bowel movement

• Normally quite stick

• Ideally happens after baby is born

• More likely to happen before baby is born if over the due date

meconium

Meconium aspiration:

• Meconium is the first interstitial dishchare of the newborn

  • Epitelial cells, fetal hair, mucus, bile

  • Intrauterine stress may cause in utero passage of meconium

  • Aspirated by fetus when fetal gasping or deep breathing occurs stimulated by hypoxia and hypercarbia

    • Warning sign of fetal distress

What is the vaginal discharge that lasts several weeks after childbirth. It consists of blood, mucus, uterine tissue and other materials from your uterus, think of very heavy period?

lochia

Different types of lochia:

• Lochia rubra: blood, fragments of deidua, and mucus; postpartal day: 1-3

• Lochia serosa: blood, mucus, and invading leukocytes; postpartal day: 3-10

• Lochia alba: largely mucus; leukocyte count high; postpartal day: 10-14(may last 6 wks)

Common problems during pregancy:

Heartburn: pushing on cardiac sphinchter 

Constipation: fetus pushing on rectum

Gestational diabetes:

• Like type 2 diabetes

• Develops during pregnancy

• Can usually be controlled by diet and exercise

• Increased risk for type 2 diabetes in mom and baby

• Baby has a high birth weight (>9lbs)

What is this? Pre-eclampsia 

• Known as toxemia 

• Cause is unknown, but only occurs in pregnant women

  • Could be related to placent failing to implant properly in the lining of the uterus; preveneting arteries from dilating as they should, restricting blood flow and leading to a host of other problems

• No known cure (other than having the baby)

• High risk for first pregnancies, multiple gestations, women under age 20, pre-existing hypertension, or diabetes

• Occurs after 20 weeks gestation

• Usually detected early with adequate prenatal care

What are four common symptoms of preeclampisa(toxemia)?

• Severe hypertension

• Severe headaches

• Protein (albumen) in urine

• Edema in face and body/ rapid weight gain

Pre-eclampsia can lead to eclampsia, what is eclampsia?

Uncontrolled convulsions and dangerous HTN

• Control of convulsions is most important aspect in the management of eclampsia, and MgSO4 is a very effective anticonvulsant

  • This drug works by inhibiting Ach releas, the neuromuscular junction, thereby reducing striated muscular contraction 

How does pre-eclampsia affect mom and baby?

• Can kill or harm the baby because of placenta recieving too little blood flow and oxygen

• Can cause low birth weight

• Ideally, you can induce labor if late enough in pregnancy

• Otherwise, bed rest and constant observation