BS6 - Pregnancy

• Biologie
• Middelbare school
• vwo
• Leerjaar 2

Unit 4 - BS6 - Pregnancy

Today's lesson

1. Learn Basics 6: pregnancy
2. Describe the fertilization of the human egg
3. Decribe how pregnancy progresses
4. Explain prenatal testing and give examples

what is fertilisation?

1. ovulation & ejaculation
2. egg cell waits 12-24h in oviduct; sperm cells swim to oviduct
3. sperm cell opens cell membrane of egg cell; cell membrane becomes impenetrable for the other sperm cells;
4. head  of sperm cell enters egg cell
5. fertilisation = nucleus of sperm cell fuses with nucleus egg cell. 

implantation 

1

Sperm enters the female body 

♂

2

Sperm swims through the uterus, towards the fallopian tubes.

♂

3

1 sperm cell can fertillize the ovum, the others die

without an ovum the sperm will die

♂

1

an ovum (egg cell) is released from the ovary = ovulation

♀

2

Ovum is fertilized by sperm cells and starts cell division.

OR

Ovum is not fertilized and dies in fallopian tube

♀

3

the fertiziled ovum starts cell division

♀

4

Implantation of the fertilized ovum, pregnancy has begun.

♀

fallopian tube

fertilization

ovulation

ovary

implantation

thick mucous lining

uterine wall

cervix

opening of uterus

Pregnancy

• embryo
• foetus
• placenta 

• umbilical cord 

Ultrasound scan and prenatal testing 

Ultrasound

Combined test

• 9th-14th week of pregnancy
• Blood test of mother and foetus
• ultrasound of neck fold measurement of foetus
• together these 2 tests determine whether a child has Down's syndrome

Nipt

• 11th week of pregnancy 
• non-invasive prenatal test
  
• Blood sample from the placenta
  
• DNA from placenta is nearly the same as the baby's
• shows likely hood of hereditary disease

Anomaly and non-medical scan

• after 20th week of pregnancy 
• Anomaly: check for abnormalities of the heart, brain, organs, and limbs
• Non-medical: 3D

• 10 weeks pregnant
• Sound waves used to make a picture of foetus in the womb
• used to see when the woman became pregnant and when the baby will be born.

amniocentesis = vruchtwater punctie

chorionic villus sampling = vlokkentest

What did we learn?

1.Describe the fertilization of the human egg

2.Decribe how pregnancy progresses

3. Explain prenatal testing and give examples

Do Now:

Read BS 6 - pregnancy

Do Qs. 1 t/m 3 and 5 t/m 8

BS8 Childbirth

• Birth of the baby
• Birth of the placenta (this includes the membranes     that held the baby, placenta and the water during the pregnancy).

Actual picture coming up on the next slide, be prepared ;)

Membranes = vliezen. We also call this the amniotic sac. This surrounds the foetus and placenta inside of the uterus. Think of it like a big balloon keeping all the water in.

Childbirth

• Birth of the baby
• Birth of the placenta (this includes the membranes     that held the baby, placenta and the water during the pregnancy).

Membranes = vliezen, these surround the foetus and placenta inside of the uterus. Think of them like a big balloon.

Childbirth

4-stage of childbirth:

contractions: amniotic fluid leaks 

out

dilation: cervix become wider

expulsion: rapid contraction push

baby out

afterbirth: placenta chorion and amnion leave

Expulsion = uitdrijving

Stage 1+2: contraction & dilation

• This can take a long time (sometimes more than 24 hours!)
• The contractions (which are just muscle cramps of the uterus) slowly start, and increase in strenght slowly. Later on they will also increase in frequency, happening more often.
• The cervix and vagina will widen, slowly making space for the baby 

In Dutch, we call this process 'ontsluiting'

Stage 3: expulsion

• When the dilation phase has widened the cervix far enough, the contractions will get very powerful and rapid.
• This is a sign for the mother to start pushing, and the baby will come out quickly.
• This stage does not take very long, as soon as the head comes out the rest follows fast.

Stage 4: afterbirth

• A little while (minutes) after the expulsion phase, the placenta will be 'born'. We call this the afterbirth.
• Again, contractions come with this. These are not as bad as the contractions of the baby's birth, of course.

And then..?

• When the baby is born, the umbilical cord is cut. This is because now the baby can breathe and eat/drink, so it doesn't need the nutrients via the placenta anymore.
• The end of the umbilical cord will slowly deteriorate and fall off eventually. This then forms the belly button as we know it.
• Fun fact: the differences in belly buttons that we have depend on the person who folds it after birth!

And then..?

• The uterus wil quickly shrink back to its normal size (no bigger than a hand)
• However, the belly muscles and skin will take some more time.
• Due to this, the mother often looks a bit pregnant for a few more weeks.

Difficult births

• Normally, the baby is positioned with its head first.
• However, sometimes the baby is on the wrong side (butt first, feet first, or even completely turned to the side).

Frank Breech = onvolledige stuit

Trunk = dwars

Difficult births

• Normally, the baby is positioned with its head first.
• However, sometimes the baby is on the wrong side (butt first, feet first, or even completely turned to the side).
• Another problem that can occur is that the umbilical cord is wrapped around the baby's throat, legs or arms
• This could cut off oxygen supply, which is dangerous.

How to solve that?

• A caesarian section is the way to solve that (keizersnede)
• This involves an operation where the surgeon opens up the uterus and takes the baby out.

What have we learned?

1. What pregnancy is and how a foetus develops in the uterus.
2. How the placenta belongs to the mother and the umbilical cord belongs to the baby.
3. The different phases of childbirth (contractions, dilation, delivery)
4. What is born along with the baby - umbilical cord, amniotic sac and placenta

To do now: 

Read BS 6 - pregnancy

Do Qs. 1 t/m 3 and 5 t/m 8

Read BS 8 - The Birth

Do Qs: 1, 3, 4, 5