Fertilisation and pregnancy

• Biologie
• Middelbare school
• vwo
• Leerjaar 4

Reproduction

Fertilisation & pregnancy

Learning objectives

• Describe the hormonal changes that occur after fertilisation happens
• Describe the hormones involved in pregnancy
• Describe the important stages during pregnancy 

During which days of a typical 28 day menstrual cycle does the follicular phase occur?

1. 0-5
2. 1-13
3. 14-17
4. 14-28

If the ovum is to be fertilised, where is the most common site of fertilisation?

1. Fallopian tube
2. Uterus
3. Vagina
4. Ovary

___________ is released from the pituitary gland and stimulates the follicles in the ovary to mature.

1. LH
2. FSH
3. Oestrogen
4. Progesterone

If the ovum is not fertilised, what causes the cycle to end and menstruation to start?

1. Peak in progesterone
2. Peak in oestrogen
3. Lack of oestrogen
4. Lack of progesterone

Fertilisation

• Sperm cells carry enzymes
  
  
• Egg cell puts up permanent block
  
  
• Egg cell completes meiosis 2
  

First period of pregnancy

• Completion meiosis
• Cleavage divisions
  - No growth
• Blastocyst
  - First structures
• Implantation

Placenta development

• Formed by embryo and mother together
• Exchange of nutrients and waste
• No direct blood contact!

Birth

• First stage

    - Cervix expands

    - Amniotic fluid released

• Second stage: delivery

    - Actual birth

• Third stage

    - Expulsion of the placenta

Lactation

• Nourishment after birth
• Hormones

    - Prolactin: promotes milk production
    - Oxytocin: stimulates release milk

• Drinking baby promotes release of prolactin and oxytocin, but inhibits release LH and FSH

    - Lactational anovulation

• Colostrum: first milk contains many antibodies

Which of these hormones does not increase during pregnancy?

1. Progesterone
2. Oestrogen
3. HCG
4. FSH

Which of these hormones stimulates lactation?

1. Oxytocin
2. FSH
3. HCG
4. Testosterone

Which of the following statements best describes the placenta?

1. it is a structure that remains in the ovary after the egg has been discharged, it produces human chorionic gonadotropin
2. it is an organ formed in the uterus during pregnancy, it produces hormones that help a pregnancy go smoothly and connects the mother and fetus
3. it is the organ that holds eggs waiting to be fertilised, in the later stages of pregnancy it becomes inactive
4. as the placenta is being formed, it produces the first detectable hormone of a pregnancy; this hormone is detected by blood or urine pregnancy tests

Mary thinks she might be pregnant and purchases a pregnancy test. The pregnancy test shows a positive result. Why did the test come back positive?

1. The test detected higher than normal levels of progesterone
2. The test detected lower than normal levels of oestrogen
3. The test detected the presence of HCG, Human Chorionic Gonadotropin
4. The test detected the presence of HPL, Human Placental Lactogen

Homework

• Complete and hand in the worksheet fertilisation&pregnancy on the Classroom