Menstrual cycle

• Biologie
• Middelbare school
• vwo
• Leerjaar 1

Reproduction

CH4.4: The menstrual cycle

Learning goals bs. 4

1. You can explain what is happening during the 3 phases of the menstrual cycle

What is menstruation?

• Release of blood from the uterus through the vagina
• Start around age 12

How does it happen? 

• Hormones estrogen en progesterone build up uterus lining
  
  
• Fertilized egg could attach to this
  
  
• No fertilized egg? --> Lining is shed
  
  
• cycle: it happens over and over again (450 times in a lifetime)

Menstrual cycle

• The menstrual cycle is the process that the female sex organs go through each month again; preparing an egg for fertilization, and getting rid of it when it is not fertilized.

• This whole process is regulated by hormones

• This cycle generally lasts somewhere between 21 and 35 days, on average it is 28 days (that is why we normally count in months)

28 days = 4 weeks

3 Phases

• Phase 1 (day 1-5) : menstrual flow
• Uterus lining is shed through the vagina (no fertilized egg)
  
  
• Phase 2 (day 6-12): pre-ovulation
• uterus lining build new layer of mucus
• new egg cell develops in the ovary

3 Phases

• Ovulation (day 14)
• A new egg cell is released and send down the oviduct
  
  
• Phase 3: Post-ovulation (day 16 - 28)
• Uterus lining grows to form a 'nest' for the egg cell
• No fertilized egg cell? --> cycle starts again!

Menstrual cycle

Exercises

Make exercise: 15, 16, 18 and 19.

Done? Read 4.5 Human Fertilisation (pg.98).

Menstruation

When an egg is not fertilised, part of the uterus lining detaches. This is menstruation.

Average age for girls to start their menstruation is 13.

The first day of menstruation is day 1 of the menstrual cycle

Learning goals bs. 4

1. You can explain what is happening during the 4 phases of the menstrual cycle

What determines the beginning of the menstruation cycle?

1. Release of blood through the vagina
2. The release of the egg cell from the ovaries
3. The growing of the uterus lining
4. The cycle can start anytime

In which part of the female reproductive system do the ova (egg cells) develop?

1. Fallopian tube/Oviduct
2. Ovaries
3. Uterus
4. Vagina

In which part of the female reproductive system does the fertilised egg cell grow into a baby?

1. Fallopian tube/Oviduct
2. Ovaries
3. Uterus
4. Vagina

On which day in the cycle does ovulation occur?

1. Day 1
2. Day 14
3. Day 20
4. Day 28

What is shed during the menstruation of a female?

1. The ovaries
2. The egg cell
3. The uterus lining
4. Nothing

How long does an released egg cell survive?

1. 15 days
2. 4 days
3. about an hour
4. 1-2 days

The cycle is for everyone the same. It is always 28 days.

1. True
2. False

How do we call the release of an egg cell into the oviduct?

1. Fertilization
2. Ovulation
3. Pregnancy
4. Contraceptive

Anne her period starts at the 10th of May. When is it most likely her ovulation occurs?

1. May 14th
2. June 14th
3. May 24th
4. June 24th

Explain why they talk about 38 weeks pregnancy instead of 36 (9 months) counting from your last menstruation