Menstrual cycle

• Biologie
• Middelbare school
• vwo
• Leerjaar 1

Reproduction

The menstrual cycle

Learning goals 

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

What is menstruation?

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

How does it happen? 

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

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 to 35 days, on average it is 28 days (that is why we normally count in months)

28 days = 4 weeks

Menstrual cycle

4 Phases

• Phase 1 (day 1-5) : menstruation
• Uterus lining is shed through the vagina (no fertilized egg)
  
• FSH starts to go up

4 Phases

• Phase 2 (day 6-12): repair phase (follicular phase)
  
• FSH --> Ovary's start making estrogen 
• FSH --> new egg cell develops in the ovary
• Estrogen --> Endometrium (uterus lining) build new layer of mucus

4 Phases

• Phase 3: Ovulation (day 13-15)
• LH --> Ovulation --> A new ova (egg) is released and send down the oviduct
• LH --> corpus luteum
• Corpus luteum --> Makes progesterone
• A new ova (egg) is released and send down the oviduct

4 Phases

• Phase 4: Receptive phase (day 16 - 28) (luteal phase)
• Progesterone --> Keeps endometrium intact
• Progesterone --> Inhibits LH and FSH
• No fertilized egg cell? --> Corpus Luteum breaks down --> no progesterone --> cycle starts again!

What 'might' you experience during menstruation

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

Not every organ responds to every hormone. Only certain organs respond to specific hormones. These are called "target organs." Which organs are the target organs for LH and LSH in women?

Anniek has noted in her agenda when she last menstruated (see image 33). She menstruates very regularly, every four weeks. Anniek wants to get pregnant.
On which day are her chances the biggest for getting pregnant?

In the month of January, Anniek did not become pregnant. On which day of her menstrual cycle is the concentration of progesterone in her blood the highest? Choose from January 18, 25, or 31. Explain your answer.

In February, Anniek does become pregnant. Throughout the entire pregnancy, menstruation no longer occurs. Why is it important that menstruation does not take place during pregnancy?

In the period between ovulation and menstruation, women sometimes experience physical or mental symptoms, such as tender breasts, headaches, or mood swings. If these symptoms are severe, it is referred to as PMS (premenstrual syndrome). The symptoms are caused by increased sensitivity to a specific sex hormone.

For which hormone are women with PMS more sensitive? Explain your answer.