1. The Menstrual Cycle
Biology 12

2. The Menstrual Cycle
controlled by internal feedback mechanisms between the reproductive system and the endocrine system
the cycle takes an average of 28 days

3. The Menstrual Cycle during the cycle: if fertilized:
an egg develops and is released from an ovary
the uterus prepares to receive a fertilized egg
if fertilized:
the egg implants and uterus and embryonic development begins
if not fertilized:
the egg is discharged

4. The Menstrual Cycle four phases: follicular phase ovulation
luteal phase
menstruation

5. The Menstrual Cycle

6. Follicular Phase begins when estrogen levels are low
pituitary secretes FSH and LH
follicle develops to maturity
follicular cells produce more estrogen
uterine lining (endometrium) thickens

8. Ovulation midway through cycle lasts 3 to 5 days
pituitary produces more FSH and LH
follicle ruptures
mature egg is released into one of the fallopian tubes

9. Luteal Phase begins when egg is released
egg moves down the fallopian tube
follicle turns yellow and is called the corpus luteum
continues to release estrogen
also releases progesterone

10. Luteal Phase
progesterone stimulates growth and development of the blood supply to surrounding tissues
within a few days of implantation, the uterus and growing embryo release hormones that keep the corpus luteum functioning for several weeks
endometrium will nourish and protect the embryo

11. Menstruation if no fertilization, the corpus luteum disintegrates
less hormones, so the endometrium detaches
tissues, blood, and the unfertilized egg are discharged through the vagina
lasts 3 to 7 days

13. The Menstrual Cycle

15. The Menstrual Cycle The Menstrual Cycle Animation
The Menstrual Cycle Graph