Download Menstrual Cycle

The Menstrual Cycle
Biology 12
The Menstrual Cycle
 controlled by internal feedback mechanisms
between the reproductive system and the
endocrine system
 the cycle takes an average of 28 days
The Menstrual Cycle
 during the cycle:
 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
The Menstrual Cycle
 four phases:




follicular phase
ovulation
luteal phase
menstruation
The Menstrual Cycle
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
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
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
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
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
The Menstrual Cycle
The Menstrual Cycle
 The Menstrual Cycle Animation
 The Menstrual Cycle Graph