Menstruation

1
Menstruation

• Estrus v. Menstruation
• Menstruation
• Evolution of menstruation
• Menstrual cycle overview
• Physiology of menstruation
• Menstrual symptoms
• Menstruation and the environment

2
I. Estrus v. Menstruation

• Estrus frenzy
• Species with estrus cycles, females are generally
  only sexually active
• Females of species with menstrual cycles

3
A. Phases of Estrus

• Proestrus
• one or several follicles of the ovary are
  starting to grow,
• Estrus
• ovarian follicles are maturing and estrogen
  secretions exert their maximal influence. The
  animal exhibits a sexually receptive behavior, a
  situation that may be signaled by visible
  physiologic changes.
• Metestrus
• Estrogen declines, and the corpus luteum starts
  to form
• Diestrus

4
(No Transcript)
5
B. Hormonal control variation in cycles
Time line specific for canines
Species Estrus Cycle
AVERAGE LENGTHS (days) OF ESTRUS AND ESTROUS
CYCLES
6
The  female on the left is  in estrus  note the
swelling around the top of the vagina and the
presence of a small opening as well as the bright
red color.    
7
II. Menstruation

• Myths http//news.bbc.co.uk/2/hi/south_asia/425050
  6.stm
• http//www.mum.org/

8
A. Evolution of menstruation

• Inflammatory response?
• Only humans great apes exhibit menstrual
  cycles, in contrast to the estrus cycle of most
  mammalian species.

9
B. Menstrual cycle overview

• Series of cyclic changes that the uterine
  endometrium undergoes each month in response to
  changing levels of hormones in the blood

10
(No Transcript)
11
C. Physiology of menstruation

• Remarkable events
• Dependant upon interrelationships between the
  brain, pituitary gland, ovaries uterus
• Preparation of egg for fertilization, preparation
  of uterus for pregnancy, evaluation of pregnancy
  status, reabsorption and excretion, begin again
• Phases

12
(No Transcript)
13
(No Transcript)
14

• Days 1-5
• Ovarian hormones at lowest point,
• Prostaglandin level is high in menstrual
• By day 5,

15

• Days 6-14,
• Follicular phase

16
(No Transcript)
17

• Day 14 Ovulation

18

• Days 15-28
• Endometrium
• Rising levels of progesterone from corpus luteum
  act on endometrium causing changes

19
(No Transcript)
20
(No Transcript)
21

• IF fertilization occurs
• Shortly after implantation,

22
(No Transcript)
23

• No fertilization
• Days 24-28, Premenstrual phase
• Degeneration of endometrium

24
(No Transcript)
25
(No Transcript)
26
D. Menstrual symptoms
27
E. Menstruation and the environment

• Amenorrhea
• Oligomenorrhea
• Effect of exercise
• 28 competitive females experience athletic
  amenorrhea or oligomenorrhea
• Diet
• Stress
• Menstrual synchrony