menstruation i. estrus v. menstruation ii. menstruation a. evolution of menstruation b. menstrual...
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Menstruation
I. Estrus v. Menstruation
II. MenstruationA. Evolution of menstruation
B. Menstrual cycle overview
C. Physiology of menstruation
D. Menstrual symptoms
E. Menstruation and the environment
I. Estrus v. Menstruation Estrus = “frenzy”
Species with estrus cycles, females are generally only sexually active
Females of species with menstrual cycles
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
B. Hormonal control & variation in cycles:
Time line specific for canines
Hamster 1 4
Sheep 2 17
Horse 5 21
Dog 7 60
Lion 9 55
Species Estrus Cycle
AVERAGE LENGTHS (days) OF ESTRUS AND ESTROUS CYCLES
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.
II. Menstruation Myths http://news.bbc.co.uk/2/hi/south_asia/4250506.stm http://www.mum.org/
A. Evolution of menstruation
Inflammatory response?
Only humans & great apes exhibit menstrual cycles, in contrast to the estrus cycle of most mammalian species.
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
C. Physiology of menstruationRemarkable 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:
Days 15-28
Endometrium
Rising levels of progesterone from corpus luteum act on endometrium causing changes