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Differences between men _ women

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					Differences between men &
          women
      By Gina Mahfoud
                     Introduction
The topic I chose concentrates on all kinds of differences between
the sexes: chromosomal differences, hormonal differences,
physical differences & capabilities, and even differences in the
brain.
I chose this topic because I was curious about why men can do
certain things women can’t do & vice versa. This is a topic that has
been researched for over a century by all kinds of scientists,
mainly men. Some of the research was based on phrenology,
which was proven to be a wrong approach in studying the brain. A
lot of the scientists, for example Darwin, believed that women had
no capabilities other than reproduction & tried to modify their
discoveries to fit their theories.
This subject is an on going research. We certainly don’t know all
the differences between men & women yet, and since it is quite a
controversial topic, scientists have to be very careful & certain
about the discoveries they make before passing them on.
     Chromosomal differences
• By grade 12, almost
  everyone knows that
  the smallest yet
  hugest difference
  between men &
  women starts in the
  formation of a fetus.
  The sex
  chromosomes X X &
  X Y, determine your
  gender.
Obvious physical differences
          Physiological differences
• Size:  The average 18year old male is 70.2 inches tall & weighs 144.8 pounds,
   whereas the average female of the same age is 64.4 inches & weighs 126.6
   pounds.
• Muscles: Males have 50% greater total muscle mass, based on weight than
   do females. A female who is the same size as a male is generally only 80% as
   strong. therefore men usually have an advantage in strength, speed, & power
   over females. But women have fewer slow twitch muscle fibers (the muscle
   cells that work best for endurance activities). However, the fact that women
   have a higher percentage of body fat than men means we can supply fuel to
   our muscles longer than men. Research at Northwester University indicated
   that in an analysis of world-record times in events on land, in water, or on ice,
   the longer the event the better the women perform. In running, swimming and
   speed skating, the differences in times and distance turned in by men vs.
   women diminished the longer the event lasted.
• Fat:    Females carry about 10% more body fat than do males of the same age.
   Men accumulate fat primarily in the back, chest, & abdomen. Females gain fat
   in the buttocks, arms & thighs. It is believed that women have this extra weight
   because of our role as “child bearers” throughout evolution.
  More physiological differences
• Bones: Females have less bone mass than males, but their
  pelvic structure is wider & their center of gravity lower, which
  also gives men an advantage in their running capabilities.
• Heart size & rate: The average female’s heart is 25%
  smaller than a male. A male’s heart can pump more red blood
  cells with each beat (more oxygen). The larger heart size
  contributes to the slower resting heart rate ( five to eight beats
  slower) in males. These figures are the same while the body is
  at rest or exercising vigorously, which means that men have
  better endurance than women.
• Flexibility: women are generally more flexible than men,
  which may explain why there are more female gymnasts. This
  may be a factor of evolution as well.
            Even more physiological
                 differences…
• Lungs: The lung capacity in males is 25% to 30% greater than that of
    females. This gives men still another advantage in the processing of
    oxygen & in doing aerobic work such as running.
•   Response to heat: Females tend to sweat less, lose less heat
    through evaporation, and reach higher body temperatures before
    sweating begins. Nevertheless, women can adapt to heat stress just
    as well as men.
•   Response to pain: Women may complain about a physical pain
    before men, but research indicates they are better able to cope with
    the emotional aspects of dealing with pain. For example, after a day of
    arthritic pain, female subjects reported less negative moods than male
    arthritic subjects. Women also do a better job of employing strategies
    to deal with pain, such as relaxation, meditation or distractions
    (preparing for childbirth, for example) than do men. Also, because of
    their menstrual cycles & the sight of blood, women are more aware of
    death.
       Hormonal differences
• General habitus and shape of body and
  face, as well as sex hormone levels, are
  similar in young boys and girls. Most of the
  biological differences between men and
  women can be accounted for by the
  differing effects of sex hormones (estrogen
  for women and testosterone for men) upon
  the body. As puberty progresses & sex
  hormone levels rise, obvious differences
  appear.
                  In women:
Estrogen diminishes growth by interfering with growth
promoting effects of growth hormone upon the cartilage
growth plates (epiphyseal plates) found near the ends of
the long bones of the body. Estrogen also causes a
smoother and thinner skin, and causes accumulations of
fat in the breasts, hips, thighs & buttocks that partly
account for the differences in appearance between men
and women. Estrogen also induces growth of the uterus,
proliferation of the endometrium, and menses. In actual
fact, the reasons why estrogen has these effects only in
certain regions of the body and not in every area are still
unknown.
                 In men:
• testosterone directly increases size and
  mass of muscles, vocal cords, and bones,
  enhancing strength, deepening the voice,
  and changing the shape of the face and
  skeleton. Converted into DHT in the skin, it
  accelerates growth of androgen-
  responsive facial and body hair. Taller
  stature is largely a result of later puberty
  and slower epiphyseal fusion.
         Some other effects:
• Both types of sex hormones also bind to
  receptors in selected regions of the brain
  and can influence sexual behavior,
  appetite for food, the regulation of body
  temperature, and sleep and breathing
  (testosterone is probably responsible for
  the fact that more men develop
  abnormalities in breathing during sleep
  than women.
    Differences in brain formation
•   Scientists, recently discovered that there is a brain region in the
    cortex, called inferior-parietal lobule (IPL) which is significantly larger
    in men than in women. This area is bilateral and is located just above
    the level of the ears (parietal cortex).
• the left side IPL is larger in men than the right side. In women, this
asymmetry is reversed, This is the same area which was shown to
be larger in the brain of Albert Einstein, as well as in other
physicists and mathematicians. So, it seems that IPL's size
correlates highly with mental mathematical abilities.
• After allowing for the natural differences in overall brain volume
which exist between the brains of men and women, there was still a
difference of 5% between the IPL volumes (human male brains are,
on average, approximately 10 % larger than female, but this is
because of men's larger body size: more muscle cells imply more
neurons to control them).
           More about the brain…
•   A study has shown that two areas in the frontal and temporal lobes
    related to language were significantly larger in women, thus providing
    a biological reason for women's excellent skills in language-
    associated thoughts.
• Using magnetic resonance imaging, scientists measured gray
  matter volumes in several cortical regions in women & men.
  The volume of the Wernicke's area was 18% larger in females
  compared with males, and the cortical volume the Broca's area
  in females was 20% larger than in males.
    • On the other hand, evidence shows that the corpus callosum, a large
    tract of neural fibers which connect both brain hemispheres, is enlarged in
    women, compared to men.
    • researchers discovered that the brain of women processes verbal
    language simultaneously in both hemispheres of the frontal brain, while
    men tend to process it in the left side only.
                  Bibliography
• www.sciencedaily.com
• www.crisiscounseling.com/Relationships/Difference
  sMenWomen.htm
• www.overspeedtraining.com/women_1.htm
• www.gfmer.ch/Books/Reproductive_health/
  Human_sexual_differentiation.html
• http://www.amsreview.org/articles/putrevu10-2001.pdf
• www.keepmedia.com/pubs/uExpress/2000/02/06/554886?extID=
  10032&oliID=213

				
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