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Male System
The
structure and function of the human male reproductive system,
is very similar to that of many other mammals. The male
system is designed to make
sperm or male gametes and is adapted to provide for the
delivery of these
gametes to the female to allow for
fertilization.
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Male Reproductive
System |
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Male
Reproductive System Structures
1. testes -- produces
sperm and the hormone testosterone
2. scrotum -- pouch enclosing the testes
keeping the sperm at an optimum temperature for
development
3. vas deferens -- tube carrying sperm
away from the testes
4. prostate gland -- the largest of
several glands which add lubricating and other fluids to
the sperm
-- this combination of sperm and fluids is
called semen
5. urethra -- tube through the penis
carrying sperm to the outside of the body
6. penis -- adaptation for internal
fertilization of the female |
Female System
The
structure and function of the human female reproductive
system, is very similar to that of many other mammals. It
is designed to produce female gametes or eggs, allow for internal fertilization,
support the internal development of the embryo and fetus, and provide nutrition
through milk for the newborn.
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Female Reproductive System |
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Female Reproductive System
Structures
1. ovary -- (females have two of these) --
produce female gametes or eggs and the hormone estrogen
2. oviduct (fallopian tube) --
carries the egg away from the uterus
-- internal
fertilization normally occurs here
3. uterus -- implantation and development
of the embryo and fetus before birth occurs here
4. vagina or birth canal -- entry
point for sperm from the male and exit tube for the baby
when it is born |
Endocrine
Interactions
Human
reproduction and development are influenced by factors such as
gene
expression, hormones, and the environment. The reproductive
cycle in both males and females is regulated by several different
hormones. Some of these hormones include:
| testosterone
-- |
produced
by the testes in the male and stimulates the development of male secondary sex characteristics (like facial hair and
deeper voice). |
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estrogen -- |
produced by ovaries in the female and stimulates the
development of female secondary sex characteristics (wider hips and
mammary glands) as well as starting the thickening of the uterus lining in
preparation for a possible pregnancy after the egg is released by the female
each month. |
| progesterone
-- |
produced by yellow tissue called corpus luteum in
the empty ovarian follicle (place in ovary producing and releasing the
egg) -- this hormone maintains the thickness of the uterus lining in case
fertilization occurs and development of a fetus occurs. |
In human
females of reproductive age, these hormones interact in a
cyclic pattern called the menstrual cycle. This pattern of events
repeats itself on average every 28 days unless
a pregnancy or other disruption occurs. A graphic
representation and written description
of the stages of the human menstrual cycle is provided below.
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Human Menstrual Cycle |
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Note the influence of the hormone progesterone
in beginning the thickening of the uterus lining and the
role of the hormone estrogen in maintaining the
thickness of that lining. Ovulation or
release of the egg occurs at the midpoint of this cycle,
while the uterine lining thins and is shed (menstruation)
when the level of estrogen begins to decline to a large
extent. |
Menstrual Cycle Stages
1. follicle stage (10-14 days average duration)
- production of ova/eggs occurs in tiny cavities in the
ovary called follicles
- enlarging follicle produces estrogen which causes
the uterus to get ready for embryo implantation (uterus thickens
its lining)
2. ovulation (1 day)
- follicle enlarges and ruptures ovary wall
- egg is released to the oviduct (usually only 1 is released
at a time)
3. corpus luteum stage (10 -14 days average
duration)
- yellow tissue fills the follicle after ovulation called the corpus luteum
- "yellow body" secretes progesterone which maintains the thickness
of the uterus in case a pregnancy occurs
4. menstruation (3-5 days average duration)
- periodic shedding of the thickened lining of the uterus
which occurs if fertilization does not occur
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