Download Human Reproductive System

The Human Reproductive
System
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The gonads-testes and ovaries-are
endocrine glands that secrete sex
hormones. However, the primary
function of the gonads is not to produce
hormones but to produce and store
gametes-sperm and eggs.
Objectives:
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1. Identify the major structures of the
male and female reproductive system.
2. Describe the function of each
structure of the male and female
reproductive system.
Reproductive System
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The Reproductive System, unlike other
systems we have studied, IS NOT ESSENTIAL
to the survival of an INDIVIDUAL.
What the Reproductive System is important
to is the Survival of the
SPECIES. Reproduction is absolutely
essential to the continuation of the
SPECIES…SOME OF US MUST REPRODUCE!
Review
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The ways in which the Gametes are
released make possible the fusion of
Sperm (Male Gametes) and Egg
(Female Gametes) in the process of
FERTILIZATION. From a Fertilized
Egg, or ZYGOTE, come all the cells in a
human body.
SEXUAL DEVELOPMENT
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For the First SIX Weeks after
fertilization, human male and female
Embryos are Identical in appearance.
During the SEVENTH Week of
development, major changes occur:
7th week changes:
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A. The TESTES, which are the PRIMARY Reproductive Organs
of a MALE, begin to produce Steroid Hormones (Sex) known as
ANDROGENS. The tissue of the Embryo responds to these
hormones by developing into the MALE REPRODUCTIVE
ORGANS.
B. The OVARIES, or the PRIMARY Reproductive Organs of
a FEMALE Embryo, produce Steroid Hormones (Sex) known as
ESTROGENS. The tissue of the Embryo responds to these
hormones by developing into the FEMALE REPRODUCTIVE
ORGANS.
. Neither Testes or Ovaries are capable of producing Active
Reproductive Cells (GAMETES) until PUBERTY.
Male Reproductive System
THE MALE REPRODUCTIVE
SYSTEM
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1. Males begin to produce Sperm during Puberty, the
adolescent stage of development when changes in
the body make reproduction possible.
2. At this time, the concentration of the hormone
Testosterone is high enough to stimulate sperm
production. Testosterone is the Main Androgen (Male
Sex Hormone) produced by the Testes.
3. The TESTES develop within the Abdominal
Cavity, just before birth the Testes descend through
a canal into an EXTERNAL SAC called the
SCROTUM.
Male Reproductive System
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4. The Testes (two egg-shaped
structures) remain in the Scrotum,
outside the body, where the
temperature is about 3 degrees C
Cooler than the body internal
temperature (27 degrees C).
5. Sperm development in the Testes
Requires the Lower Temperature.
Male Reproductive System
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6. The Testes are clusters of hundreds of Tiny Tubules called
SEMINIFEROUS (sehm-uh-NIHF-er-uhs) TUBULES, which
means "SEED BEARING". Sperm Form through Meiosis in the
specialized lining of this extensive network of tubules.
7. As the Pituitary Gland begins to release FSH and LH, these
Hormones stimulate the Testes to make the PRINCIPAL MALE
SEX HORMONE TESTOSTERONE.
8. Cells that respond to Testosterone are found all over the
body.
9. Testosterone produces a number of SECONDARY SEX
CHARACTERISTICS that appear in Males at Puberty – Voice
Deepens, Beard Grows, and Body Hair.
Male Reproductive System
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10. FSH and Testosterone stimulate the
development of Sperm. When large
numbers of sperm have been produced
in the Testes, the development process
of Puberty is completed - THE
REPRODUCTIVE SYSTEM IS NOW
FUNCTIONAL.
Sperm Development
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1. Sperm are derived from Special Cells within the Testes that
go through the process of MEIOSIS to form HAPLOID NUCLEI
found in Mature Sperm. The Chromosome number drops from
46 to 23, Four sperm cells result from each cell that begins
meiosis.
2. A Mature Sperm consists of THREE Regions:
A. HEAD - which contains the Nucleus (The 23
Chromosomes) and enzymes that help the sperm penetrate the
protective layers that surround and Egg Cell.
B. MID PIECE - packed with energy releasing Mitochondria
(Energy Source). The Mitochondria supply the energy that is
required for sperm to reach an Egg.
C. TAIL – Consists of a Single, Powerful FLAGELLUM that
propels the Sperm.
Male Reproductive System
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4. Although most Sperm remain stored in each
Epididymis, some leave the Epididymis and pass into
through the VAS DEFERENS, a duct that extends
from the Epididymis.
5. Each Vas Deferens enters the Abdominal Cavity,
where it loops around the Urinary Bladder and
merges with the Urethra. In a Male, both Urine and
Sperm exit the body through the Urethra.
6. In the Urethra, Sperm Mix with Fluids that are
secreted by Three Exocrine Glands- the Seminal
Vesicles, Bulbourethral Glands, and the Prostate
Gland- to produce SEMINAL FLUID -which Protects
and Nourishes the Sperm.
Male Reproductive System
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THE COMBINATION OF SPERM AND SEMINAL
FLUID IS KNOWN AS SEMEN
BETWEEN 100 AND 200 MILLION SPERM ARE
PRESENT IN 1 milliliter OF SEMEN OR ABOUT
5 MILLION SPERM PER DROP!
The Penis is the Male Reproductive Organ
that makes it possible for Sperm to be
delivered to the body of the Female.
Male Reproductive System
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300 - 400 million Sperm are released in the
Reproductive Tract of a Female during a
single Ejaculation; the chances of a Single
Sperm Fertilizing and Ovum (Egg OR Female
Gamete), if one is available, are quit GOOD
Most sperm are Killed by the Acidic
Environment of the Female Reproductive
Track. Only a few Sperm reach the site of
Fertilization.
Female Reproductive System
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The Ovaries are located in the Lower
Abdominal Cavity; the Ovaries USUALLY
produce only ONE EGG or OVUM per month.
In addition to producing eggs, the female
reproductive system has another important
job to perform - EACH TIME AN EGG IS
RELEASED, THE BODY MUST BE PREPARED
TO NOURISH A DEVELOPING EMBRYO.
Female Reproductive System
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Puberty in females starts with changes in the
Hypothalamus that causes the release of FSH and LH
from the Pituitary Gland.
FSH (follicle stimulating hormone) stimulates cells
within the Ovaries to produce the Hormone
ESTROGEN.
Estrogen causes the reproductive system to complete
its development, and also produce SECONDARY SEX
CHARACTERISTICS - Enlargement of Breast and
Reproductive Organs, Widening of the Hips, and
growth of Body Hair.
Female Reproductive System
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Each Ovary contains about 400,000
PRIMARY FOLLICLES, which are clusters of
cells surrounding a single ovum (egg).
2. During her lifetime fewer than 500 Ova
(Eggs) will actually be released, averaging
one egg about every 28 days.
When a Follicle has completely matured, the
Ovum (Egg) is released. THIS PROCESS IS
CALLED OVULATION
Female Reproductive System
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If TWO Eggs mature, Fraternal, or Non
Identical Twins may result.
Ovulation begins at Puberty and USUALLY
continues until a female is in her late forties,
when MENOPAUSE occurs.
During Ovulation the Follicle literally ruptures,
and the Ovum is swept from the Ovary into
one of the TWO FALLOPIAN TUBES. The
Fallopian Tubes provide a way for an egg to
travel from the Ovary to the Uterus.
Female Reproductive System
Female Reproductive System
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IT IS DURING ITS JOURNEY THROUGH THE
FALLOPIAN TUBE THAT AN EGG CAN BE
FERTILIZED. An Egg must be fertilized within
48 hours of its release - after that, the egg
begins to break down. Unfertilized eggs
dissolve in the Uterus.
After a FEW DAYS, the Ovum passes from the
Fallopian Tube into the UTERUS
Female Reproductive System
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Leading from the Uterus (CERVIX) to
the outside of the body is a muscular
tube called the VAGINA or Birth Canal.
Menstrual Cycle
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THE MENSTRUAL CYCLE IS THE SERIES OF
CHANGES THAT OCCUR IN THE UTERUS
EACH MONTH.
The Menstrual Cycle has FOUR Stages: THE
FOLLICULAR PHASE, OVULATION, THE
LUTEAL PHASE AND MENSTRUATION
These Stages are Regulated by the Hormones
of the Endocrine System
Menstrual Cycle
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During the 1st Stage-THE FOLLICULAR
PHASE, the Egg Matures, and the Lining of
the Uterus GROWS THICKER, many tiny
Blood Vessels grow into the thickened lining,
in preparation for receiving a Fertilized Egg.
The development of an Egg in this stage of
the Cycle takes about 14 DAYS
Menstrual Cycle
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The 2nd Stage, OVULATION, the
shortest phase in the Cycle (3-4 DAYS),
is the release of an egg from a ruptured
follicle. Following Ovulation, an egg is
swept into a fallopian tube, where it
travels toward the uterus awaiting
fertilization. The Egg has enough
stored nutrients to survive about 48
hours.
Menstrual Cycle
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The 3rd Stage, LUTEAL PHASE, lasts
about 14 Days, the Cells of the
Ruptured Follicle grow larger and fill the
cavity, forming a New Structure called a
CORPUS LUTEUM. The Corpus Luteum
begins to secrete large amounts of
PROGESTERONE and ESTROGEN. The
Increase levels cause the Pituitary
Gland to stop Secreting LH and FSH.
Menstrual Cycle
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Progesterone causes the lining of the Uterus to
become even thicker
The Lining is prepared to receive the Embryo four or
five days after the Egg is released from the Ovary.
An Embryo that settles into the lining of the uterus,
the Corpus Luteum continues to release Hormones
that causes the Uterus to maintain its thickened
lining.
Most of the time, no embryo arrives, and the Corpus
Luteum begins to produce Less and Less Estrogen
and Progesterone
Menstrual Cycle
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The Decrease in Levels of Estrogen and
Progesterone causes the Blood Vessels in the
uterine lining to begin closing and then Break.
The Cells of the Uterine lining DO NOT
receive adequate blood supply and come
loose from the inside of the uterus
The mixture of Blood and the Cells that made
up the lining of the uterus is called
MENSTRUAL FLUID.
Menstrual Cycle
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The passage of this Fluid through the Vagina
and out of the body is called
MENSTRUATION OR THE MENSTRUAL
PERIOD THE LAST STAGE. IT USUALLY
LASTS FROM THREE TO SEVEN DAYS. At the
end of the Period, a NEW Cycle Begins- THE
FOLLICULAR PHASE.
The AVERAGE Menstrual Cycle is 28 DAYS
LONG.
Menstrual Period
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Almost ALL Women START their
Menstrual Period 14 DAYS AFTER
Ovulation occurs.
The length of the First stage of the
cycle, the period when the Follicle is
growing, DIFFERS from women to
women.