Transcript Sexual Reproduction Power Point Notes

Vocabulary
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Zygote
Implantation
Gastrulation
Fetus
Menstrual cycle
Fallopian tube
Scrotum
Corpus luteum
Vas deferens
Urethra
Sexual Reproduction
Meiosis in Males: Spermatogenesis
•Occurs in the testes
•Sperm are haploid (n) In humans they contain 23
chromosomes.
•Sperm begin to be released during puberty when
hormones released by the pituitary regulate the
functioning of the testes.
Head with
very little
cytoplasm
Enzymes at tip
allow it to
penetrate the egg
Tail: (flagellum)
to propel sperm
through the female
reproductive tract.
Midpiece: contains
mitochondria that
supply energy
Male Reproductive Anatomy
Testes: Located in the
scrotum- and external sac of
skin.
Scrotum are located outside
the body to maintain optimum
temperature for sperm
production.
Each testes contains highly
coiled tubules called
seminiferous tubules.
Immature sperm enter a long
coiled tube called the
epidydmis. Here they
become motile.
Mature sperm enter the
Vasdeferens to exit from
the body using the same
urethra which is connected
to the bladder.
Vasectomy: Cutting of the
vasdeferens to prevent
fertilization.
3 sets of glands contribute
to the semen.
1. Seminal vessicles:
contribute 60% to total
volume of semen. Contains
large amount of fructose
which provides energy for
the sperm.
2. Prostate Gland: largest –
secretes directly into the
urethra through several
small ducts.
Fluid is thin and basic
which helps neutralize the
acids in the urethra and
vagina.
In men over 40- it is
common to have an
enlargement of this gland
which could lead to cancer.
Hormones and male reproductive development.
Androgens: Testosterone
•Cause development of the genitalia and development of the
vas deferens
•Initiate sperm production
•Deepening of the voice
•Distribution of facial and pubic hair
•Increased muscle growth and generally increased levels of
aggressiveness.
How are sperm delivered?????
Delivery of sperm:
Urethra passes through the penis.
During intercourse, blood flow to the penis increases
causing the penis to become erect.
About 3.5 ml of semen released which contains 300-400
million sperm
Few ever reach the egg
Fertilization requires a high sperm count
Males with fewer than 20 million sperm/ml are considered
sterile
Sperm survive only 48 hours.
This type of fertilization is called internal fertilization: Sperm
are deposited inside the female reproductive tract and fertilization
occurs within the female body.
This requires special organs to deposit sperm and to receive
sperm.
Do you know????
Where are female gametes produced?
Where do they unite with male gametes?
Where does development of the fetus occur?
What is the function of the placenta?
What is invitro fertilization?
How can a woman give birth to another woman’s child?
How can a drug used by the mother produce genetic defects?
Female Reproductive Anatomy:
Meiosis in females: Oogenesis
•Occurs in the ovaries
•Produces 4 cells but only 1 gets all
the cytoplasm.
•Egg development begins before
birth
•The other 3 are called polar bodies
•Eggs are haploid
•During puberty eggs begin to
mature
•In a lifetime release will release only
300-400 eggs.
•Eggs are “stored” in the
ovaries
•Once released
(ovulation)they travel into
the fallopian tubes (takes 34 days to go through the
tube.)
•Egg will die if not
fertilized during 24-48
hours after ovulation.
•Uterus: Hollow, muscular
organ the size of a fist.
Cervix: The entrance to the
uterus.
Diaphragm: A rubber
cap which can cover the
cervix and prevent
fertilization.
•Sperm are deposited into
the vagina. A muscular
tube leading to the uterus
from outside the body.
Ovary
Uterus
Cervix
Where must fertilization occur to be successful?
Some Possible complications
Hormonal Control in the Human Female: The
Ovarian Cycle
1.Follicle Phase:
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Follicle: a cluster
of cells that
surround the egg
and provide it with
nutrients.
Anterior Pituitary
releases FSH and
LH(lutenizing
hormone) which
causes the follicle
to produce estrogen
and mature.
Surge of LH causes
follicle to rupture
and the egg is
released
2. Ovulation: Follicle
releases more estrogen
causing more LH to be
released
3. Luteal Phase: Ruptured
follicle grows into a
corpus luteum: A body of
cells which produces
estrogen and progesterone.
•This prevents the release
of FSH and LH so no more
eggs are released.
•The lining of the uterus
thickens in preparation for
the egg.
4. Menstruation: If the egg is
fertilized the corpus luteum will
produce more estrogen and
progesterone which further
thickens the lining of the uterus.
If fertilization does NOT occur,
the CL stops producing
hormones
The lining of the uterus is then
shed
Usually 14 days after ovulation
When no more hormones are
produced by the CL, FSH and
LH are released from the
anteriour pituitary and the cycle
begins again.
Chuck and Diane have been married for 5 years. They have
been unsuccessful in having children. After a doctor’s
examination, Chucks reproductive system was found to be
perfectly normal. Using your knowledge of the female
reproductive system, give at least 2 possible reasons for the fact
that Diane has not yet become pregnant.
Fertilization: Once male and female gametes unite the result is a
diploid cell called a zygote.
Sperm Meets Egg
Human Embryonic Development: Occurs internally
Takes about 266 days.
3 Independent processes must occur:
1. Mitosis: Causes the single celled zygote to grow into a
large number of cells
2. Differentiation: Cells become specialized to become
different tissues and organs. How does this happen?
** Different genes are “turned on” in each cell thus
programming different type of development.
3. Morphogenesis: Organization of those specialized tissues
and organs into the specific body plan of that species.
Do Now
• The pictures on the cards represent the
sequence of early development.
• Organize the index cards with the pictures
in a way that you think they belong.
• Answer the following questions based on
the pictures.
Life After Fertilization
This picture is a fertilized egg, only thirty hours after
conception.
Magnified here, it is no larger than the head of a pin.
Still rapidly dividing, the developing embryo is called a zygote
at this stage,
The Zygote floats down from the fallopian tube and towards
the uterus
Cleavage by Mitosis:
Series of rapid mitotic
divisions which
produces a ball of cells
called a morula
The ball of cells hollows out and forms a blastula
The cells begin to invert and form
distinct layers. At this stage it is
called a gastrula.
Here the layers begin to
differentiate: develop into
specific structures
3 layers:
1. Endoderm: Becomes the lining
of the digestive tract and
associated organs (liver,
pancreas) and respiratory
systems
2. Ectoderm: Forms tissues
associated with outerlayers.
Nervous system, Skin.
3. Mesoderm: Forms structures
associated with movement and
support, reproductive organs.
By stage 9, if you could look at the embryo
from a top view, it would resemble the sole of
a shoe with the head end wider than the tail
end, and a slightly narrowed middle.
Every ridge, bump and recess now indicates
cellular differentiation.
Embryo
The unborn child at seven weeks (5 weeks
after conception)
8 weeks - The unborn
child, called a fetus at
this stage, is about half
an inch long. The tiny
person is protected by
the amnionic sac, filled
with fluid. Inside, the
child swims and moves
gracefully. The arms
and legs have
lengthened, and
fingers can be seen.
The toes will develop
in the next few days.
Brain waves can be
measured
16 weeks - Five and a half inches tall and only six ounces in
weight, eyebrows, eyelashes and fine hair appear. The child
can grasp with his hands, kick, or even somersault
24 weeks - Seen here at six months, the unborn child is
covered with a fine, downy hair called lanugo. Its tender
skin is protected by a waxy substance called vernix. Some
of this substance may still be on the child's skin at birth at
which time it will be quickly absorbed. The child practices
breathing by inhaling amnionic fluid into developing lungs.
32 weeks - The fetus sleeps 90-95% of the day, and
sometimes experiences REM sleep, an indication of
dreaming.
External fertilization: Union of sperm and egg occurs
outside the body.
Who reproduces using external fertilization?
Most aquatic animals.
What are some challenges presented by external fertilization?
Development of the zygote: Where does it occur?
Internal development: Embryo is attached to the mother’s
placenta which is an outgrowth of the uterus. The connection
occurs through the umbilical cord which “communicates” with
the mother’s blood by diffusion. All nutrients (and toxins) can
diffuse from mother to fetus through the placenta.
External development:Zygote develops outside the female
body. This presents many challenges for the survivorship of the
offspring.
What are some adaptations that might increase survivorship?
•Protective covering on the land eggs to prevent drying out
•Must contain yolk for nourishment
•Many more eggs produced because they make tasty meals for
predators.
Hard shell, food supply, air space for diffusion of harmful
gaseous wastes.
Internal Versus External Fertilization: Adaptations for each
EXTERNAL
INTERNAL
Little/no parental
contact
Very little
specialized organs
Low survivorship
Male & female
make contact
Specialized organs
for delivery of
sperm
High survivorship
Little/no parental
involvement
Large number of
eggs produced
Lots of parental
involvement
Comparatively few
eggs
Shell
Air Space
Embryo
Eye SPot
Yolk Sac
Allantois
Intrauterine Insemination
In Vitro Fertilization
More than 10% of children have been exposed to high
levels of alcohol in utero. All will suffer varying degrees of
effects, ranging from mild learning disabilities to major
physical, mental and intellectual impairment. It takes very
little alcohol to cause serious damage. Research has
shown that even a single exposure to high levels of
alcohol can cause significant brain damage in the infant.
Which one is the human????
Now which one is human???