Transcript human reproduction and development regents 09

Human Reproduction &
Development
AP Biology
2005-2006
Reproductive hormones
 Testosterone


from testes
functions
LH &
FSH
 sperm production
 Secondary sex
characteristics
 Estrogen


from ovaries
functions
 egg production
 prepare uterus for
fertilized egg
 Secondary sex
characteristics
AP Biology
testes
or
ovaries
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Gametogenesis
 Occurs in the gonads (ovaries and testes)
 Meiosis that results in the production of

gametes (haploid cells) from germ cells
(diploid cells)
Spermatogenesis and Oogenesis
AP Biology
Slide 2 of 18
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Spermatogenesis
 Occurs in the testes in


the seminiferous
tubules —results in the
production of 4 sperm
Mature in the
epididymis and gain
mobility
Produced immediately
after puberty
AP Biology
Slide 6 of 18
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Spermatogenesis
Epididymis
Testis
Coiled
seminiferous
tubules
Germ cell
(diploid)
1°
spermatocyte
(diploid)
MEIOSIS I
2°
spermatocytes
(haploid)
MEIOSIS II
Vas deferens
Spermatids
(haploid)
Spermatozoa
Cross-section of
seminiferous tubule
AP Biology
2005-2006
Spermatogenesis
 The sperm contains lots of
mitochondris (powerhouse of the cell)
—why?

AP Biology
The sperm have a long journey  they
need a lot of energy (hence the need for
lots of mitochondria)
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Male
reproductive
system
 Sperm production
over 100 million produced per day!
AP Biology
 ~2.5 million released per drop!

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Male reproductive system
 Testicles

produces sperm and hormones
 Scrotum

sac that holds testicles outside of body
 Epididymis

where sperm mature
 Vas deferens

tubes for sperm to travel from testes to penis
 Glands


nutrient rich fluid to feed and protect sperm
buffer to counteract acids in vagina
AP Biology
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Male reproductive system
AP Biology
2005-2006
Pathway of Semen
 epididymis (testes)  vas deferens 

urethra
A vasectomy is a procedure in which
the vas deferens is cut so that the man
will no longer be able to father children.
AP Biology
2005-2006
Female reproductive system
AP Biology
2005-2006
Oogenesis
 unequal division of

cytoplasm
Allows for more
nutrition to be available
to the egg in case
fertilization occurs.
AP Biology
Slide 5 of 18
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Female reproductive system
 Ovaries

produces egg and hormones
 Uterus

Nourishes fetus; lining builds up each month
 Fallopian tubes

tubes for eggs to travel from ovaries to uterus
 Cervix

opening to uterus, dilates 10cm (4 inches) for
birthing baby
 Vagina

Birth canal for birthing baby
AP Biology
2005-2006
Female Reproductive System
 ovaries – where



oogenesis takes place
oviduct (Fallopian
Tube) – where
fertilization takes
place
uterus – where the
embryo grows and
develops
vagina – birth canal
AP Biology
Slide 12 of 18
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Female reproductive system
AP Biology
2005-2006
Female Reproductive Hormones
 LH and FSH act on the
ovaries and cause them to
produce progesterone and
estrogen
AP Biology
2005-2006
Slide 13 of 18
Female Menstrual Cycle
 Each month, a woman’s body prepares for
the possible fertilization of an egg
 Ovarian cycle = an egg matures and is
released
 Uterine cycle = the endometrium (lining) of
the uterus thickens (becomes ready to
have a fertilized egg implant) then breaks
down (if no fertilization occurs).
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Slide 14 of 18
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Female Menstrual Cycle
 ovulation –
release of egg
from ovary
triggered by a
surge of LH.
AP Biology
Slide 15 of 18
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Female Menstrual Cycle
 Day 1 = first day of a
woman’s period
 Hormonal control is
complicated!

During different times
of the cycle, estrogen
can either stimulate
or inhibit other
hormones
AP Biology
2005-2006
Slide 17 of 18
Female Menstrual Cycle
 If fertilization occurs, the embryo secretes
HcG which maintains the lining of the
uterus

hCG is what is tested for in pregnancy
tests
 Birth control pills are synthetic
progesterone and estrogen that “trick”
the body into thinking the woman is
pregnant – no ovulation occurs
AP Biology
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Fertilization
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Fertilization
 Joining of sperm & egg

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sperm head enters egg
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Cleavage
 Repeated mitotic divisions of zygote
1st step to becoming multicellular
 Unequal divisions establishes body plan

 different cells receive different portions of egg
cytoplasm & therefore different regulatory signals
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Cleavage
 zygote  morula  blastula

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establishes future development
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Gastrulation
 Establish 3 cell layers

ectoderm
 outer layers
 skin, nails, teeth,
ectoderm
nerves

mesoderm
mesoderm
 blood, bone & muscle

endoderm
 inner lining
 digestive system
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endoderm
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Placenta
 Materials exchange across membranes
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Human fetal development
4 weeks
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7 weeks
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Human fetal development
10 weeks
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Human fetal development
12
weeks
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20 weeks
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Human fetal development
 The fetus just spends much of the 2nd &
3rd trimesters just growing
…and doing various flip-turns & kicks
inside amniotic fluid
Week 20
AP Biology
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Human fetal development
 24 weeks (6 months; 2nd trimester)
fetus is covered
with fine, downy
hair called
lanugo. Its skin
is protected by
a waxy material
called vernix
AP Biology
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Human fetal development
 30 weeks (7.5 months)
umbilical cord
AP Biology
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Getting crowded in there!!
 32 weeks (8 months)
The fetus
sleeps 90-95%
of the day &
sometimes
experiences
REM sleep, an
indication of
dreaming
AP Biology
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Hormone
induction
positive feedback
AP Biology
Birth
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Birth (36 weeks)
Intestine
Placenta
Umbilical
cord
Wall of
uterus
Bladder
AP
Cervix
Vagina
Biology
2005-2006
The end of the journey!
AP Biology
2005-2006