Transcript human reproduction and developement

HUMAN REPRODUCTION
AND DEVELOPMENT
THE BIOLOGICAL
MIRACLE OF BIRTH
HOW I BECAME ME?
A million, million spermatozoa
All of them alive
Out of their cataclysm but one poor Noah
Dare hope to survive
And among that billion minus one
Might have chanced to be
Shakespeare, another Newton, a new
Donne
But the One was Me.
GAMETOGENESIS
Oogenesis in
female produces
the ovum
Spermatogenesis
in male produces
the sperm
30.3 Males
Fig. 30.11 The
male
reproductive
organs
• The testis produces sperm and testosterone
– Enclosed in a hanging sac called the scrotum
• Sperm need cooler temperature to develop
• Spermatogenesis occurs in the seminiferous tubules
Sperm are then transferred
to the epididymis for
storage and maturation
From there to the vas
deferens
To the urethra
which empties
through the penis
Contains 23
chromosomes
Fig. 30.13 Human sperm cell
Fig. 30.12 The testis and formation of sperm
30.4 Females
Fig. 30.15 The
female
reproductive
organs
• At birth, a female’s ovaries contains all the oocytes she
will ever produce
– ~ 2 million oocytes are arrested in prophase I of the
first meiotic division
• At puberty, the release of FSH causes the
resumption of meiosis I in a few oocytes
–However, only one becomes dominant and is
ovulated
»Mature egg cells are called ova (singular,
ovum)
• This cycle is repeated about every 28 days
Fig. 30.16 The ovary and formation of an ovum
“ And
two
become
one.”
FERTILIZATION
A million,
million
spermatozoa
All of them
alive…..
What is
Fertilization?
Fusion of Egg and Sperm
to form a Zygote
“ Out of
their
cataclysm
but one
poor Noah
Dare hope
to survive…”
• Fertilization of the egg occurs high in the Fallopian tubes
(also called uterine tubes or oviducts)
– The fertilized egg is now called a zygote
• It is transported to the uterus
–A muscular pear-shaped organ about the size of
a fist
»It narrows to a muscular ring called the cervix
Leads to the vagina
CLEAVAGE
•Zygote
•Morula
MORPHOGENESIS
•What happens to
the morula during
morphogenesis?
•What is a blastula?
GASTRULATION
•Gastrula
•Ectoderm
•Mesoderm
•Endoderm
IMPLANTATION
What are the functions of
implantation?
Where does the embryo
gets its nourishment at
this stage?
NEURALATION
AND
ORGANOGENESIS
Neurulation: Determination of Body Architecture
• In the third week, the three primary germ layers begin
development into body tissues and organs
– First, the notochord develops from the mesoderm
• The neural tube develops from the ectoderm
–The gut develops from the endoderm
• On either side of the notochord blocks of tissue form
– These somites give rise to muscles, vertebrae and
connective tissues developing notochord
• By the end of the third week, the embryo is about
mm (< 0.1 inches) long
2
FETAL
And among
that billion
minus one
Might have
chanced to
be …..
DEVELOPMENT
30.7 Fetal Development
Fourth week
Formation of body
organs, or
organogenesis
Critical time in
development
Alcohol use may
cause fetal alcohol
syndrome
Embryo reaches about
5 mm
30.7 Fetal Development
Second month
Great changes in
morphology occur
Limbs assume
adult shape
Major internal
organs are evident
Embryo reaches
about 25 mm
30.7 Fetal Development
Third month
Development is
essentially complete
except for lungs and
brain
Developing human is
now called a fetus
It carries out
primitive reflexes
like sucking
30.7 Fetal Development
Second trimester
A time of growth
Bone formation occurs
Hair and body are
covered with fine hair
called lanugo
By the end of the 6th
month, the fetus is 30
cm (1 foot) long
30.7 Fetal Development
Third trimester
Pace of growth
accelerates
Weight of fetus
more than doubles
Nutrients
provided by
mother’s blood
via the placenta
Most major nerve
tracts are formed in
the brain
Fig. 30.21
PARTURITION
But
the
One
was
Me!
 Dr. Naegele, circa 1850, determined that the average
length of human gestation was approximately 266
days from conception. He assumed that the average
woman had cycles that lasted 28 days and that she
ovulated on Day 14 of her cycle. He used his data to
come up with a mathematical calculation for due
dates:
((LMP + 7 days) - 3 months) = Due Date
EX:
((January 1, 1996 + 7 days) - 3 months)
Due date = October 8, 1996
LABOR AND BIRTH
•
•
•
•
• Stage 1 (labor pains)
Mother becomes aware of strong
uterine contractions
cervix becomes dilated (10cm/4 in)
cervix is effaced (continuous with the
uterine wall; indistinguishable)
Lasts 8 to 24 hours if 1st pregnancy
LABOR AND BIRTH
•
•
•
•
• Stage 2 (actual birth)
amniotic sac burst, “ My water broke!”
contractions have 2-3 minutes interval
Baby is expelled into the vagina (baby is
delivered)
Infant’s head slowly emerges and 2-3
contractions ejects the body, “Push,push!”
LABOR AND BIRTH
• Stage 3 (Afterbirth)
• Umbilical cord is tied and cut
• 10-20 mins. After birth, placenta
separates from the uterus and is
expelled
• placenta is inspected for
abnormalities and later discarded
NATURAL VAGINAL BIRTH
CEASARIAN BIRTH
Stage 1: INCISION
Stage 2:
ACTUAL
BIRTH
The fetus is
removed
from the
mother’s
womb
HERE
I
AM !!!
SUMMARY OF
HUMAN
REPRODUCTION
AND
DEVELOPMENT
I. Pre-embryonic - Gametogenesis
- Fertilization
II. Embryonic
- Cleavage
- Morphogenesis
- Implantation
- Gastrulation
- Neuralation
- Organogenesis
III. Post Embryonic - Fetal Development & Growth
- Parturition
- Post - natal Development
- Reproductive Maturity
- Aging
- Death
Once this was YOU, what have you
made it into?