Transcript Human Reproductive System

Human Reproductive
System Review
Male Reproductive
System
Sperm Formation
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MEIOSIS forms sperm ( male gametes)
Sperm forms in testes
Scrotum kept 5˚ cooler than rest of body
Semen is sperm plus protecting fluid
Semen leaves testes through the epididymis
and then vas deferens (sperm ducts) to the
urethra before it exits.
Secondary Sexual
Characteristics - Male
• Produced by testosterone
– Deeper voice
– Chest and facial hair
– Lengthen bones
– Increased size of testes for
sperm production
Female Reproductive
System
Mrs. Degl
Ovum Formation
• MEIOSIS forms the eggs (ova)
• Eggs are formed before birth
• 1 egg per month is matured and
released from ovaries, most of the
time
• Eggs travel through the fallopian tube
where they may become fertilized
• If not, a mature female will
menstruate and begin cycle again
Secondary Sexual
Characteristics - Female
• Induced by increased LH, FSH,
estrogen, and progesterone
hormone levels
– Pubic hair
– Widen pelvis
– Enlarge mammary tissue
(breasts)
– Begin menstrual cycles
Overview of
Fertilization/Development
- We’ve already learned how
gametes are produced
(gametogenesis) through
meiosis
- What process produces
every other cell in the
human body?
MITOSIS
Fertilization
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Occurs in upper 1/3 of Fallopian tube
Only 1 sperm can fertilize an egg
Fertilized egg = zygote
An average woman is pregnant (gestational
period) for 9 whole months. That is 40 weeks.
Zygote  Morula
• The zygote undergoes
several mitotic divisions
(cleavage) over a 3-4 day
period
– 2-cell  4-cell  8cell  16 cell
• Finally it becomes a (16celled) morula. It is still a
solid ball of cells with
defining shape
Stem Cells
• Totipotent cells: capable of developing into all
the different cell types
– all cells of mammalian embryos are totipotent
until the 16-cell stage
• Plueripotent cells – can differentiate into many
tissues, but not all
– Come from the ICM of blastocyst
The
Controversy
Morula  Blastocyst
• Slowing, the morula cavitates and the inner
cells begin to migrate to one small section
of the embroyo forming the inner cell mass
(ICM)
• The outer, trophoblast cells will become the
placenta
• The ICM cells will become the embryo
Implantation
• As the fertilized egg developed from
zygote to blastocyst, it was being moved
down the fallopian tubes via smooth muscle
contractions to the uterus
• In apes (not like this in most species), the
blastocyst actually digs through the
uterine wall causing some women to
experience implantation bleeding
Implantation
• Blastocyst implants into thick walls of uterus
• Embryo gets air and nutrients through the
umbilical cord
• Once pregnant, progesterone levels stay high in
mom (“pro” = for “gestation” = pregnancy)
• Mom’s uterus grows with the baby
Blastocyst 
Gastrula
• Gastrulation – The outer-wall of the blastocyst invaginates
on itself (folds in) and three distinct germ layers form
• A germ layer is a primary layer of cells that form during
embryogenesis
• These layers become specific structures
– Ectoderm, Mesoderm, Endoderm
1st Trimester =
1st 12 weeks
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Heart develops first
Neural tube develops
Tissues and organs are laid out
All body systems appear by Week 8 =
“organogenesis”
• Now a Fetus
2nd Trimester =
up to 24 weeks
3rd Trimester
= Up to 40 weeks
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More growth
Kicking, rolling, stretching
Eyes open – Week 32
Lungs mature
Rotates to head-down
position, unless baby is
breech
Birth
• Labor
– Uterine contractions begin
– Cervix dilates to 10 cm.
• Birth
– Uterus pushes baby through vaginal
canal
– Placenta delivered after baby
– Cesarean Section (c-section) is a surgery
that cuts through the uterus to deliver
the baby if it cannot be born vaginally
Mrs. Degl
Throw Back
Mrs. Degl