sexual reproduction in human testis sperms ovary eggs (ova) zygote embryo fetus baby meiosis...
TRANSCRIPT
Sexual Reproduction in Human
testis
sperms
ovary
eggs (ova)
zygote
embryo
fetus
baby
meiosis meiosis
fertilization
Male Reproductive System
testis
epididymis
vas deferens (sperm duct)
here
Testes
• For production of male gametes (sperms)
• For production of male sex hormones
http://www.youtube.com/watch?v=i93q0tKWX6g
Epididymis
• For temporarily storage of sperms
• During copulation, muscles of epididymis contract to release sperms
Testis and epididymis
sperm tubules
epididymis
vas deferens (sperm duct)
Male Reproductive System
seminal vesicle
prostate gland
Cowper’s gland
secrete seminal
fluid
Functions of Seminal Fluid
• To provide a medium for the sperms to swim
• To activate and nourish the sperms
• To neutralize the acidity in the female reproductive tract
Male Reproductive System
urethra
penis
Penis
• Erected during copulation for insertion into vagina– Dilation of arterioles causes the erectile tissue
of penis become turgid– Muscles of epididymis contract– Semen is squeezed from the penis to the top of
vagina
• Ejaculation http://www.youtube.com/watch?v=YOvHKSxxuYw
Female Reproductive System
vagina
cervix
uterus
oviduct
ovary
Female Reproductive Organs
H
BB
K
I
A
C
E
D
F
J
G
MM
Functions of Ovary
• For production of female gametes (ova/eggs)
• For production of female sex hormones
http://www.youtube.com/watch?v=a8fgm-zEYjQ http://www.youtube.com/watch?v=SkcddD0LGlM
Oviduct
• Carries the ovum forward by– the beating action of the cilia on its inner
surface– the contraction of muscles of oviduct
Ovulation
• The release of an ovum from an ovary
Menstrual Cycle
• Once in about 28 days
• The uterine lining becomes thickened 14 days after ovulation to prepare for the fertilized ovum to implant in it
Menstrual Cycle• Day 1 - 5
– Menstruation starts– Uterine lining decreases in thickness to a
minimum
• Day 6 - 14– Lining becomes thicker with increased blood
supply– Day 14 : ovulation
• Day 14 - 28– Lining remains thick to ready for implantation
of fertilized ovum
• Day 28– No implantation of fertilization ovum– Uterine lining breaks down; menstruation starts
Sexual Intercourse
• View film clip from Architectural Design of Men and Women
Implantation
• Fertilized eggs are implanted into thick walls of uterus
• Chorion membranes dig into uterus to form placenta
• Zygote grows into an embryo• Embryo gets air and nutrients through the
umbilical cord• Once pregnant, progesterone levels stay high in
mom• Mom’s uterus grows with the baby
Events Happened after Fertilization
• Ovum is fertilized at the oviduct
• Fertilized ovum is carried to the uterus by– the beating cilia on the inner wall of oviduct– the contraction of muscles of oviduct
• After reaching the uterus, the fertilized ovum fixed firmly onto the thick uterine wall
Implantation
Development of Human Foetus
uterusfetus
placenta
umbilical cord
amnion
amniotic fluid
Functions of the Uterus
• During embryo development– Protect the embryo– Provide a constant environment for the embryo
to develop– Allow placenta to attach on
• During birth of baby– Push the baby out by muscular contraction
Functions of the Amniotic Fluid
• To keep the foetus moist to prevent dessication
• As a water cushion to – support the fetus– allow it to move freely– absorb shock– protect the foetus from mechanical injuries
• To reduce temperature fluctuation
• To lubricate the vagina during birth
The Placentaoxygenated blood from
mother’s artery
villus
umbilical vein
umbilical artery
deoxygenated blood to mother’s vein
Functions of the Placenta
• As a place of exchange of materials between mother and the foetus
• For secreting hormones
Adaptations of the Placenta
• Finger-like villi– to increase the surface area for efficient diffusion
• Maternal blood and foetal blood flows in opposite direction– to speed up diffusion of materials between them
• Maternal blood capillaries and foetal blood capillaries are separated by thin membrane – to shorten the distance of diffusion of materials
Adaptations of the Placenta
• Maternal blood is separated from foetal blood by capillary wall– to prevent high pressure of maternal blood to
break the delicate foetal blood vessels– to prevent harmful substances to enter the
foetus– to prevent clotting of maternal and foetal blood
if their blood groups are incompatible
1st Trimester = 1st 12 weeks
• Heart develops first
• Neural tube develops
• All body systems appear by Week 8 – Now a Fetus
2nd Trimester = up to 24 weeks
• Most growth
• Looks more like a baby
• Some preemies survive at this stage
3rd Trimester= Up to 40 weeks
• More growth
• Kicking, rolling, stretching
• Eyes open – Week 32
• Lungs mature
• Rotates to head-down
position, unless baby is breech
Mrs. Degl
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
The Birth Process
• Onset of labor– Uterine muscles begin
to make rhythmic contractions
– Contractions gradually become stronger and closer
The Birth Process• Dilation of cervix
allow the head of the foetus to pass through
• Uterine contractions causes amnion to break and amniotic fluid to escape out of the vagina
• Muscular contractions push the foetus head first through the vagina, and the umbilical cord is cut and tied
• Further contractions push the placenta out of the body– “After birth”
Parental Care
• To increase the chance of survival of the young
• Mother feeds milk to the baby– Milk provides the babies with a
balanced diet– It also contains antibodies
which defend the babies against infection