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