Human Growth and DevelopmentGrade 7

• Female Reproductive System• The Journey of the Egg• Male Reproductive System• The Journey of the Sperm• Fertilization• Pregnancy and Fetal Development• Labour and Delivery

Female Reproductive System

Journey of the Egg

• 300,000-400,000 eggs stored in the ovaries• 300-500 eggs released during fertile years- 12-52• Average Menstrual cycle 23-35 days• First half of cycle- FSH is released - causing the egg to

“mature”• As the egg matures – estrogen is increased – prepares the

“bed” (endometrium) for the egg • On day 14- LH causes the egg to be released – (Ovulation)

• Egg lives for 1 day only- most fertile time• Progesterone also increases to prepare the (womb)

uterus and prevent it from contracting• The rise in Hormones prevents the ovaries from

releasing any more eggs• If sperm does not fertilize the egg—stop production---

start over • Hormones drop and the lining is shed about 14 days

later- Menses begins.

Male Reproductive System

Journey of the Sperm • Sperm production starts in the

scrotum (thermostat)• Scrotum holds the 2 testes

(gonads) which secrete the sex hormone –testosterone and make sperm– ½ billion made every day

• It takes 70 days for one sperm to mature.

• Sperm have a head (DNA) and a tail (swim)

• Once the sperm is made in the testes- other parts of the RS are responsible for the Semen.

• Semen is the pool that the sperm swim in.

Journey of the Sperm• Immature sperm move from the

testes to the epidydmis (Learn to swim)- this process takes 3 weeks.

• When the epidydymis is full- wet dream may happen

• Move to the vas deferens (moves sperm along)

• Sperm need to be nourished along the way:

• Seminal Vesicle- Sugar• Prostate- Protein• Cowpers gland- Oil/cleanses

tube of urine • Penis - Spongy tissue• Valve closes urinary system-

during sexual arousal• 200-500 million sperm released

at once

Race to the Egg

Fertilization

- when a sperm cell and an egg join together fertilization (conception)

occurs - the sex of the baby and genetic

make-up has been determined - the fertilized egg then starts to

divide rapidly into many cells- about three days after conception,

the egg passes through the fallopian tube into the uterus where it attaches to the uterine wall

- the placenta begins to form - will nourish the baby during pregnancy

4 weeks gestation

- structures that eventually form the face and neck are becoming evident

- the heart and blood vessels continue to develop

- the lungs, stomach, and liver start to develop

- a pregnancy test may now be positive

8 weeks- the fetus is about the size of a grape - almost

an inch in length- eyelids and ears are forming - the tip of the nose is visible- the arms and legs are well formed with the

fingers and toes growing longer and more distinct.

12 weeks

- the fetus measures about 2 inches and is starting to move on its own

- sex organs may be seen

- heart rate may be heard by your doctor

16 weeks- fetus is about 4.3 to 4.6 inches, weighs about 2.8

ounces- baby can blink his eyes - heart and blood vessels are fully formed- fingers and toes should have fingerprints- the top of your uterus should be felt about three

inches below your belly button

20 weeks- weighs about 9

ounces and is about six inches long

- can suck a thumb, yawn, stretch, and make faces

- mom can feel her baby move which is called "quickening."

- uterus should be at the level of the belly button

Ultrasound Time

An ultrasound is generally performed for all pregnant women at 20 weeks of gestation

- doctor will check to make sure the placenta is healthy and attached normally and that your baby is growing well

- heartbeat can be seen - body, arm, and leg

movements can also be seen

- baby’s gender can usually be determined at 20 weeks

• 2D ultrasound (inset) contrasted with a 4D ultrasound, both at 20 weeks

24 weeks- weighs about 1.4 pounds now- can respond to sounds by moving around or

with an increased heart rate- may develop hiccups- jerking motion to mom - inner ear is fully developed, may be able to

sense being upside down in the wombT

28 weeks

- weighs about 2 pounds 6 ounces

- changes position frequently

- increased survival rate if your baby is born early (premature)

32 weeks- weighs almost 4 pounds- often moving- skin has less wrinkles as a

layer of fat starts to form under the skin

- will gain up to half its birth weight between now and delivery

- mom may leak some colostrum from her breasts, a yellowish fluid that is produced before breastmilk

32 Weeks

36 weeks- weighs around 5.5

pounds, about 12.5 inches

- brain has been developing rapidly

- lungs are nearly fully developed

- head is usually positioned downward into the pelvis for delivery

- pregnancy is considered 'at term' once 37 weeks has occurred and baby is ready to be born!

39-40 Weeks

• At birth, the average baby is more than 20.5 inches long from head to toe and weighs approximately 7.5 pounds, but babies vary widely in size at this stage.

• All organs are fully developed and baby is ready to begin life outside of the uterus.

Stages of Labour and Delivery

References

• http://www.medicinenet.com/fetal_development_pictures_slideshow/article.htm