Ch 3 Sexual Reproduction in Humans. Recall: Human gametes are produced in the gonads. The female gonads are the ovaries, the male gonads are the testes.

Ch 3 Sexual Reproduction

in Humans

Recall:

• Human gametes are produced in the gonads.

• The female gonads are the ovaries, the male gonads are the testes.

Puberty

Hormones

• Substances which act like messengers in the body.

• They are made in one part of the body (in tiny amounts) and travel through the blood stream causing certain cells to respond in specific ways.

Puberty (cont’d)

Follicle stimulating hormone (FSH)

• Produced by the pituitary gland at the base of the brain.

• It is released into the blood in tiny amounts and travels to the gonads.

In Males In Females

FSH is received by testes which begin to make sperm. Sperm made daily.

FSH is received by ovaries which start maturing and releasing eggs. 1 egg released per month.

FSH causes testes to start producing the hormone testosterone.

FSH causes ovaries to start producing the hormone estrogen.

In Males In Females

Secondary sexual characteristics are directed by testosterone:

- facial hair

- underarm hair grow

- pubic hair grow

- shoulders broaden

- voice changes

Secondary sexual characteristics are directed by estrogen:

- fat deposits in breasts

- fat deposits on hips

- pubic hair grow

- underarm hair grow

Male Reproductive Anatomy• Designed to produce 350 – 500 million

sperm a day.

• Scrotum – a sac of tissue which holds the testes. The sac is outside of the body so it’s cooler which helps meiosis.

 • Seminiferous tubules – are tiny tubes inside

the testes where sperm are produced. Sperm stay and mature in the tubes for 9 to 10 weeks.

• Epididymis – long coiled tubes outside the testes. Used for sperm storage.

• Vas deferens – tubes which carry the sperm out of the epididymis when it’s time to leave the body.

• Seminal vesicles and prostate gland – produce thick, milky fluid which is rich in sugars. The fluid is released into the vas deferens and provides the sperm with a fluid in which to swim.

• Semen – a mixture of sperm and sugar rich fluids.

• Urethra – a single tube from the bladder to the end of the penis. It carries both semen and urine. Muscles contract to ensure that the tube is only used for one thing at a time.

Male Reproductive AnatomyDiagrams p 82-83

Male Reproductive Anatomy Crossword

Female Reproductive Anatomy• Purpose: to prepare for fertilization

Parts:• Ovaries – two almond-shaped organs inside

a woman’s main body cavity where eggs are stored and mature.

• Ovum – another name for egg. Plural is ova.

Sperm Pathway

• http://www.argosymedical.com/flash/Sperm/landing.html

• Ovulation – the process where an ovary releases 1 ovum every 28 days.

• Follicles – fluid filled cavities inside the ovary which contains 1 egg each.

• Corpus Luteum – the empty follicle after the egg has been released. It starts making hormones.

• Oviducts – (Fallopian tubes) – tiny tubes which have a hair-like lining move egg toward the uterus. If sperm are present they fertilize the egg in the oviducts. The egg lives for only 24 – 48 hours after ovulation.

• Uterus – a hollow pear-shaped organ with thick muscular walls.

• Cervix – the lower entrance to the uterus.

• Vagina – a muscular passageway, sometimes called the birth canal.

• Urethra – the tube which carries urine from the bladder out of the body. In women it is separate from the vagina.

• Menstrual cycle – a one month cycle of changes that surrounds ovulation.

Menstrual Cycle

• lasts about one month.• prepares the body for the possibility of

pregnancy.• is controlled by hormones.

Steps:1) Pituitary releases FSH.2) FSH stimulates follicles to develop.3) follicle begins releasing estrogen.

4) estrogen causes:

a) the lining of the uterus to thicken.

b) pituitary gland to release luteinising hormone (LH).

5) LH causes:

a) the follicle to release its mature egg (ovulation).

b) empty follicle to develop into a hormone maker called the corpus luteum.

6) corpus luteum produces progesterone and estrogen.

7) progesterone causes:

a) thickening of uterus lining.

b) pituitary to decrease FSH and LH production which prevents another egg from being released.

8) IF no fertilization:a) corpus luteum breaks down, decrease levels progesterone b) decresed levels of progesterone causes uterus to shed its lining.

 • Menstruation – the breaking down and

shedding of the uterine lining and blood. Flow lasts about 4 to 7 days. Reduced progesterone causes pituitary to decrease FSH. Go to step 1)

Assignment

• http://www.argosymedical.com/flash/ovulation/landing.html

• NOVA Online | Life's Greatest Miracle• http://health.howstuffworks.com/adam-roun

dup.htm reproduction animations

• Human Reproductive Systems Questions (P 80-90)

Human Reproductive Systems Questions (P 80-90)

1. What role(s) do hormones have in the body? (1)

– They are chemical messengers in the body.

2. What starts the period of life called puberty? (1)

– The pituitary gland releases FSH.

3. Which part of the brain produces FSH? (1)

– The pituitary gland.

4. FSH has different effects on males and females. What two things do the testes produce as a result of FSH? (2)

– Sperm and testosterone.

5. What are the secondary sex characteristics for males? (3)

– Lower voice, facial hair, broader shoulders, pubic hair, & armpit hair

6. When FSH reaches the ovaries what does it stimulate? (2)

– Maturation and monthly release of eggs– estrogen

7. Estrogen is a female reproductive hormone, what secondary sex characteristics does it bring about in females? (3)

– Breast development, broadening hips, pubic hair and armpit hair.

8. What percentage of women lived to age 15 in Canada in the 1700’s? (1)

– 67%

9. By 1951 this percentage increased to what number? (1)

– 96%

10. Why do you think this increased so dramatically? (1)

– Better health care and nutrition

11. Do questions 1 and 2 on Page 81. (2)

1. The trend in women’s life expectancy was increased longevity.

2. The trend in the average number of children born to each woman was a dramatic decrease from 4.3 down to 1.8.

- a 60% decrease

3.2 Pregnancy

If the egg is fertilized:• Only one sperm is

allowed to fertilize it.

• The resulting cell is called a zygote.

• It begins to divide by mitosis 24-36 hours after fertilization.

• These divisions are called cleavages

• By the time it reaches the uterus, these mitotic divisions have formed a hollow ball of cells called a blastocyst.

The outer cells will turn into a placenta and the inner cells will turn into the embryo.

• 6 – 10 days later the baltocyst reaches the uterus • The embyro becomes implanted in the thick

uterine lining.• The embryo releases hormones that cause the

corpus luteum to continue producing progesterone (uterine lining is not shed)

• identical twins

Embryo Development

After about one week:

• Cells begin to specialize and form a gastrula.– Three layers of types of cells called germ layers– Ectoderm forms the skin & nervous system.– Mesoderm forms the kidneys, muscles, skeleton,

blood vessels, gonads. – endoderm forms lungs and digestive tract lining.

After 10 – 14 days:• Outer portions of the embryo form into 4 tissues.

– yolk sac – nutrients for embryo’s first 2 months

– amnion – a sac of fluid around the embryo.

– allantois – helps in waste removal.

– Chorion – surrounds embryo and grows finger-like projections filled with blood vessels into the uterus wall.

• Develops into the placenta which provides the fetus with all of the oxygen, nutrients and waste removal needs from 2 months until birth.

• The umbilical cord attaches the placenta with the embryo at the belly button.

Assignment

• Pregnancy Questions (pages 91 – 94)

• CYU questions 1-5 on page 94.

3.3 Differentiation & Birth

Differentiation and Pre-Natal Development

• The process of cells becoming specialized to perform specific functions.

Example

• Embryo heart starts beating even though there is no blood yet.

• embryo is 500 times original size in just 4 weeks.

Trimesters

• A normal pregnancy lasts around 40 weeks and is called the gestation period.

• Gestation is broken into 3 equal parts of about 12 weeks each.

First Trimester (weeks 1 – 12)

• At four weeks nerve cells begin to form• At 8 to 9 weeks the first bone cells begin to

form. – The embryo is now called a fetus.

• By week 12:– All major organs have begun to form– Fetus is about 100 mm long– Gender can be identified using ultrasound.

Second Trimester (weeks 12 – 24)

• By week 16:– Placenta is too small to surround the fetus – it moves to

one side.

– Mom begins to feel the fetus move.

• By week 24:– Fetus is 300 mm long

– Most organs formed but not yet fully developed.

– Fetus still has little chance of survival if born prematurely.

Third Trimester (weeks 24 – 40)

• rapid growth• fetus begins to stretch and kick• Immune system develops• Proper nutrition is important for building brain tissue• brain develops rapidly• by 8 months eyes are open• babies are born with an average length of about 500 mm

(21 inches)• average weight between 2700 and 4100 grams. (~ 7.5 lbs)

Birth

• Sudden dramatic changes in hormone levels are responsible for starting the birth process.

• There is a sharp drop in progesterone & estrogen levels causing the uterus walls to contract.

• The pituitary releases the hormone oxytocin. This hormone is also used to induce labour.– It causes:

• The cervix to become thinner

• The uterus to contract

Labour

• Labour can occur when the cervix is thin enough to allow the baby to move through it.

• At this point the mother is able to help push the baby out.

• Some problems that may arise during childbirth are– The mother’s pelvis is too small for the baby to

pass through the birth canal.– The baby may not be in the correct position

(not head first).

• In both of the above cases the baby will be delivered by cesarean section.– This involves removing the baby through an

incision in the mother’s abdomen & uterus.

Stages

1. Dilation Stage - waiting for cervix to dilate or open. Amniotic sac often breaks releasing amniotic fluid under the pressure of the uterus. (often known as ‘the water broke’)

2. Expulsion Stage– Uterus contracts more forcefully.– Mom begins to push. – Baby’s head (hopefully looking down) turns

to look over the left shoulder to squeeze through the Mom’s pelvis.

– Baby moves down birth canal and out.

3. Placental Stage– a few minutes after Baby is born the placenta

detaches from the inside of the uterus. – Then the placenta and the umbilical cord are

delivered.– http://www.doereport.com/generateexhibit.ph

p?ID=12019l– c-section

Assignment

• Complete Investigation 3-C on pg 99 and do #1 – 3

• Read & Discuss p 100, 101, 103, 104• Risk Factors During Development

Questions• BLM 3-16• Read Pages 100-101 and do the questions

below.

Research Assignment• Athletic Amenorrhea (BLM 3-10), FASD, Down’s

Syndrome, Spina Bifida, Placenta Previa, Ectopic Pregancy, Menopause, Smoking & Pregnancy, Prescription Drugs & Pregnancy (pain killers, anti-histamines, anti-nauseants, antacids, anti-diarrhea, constipation, diet pills, sleeping pills, anti-depressants, antibiotics, allergy meds, pills for skin problems, etc.), Thalidamide, Cannabis & Pregnancy, Street Drugs & Pregnancy, Exercise & Pregnancy, Caffeine & Pregnancy, Sudden Infant Death Syndrome, Environmental Toxins

•  Choose one of the topics listed above (or another approved topic) and research the following:– Description– Cause (if known)– Prevention (if possible)– Medical advances– Effects

• http://www.argosymedical.com/flash/Placenta_Previa/landing.html

• http://www.argosymedical.com/flash/HPV/landing.html