REPRODUCTIVE SYSTEM & HORMONESEMPHASIS 10-15%

DIFFERENTIATION AND DEVELOPMENTEMPHASIS 5-10%

UNIT B:

ADVANTAGES OF SEXUAL VS

ASEXUAL REPRODUCTION

Meiosis

� Crossing over, independent assortment, haploid gametes producing a diploid zygote

� Produces a variety of diverse offspring

� Can increase chance of survival (Natural Selection)

SEX CHARACTERISTICS

Primary

= genitals present at birth (penis or vagina)

Secondary

= appear at puberty as a result of hormones

MALE REPRODUCTIVE SYSTEM

SEMINIFEROUS TUBULES

• 250 meters of microscopic tubes

• Site of sperm production

• Spermatogenesis

• Mitosis by diploid (2n) stem cells

• Meiosis � 1n gametes

HORMONAL STIMULATION OF

SPERMATOGENESIS IN TUBULES

FSH – follicle stimulating hormone

• Released from anterior Pituitary Gland

Other cells in the testes

• Sertoli cells

• Nourish/protect sperm• Make hormone inhibin

• Prevents sperm production

Other cells in the testes

• Leydig/Intersticial cells

• Make testosterone• Primary and secondary

sex characteristics

• Also stimulates sperm production

• Regulated by hormone from the anterior pituitary gland

• LH = LeutinizingHormone

EFFECTS OF TESTOSTERONE

MALE STRUCTURES CONT’D

Epididymis

• Sperm mature for 2-3 months

• Sperm are not produced here (storage only)

Scrotum

• Thin muscular surrounding layer around testicles

• Normal sperm development need 2-3°C less than body temperature

• Sterility issues

• Testes drop form the abdominal cavity before birth

SPERM CELL (SPERMATOCYTE) = GAMETE

NOTE: you will not be asked to identify the parts of a sperm cell on the diploma

HOW SPERM MEET EGG

Erection:

• Parasympathetics nerves

• Vasodilation of arterioles in penis

• Spongy/erectile tissue fills with blood

Emission:

• Sympathetic nerves

• Contraction of testes, glands

EMISSION

1. Bulbourethral Gland (Cowper’s)

• Neutralizes any urine residue in urethra

2. Epididymis

• 400 million sperm exit

• 5% of semen

3. Vas Deferens (2) (ductus deferens)

• Sperm travel up into abdominal cavity near bladder

• Vasectomy = surgical procedure to prevent sperm from reaching urethra

4. Seminal vesicles - 2 sacks behind bladder

• Yellow fluid (60% of semen)

• Fructose = fuel for sperm

• Mucous = enhance mobility

• Prostaglandins = uterine contractions

5. Prostate gland

• White secretion (30% of the semen)

• Basic/alkaline = buffers against pH of vagina

• Muscular, contracts = force behind ejaculation

• Can become enlarged

• Difficult/painful urination and ejaculation issues

Urethra

• Ejaculation – sperm exit body

• Part of both the excretory and reproductive

systems

4 GLANDS THAT CONTRIBUTE TO SEMEN

Cowpers – cleanse urethra

Prostate – alkaline to protect sperm from acidic vagina

Seminal vesicle – fructose sugar

Testes = SPERM (non fluid component)

KEY IDEAS:

1) Structures sperm travel through from production to exit from the body

2) 4 glands and what they contribute to semen

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FEMALE REPRODUCTIVE SYSTEM

ANATOMY

Vagina

• Elastic, muscular tube

• Entry for sperm

• Birth canal

Cervix

• Enterance to uterus/womb

• Ring of muscle

• Dilates for birth (10 cm)

• Pap smear

• Cervical cells (cancer?)

Uterus/womb• Muscular organ (size of fist)

• Site for fetal growth/

development in the Inner

layer = endometrium

• Shed once/month

• Period or mensus

Fallopian Tubes (2)• A.k.a. oviducts

• Fimbrae = sweep egg into tube

• Site of fertilization

• Scarring ���� STI (Chlamydia)

• Ectopic pregnancy

• Tubal ligation (tubes tied) = sterility

Ovaries

• Oogenesis and ovulation

• Hormone production

• Estrogen

• progesterone

FEMALE HORMONES

Ovarian/Menstrual Cycle

• 4 stages:

• Flow phase

• Follicular phase

• Ovulatory phase

• Luteal phase

MENSTRUAL CYCLE

Follicular phase

• FSH (Follicle Stimulating Hormone)

• Released by anterior pituitary gland

• Target = ovary (follicular cells around oocyte)

• Causes follicle to:

• Become larger (filled with fluid)

• Produce estrogen

• Estrogen – causes endometrial layer of uterus to

thicken

• Negative feedback loop for FSH

• Positive feedback loop for LH (around day 12)

Ovulatory Phase (Ovulation)

• High levels of LH is released by anterior pituitary gland (due to high estrogen)

• target (ovary)

• causes ovulation – oocyte released from ovary

• LH (Leutenizing Hormone)

• Causes remnant follicle cells to transform into the corpus luteum

• Corpus luteum produces progesterone (and estrogen –second peak in bloodstream)

• Causes = further thickening of endometrium/prevents uterine contractions

MENSTRUAL CYCLE

Flow Phase (Menstrual Stage)

• Negative feedback loop

• Causes � LH and � of FSH

• New follicle starts to mature

• Corpus luteum shrinks

• Progesterone levels fall

• Uterine contractions

• Shedding of endometrial layer = menstruation

FEEDBACK LOOPS

Negative (-) feedback loop

• Estrogen and FSH

• Progesterone and LH

Positive (+) feedback loop (~day 12)

• Estrogen and LH

MISCELLANEOUS

The Birth Control Pill

• Contraception

• Estrogen and/or progesterone

• Keeps FSH and LH levels low

• No maturation of follicle or ovulation

Menopause

• Ovaries decrease production of estrogen and

progesterone

• Ovulation and menstruation stop

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DIFFERENTIATION AND DEVELOPMENT

Fertilization

• Secondary oocyte meets sperm in fallopian tube

• Sperm releases enzymes from acrosome

• One sperm in � zona hardens

• Meiosis II � ovum

• 2 nuceli fuse = zygote (2n)

FIRST TRIMESTER: (3 MONTHS)

Stage 1:

• 30 hrs after fertilization

• Zygote splits in half (cleavage)

• Mitosis � ball of 16 tiny cells

• Zygote now called a Morula

Day 4 – enters uterus

• Morula fills with fluid to become a hollow ball

• Called a blastocyst or blastula

TWINS?

Monozygotic (identical)

• Blastocyst splits

• 1 egg + 1 sperm

• DNA identical – must be same gender

Dizygotic (fraternal)

• 2 eggs + 2 sperm

• DNA different

• Can be different genders (or the same)

FIRST TRIMESTER CONTINUED

Stage 2: Implantation

• After 1 week, blastula releases enzymes

• Digests a hole into mothers endometrium

Mother’s hormone cycle - ����LH – corpus luteum will die

Blastula must prevent menses

• Releases HCG (human chorionic gonadotropin)

• Very similar to LH

• Keeps corpus luteum in mother’s ovary intact

• Keeps progesterone high = no menstruation

• Pregnancy tests – detect HCG in mother’s urine

Stage 3: Embryogenesis

Day 12 – blastula undergoes transformation

• Gastrulation

• Becomes a gastrula

• Inner cell mass develops into 3 germ layers

• These cells give rise to the various human tissues and

organs

3 GERM LAYERS (EMBRYOGENESIS)

Ectoderm = outside – hair, skin, teeth, etc & Nervous system

Mesoderm = middle – muscles, skeleton, reproductive system

Endoderm = inside – lining of digestive/respiratory system, some

endocrine glands

**MUST MEMORIZE!

EXTRA EMBRYONIC MEMBRANES

EXTRA EMBRYONIC MEMBRANES

1. Yolk Sac

• Makes blood until liver forms

• Fate – intestine/gonads/stem cells of the immune system

2. Amnion

• Lines abdominal cavity and produces fluid

• Protection for fetus – shock absorber

• Amniocentesis – contains DNA of embryo

• Breaks before birth

3. Allantois

• Umbilical arteries (2) and vein (1)

4. Chorion

• Forms fetal portion of placenta

• CVS – chorionic villus sampling (biopsy)

• Test for genetic disorders

FIRST TRIMESTER CONTINUEDStage 4: Placentation

A. Interface – exchange site

• Embryo needs to access moms blood supply

Chorion ���� protrusions ���� chorionic villi

• Penetrate deeply into uterine tissue (endometrium)

• Placenta = genetically is ½ embryo ½ mom

PLACENTA CONT’D

• Chorionic villi surrounded by pools of maternal blood

• Fetal blood does NOT mix with moms

• Diffusion across membrane

• Concentration gradients

• Cells of chorion – semipermeable

• RBC/WBC too big

PLACENTA CONT’D

B. Hormone production

By 10th week, placenta fully develops

Progesterone

• Takes over roll of corpus luteum

• Keeps FSH low – no ovulation

• HCG will drop

Estrogen = breast growth and changes

PLACENTA CONT’D

C. Barrier?

TERATOGENS

• Cause fetus to develop abnormally

• During what stage of pregnancyare teratogens most harmful?

Alcohol (F.A.S.D.)

Smoking

Thalidomide

Bacteria

Virus

• Chicken pox

• German measles

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DEVELOPMENTEmbryonic DEVELOPMENT

• Embryonic stage (up to 8 weeks)

• Development (organogenesis)

• Specialization, differentiation

Fetal GROWTH

• Fetal stage (after 8th week to parturition)

• Growth and “maturation” of structures formed

• Increase in # cells

KNOW THE MAJOR CHANGES

OF EACH TRIMESTER

1st = differentiation, gastrulation, organogenesis

2nd = organs begin to function, continue

development (not yet functional organs)

3rd= growth, ossification of bones, myelination of

neurons

PARTRUITION

During the last few weeks

The placenta produces another hormone

• RELAXIN

• Causes cervix to relax/dilate

• Ligaments in pelvis loosen

• Baby turns upside down

• Applies pressure to cervix (helps dilate)

PARTRUTION

Placenta ���� progesterone output

Posterior pituitary gland

• Releases hormone OXYTOCIN (made in hypothatlamus)

• Causes contraction of uterine muscles

***Positive feedback loop

�oxytocin �contractions = �oxytocin �contractions

STAGES OF PARTRUITION

1st Stage (8-24 hrs or minutes)

• Contractions become regular

• Amnionic sac rupture – water breaks

• Cervix dilates

2nd stage (min-hrs)

• Forceful/frequent contractions

• Fetus enters birth canal

3rd stage (10-45 min)

• Contractions expel placenta – the “after birth”

POST-NATAL PERIOD

Breastfeeding

• First few days = colostrum

• PROLACTIN = causes breast to make milk

• Prolactin = production

• Baby “latches on”

• Posterior pituitary releases OXYTOCIN

• Milk is released from breast

REPRODUCTIVE

TECHNOLOGIES (STS)

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UNIT B:

REPRODUCTIONS

Questions?

Comments?

Next is Unit C – Genetics