Human Reproduction

Battle of the sexes!!!

Are males & females all that different?

Well…….…..YES and NO

Same embryonic tissues becomes male or female reproductive organs.

Male or Female???DNA determines baby’s gender

XX = FemaleXY = Male

All humans are female by defaultAt ~ 7 weeks the baby’s body may be “told” by DNA to become male

SRY gene located on the Y chromosome

Anatomy - similar

Testicles & Ovaries Glands responsible for the production of sex hormones and gametes

Start out inside body the Testicles “descend” before birth

Vas Deferens & OviductPassageway of gametes

Penis & ClitorisContain thousands of nerve ending to aid in sexual stimulation

Fetus begins with “starter parts” that could develop into either gender.

Same tissue – Same function

Physiology – VERY different!

MaleUncomplicatedProduce sperm

2-4 MILLION every day

FemaleVery Complicated!Born with ~ 400,000 eggs

Uses ~500

Ovulation1 egg “ripens” and is released once a month

Careful coordination of hormones & bodySupport life

Males

Produces male sex hormoneProduce 2-4 million sperm every day Outside body – why?Sperm like temps 1-2 cooler than body temp

Tube that carries sperm to the seminial vesicle and prostate

Temporary storage of spermDuring copulation, muscle contract to release sperm

Testes

Vas Deferens

Bladder

Epididymis

Prostate gland

Seminal vesicle

Urethra

Penis

Tube taking both urine and semen outside the bodyBulboureathral gland adds lubricant to aid travel of semen through the ureathra

Erected during copulation for insertion into vaginaDilation of arterioles causes the erectile tissue of penis become turgidSemen is squeezed from the penis to the top of vagina

Sperm

Semen contains300-500 million sperm – 5%Sperm food (fructose) – 30%Alkaline fluid (pH buffer) – 65%

Why so many sperm?

Why a pH buffer?

What is sperm?Then…

Used to think it was a tiny human inside each cellSpermists vs. Ovists

Now…Contains several partsHead

Contains chemicals to dissolve egg gooDad’s genetic information – one each of 44

autosomal chromosomes and 1 sex chromosomeMitochondria

EnergyContains mitochondrial DNA

from motherFlagellum

“tail” used for locomotion

Females

Vagina

Cervix

UterusOviduct

Ovary

For production of female gametes (ova/eggs)For production of female sex hormones

Carries the ovum forward by the beating action of the cilia on its inner surface and the contraction of muscles of oviduct

Allows for placenta to attachmentDuring embryo development it protects the embryo and provides a constant environment for the embryo to developDuring birth of baby it pushes the baby out by muscular contraction

Opening between the uterus and vagina

Birth canal

Menstrual Cycle

All about timing!!!Uterus must be ready when egg gets there in case it was fertilizedIf no fertilization, tear down lining of uterus and rebuild for next month

Estrogen Ovaries

Drop in levels causes shedding of uterine liningIncrease in levels causes uterine lining to thicken

Progesterone Corpus litheum (ruptured follicle)

Drop in levels causes shedding of uterine liningIncrease in levels causes uterine lining to thicken

LH (leuteinizing hormone) Pituitary gland & hypothalamus

Stimulates release of mature egg from ovary

FSH (follicle stimulating hormone) Pituitary gland

Acts on ovaries to mature the egg

HCG (Human Chorionic Gonadotropin) Corpus litheum (ruptured follicle)

Produced if fertilization occursStimulates continued secretion of progesterone

Hormones

Spermatogenesis

Oogenesis

Occurs in the testesProduces 4 hapoid

cellsProduces 4 viable

spermatozoaMotile – swim with

tailProduction begins at

pubertyProduction continues

for entire life

Occurs in the ovariesProduces 4 hapoid

cellsProduces 1 Ovum & 3

polar bodies Nonmotile – moved

by currentsAll eggs present at

birthEggs mature from puberty to

menopause

Birth ControlBirth Control Pills

Use hormones to “Trick” body into thinking it’s pregnant

No ovulation occursNo ovulation = no egg = no fertilization = no baby!No hormones taken for 7 days = menstruation

Barrier MethodMale and female condoms prevent sperm from entering the vaginaDiaphragm fitted over the cervix & along with use of spermacide to kill spermNo sperms= no fertilization= no baby!

Rhythm MethodPrevent copulation 7 days before and 7 days after ovulationUses basal temperature as guide

Surgical SterilizationCut and tie the vas deferens prevents sperm from leaving testesCut and tie the oviducts prevents egg from leaving ovary and sperm from finding egg

Birth Control

Sexual Reproduction in Humantestis

sperms

ovary

eggs (ova)

zygote

embryo

fetus

meiosis meiosis

fertilization