Unit 19: Reproductive System

Male Reproductive System

Major Structures:

Testes

Vas Deferens

Prostate

PenisTestes - make sperm via

meiosis. The testes also

produce testosterone, the male

hormone.

- They are enclosed in the

scrotum

Testosterone is responsible for

many of the male

characteristics.Epididymis - collects mature sperm

which is eventually propelled through

the vas deferens

Vas deferens -sperm travel through

this tube, joins with urethra

Vasectomy - the tube is cut to prevent

sperm leaving (and fertilizing an egg)

This procedure can be done right in

the doctor's officeProstate - gland that produces a fluid

that carries sperm during ejaculation. It

surrounds the urethra

Doctors use the digital rectal exam

(DRE) as a relatively simple test to

check the prostate

BPH = benign prostate

hypertrophy, prostate enlarges

with age, slowing the flow of urineA robotic butt and virtual patient software allows medical students to

receive feedback on the prostate exams they administer.WORD BANK

Bladder

Vas deferens

Vas deferens

Scrotum

Seminal Vesicle

Urethra

Prostate

Urethra

Prostate

Epididymis

Epididymus

Bladder

Teste

Scrotum

Teste

Seminal Vesicle

See also: Kidshealth Male ReproductiveIn a study in mice published in October 2015, a protein called

Calcineuron was found to be crucial in helping sperm swim and break

through the membrane of a female egg.

When the genes behind this protein were blocked, the mice became

infertile. Effects were seen in the mice within four to five days after

treatment. The effects were also reversible as fertility was restored

one week after treatments were stopped.

The midpiece of the sperm tail

(flagella) contains the sperm’s

mitochondria and operates the

movement of the tail. When sperm

are deprived of the chemical

calcineurin, the midpiece becomes

more rigid and adopts a hook-like

shape that constricts the tail’s range

of motion.FEMALE REPRODUCTION

Main Structures

● Ovary

● Uterus

● Fallopian Tubes

● Vagina

● CervixOVARY - this is where the eggs are produced through cell

division (MEIOSIS)

Meiosis results in four

daughter cells being

produced that have HALF

the number of the original

cell.

Human body cells = 46

chromosomes

Human sex cells = 23

chromosomesTwins

Identical twins a single zygote develop when

splits

The babies are genetically

identical. They also share

one placenta.

Fraternal twins develop from

the fertilization of two

individual eggs.

The babies are not the same.Can twins have different fathers?

Dutch couple Wilma and Willem Stuart

used in vitro fertilization to get pregnant.

When twins were born, Koen came out

with blue eyes and pink skin, and Tuen

had dark eyes and brown skin. The

hospital made a “deeply regrettable

mistake,” and it turned out that Koen was

their child, but Tuen was not Willem’s

son. A utensil had been used twice, and

another man’s sperm was mixed with

Willem’s.

Bipaternal twins.Ovaries secrete hormones:

Estrogen is responsible for the

appearance of secondary sex

characteristics of females

Progesterone regulates menstruation

Estrogen reduces the size of the nose and

chin, and leads to large eyes, increased

thickness of lips and fat deposition in the

cheek area, along with hips and buttocks,

features that announce that a woman is

fertile.

Studies show that higher levels of estrogen

may correlate with increased attractiveness.A fertilized egg is called a ZYGOTE.

An egg is usually a few days old before it implants in the

uterus. At this point, it has already divided several times

and is called a blastula.The uterus consists of a body

and a cervix. The cervix protrudes

into the vagina.

The uterus maintains an

environment for accepting a

fertilized egg.

The fertilized ovum becomes an embryo, attaches to a wall of the

uterus, creates a placenta, and develops into a fetus (gestates) until

childbirth.

If no fertilized egg reaches the uterus, the lining is shed monthly process known as menstruation

in aOvary

Fallopian Tubes

Uterus

Cervix

VaginaWhat is the difference between the vulva and the vagina?

The hymen is tissue that

partially covers the opening of

the vagina, often associated

with “virginity.” The tissue

actually thins and disappears

over time and may have

stretched during activities

other than sex. See “6 Things

You Never Knew About Your

Hymen”Speculum

Women should receive an

annual PAP test. A doctor

removes cells from around the

cervix and a lab checks them for

abnormalities. A gynecologist performs this

procedure.Cervical cancer: Virtually all cases

of cervical cancer are caused by

HPV, human papillomavirus.

Because HPV infection is so common, most

people get HPV infections shortly after

becoming sexually active for the first time.

Fortunately, there is a VACCINE,

recommended for young girls (and boys)

before they become sexually active.

Source: Cancer.govThe doctor can also check for abnormalities with

the uterus and the bladder.FERTILIZATION normally occurs in the Fallopian Tubes

The fertilized egg

(zygote) implants in the

uterus

Sometimes the egg

implants in the fallopian

tube, this is called an

ectopic pregnancy. In

this case, the embryo is

NOT VIABLE. In animals that have a large

number of offspring (like cats)

the uterus is divided into two

uterine horns (the fallopian

tubes in humans). Gestation

of embryos occurs in these

tubes.FERTILIZATION & PREGNANCY

Sperm must travel to the egg and

penetrate to combine the DNA from both

parents -- this creates the first cell after

fertilization: the ZYGOTE

23 chromosomes from each parent;

zygote has a total of 46 chromosomesSEX DETERMINATIONIf the zygote has the incorrect number of

chromosomes, it may never start growing. An

extra chromosome #21 will result in the baby

having Down Syndrome.Fetal DevelopmentFetal DevelopmentAt the 8th week, the embryo is called a FETUS