Human Reproduction
Biology
The Reproductive System
The reproductive system functions in the
production, support, and transport of
sex cells (egg and sperm), as well as the
production of sex hormones.
Reproduction Overview
A. Asexual reproduction –
One parent makes identical babies (clones)
B. Sexual reproduction –
fusion of _gametes (sex cells)_ of two parents
to form a _zygote (fertilized egg)
1. Fertilization –
fusion of egg and sperm
Reproduction Overview
2. Human reproduction – includes
a. Formation of gametes (process of meiosis)
b. Preparation for pregnancy
c. Sexual Intercourse
d. Fertilization which leads to pregnancy
e. Lactation (milk production)
3. All coordinated by hormones of anterior
pituitary (in brain) and the gonads
(ovaries/testes) **Primary sex organs**
Male Reproductive System-side view
glans
(AKA: Cowper’s
gland)
A. Functions: to produce sperm and deliver them to the female
reproductive tract.
Male Reproductive System-front view
Male Reproductive System
MALE REPRODUCTIVE STRUCTURES:
1.
TESTIS: Primary male sex organs
which produce sperm cells and the
male sex hormone testosterone.
Made up of highly coiled tubes
called seminiferous tubules.
2.
SCROTUM: Houses and protects
testes by maintaining optimal
temperature for sperm
production.
Male Reproductive System
3. SEMINIFEROUS
TUBULES: Sperm
production and transport
of sperm to the epididymis.
If stretched out will equal
20 feet.
4. EPIDIDYMIS: stores and
matures sperm (gain
motility).
Male Reproductive System
5. VAS DEFERENS: Tube that carries
sperm away from the epididymis
6. EJACULATORY DUCT: Transports
sperm from the vas deferens to the
urethra. This duct passes through the
prostate gland.
Male Reproductive System
Production of sperm: is called Spermatogenesis
Male Reproductive System
1.
Happens in
seminiferous tubules
of testes.
Spermatogonia
("stem cells") divide
by mitosis - half
undergo meiosis and
mature to sperm cells
(1 to 4 cells, this
takes TWO months!)
Male Reproductive System
2. Sperm consists of head,
nucleus, midpiece and tail.
SPERM CELLS: up to 350 million
produced per day
HEAD portion contains enzymes
(to penetrate the egg’s outer
layer) and a Nucleus with
DNA.
MIDPIECE: Contains
mitochondria for energy.
FLAGELLUM: Movement
Size: 0.002 inches or
0.05mm
Male Reproductive System
3.
Scrotum –skin covered
bag which contains testes
a. Testes descend through
inguinal canals 2 months
before birth
(inguinal hernia – part of intestines
bulge through the inguinal canal and
become stuck this could lead to
surgery)
b. Maintains temperature
2°C (3.5°F) below body
temp. .
Male Reproductive System
D. Sperm Transport
1. From testes to epididymis (in scrotum)
for storage & maturation (they
remain here until they are
released from the body).
2. To vas deferens (sperm duct) from
scrotum to abdominal cavity
peristaltic contractions move it
along.
3. To ejaculatory duct which passes
through the prostate gland.
4. To urethra through penis and out of
body (urethra also for urine, a
muscle located at the base of the
bladder prevents urine and sperm
from mixing.)
Male Reproductive System
E. Semen production:
1. Per ejaculate 300-400 million sperm plus
secretions of accessory glands.
Sperm makes up only about 2-% (If male
produces <40 million sperm per ejaculate
sterile) .
(Note: only about 50 or so sperm make it
alive to where the egg is waiting for it. 60%
are usually deformed in some way. But, only
one is needed to fertilize the egg)
2.Seminal vesicles empty
into the vas deferens a
mucus-like fluid that
contains :
*about 60% fructose
(fruit sugar) for fuel.
*bases to balance pH
*hormones to stimulate
contractions of
female reproductive
organs to move sperm
toward the ova
Male Reproductive System
3. Prostate gland--thin,
milky, alkaline secretion
which will neutralize
the acid of other
seminal fluids and the
female's vagina.
Male Reproductive System
4. BULBOURETHRAL
GLANDS: (aka the
Cowper’s gland). clear,
alkaline fluid to neutralize
urethra and lubricates the
glans part of the penis
(Note: there could be sperm in this
fluid and therefore “pulling out”
before ejaculation doesn’t work
effectively as a form of birth
control)
Male Reproductive System
F. Penis
1. The shaft ends in expanded
tip, called the glans.
Foreskin may cover the glans
-- It is removed during
circumcision (infections may
occur if secretions are
retained in this area)
2. Cavernous bodies--3 cylinders
of erectile tissue with large
blood vessels which fill during
an erection.
Male Reproductive System
G. MALE REPRODUCTIVE HORMONES:
1. Puberty – sexual maturation. Begins at 12-13 years of age.
2. Testosterone: secreted during fetal development and shortly
after birth. The production nearly stops until puberty - At
puberty it promotes growth and …
a. Primary sex characteristics– these are required for
reproduction
they are: making sperm, getting and maintaining an
erection, and ejaculation.
b. Secondary sex characteristics—these are not necessary
for reproduction
they are: deep voice, facial/body hair, broad chest,
increased muscle mass.
QUIZ time over the
male’s system
Female Reproductive System-side view
Fallopian tube
Ovary
Uterus
Cervix
Urinary bladder
Rectum
Pubic bone
Vagina
Urethra
d. Clitoris
e. Labia minora
f. Labia majora
Female Reproductive System-front view
Female Reproductive System
A. Functions
1. Produce Ova (eggs)
2. Receive the penis and sperm
3. House and nourish the embryo
(it is called this until the 8th week then it is called a fetus.)
4. Nourish the infant with milk
Female Reproductive System
B. Regulation of system
Regulated by the Menstrual cycle
Female Reproductive System
A. FEMALE REPRODUCTIVE STRUCTURES:
The primary sex organs
are the ovaries.
1. OVARIES:
Produce eggs
and the sex
hormones
estrogen
and
progesterone.
Female Reproductive System
2. FALLOPIAN TUBES: (aka oviduct
tubes) The Fallopian tube expands to
form a funnel shape with fingerlike
extensions called fimbriae, which
encircle each ovary and help direct
the ovum (egg) into the
Fallopian tube.
• Main functions: site of
fertilization and transport
of ova to the uterus.
Female Reproductive System
3. UTERUS: Where implantation and
development of fetus takes place.
Composed of three layers myometrium,
perimetrium, and endometrium (some of
this layer is lost during menstruation.)
• Opening to the
uterus is called
the cervix.
Female Reproductive System
4. Vagina:
receives
sperm and is
the birth
canal.
5. Cervix:
entrance from
vagina to the
uterus
Female Reproductive System
All of the external structure are called the Vulva
1. Labia minora (inner) and Labia majora (outer)
folds of skin. (protects the vaginal and urthral openings)
2. Clitoris -- similar to glans
in male; center of
sexual stimulation.
3. Hymen-- tissue that
Urethra
may partially block
the vagina
Clitoris
4. Urethra (not part of
Labia minora
the reproductive
Labia majora
tract)-- in front of
vaginal opening; urinary passage
Vagina
Female Reproductive System
D. Ova production and Female Hormones
1. Ovaries (primary female sex organ) produce
and contain eggs in various stages of
maturation
2. Oogonia (egg stem cells) are surrounded by
follicle cells (where the eggs grow and
mature). All eggs are produced before birth!
However, only about 400 eggs will mature
and have the ability to be fertilized.
Note: “oo” means egg in latin
Female Reproductive System
3. OOGENESIS:
primary oocytes
grow and begin
meiotic division,
then halt until
puberty -then a few
follicles develop
each month due to
the hormone FSH.
Female Reproductive System
4. Ovulation -- mature follicle ruptures due to
FSH and LH stimulation and ejects
ovum into the pelvic cavity.
5. Follicle turns into the corpus luteum
(yellow body) which secretes
progesterone and estrogen which
prepare uterus for pregnancy.
Female Reproductive System
Hormones functions:
Control egg production, sexual
function, and secondary sex
characteristics.
Female’s hormones:
1. Gonadotrophin Releasing Hormone
(GnRH): the release of this hormone
starts puberty.
Female Reproductive System
2. Estrogen: At puberty, the ovaries
secrete higher amounts which stimulate
the growth and development of female
primary sex characteristics and
accessory organs. Estrogen and
progesterone also develop and maintain
female secondary sex characteristics
such as increase in fat deposits,
broadening of hips, and breast
development.
Female Reproductive System
3. Follicle Stimulating Hormone
(FSH): stimulates the ovary to
respond to estrogen and
progesterone and initiates
oogenesis.
4. Leutinizing Hormone (LH): gets the
ovaries ready for egg production
and causes ovulation at puberty. LH
and FSH start the process of
ovulation.
Female Reproductive System
5. Progesterone: produced by the ovaries
and prepares the lining of the uterus
for pregnancy.
6. Testosterone: secreted by the
pituitary gland causes a growth spurt
at puberty and the growth of pubic
hair and axillary hair.
Female Reproductive System
OVULATION: A surge of LH causes an
egg to be released from the ovary
and its follicle. The egg travels into
the Fallopian tube where it either
disintegrates (if not fertilized) or
starts to mature
(if fertilized)
before going to
the uterus.
Female Reproductive System
E. Ovum transport and pregnancy
1. After ovulation, ovum enters a fallopian tube (also called
oviduct or uterine tube)
a. It’s moved by muscular contractions and cilia.
b. This is where fertilization occurs.
(ectopic pregnancy = egg grows in the fallopian tubes)
2. Endometrium-- uterine lining
which thickens in
preparation for pregnancy.
If egg is not fertilized,
menstruation occurs.
Female Reproductive System
3. Cervix lower part
(neck) of uterus.
Cancer detected
here by a pap smear
4. Vagina -- internal tube,
the birth canal; also
receives the penis
during intercourse.
Female Reproductive System
F. Menstural Cycle
28 day cycle that prepares the uterus for pregnancy
1. Begins at puberty (11-13 years): anterior pituitary
secretes hormones FSH and LH
2. Ends at menopause
(about 50 years)
3. Hormones use feedback
mechanism between the
reproductive system and
the endocrine system
Female Reproductive System
Note: If an embryo
becomes embedded in
the uterine wall, the new
glandular pockets will be
stimulated to secrete
hormones similar to
progesterone/estrogen
and the uterine lining will
be maintained all
through the pregnancy.
Progesterone =
stimulates the uterus to
maintain its thickened
lining and develop
pockets that contains
glands.
Female Reproductive System
Blood vessels grow in
lining as it thickens
Lining ready to
receive an embryo
4-5 days after
ovulation.
If no embryo
arrives, the blood
vessels begin to
break down. Blood
cells from the lining
pass through vagina
during the menstrual
period.
Menstrual/ovarian
cycles begin a new.
Female Reproductive System
Ovulation day 14-16:
**Egg is able to stay
alive 36-48 hours.
**Sperm can live up to
72 hours in the
female reproductive
tract.
Low levels of both
estrogen/progesteron
e signal onset of
menstruation = also
w/low levels of FSH, a
new follicle will be
stimulated to develop
Female Reproductive System
NOTE: After a
women has a baby,
it can be anywhere
from 4-weeks to
3- months before
her menstrual
(bleeding) cycle
reoccurs
depending on if
she is breast
feeding or not. It
doesn’t however,
effect ovulation.
She can still get
pregnant.
FERTILIZATION AND IMPLANTATION
G.
FERTILIZATION:
Once an egg ruptures its follicle it has about 24
hours to be fertilized or it will die. Therefore
sperm must be present in the Fallopian tube in
order for fertilization to occur. Of the 100 to 305
million sperm released during ejaculation only about
50-100 will make it through the highly acidic
environment of the vagina to the Fallopian tubes.
When sperm meets the egg the enzymes in the head
penetrate the egg and the sperm enters losing it’s
tail and mid-section. Once inside no other sperm can
penetrate the egg. Then the nucleus of the sperm
with 23 chromosomes and the egg with 23
chromosomes form a zygote with 46 chromosomes.
FERTILIZATION
NOTE: A pregnancy test, using either urine
or blood, tests for the presence of hCG
(human chorionic gonadotropin) which is
produced in the placenta)
FERTILIZATION AND IMPLANTATION
H. IMPLANTATION:
The now fertilized zygote passes down the
oviduct and begins mitosis (cell division
resulting in cells exactly like the original
cell.) On the 6th day the zygote reaches the
uterus. The zygote is now surrounded by a
hollow body of cells and is now called a
blastocyst, which attaches to the lining of
the uterus 7 to 8 days after fertilization.
This process is called implantation.
IMPLANTATION
Quiz over Female
Reproductive System
IV. EMBRYONIC DEVELOPMENT
A placenta is formed and is attached to
the inside of the uterus. It unites the
fetus to the uterus of the mother
through the umbilical cord. This cord is
made up of blood vessels.
UMBILICAL CORD AND
PLACENTA
EMBRYONIC DEVELOPMENT
EXCHANGE BETWEEN THE EMBYRO AND
MOTHER: The blood supply of the mother
and embryo do not mix. The nutrients and
oxygen that the embryo needs are diffused
from the mother’s blood vessels and taken in
by the blood vessels of the embryo. Waste
products from the embryo are diffused
from the blood vessels in the umbilical cord
to the mother’s blood vessels, where they
are removed by the mother’s excretory
system.
A. FETAL DEVELOPMENT
FETAL DEVELOPMENT INVOLVES 3
PROCESSES
1. Growth: increase in number of cells
2. Development: movement of cells in the
embryo to develop into specific organs
3. Cellular differentiation: cells become
specialized to perform specific tasks
and functions.
B. PERIODS OF PREGNANCY
FIRST TRIMESTER (months 1 to 3):
• Body systems begin to form
• Woman may not realize she is pregnant
• Embryo highly susceptible to external
influences such as drugs, alcohol, and
cigarette smoke; which increase likelihood
of birth defects.
• At 8 weeks all body systems are developed
• Sex of fetus can be determined by
appearance of male or female sex organs
FIRST TRIMESTER (months 1 to 3)
One Month weeks 4-7
Your baby is an embryo
consisting of two layers of
cells from which all her organs
and body parts will develop.
Two Months weeks 8-12
Your baby is now about the
size of a kidney bean and is
constantly moving. He has
distinct, slightly webbed
fingers.
Three Months weeks 13-16
By now your baby is about 3
inches long and weighs nearly
an ounce. Her tiny, unique
fingerprints are now in place.
http://www.babycenter.com/pregnancy-fetal-development-index
PERIODS OF PREGNANCY
SECOND TRIMESTER (months 4 to 6):
• Growth primary focus
• Rapid growth during 4th month
• At 5 months fetus can survive outside the
uterus but only with much medical
assistance
• Homeostasis not maintained by the body of
the fetus
• Immature lungs not able to provide a working
respiratory rate
SECOND TRIMESTER (months 4 to 6)
Four Months weeks 17-20
Your baby is now about 5
inches long and weighs
5 ounces. His skeleton is
starting to harden from
rubbery cartilage to
bone.
Five Months weeks 21-24
Eyebrows and eyelids are
now in place. Your baby
would now be more than
10 inches long if you
stretched out her legs.
Six Months weeks 25-29
Your baby weighs about a
pound and a half. His
wrinkled skin is starting to
smooth out as he puts
on baby fat.
http://www.babycenter.com/pregnancy-fetal-development-index
PERIODS OF PREGNANCY
THIRD TRIMESTER (months 7 to 9):
• Weight
of fetus doubles
• Movement very common
• Eyes open in 8th month
• Rotates head to down position
during the 9th month
THIRD TRIMESTER
( months 7 to 9)
Seven Months weeks 30-33
By now, your baby weighs about 3
pounds and is more than 15
inches long. She can open and
close her eyes and follow a
light.
Eight Months weeks 34-37
Your baby now weighs about 4
3/4 pounds. His layers of fat
are filling him out, making him
rounder, and his lungs are
well developed.
Nine Months weeks 38-41
The average baby is more than
19 inches long and weighs
nearly 7 pounds now, but
babies vary widely in size at
this stage
http://www.babycenter.com/pregnancy-fetal-development-index
Fraternal Twins
4 weeks
8 weeks
12 weeks
16 weeks
Fraternal Twins
20 weeks
32 weeks
24 weeks
36 weeks
BIRTH
C. BIRTH: 3 stages
1. DILATION OF CERVIX: Labor
begins with mild contractions of
the uterine muscles – stimulated
by the hormone oxytocin. These
contractions open or dilate the
cervix so the baby can pass
through the vagina. Can last up
to 24 hours.
BIRTH
2. EXPLUSION OF
BABY: Uterine and
abdominal muscles
work together to
push the baby
through the cervix
into the birth canal
or vagina. Can last
20 minutes to 1
hour.
BIRTH
3. PLACENTAL STAGE:
Placenta detaches
from uterine wall and
is expelled through
the vagina.
Contractions continue
to prevent the
mother from
hemorrhaging or
bleeding to death.
V. Breasts: Mammary glands
1. Function --lactation (milk production)
2. During pregnancy estrogen and
progesterone stimulate their growth
3. After child birth colostrum is produced (high
protein substance that can increase
immunity of the child, comes before the
actual milk)
4. By 3rd day after birth prolactin (hormone)
from anterior pituitary gland in the brain
stimulates milk production.
5. Advantages of breast feeding
a. Bonding occurs between mother and
child
b. Nutritionally perfect
c. Child gets antibodies from mother
d. Enhances recovery of the uterus after
birth
6. Breast cancer --most common kind (after
lung cancer)
VI. Birth Control
If you are against conception (having kids)–
and you are using no method of birth control,
90% of women become pregnant in 1 year
A. Very effective
#1. Abstinence-- NOT having SEX = 100%
EFFECTIVE!
http://www.fda.gov/Fdac/features/1997/babyguide2.pdf
If you think, just once won’t hurt…
VI. Birth Control
2. Oral contraceptives – “The Combination Pill” is
99.9% effective; it prevents Ovulation (pregnancy
25/100,000) “The Mini-pill” only contains one
hormone, progestin (it thickens the cervical
mucus and makes the uterus less receptive to
the implantation of the egg. Recommended for
women who are breast feeding)
3. The Patch - thin, beige, plastic patch that sticks
to the skin. It is used to prevent pregnancy. A new
patch is placed on the skin once a week for three
weeks in a row, followed by a patch-free week.
(pregnancy <1/100 per year)
VI. Birth Control
4. Sterilization
a) Male – vasectomy (tying the vas deferens)
b) Female – tubal ligation (tying the fallopian tubes)
5. Abortion (Ending of the pregnancy)
a) A miscarriage – 50-67% of all pregnancies end
in this type of spontaneous abortion
b) Therapeutic -- to save mother's life
c) As birth control – VERY controversial !!!
VI. Birth Control
B. Somewhat effective
1. Condom -- prevents sperm from getting into
the female body.
2. Diaphragm -- prevents sperm from entering
uterus.
VI. Birth Control
C. Not too effective
1. Rhythm -- abstinence during the fertile period
2. Douche --flushes semen from vagina.
VII. Sexually Transmitted Diseases
What are they?
•Diseases that spread from one person to another during
sexual contact
•STDs are a serious problem in the U.S., infecting
millions of people each year and accounting for
thousands of deaths.
VII. Sexually Transmitted Diseases
•STDs caused by bacteria include
chlamydia, syphilis, and gonorrhea.
•STDs caused by viruses include hepatitis B,
genital herpes, genital warts, and HIV/AIDS.
•STDs caused by parasites include vaginitis,
public lice, trichomoniasis and scabies.
How STD’s affect a baby.
STDs can have many of the same consequences for
pregnant women as women who are not pregnant. STDs
can cause cervical and other cancers, chronic hepatitis,
pelvic inflammatory disease, infertility, and other
complications. Many STDs in women are silent; that is,
without signs or symptoms.
STDs can be passed from a pregnant woman to the baby
before, during, or after the baby’s birth. Some STDs (like
syphilis) cross the placenta and infect the baby while it is
in the uterus (womb). Other STDs (like gonorrhea,
chlamydia, hepatitis B, and genital herpes) can be
transmitted from the mother to the baby during delivery
as the baby passes through the birth canal. She should
consider a C-section to protect the baby from being
infected. HIV can cross the placenta during pregnancy,
infect the baby during the birth process, and unlike most
other STDs, can infect the baby through breastfeeding.
How STD’s affect a baby.
A pregnant woman with an STD may also have early onset
of labor, premature rupture of the membranes
surrounding the baby in the uterus, and uterine infection
after delivery.
The harmful effects of STDs in babies may include stillbirth
(a baby that is born dead), low birth weight (less than
five pounds), conjunctivitis (eye infection), pneumonia,
neonatal sepsis (infection in the baby’s blood stream),
neurologic damage, blindness, deafness, acute hepatitis,
meningitis, chronic liver disease, and cirrhosis. Most of
these problems can be prevented if the mother receives
routine prenatal care, which includes screening tests for
STDs starting early in pregnancy and repeated close to
delivery, if necessary. Other problems can be treated if
the infection is found at birth.
What are the FACTS about STD’s?
You are going to look at a list of STD’s and
record the following:
– Type of pathogen: Viral, Parasitic, or
Bacterial.
– Where it would be found in the body.
– How you would contract the STD.
– Symptoms you would experience if you have
that STD.