Bio11 schedule
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Lecture: Reproductive system
Lecture exam 2 - Thursday Feb 24
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Posted: Your total points so far (your “grade”
in class)
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Same format as before
Covers Ch 5-8, 11-15
Study guide is posted
Last day to drop with a “W” is this Fri 2/25
Extra credit is due Thur Mar 3
Ch 16 Reproductive System
Males & Females
Embryonic Development
Family planning
HIV/AIDS
The male reproductive system
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Designed for the
continuous production
of a large number of
sperm
Produces
testosterone, the male
sex hormone
Sperm cells
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Highly specialized for
their role in fertilization
Head: contains the
nucleus
Acrosome: contains
enzymes to digest a
passage to the egg
Mitochondria: function?
Tail: for movement
Formation of sperm
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The testes
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produce sperm
the hormone testosterone
Sperm do not complete
their development at body
temp (37°C)
So the testes are outside
of the body in the scrotum
Spermatogenesis
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The testis is packed with
tightly coiled seminiferous
tubules
Sperm production, or
spermatogenesis, takes
place inside the tubules
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Spermatogenesis begins in
germ line cells on the
outside of the tubule
Spermatogenesis
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Germ line cells in the
seminiferous tubules
undergo meiosis to form
sperm
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Are sperm haploid or diploid?
They are released into the
seminiferous tubule
Adult males produce
several hundred million
sperm each day
Meiosis: review
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Germ line cell is diploid
DNA is replicated
Two cell divisions
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2n
Meiosis I and Meiosis II.
The result?
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4 haploid daughter cells
Produces gametes
n
Spermatogenesis
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Sperm cells are made in
the testis
Develop motility in the
epididymis
Delivered to the vas
deferens
When sperm is ejaculated,
it travels from the vas
deferens to the urethra
Spermatogenesis
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Sperm leave the penis
in a fluid called semen
Various glands
(seminal vesicle,
prostate gland and
Cowper’s gland) add
fluids which help
nourish the sperm
Sperm delivery system
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The penis contains 3 long
cylinders of spongy tissue
It is designed to inflate
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Nerve impulses cause the
blood vessels leading into this
tissue to expand
Blood collects in the spongy
tissue and causes the penis to
become erect and rigid
Continued stimulation is
required for ejaculation
Hormones control the male
reproductive system
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FSH
LH
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The pituitary gland
secretes 2 hormones, FSH
and LH
FSH stimulates sperm
formation
LH stimulates the testis to
produce testosterone
Testosterone
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Develops male sex
characteristics
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Develops sexual function
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Enlarges the sex organs
Body hair, beard
Voice change
Sex drive (libido)
Sperm maturation
Stimulates bone and
muscle growth
The female reproductive system
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Designed to
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Ovulation
Produce 1 egg each month
Prepare the uterus for
implantation of the fertilized
egg
Anatomy of the
female reproductive system
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The eggs, or ova, mature in the
ovaries
The fallopian tubes transport
egg to the uterus
The uterus is lined with epithelial
tissue called the endometrium
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the surface of the endometrium
is shed during menstruation
the uterus narrows to a muscular
“neck” called the cervix
The vagina leads from the
uterus to the external genitalia
The Female Reproductive Cycle
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The female reproductive cycle is
actually two cycles in one:
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The ovarian cycle
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Growth and release of 1 egg each month
Coordinated by FSH and LH
The menstrual cycle
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prepares the uterus for possible implantation
of an embryo.
Coordinated by estrogens and progesterone
The ovarian cycle
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Eggs develop from
cells called oocytes
During each
reproductive cycle, one
(usually) of the oocytes
matures
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Only ~400 oocytes
mature and are
ovulated in a woman’s
lifetime
Ovary and Fallopian tube
Ovulation –
only 1 egg matures each month
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Ovulation: the mature
follicle discharges the
egg
The egg is swept up
into the Fallopian tube
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where fertilization may
occur
Ovary and Fallopian tube
FSH and LH coordinate the
ovarian cycle
FSH
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FSH stimulates the growth and maturation of
a follicle
The follicle cells secrete estrogen into the
bloodstream
FSH and LH coordinate the
ovarian cycle
FSH
FSH and LH
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Estrogen levels peak at 12 days
this causes LH levels to surge
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and stimulates ovulation at 14 days
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The mature follicle bursts and releases an egg
FSH and LH coordinate the
ovarian cycle
FSH
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LH
LH (luteinizing hormone) stimulates
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FSH and LH
Formation of the corpus luteum
Secretion of progesterone and estrogens
If the egg is not fertilized, the corpus luteum
breaks down
The uterine (menstrual) cycle
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Rising levels of progesterone and estrogens promote
thickening of the endometrium
When the corpus luteum breaks down  drop in
levels of these hormones
Endometrium begins to shed – menstruation
Pituitary
28_24a
FSH
LH
Ovary
Uterus
Time
Female reproductive cycle
X
FSH, LH
Negative
feedback
Estrogen
Progesterone
Menstrual cycle
Ovarian cycle
Estrogens have several
important functions
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Develop and maintain
female reproductive
structures, secondary
sex characteristics, and
the breasts
Increase protein
synthesis
Preserve bone density
Regulate synthesis of
cholesterol by liver
Embryonic Development
It all starts with fertilization
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Copulation releases hundreds of millions of sperm
into the vagina
Only a few hundred survive the trip to the egg
Only one will fertilize it.
The process of fertilization
Only one sperm reaches the egg
Figure 26.13
The egg’s journey
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Fertilization takes place
in the Fallopian tube
The fertilized egg begins
mitosis – a series of cell
divisions called cleavage
It eventually forms a ball
of cells called a
blastocyst which
implants in the lining of
the uterus
The blastocyst
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Implantation occurs at day 7
The inner cell mass forms the developing embryo
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These are pluripotent stem cells – they give rise to all types of
cells in the body
The outer cell layer (trophoblast) becomes part of the placenta
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Provides nutrients and oxygen to the embryo
What prevents menstruation?
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The implanted embryo
secretes a hormone,
human chorionic
gonadotropin (hCG)
hCG tells the corpus luteum
to continue secreting
estrogen and progesterone
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This prevents menstruation
Because hCG comes from
the embryo and not from
the mother, pregnancy tests
measure hCG
Stages of early development
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Fertilization
Cleavage
Implantation of the blastocyst
(day 7)
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Neural tube forms (days 16-25)
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Organogenesis (4 weeks)
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the first tissue to develop
Formation of body organs
From embryo to fetus 1 4:18
http://www.youtube.com/watch?v=0xvJ-NNuR6M
Fetal Development:
organogenesis
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The process of forming body
organs begins in the 4th week
of pregnancy
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This is a crucial time
Most spontaneous abortions (or
miscarriages) occur during this
period
Alcohol use during pregnancy is
one of the leading causes of
birth defects, producing fetal
alcohol syndrome
Human embryo at 4 weeks
A month-old embryo
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Brain and spinal
cord have begun to
take shape
Four stumpy limb
buds
A short tail
Looks like most
month-old
vertebrate embryos
Programmed cell death –
a key developmental process
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Certain tissues produced during embryonic
development are destroyed– apoptosis
Cells in the developing hands and feet are
killed, separating the fingers and toes
Fetal Development:
the first trimester
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Development is
essentially complete at
the end of the third
month of pregnancy
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All the major organs are
present
Arms and legs begin to
move
The developing human is
now referred to as a fetus
Human fetus at 3 months
2 From embryo to fetus 3:20
http://www.youtube.com/watch?v=aw5v6_5GaLQ&NR=1
Ultrasound imaging
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By the end of the 1st
trimester, the sex of the
fetus can be determined
by an ultrasound exam
An ultrasound image is
produced when highfrequency sound waves
are bounced off the
fetus
Fetal Development
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The second trimester is a
time of growth
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During the 4th month, the
bones enlarge
Mother can feel baby
kicking
By the end of month 6, the
fetus can survive outside
the uterus with special
medical care
Human fetus at 4 months
Fetal Development
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The third trimester is a period of rapid growth
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The weight of the fetus doubles
Brain and lungs complete development
The growing fetus is fed by the placenta
which passes nutrients from the mother’s
bloodstream into the fetal blood supply
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But maternal and fetal blood don’t mix
The placenta
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An organ unique to mammals
Allows close contact between
the bloodstreams of the
developing fetus and mother
The placenta supplies the
fetus with oxygen and
nutrients, and allows fetal
Oxygen,
waste to be disposed of via nutrients and
hormones to
the mother’s kidneys
baby
Placenta also synthesizes
hormones required to
maintain pregnancy
Wastes and CO2
from baby
Childbirth
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The birth of a child is
brought about by a
series of strong,
rhythmic contractions
of the uterus called
labor
Labor is induced by a
strong surge of 3
hormones
Three stages of
labor
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Dilation of the cervix
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Delivery of the infant
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Opens to a width of 10
cm (4 inches)
Strong uterine
contractions
Delivery of the
placenta
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The “afterbirth”
Family planning
Preventing pregnancy
Birth control
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Contraception methods differ in their effectiveness
Most effective
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Least effective
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Sterilization (vasectomy, tubal ligation)
IUD
Implant
Withdrawal
Spermicides
See Birth control effectiveness chart on Planned Parenthood website
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http://www.plannedparenthood.org/health-topics/birth-control//birth-control-effectiveness-chart-22710.htm
Sterilization
vasectomy
tubal ligation
What is an IUD?
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Intrauterine device
IUDs are small, "T-shaped" devices
inserted into a woman's uterus to
prevent pregnancy.
Effective for at least 5 years
How Does an IUD Work?
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Copper affects the motility of sperm,
preventing fertilization.
Also alters the lining of the uterus and
prevents the fertilized egg from
implanting in the uterus.
The implant
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A matchstick-sized rod that is
inserted in the upper arm
Releases the hormone
progestin and prevents
ovulation
It protects against pregnancy
for up to 3 years.
Other methods that use
hormones to prevent ovulation
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Hormone methods
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Birth control Shot, Pill, Ring, Patch
Breast feeding
The birth control shot contains
progestin
The pill, ring and patch contain
both estrogen and progestin.
The hormone methods work
by preventing ovulation
How do these hormones prevent
ovulation?
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FSH
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LH
Negative
feedback
Estrogen
Progesterone
Female sex hormones
coordinate the reproductive
cycle
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FSH and LH  Ovulation
Estrogen and progesterone 
prepare the uterine lining for
implantation
Birth control pills contain
estrogen and progestin
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Turn off production of FSH and LH
Prevent ovulation
Breastfeeding
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While a woman is continuously
breastfeeding, her body does
not make hormones that are
necessary for ovulation
Less than 1 out of 100 women
who practice continuous
breastfeeding perfectly will
become pregnant.
Using breastfeeding as birth
control can be effective for 6
months
Condoms
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Condoms are thin latex or plastic sheaths that are worn on the
penis during intercourse.
Condoms prevent pregnancy by collecting semen when a man
ejaculates. This keeps sperm from entering the vagina and
“meeting” the egg.
They also reduce the risk of sexually transmitted infections.
The Diaphragm
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A shallow latex cup inserted into
the vagina. When in place, it covers
the cervix (the opening to the
uterus)
Diaphragms prevent pregnancy by
keeping sperm from entering the
uterus
In order to be as effective as
possible, the diaphragm is used
with spermicide cream or jelly.
Recap: How different birth
control methods work
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Prevent ovulation
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Prevent implantation of embryo
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IUD
Block or kill sperm
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Hormone methods – Implant, birth control pill, shot, ring, and
patch; Plan B; breast feeding
IUD, condom, diaphragm, spermicidal jellies
Sterilization
Which of these prevent STIs?
Which are the woman’s responsibility?
Plan B (morning after pill)
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What is Plan B?
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Emergency contraception
Should be taken within 3 days after
intercourse
Plan B contains only progestin, a
synthetic hormone used in birth control
pills
How does Plan B work?
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X
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Stops ovulation
may prevent
fertilization and
implantation
But …
Plan B will not work
after the fertilized
egg is implanted.
How does the pregnancy test
work?
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It measures hCG levels
The embryo secretes
human chorionic
gonadotropin (hCG)
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hCG
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hCG comes from the embryo
and not from the mother
Excess hCG is excreted in
the mother’s urine
The AIDS pandemic
Speaking of STIs
HIV/AIDS
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The problem is massive
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4th leading cause of death worldwide
~40 million people are infected
95% live in developing countries
What makes HIV so lethal?
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The HIV retrovirus highjacks immune cells
HIV infects and destroys the very cells that
normally suppress viral attacks
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the helper T cells of the human immune system
Long incubation period
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The victim feels healthy but is highly infectious
HIV highjacks immune cells
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HIV binds to the plasma
membrane of helper T cells
Penetrates the cell
Viral RNA is integrated into
the cell genome
Human helper T cells
‘manufacture’ the virus
Infected cells are killed
eventually
HIV life cycle 3:10
http://www.youtube.com/watch?v=9leO28ydyfU&feature=related
HIV budding from an immune
cell in culture
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The viruses bud so
rapidly that the cell
eventually lyses
The number of helper T
cells drops, and the body
cannot fight off other
infections
These secondary
infections cause AIDS
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Acquired immune
deficiency syndrome
Where is the virus?
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HIV is found in all body fluids
Only semen, blood, breast milk and
vaginal discharge have enough virus to
transmit HIV
Saliva, tears and sweat do not
How is HIV transmitted?
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Unprotected sexual intercourse
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Heterosexual or homosexual
Direct contact with infected blood
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Sharing needles
Blood transfusions
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blood is tested for HIV (not always in poor countries)
Mother-to-child
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HIV can infect the fetus in utero, or during birth
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Without treatment, rate of transmission is 25%
Breast-feeding
Treating AIDS:
Antiretroviral therapy (ART)
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More than 25 drugs have been developed
Usually given in a “cocktail” of 3 or 4 pills
ART is costly, must be maintained every day
for the rest of the patient’s life
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Still no cure or vaccine for HIV
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Avoid developing resistance to drugs
The virus is constantly mutating – a moving target
Prevention is key
Risk of HIV infection
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90% of HIV-positive people do not
know they are infected
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Long incubation period btwn infection
and major illness
Most people have no access to testing
Stigma
If there’s no treatment available, why get
tested?
Prevention efforts have lagged
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ABC program - ineffective
New approaches
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Routine HIV testing: Know your status
Take ARVs – reduce level of HIV and transmission
Male circumcision
Female condoms
Still in R&D stage
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Vaginal microbicides
HIV Vaccine – the holy grail
Pop quiz – Name the 3 main
routes of HIV transmission
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Sexual intercourse
Blood or blood products
Mother-to-child transmission