Lesson 1: Reproductive Systems
Male
reproductive
system
Further functions
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Urethra: tube from ejaculatory duct
through penis that carries semen and urine
(but not at the same time)
Prostate: also neutralizes acidity of vagina
Bulbourethral gland: also “cleans out”
urethra, releases fluid before ejaculation,
contributes to unplanned pregnancies
Sperm make only a small part of semen;
90+% of volume from seminal vesicles
1.Mitosis
makes
enough cells from
spermatogonium to
keep the same
number and produce
sperm
2.Primary
spermatocytes grow
3.Cells divide through
the two divisions of
meiosis (secondary
spermatocytes)
4.Cells (spermatids)
differentiate as they
develop
Sertoli cells support
developing sperm.
(germinal epithelium)
(nurse cell)
(produce
testosterone)
(spermatozoa)
Structure of a Mature
Sperm (50 um)
 Acrosome: chemicals to
enter egg
 Nucleus: haploid
 Midpiece: “motor”, many
mitochondria
 Flagellum: protein, 9+2
microtubule pattern

Flagellum ~40 um
Hormonal Control of
Spermatogenesis
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Luteinizing hormone
(LH): increases
testosterone levels
Follicle Stimulating
hormone (FSH):
controls meiosis /
number of sperm
Testosterone: helps
sperm production and
development
* FSH and LH named for role in females
(menstrual cycle)
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Secondary sexual characteristics
Related to
sexual
development,
but not
necessary for
reproduction
Development
occurs during
puberty
Roles of Testosterone in Males
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Gonads become either testes
or ovaries (ovary is default)
Gene on Y chromosome (when
fetus is in week 7) shifts
gonads to testes
Testes release testosterone
Testosterone leads to
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development of secondary
sexual characteristics at puberty
Production of sperm
Maintenance of sex drive
Timing and Number of Sperm
Production
Begins at puberty, continues until death
 Continually produced, millions each day
 Complete process takes several months
 One diploid cell produces 4 haploid sperm with
equal amounts of cytoplasm
 May be released voluntarily
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1
2
3
11
4
5
6
10
7
9
8
1. Ureter
2. Urinary
bladder
3. Seminal
vesicle
4. Prostate
5. Bulbourethral
gland
6. Vas deferens
(ductus
deferens)
7. Epididymis
8. Scrotum
9. Testes
10. Urethra
11. Penis
(holds fetus in uterus)
(site of fertilization)
(for urination)
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All follicles present at
birth (one primary oocyte
each)
Follicle stimulating
hormone (FSH) causes
some follicles to develop;
usually one per month
will mature
The follicle stays in the
same place in the ovary
The mature, large, fluidfilled follicle seen before
ovulation is called a
Graafian follicle.
After ovulation, the
follicle becomes the
corpus luteum
Mature (Graafian)
follicle
unequal division of cytoplasm
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A secondary oocyte is released to the fallopian
tubes (oviduct) in ovulation
When triggered by the arrival of a sperm,
meiosis will finally be completed, releasing the
second polar body.
(also called yolk, contains lipid droplets)
for
(and centrioles)
first
Haploid DNA in metaphase II

Estrogen and progesterone are major
female hormones. They cause
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Pre-natal (embryonic/fetal) development of female
sex organs
Development of secondary sexual characteristic
during puberty
Timing and Number of Ova
Production
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All eggs begin meiosis during fetal development
At puberty, ~1 egg / month continues meiosis,
release time hormonally controlled (menstrual
cycle)
Meiosis only completed if sperm enters egg
Unequal division of cytoplasm; one diploid cell
produces one ovum and 2-3 polar bodies
Compare oogenesis and spermatogenesis.
Spermatogenesis v. Oogenesis
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In testes

Millions produced continually 
(after puberty); released as
needed / voluntary control 
Four motile sperm produced
per meiosis (equal
cytoplasm)

Meiosis begins (primarily) in
puberty
Sperm made indefinitely
Requires testosterone and 
Sertoli (nurse) cells
In ovaries
One oocyte released per month
long cycle, hormonal control
One egg per meiosis (+2-3
small polar bodies) with
unequal division of cytoplasm
Meiosis begins during fetal
stage, none in childhood,
completed after puberty (when
sperm present)
Viable egg supply gone by
menopause
Similarities include: mitosis in germ cells, cell growth before meiosis,
two divisions of meiosis, haploid nuclei, need for LH and FSH, etc.
1. Uterus
2. Fallopian
tube
(oviduct)
3. (Fimbriae)
4. Ligament
5. Cervix
6. Vagina
7. Endometrium
8. Ovary
9. Urinary
bladder
10. Urethra
11. Pelvic bone
12. Clitoris
13. Labia
14. Urethral
orifice
15. Intestine
16. Anus
Lesson 2:
Menstrual Cycle and Fertilization
MC - FOLLICULAR PHASE
1.
Low levels of hormones as
lining of uterus
(endometrium) is shed
2.
Increase in FSH stimulates
primary follicle to develop
3.
Growing follicle releases
increasing estrogen, at first
increases FSH receptors,
which means more estrogen
from follicle! (positive
feedback)
4.
Estrogen develops the
endometrium and, at its
peak (critical level), inhibits
FSH and (negative
feedback) releases burst of
LH from the pituitary
5.
LH releases egg from follicle
(ovulation), follicle becomes
corpus luteum
Ovulation
This is the point
when the egg can be
fertilized by sperm.
If the egg is NOT
fertilized, the
menstrual cycle will
continue through the
luteal phase (next
slide)
If the egg IS
fertilized and
implants in the
uterus, a pregnancy
will begin.
MC - LUTEAL STAGE
1. Due to high LH, corpus
luteum develops
2. Corpus luteum releases
more progesterone and
some estrogen
3. Progesterone maintains
endometrium and thickens
it for embryo
4. High progesterone inhibits
FSH and LH
5.
6.
IF no embryo releasing
HCG, corpus luteum
breaks down, decreasing
estrogen and
progesterone 
Endometrium is shed, low
progesterone allows FSH
release, follicle develops,
cycle repeats…
Menstrual cycle: continues until
pregnancy or menopause
Fertilization occurs in the fallopian
tube (oviduct). Only a small
percentage of sperm will reach the
egg.
In animals fertilization can be
internal or external
External fertilization: sperm and egg meet outside the body (usually aquatic
species). More sperm and egg are needed as there is less chance of fertilization and
less protection.
Internal Fertilization
Internal
fertilization:
Sperm meet
egg inside
female body.
More
protection,
more chance
of fertilization.
Human Fertilization
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Sperm push through the corona
radiata (follicular cells) and
then release the enzymes in the
acrosome.
ACROSOMAL REACTION: The
acrosome dissolves the zona
pellucida
The sperm membrane fuses
with the oocyte membrane,
allowing its nucleus to enter
CORTICAL REACTION: The
cortical granules inside the egg
fuse into the perivitelline space,
which distances the cell
membrane and hardens the
zona pellucida
No more sperm can enter!
Prevention of polyspermy!
Summary of Fertilization
(in oviduct / fallopian tube)
Two Become One (awww)
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Before sperm enters, egg is
“stuck” in Metaphase II.
Sperm entry triggers the egg
to complete Meiosis (a polar
body is formed)
The sperm and egg nuclei
replicate their DNA, still in
separate nuclei
In the first mitosis, both
nuclei dissolve and all
chromosomes line up together
in Metaphase
Menstrual cycle review

What is happening in the ovary and the
uterus at each stage?
3
1
2
4
5
Menstrual Cycle review
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Which hormones cause these changes? How
are their levels changing?
4
1
2
3
Lesson 3: Pregnancy and IVF
Early embryo development
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Once the sperm and egg nuclei combine into a single
diploid cell (the zygote), it will begin to divide by
mitosis.
2 cells become 4, 4 become 8, which become a solid
ball of cells (the morula)
The morula becomes a hollow ball of cells called the
the blastocyst
The blastocyst reaches the uterus (from the
fallopian tube), hatches from its envelope, and
implants in the endometrium of the uterus
Pregnancy can only continue if endometrium begins
nourishing implanted blastocyst embryo.
The role of HCG in pregnancy
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HCG: human chorionic gonadotropin
Secreted ONLY by the embryo
Pregnancy tests screen for HCG in the blood
HCG stimulates the corpus luteum to grow
and continue producing estrogen and
progesterone
The corpus luteum will last several months
into pregnancy (1st trimester)
Then the placenta will take over producing
estrogen and progesterone (2nd/3rd trimesters)
The Placenta
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Organ grown of fetal
and maternal cells in
the endometrium
Where materials are
traded between the
mother and the fetus
Produces estrogen
and progesterone to
maintain pregnancy
Placental structure and function
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The disc-shaped placenta is full of
villi that provide surface area
Fetal blood (from the fetus) comes
to/from the placental villi through
the umbilical cord
Maternal blood goes to/from the
placental intervillous spaces
through the uterus
The chorion is the barrier
between maternal and fetal blood
which DO NOT touch, though
the distance between them is
small.
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Placenta
The Fetus and the Amniotic Sac
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Around the fetus grows a complete sac
The amniotic sac is filled with fluid as well as
fetal cells, bits of protein, etc.
In a healthy pregnancy the fluid is sterile and
protects the fetus from being hit or squashed.
Labor and Birth
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At the end of pregnancy,
progesterone levels fall
Oxytocin is made made by
the fetus and the mother
(pituitary)
Estrogen rises, which leads to
more oxytocin receptors in
the uterine wall
Oxytocin encourages the
uterus to contract
Contractions causes the
release of more oxytocin
(positive feedback)
The contractions get stronger
The cervix dilates to 10 cm
Eventually, the baby is pushed
out through the vagina
followed by the placenta
Positive feedback leads to
a climactic event, in this
case birth.
In vitro fertilization
1.
2.
3.
4.
5.
6.
7.
3 weeks of hormone injections or
nasal spray stop the menstrual cycle
High levels of FSH injected for 1.5
weeks to stimulate MANY follicles
HCG (similar in structure to LH) is
injected to cause ovulation
The next day eggs are collected with a
micropipette and the father-to-be
provides sperm
The eggs are collected and combined
with the sperm in a dish
The eggs are incubated and checked
for fertilization
Embryos are selected for health and
implanted into the uterus with
progesterone to support endometrium
For
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IVF
Allows childless couples to have 
(genetic) children, prevents
suffering and sadness
Allows genetic screening to
prevent genetic disease
Women who can’t be pregnant
(organs removed due to disease / 
accident) can have genetic
children through a surrogate
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Against
Usually more embryos are
created than can be used,
these “potential people”
will never develop (stored,
used in research, or
allowed to die)
Embryos are selected,
which some consider
wrong on any grounds
High risk of multiple births;
health risks for fetuses
Inherited fertility problems
are passed on
Expensive, not available
to all
Ethics: OLD SYLLABUS!
William Harvey and Reproduction
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Recall: Galen v. Harvey in
circulation (same guy)
Also researched reproduction
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Studied deer
Failed to discover eggs or
solve reproductive process
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No effective microscopes
Suggested mating did not
produce offspring
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Oops!
Opposed theory that male
“seed” becomes an egg
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Correct, that theory was wrong.
Anatomy and Physiology
Introduction to Homeostasis
Homeostasis
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Maintaining an internal environment
within narrow limits
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Adaptive because it improves enzyme function, etc.
Varying limits, but necessary for all living things
In humans, blood and tissue fluid
Examples include
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pH of the blood / [CO2]
Blood glucose levels
Body temperature
Water balance
Maintaining Homeostasis
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Must SENSE levels of variables
Must DETERMINE if levels are correct
Must RESPOND when levels are not correct
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There is a set point for variables
Small variations around the set point do not
cause a reaction
Larger variations trigger negative feedback,
which will return the variable to the set point
Body Systems Involved in
Homeostasis
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Many systems contribute to homeostasis,
BUT they are all coordinated by two:
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Endocrine: glands that release hormones
carried in blood
Nervous: neurons integrate information from
the entire body
The endocrine and nervous systems work
together (hormones affect neurons; the
hypothalamus affects the pituitary)
Blood glucose concentration
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Blood glucose level is increased:
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Blood glucose level is decreased:
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Absorbed from food
Released from storage molecules
Used in cellular respiration (diffuses from blood into
cells)
Stored in larger molecules (glycogen, lipids)
Sometimes referred to as “blood sugar” but that
is not accurate because there are some other
sugars in the blood
Controlling Blood Glucose Levels
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PANCREAS controls blood glucose
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Receptors in pancreas monitor glucose level
α-islet cells produce glucagon hormone if glucose
levels are too LOW
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Cells release glucose by breaking down glycogen (found
in liver / muscles)
β-islet cells produce insulin hormone if glucose
levels are too HIGH
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Cells absorb more glucose
 Glucose then replaces fat in cellular respiration
 Liver and muscle cells convert glucose into glycogen
Uncontrolled
Diabetes
symptoms
Diabetes
Type I (Insulin-dependent / Type II (Insulin-resistant /
juvenile onset)
lifestyle / adult-onset)
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10% of cases
More commonly diagnosed
in children
(Sufficient) insulin is not
produced
Risk associated with
genetics, autoimmune
attack, and exposure to
some viruses
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90% of cases
More commonly diagnosed
in adults (but increasingly
in children)
Insulin is produced but the
body does not respond
(sufficiently)
Risk associated with
genetics, inactivity,
obesity, and diet
Diabetes – Type 1
Diabetes – type 2
*The stomach does NOT convert
food to glucose! See digestion ppt!
Risks from Diabetes
 Acute
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Weakness
Irritability
Confusion
Dizziness
Dehydration
Coma
Chronic
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TREATMENT of Diabetes
 Type I
Eye damage / blindness
Nerve damage
Kidney damage
Blood vessel hardening
and damage
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Monitoring of blood glucose
multiple times each day
Carefully calculated dosing
with insulin (harvested from
GM bacteria)
Careful diet and exercise
choices
Type II
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Dietary changes: Low GI
(glycemic index) foods
Lifestyle changes: increased
exercise, etc.
Insulin and additional
medications
Control of Body Temperature
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Body heat is a byproduct of cellular respiration
Blood carries heat
Body temperature is sensed by hot- and coldreceptors in the skin, body core, and brain
The hypothalamus integrates the information
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When needed it (stimulates the pituitary to release
a hormone that) stimulates the thyroid to produce
the hormone THYROXIN
Thyroxin has receptors in many body cells;
thyroxin increases body temperature
Understanding arterioles
Arterioles in
temperature
control
Thyroxin
constricts skin
surface arterioles;
less heat is lost.
Increasing Body Temperature

When body temperature is too low:
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HIGH thyroxin from thyroid
Increased metabolism in many cells
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Byproduct of respiration is heat
Shivering (rapid skeletal muscle
contraction)
Increased need for ATP, more cellular
respiration
 Increased heat produced in cells
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Skin Arterioles become narrow
(vasoconstriction)
Less blood flows through skin
 Less heat is lost to the environment
 Core temperature is protected

Decreasing Body Temperature

When body temperature is too
high
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Low throxin levels
Skin arterioles dilate (vasodilation)
More blood flows to the skin, close to
the surface
 More heat is lost to environment
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Reduced metabolism in body cells
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Controlled by nerves:

Sweat glands create sweat (ions and
water)

As water evaporates, heat energy is lost
-- thryoxin
+ thryoxin
+ thryoxin
Typical human temperatures
May vary ±1ºC from set point during a day
 Around 37ºC
If homeostasis fails:
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Too low:
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Too high:
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Frostbite
Hypothermia
Heat exhaustion, heat stroke
Fever

Body sets new set point!
Leptin and Obesity
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Adipose (fat) cells secrete
the hormone leptin
Leptin binds to receptors
in membrane of appetite
center of hypothalamus

Stimulates sympathetic
nervous system
 Increased energy use
 Decreased appetite
Hormones can be lipid or
protein. Which is leptin
and how do you know?
Leptin to treat obesity in humans

Non-functional leptin
alleles can cause
obesity BUT:

Most obese humans are
leptin-RESISTANT (as
opposed to leptinDEFICIENT)
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ob/ob
Injections of leptin need
to be frequent and cause
irritation
There are other causes
of obesity
Benefits only last while
injections are continued
Wild type
Leptin
injections
worked to
reduce
obesity in
ob/ob mice
Melatonin Production
Photoreceptors signal
Photoreceptors
detect
light
darkness to pineal
gland
stimulating
melatonin
In darkness,
the
production.
Melatonin production drops with age.
Melatonin and Circadian Rhythms
Melatonin increases
drowsiness and sleep
duration.
Melatonin is broken
down rapidly.
Secretion from the
pineal gland may take
days to switch to a new
sleep-wake cycle.
Circadian
Rhythms
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With no light input, the
“clock” runs on a slightly
longer day
However, cues like light
entrain the clock to keep
it in synch with the
environment.
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Being off by 10 min.
wouldn’t matter, but off by
another 10 min every day
would have huge
consequences
Problems can come from:
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Age
Night-shift work
Total blindness
Melatonin and Jet Lag
Melatonin pills are taken 30 minutes before
the “new” bedtime on the travel day and/or
the first few days in the new time zone.
JET LAG
 Symptoms due to
rapid shift in 24hour cycle
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Trouble sleeping
Tiredness
Headache
Feeling unwell
and disoriented
Most studies
suggest a benefit
especially for
greater numbers of
time zone changes.