New Fall2018 104 Talk9 - Reproductive Systems.ppt

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1. Human Biology (BIOL 104)
Talk Nine: Reproductive Systems
Animal Reproduction and Development (Chapter 34)

2. A step sideways – global population
Graph courtesy of the Bixby Center on Population,
Health & Sustainability (populationgrowth.org)
•Earth is currently experiencing
the most population increase in
Human history.
•2.5 billion in 1955 to 7.4 billion
in 2017
•At current rate, will double
within 30 years!
•Fastest growing nations have
growth rates at or above 4% -
this will double the countries
population every 17 years

3. From Wikimedia Commons, a freely licensed
media file repository
A step sideways – global population
•Total area (including land and
water) of Earth is 197 million
square miles.
•Population density is calculated as
population divided by total land
area.
•As of 2015, the Earth’s total
population is 7,324,782,225. The
Worldwide human population
density is around 36.66 per sq. mile.
•Many factors influence where
pockets of populations occur on
earth
(Data from worldbank.org)

5. Male Reproductive Anatomy
•In the male reproductive system,
the scrotum houses the testicles
including providing passage for
blood vessels, nerves, and muscles
related to testicular function.
•The testicles are a pair of male
reproductive organs that produce
sperm and some reproductive
hormones.
•Coiled in each wedge are many
seminiferous tubules that produce
sperm.
•Also contain interstitial cells to
make and release testosterone
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University

6. Sperm
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•Sperm are haploid cells, consisting of a
flagellum as a tail, a neck that contains
energy-producing mitochondria, and a
head that contains the genetic
material.
•An acrosome is found at the top of the
head of the sperm.
•Acrosome contains lysosomal enzymes
that can digest the protective
coverings that surround the egg to help
the sperm penetrate and fertilize the
egg.
•Average ejaculate contains from two to
five milliliters of fluid with from 50–
120 million sperm per milliliter.

7. Male Reproductive System
Copyright: OpenStax Biology for AP
Courses, OpenStax, and Rice University
•Sperm mature in seminiferous
tubules that are coiled inside the
testes.
•The walls of the seminiferous
tubules are made up of the
developing sperm cells, with the
least developed sperm at the
periphery of the tubule and the
fully developed sperm in the
lumen.
•When the sperm have developed
flagella and are nearly mature,
they leave the testicles and
enter the epididymis.

8. Male Reproductive System
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•The sperm leave the epididymis and
enter the vas deferens which
carries the sperm, behind the
bladder, and forms the ejaculatory
duct with the duct from the
seminal vesicles
•Semen is a mixture of sperm and
spermatic duct secretions (about
10 percent of the total) and fluids
from accessory glands that
contribute most of the semen’s
volume.

9. Male Reproductive System
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•Semen comes from accessory
glands. These are:
•Seminal vesicles
•Solution is alkaline, contains mucus
and fructose (a sperm mitocondrial
nutrient). Accounts for 60 % of the
bulk of semen
•Prostate gland
•Milky fluid - contains citrate (a
nutrient), an antigen to liquefy the
ejaculate. Account for about 30 %
of the bulk of semen.
•Bulbourethral gland
•It neutralizes any acid residue in
the urethra left over from urine.

10. Male Reproductive System
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•The penis – the copulatory organ
during intercourse.
•Contains three tubes of erectile
tissue running through the length
of the organ.
•During intercourse, the smooth
muscle sphincters at the opening
to the renal bladder close and
prevent urine from entering the
penis.

11. Circumcision
•Cuts or otherwise removes some or all of the foreskin
(prepuce) from the penis.
•Circumcision predates recorded human history, with
depictions found in stone-age cave drawings and Ancient
Egyptian tombs. The origins of the practice are lost in
antiquity.
•Theories include that circumcision is a form of ritual
sacrifice or offering, a sign of submission to a deity, a rite of
passage to adulthood, a mark of defeat or slavery, or an
attempt to alter aesthetics or sexuality.
• Circumcision of males is a religious requirement of the
Islamic and Jewish faiths

12. Circumcision
•The American Medical Association states that
medical associations in the US, Australia, and
Canada do not recommend routine “non-
therapeutic” circumcision, which it defines as the
non-religious, non-ritualistic, not medically
necessary, elective circumcision of male newborns.

•Why?
•What about HIV ?

13. Circumcision
•Religion:
•Circumcision is fundamental to Judaism. It is an
essential component of Jewish practice and is a
commandment obligatory under Jewish law for all
Jewish males on the eighth day after birth unless
health reasons force a delay.
•In Islam, the timing of Muslim circumcision varies.
•While circumcision may be performed at all ages
from newborn period to adulthood, the medical
profession has encouraged medical circumcisions in
the first week after birth to reduce complications.

14. Circumcision
•Cultural:
•Circumcision can be part of an initiation rite in
some African, Pacific Islander, and certain
isolated Australian aboriginal traditions.
•Among the Urhobo people of southern Nigeria it is
symbolic of a boy entering into manhood. The
ritual expression, Omo te Oshare ("the boy is now
man"), constitutes a rite of passage from one age
set to another.

15. Circumcision
•HIV:
•The most recent data indicate that circumcision is
correlated with significantly reduced risks of HIV transfer
during heterosexual intercourse.
•Between 48% and 53% reduction, although the topic
remains the subject of ongoing research and debate in the
medical community.
•There are also fears that some may mistakenly believe
they will be protected against HIV through circumcision
and see circumcision as a safe alternative to other
forms of protection, such as condoms.

16. Circumcision
•In the USA:
• WHY?
•WHEN?
•WHAT DO YOU THINK?

17. Female Reproductive System
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•Ovaries consist of a medulla and
cortex: contains nerves and blood
vessels to supply the cortex with
nutrients and remove waste.
•The outer layers of cells of the
cortex are the functional parts of
the ovaries.
•The oviducts, or fallopian tubes,
extend from the uterus in the lower
abdominal cavity to the ovaries,
•Are not in contact with the ovaries.
•The lateral ends of the oviducts
flare to a trumpet-like structure
and have a fringe of fingerlike
projections.

18. Egg (Oocyte) development
•Oocytes develop in follicles, located in
the ovary.
•At the beginning of the menstrual
cycle, the follicle matures.
•At ovulation, the follicle ruptures,
releasing the egg.
•The follicle becomes a corpus luteum,
which eventually degenerates.
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University

19. Female Reproductive System
Copyright: OpenStax Biology for AP
Courses, OpenStax, and Rice University
•The uterus is a structure about the
size of a woman’s fist. This is lined
with an endometrium rich in blood
vessels and mucus glands.
•The uterus supports the developing
embryo and fetus during gestation.
•The thickest portion of the wall of
the uterus is smooth muscle.
Contractions in the uterus aid in
passing the baby through the
vagina during labor.
•Part of the uterus, called the
cervix, protrudes into the top of
the vagina. The cervix functions as
the birth canal.

20. Female Reproductive System
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•The vagina is a muscular tube that
serves several purposes. It allows
menstrual flow to leave the body.
It is the receptacle for the penis
during intercourse and functions
as the birth canal.
•The clitoris is a structure with
erectile tissue that contains a
large number of sensory nerves
and serves as a source of
stimulation during intercourse.
•The labia are elongated folds of
tissue that enclose components of
the reproductive system
•made from the same tissue that
produces the scrotum in a male

21. Hormonal Control of Human
Reproduction
•In both males and females the
Hypothalamus ultimately control
this process as it secretes
gonadotropin-releasing hormone
(GnRH).
•GnRH stimulates the anterior
pituitary to release:
•Follicle-stimulating hormone
(FSH)
•Luteinizing hormone (LH)
•Which stimulate the male &
female gonads
•A negative feedback system
governs to level of all hormonesFrom Wikimedia Commons, a freely licensed media
file repository

22. Male Hormones
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
•The hypothalamus causes the
release of follicle stimulating
hormone (FSH) and luteinizing
hormone (LH)
•FSH enters the testes -
stimulates the Sertoli cells to
facilitate spermatogenesis using
negative feedback
•LH also enters the testes and
stimulates the interstitial cells
to make and release testosterone
into the testes and the blood.
•The Sertoli cells produce the
hormone inhibin, which is released
into the blood when the sperm
count is too high

23. Female Hormones
•The control of reproduction in females is more complex.
•As with the male, the anterior pituitary hormones cause the
release of the hormones FSH and LH.
•In addition, estrogens and progesterone are released from the
developing follicles.
•Estrogen is the reproductive hormone in females that assists in
endometrial regrowth, ovulation, and calcium absorption
•Progesterone assists in endometrial re-growth and inhibition of
FSH and LH release.

24. Female Hormones
•FSH stimulates development of egg cells, called ova, which
develop in structures called follicles.
•Follicle cells produce the hormone inhibin, which inhibits FSH
production.
•LH also plays a role in the development of ova, induction of
ovulation, and stimulation of estradiol and progesterone
production by the ovaries.
•Estradiol and progesterone are steroid hormones that prepare
the body for pregnancy.
•Estradiol produces secondary sex characteristics in females,
while both estradiol and progesterone regulate the menstrual
cycle.

25. Ovarian and Menstrual Cycles
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
Follicular phase:
•Slowly rising levels of FSH and LH
cause the growth of follicles on the
surface of the ovary. This process
prepares the egg for ovulation.
•As the follicles grow, they begin
releasing mainly estrogens (and a low
level of progesterone.)
•Progesterone levels help maintain the
endometrium to help ensure pregnancy.

26. Ovarian and Menstrual Cycles
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
Ovulation phase:
•Just prior to the middle of the
cycle (approximately day 14), the
high level of estrogen causes FSH
and especially LH to rise rapidly,
then fall.
•Spike in LH causes ovulation: the
most mature follicle ruptures and
releases its egg.
•The follicles that did not rupture
degenerate and their eggs are lost.
•The level of estrogen decreases
when the extra follicles start to
degenerate.

27. Ovarian and Menstrual Cycles
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
luteal phase:
•Menstrual cycle enters its secretory
phase (day 15 to 28).
•The cells in the follicle change to
form corpus luteum - produces
progesterone (and a low level of
estrogen).
•The progesterone facilitates the
regrowth of the uterine lining and
inhibits the release of further FSH
and LH.

28. Ovarian and Menstrual Cycles
Copyright: OpenStax Biology for AP Courses,
OpenStax, and Rice University
luteal phase:
•The uterus is being prepared to
accept a fertilized egg, should it occur
during this cycle.
•The inhibition of FSH and LH
prevents any further eggs and follicles
from developing, while the
progesterone is elevated.
•The level of estrogen produced by the
corpus luteum increases to a steady
level for the next few days.

29. Ovarian and Menstrual Cycles
Copyright: OpenStax Biology for AP Courses, OpenStax, and Rice
University
The ovarian cycle
•governs the preparation of
endocrine tissues and release
of eggs,
The menstrual cycle
•governs the preparation and
maintenance of the uterine
lining.
•Occur concurrently and are
coordinated over a 22–32 day
cycle, with an average length
of 28 days.

30. Ovarian and Menstrual Cycles
•If pregnancy does not occur:
•The corpus luteum degenerates and the levels of estrogen and
progesterone decrease.
•The endometrium begins to degenerate as the progesterone
levels drop, initiating the next menstrual cycle.
•The decrease in progesterone also allows the hypothalamus to
send GnRH to the anterior pituitary, releasing FSH and LH and
starting the cycles again.
•The endometrium begins to regrow, replacing the blood vessels
and glands that deteriorated during the end of the last cycle.

31. Menopause
•As women approach their mid-40s to mid-50s, their ovaries
begin to lose their sensitivity to FSH and LH. Menstrual periods
become less frequent and finally cease.
•There are still eggs and potential follicles on the ovaries, but
without the stimulation of FSH and LH, they will not produce a
viable egg to be released.
•The side effects of menopause include:
•hot flashes and heavy sweating (especially at night)
•headaches,
•some hair loss
•muscle pain
•vaginal dryness
•Insomnia
•Depression
•weight gain
•mood swings.

32. Menopause
•Estrogen is involved in calcium metabolism, without it, blood
levels of calcium decrease. To replenish the blood, calcium is
lost from bone which may decrease the bone density and lead
to osteoporosis.
•Hormone replacement therapy (HRT) can prevent bone loss, but
the therapy can have negative side effects -increased risk of:
•stroke or heart attack
•blood clots
•breast cancer
•ovarian cancer
•endometrial cancer
•gall bladder disease
•dementia

33. The end!
Any Questions?