reproduction and human development for 44 weeks

2. Reproduction
- the creation of new individuals
from existing ones.
2 principal modes:
 Asexual
 Sexual

3.  Asexual reproduction
- (reproduction without sex) is the
creation of genetically identical offspring by a
lone parent.
Types of Asexual reproduction:
 Budding- splitting off new individuals from
outgrowths of existing ones
 Fission- the separation of a parent into two or
more individuals of about equal size.
 Fragmentation-Regeneration- the breaking of
the parent body into several pieces, followed
by regeneration, the regrowth of lost body
parts.

5. ADVANTAGES (Asexual Reproduction):
 It allows animals that do not move from
place to place or that live in isolation to
produce offspring without finding mates.
 it enables an animal to produce many
offspring quickly; no time or energy is lost in
production of eggs and sperm or in mating
DISADVANTAGE:
 It produces genetically uniform populations.

6.  Sexual reproduction
- the creation of offspring through
the process of fertilization, the fusion of two
haploid (n) sex cells, or gametes, to form a
diploid (2n) zygote (fertilized egg).
 Sperm- a male gamete, is a relatively small
cell that moves by means of a flagellum.
 Egg- female gamete, is a much larger cell
that is not self-propelled.
 Zygote- the new individual it develops into,
contains a unique combination of genes
inherited from the parents via the egg and
sperm.

8. How to find a mate?
 Hermaphroditism
- in which each individual has both
female and male reproductive systems.

9.  External
fertilization
- The
parents discharge
their gametes into
the water, where
fertilization then
occurs, often without
the male and
female even making
physical contact.
2 Mechanics of Fertilization:

10.  Internal fertilization-
occurs when sperm
are deposited in or
close to the female
reproductive tract
and gametes unite
within the tract.
2 Mechanics of Fertilization:

11. In terms of genetic makeup, what is
the most important difference
between the outcome of sexual
reproduction and that of asexual
reproduction?
The offspring of sexual reproduction are
genetically diverse, whereas the offspring of
asexual reproduction is genetically identical.

12.  Ovaries
- woman’s gonad,
are each about an
inch long, with a
bumpy surface
 The bumps are follicles, each
consisting of one or more layers of
cells that surround, nourish, and
protect a single developing egg
cell.

13.  An immature egg cell is ejected from the
follicle in a process called ovulation.
 the follicular tissue
that had been
surrounding the
egg that was just
ejected grows
within the ovary to
form a solid mass
called the corpus
luteum

14.  secretes additional
estrogen as well as
progesterone, a hormone
that helps maintain the
uterine lining during
pregnancy.
Corpus luteum
 If the released
egg is not
fertilized, the
corpus luteum
degenerates,
and a new
follicle matures
during the next
cycle.

15.  each ovary lies next to
the opening of an
oviduct, also called a
fallopian tube.
 The oviduct
opening
resembles a
funnel fringed
with finger-like
projections.

16. Uterus
 known as the womb, is
the actual site of
pregnancy.
 about 3 inches long in
a woman who has
never been pregnant.
 The uterus has a thick
muscular wall, and its
inner lining, the
endometrium, is richly
supplied with blood
vessels.
 The term embryo is
used for the stage
in development
from the first
division of the
zygote until body
structures begin to
appear, about the
9th week in
humans.
From the 9th week until
birth, a developing
human is called a fetus.

17.  An ectopic
pregnancy is a
serious medical
emergency that
requires surgical
intervention;
otherwise, it can
rupture surrounding
tissues, causing
severe bleeding
and even death of
the mother.

18.  The narrow neck at the bottom of the
uterus is the cervix, which opens into the
vagina.
 The cervix opens
to the vagina, a
thin-walled, but
strong, muscular
chamber that
serves as the
birth canal
through which
the baby is born.

19.  Vulva is the
collective term for
the external
female genitalia.
 A pair of slender
skin folds, the labia
minora, border the
openings.

20.  a pair of thick,
fatty ridges, the
labia majora,
protect the
vaginal opening.
 The vagina, labia
minora, and a small
erectile organ called
the clitoris all engorge
with blood and enlarge
during sexual activity.

21. Where does fertilization
occur? In which organ
does the fetus develop?
 The Oviduct
 The uterus

23.  The male gonads,
or testes (singular,
testis), are each
housed outside the
abdominal cavity
in a sac called the
scrotum.
 A testis and
scrotum together
are called a
testicle.

24.  From each testis,
sperm pass into a
coiled tube called
the epididymis,
which stores the
sperm while they
continue to
develop.
 Sperm leave the
epididymis during
ejaculation, the
expulsion of
sperm-containing
fluid from the
penis.

25.  Next to the bladder, the vas deferens joins a
short duct from a gland, the seminal vesicle.
 The two ducts unite to form a short
ejaculatory duct, which joins its counterpart
conveying sperm from the other testis.

26.  At that time, muscular contractions propel the
sperm from the epididymis through another
duct called the vas deferens.
 The vas deferens passes upward into the
abdomen and loops around the urinary
bladder.

27. Three sets of glands:
 Seminal vesicles (2)- secrete a thick
fluid that contains fructose, which
provides most of the energy used by the
sperm as they propel themselves through
the female reproductive tract.
 Prostate gland- secretes a thin fluid
that further nourishes the sperm.
 Bulbourethral glands (2)- secrete a
clear, alkaline mucus.

28.  Together, the sperm and the glandular
secretions make up semen, the fluid
ejaculated from the penis during orgasm,
a series of rhythmic, involuntary
contractions of the reproductive structures.
 About 2–5 mL (1 teaspoonful) of semen
are discharged during a typical
ejaculation.
 About 95% of the fluid consists of glandular
secretions, 5% is made up of sperm
(typically 200–500 million of them), only
one of which may eventually fertilize an
egg.

29.  Reproductive cycle
- a recurring sequence of events that
produces eggs, makes them available for
fertilization, and prepares the body for
pregnancy.
 Ovarian cycle
- cyclic events that occur about every 28
days in the human ovary.
 Changes in the uterus define the
menstrual cycle.

30. Sexually transmitted diseases (STDs) are
contagious diseases spread by sexual contact.

31.  Contraception is the deliberate prevention
of pregnancy.
 A woman may have a tubal ligation
(“having her tubes tied”), in which a doctor
removes a short section from each oviduct,
often tying (ligating) the remaining ends.
 A man may undergo a vasectomy, in which
a doctor cuts a section out of each vas
deferens to prevent sperm from reaching
the urethra.
Contraception can prevent
unwanted pregnancy

32.  Temporary abstinence, also called the
rhythm method or natural family planning,
depends on refraining from intercourse
during the days around ovulation, when
fertilization is most likely.
 Oral contraceptives, or birth control pills,
come in several different forms that
contain synthetic estrogen and/or
progesterone (or a synthetic
progesterone- like hormone called
progestin).

33. What is the fundamental
difference between barrier
methods (such as condoms)
and oral contraceptives in terms
of their means of preventing
pregnancies?
Barrier methods prevent sperm
from reaching an egg, while
birth control pills prevent the
release of eggs altogether.

34.  Pregnancy, or gestation
- is the carrying of developing young
within the female reproductive tract.
 Human pregnancy averages 266 days (38
weeks) from fertilization (also called
conception in humans), or 40 weeks (9
months) from the start of the last menstrual
cycle.

37. Affects the Embryo:
1. German measles virus- can cause
serious birth defects
2. HIV- HIV-infected babies usually die of
AIDS within a few years without
treatment.
3. Alcohol and the chemicals in tobacco
smoke, for instance, raise the risk of
miscarriage and birth defects.
4. Alcohol can cause a set of birth defects
called fetal alcohol syndrome, which
includes mental retardation.

38.  First Trimester

39.  Second Trimester

40.  Third Trimester

41. Certain drugs cause their most
serious damage to an embryo
very early in pregnancy, often
before the mother even realizes
she is pregnant. Why?
Because organ systems, such as
circulatory and nervous systems,
begin to develop in the first trimester.

42.  The series of events that
expel an infant from the
uterus is called labor.
 Estrogen- trigger the
formation of numerous
oxytocin receptors on
cells of the uterus.
 Oxytocin- stimulates the
smooth muscles in the
wall of the uterus,
producing the series of
increasingly strong,
rhythmic contractions
characteristic of labor.
 Prostaglandins, local
tissue regulators that
stimulate the uterine
muscle cells to contract
even more.

43. The induction of labor involves
positive feedback, a type of
control in which a change
triggers mechanisms that
amplify that change.

44.  The first stage,
dilation, is the time
from the onset of
labor until the cervix
reaches its full
dilation of about 10
cm. Dilation is the
longest stage of
labor, lasting 6–12
hours or even
considerably longer.

45.  Expulsion stage.
Strong uterine
contractions, lasting
about 1 minute
each, occur every 2–
3 minutes, and the
mother feels an
increasing urge to
push or bear down
with her abdominal
muscles.

46.  Delivery of the
placenta.
(“afterbirth”),
usually within 15
minutes after the
birth of the baby.
 Prolactin and
oxytocin promote
milk production
and release (called
lactation) by the
mammary glands.

47. Reproductive technologies increase our
reproductive options
 About 15% of couples who want children are
unable to conceive, even after 12 months of
unprotected intercourse. Such a condition,
called infertility, can have many causes.
 Infertility is caused by impotence, also called
erectile dysfunction, the inability to maintain
an erection.

48. Reproductive technologies increase our
reproductive options
 Female infertility can result from a lack of
eggs, a failure to ovulate, or blocked
oviducts (often caused by scarring due to
sexually transmitted diseases).
 Other women are able to conceive, but
cannot support a growing embryo in the
uterus. The resulting multiple miscarriages
can take a heavy emotional toll.

49.  Drug therapies (including Viagra) and
penile implants can be used to treat
impotence.
 If a woman has normal eggs that are not
being released properly, hormone injections
can induce ovulation.
 If a woman produces eggs but is unable
to support a growing fetus, she and her
partner may hire a surrogate mother.

50.  Many infertile couples turn to fertilization
procedures called assisted reproductive
technologies.
 In vitro fertilization (IVF), the most common
assisted reproductive technology
procedure, a woman’s eggs are mixed with
sperm in culture dishes (in vitro means “in
glass”) and incubated for several days to
allow fertilized eggs to start developing.