Download Reproductive System

Chapter 25
Reproduction and Development in
Humans
(I) Female
Reproductive
System
Terms
Gonads
Females Ovaries
Males
Testes
Gametes Gametogenesis
(The process)
Ova
Oogenesis
Sperm
Spermatogenesis
Gametogenesis
The production of gametes
(sex cells)
Males = spermatogenesis in
the testes
Females = oogenesis in the
ovaries
(A) Ovaries
The female gonads
1. Located within the lower
portion of the body cavity
2. In the ovaries, each egg cell
(ovum) is present in a tiny sac
called a follicle
(A) Ovaries
3. About once a month, a follicle
matures and bursts. The egg
is then released and travels
into the oviduct (Fallopian
tubules)
****This is known as ovulation
4. Fertilization takes place within the
Fallopian tubules (oviduct) forming
a zygote
5. The zygote then travels down and
into the uterus where it implants
into the uterine lining and develops
6. When embryonic development of
the baby is completed, the cervix
dilates (opens) and the baby
travels through the birth canal
known as the vagina
7. The ovaries also produce sex
hormones known as estrogen and
progesterone
a) estrogen- used for the
development of secondary sex
characteristics like mammary
glands (breasts)
b) progesterone- maintains
pregnancy
Figure 39–14 The Female
Reproductive System
Section 39-3
The Arethra:
Oops, wrong one
Ovary
Female Reproductive Structures, (side VW)
Vertebrae
Bladder
Rectum
Sperms path
Figure 39–2 The
Endocrine Glands
Section 39-1
Hypothalamus
The hypothalamus makes
hormones that control the
pituitary gland. In addition, it
makes hormones that are stored
in the pituitary gland.
Pituitary gland
The pituitary gland produces
hormones that regulate many of the
other endocrine glands.
Parathyroid glands
These four glands release
parathyroid hormone, which
regulate the level of calcium
in the blood.
Thymus
During childhood, the thymus
releases thymosin, which
stimulates Tcell development.
Adrenal glands
The adrenal glands release
epinephrine and nonepinephrine,
which help the body deal with stress.
Pineal gland
The pineal gland releases melatonin, which
is involved in rhythmic activities, such as
daily sleep-wake cycles.
Thyroid
The thyroid produces thyroxine, which
regulates metabolism.
Pancreas
The pancreas produces insulin and glucagon, which
regulate the level of glucose in the blood.
Ovary
The ovaries produce estrogen and progesterone.
Estrogen is required for the development of secondary
sex characteristics and for the development of eggs.
Progesterone prepares the uterus for a fertilized egg.
Testis
The testes produce testosterone,
which is responsible for sperm
production and the development of
male secondary sex characteristics
The Effects of Estrogen
Section 39-3
Figure 39–22 The
Placenta
Section 39-4
(II)
Menstrual Cycle
Mature egg develops and is released
Begins at puberty and ends at
menopause
Hormones involved:
FSH
estrogen
LH
progesterone
Stages involved in order:
follicle stage  ovulation  corpus
luteum  menstruation
1. Follicle
Stage 10-14
days
* FSH is secreted by the pituitary gland which
stimulates maturation of egg in the follicle
** As the follicle develops, it releases estrogen
which stimulates the uterine lining to thicken
with blood
2. Ovulation
Secretion of LH (lutenizing hormone) from the
pituitary causes a mature egg to be released
from the follicle and into the fallopian tubules
(oviduct)
3. Corpus
Luteum
10-12 days
* The burst follicle fills with cells forming the
corpus luteum, which produces progesterone
fuher thickening of the uterine lining
4.
Menstruation
3-5 days
If the egg is not fertilized, progesterone secretion
decreases and the lining of the uterus breaks
down
The lining of the uterus is sloughed off and
discharged from the body through the vagina as a
result (period).
The Menstrual Cycle
Section 39-3
The Menstrual Cycle
Section 39-3
Do Now 4/26
1. Describe the menstrual cycle.
(remember there are 4 stage!!!!)
2. What is a Feedback Mechanism?
(II)
Menstrual Cycle
FSH stimulates
from the ___
1. Follicle
stage
4.
Menstruation
Progesterone
maintain the ___
Estrogen
thickens the ___
2.
Ovulation
3.
Corpus
Luteum
Luteinizing
hormone is
produced by ___
1. Follicle Stage
10-14 days
FSH is secreted by the pituitary gland
which stimulates maturation of egg in
the follicle
As the follicle develops, it releases
estrogen which stimulates the uterine
lining to thicken with blood
2.
Ovulation
Secretion of LH (lutenizing
hormone) from the pituitary causes
a mature egg to be released from
the follicle and into the fallopian
tubules (oviduct)
3. Corpus Luteum Stage
10-12 days
The burst follicle fills with cells
forming the corpus luteum, which
produces progesterone
Progesterone stimulates further
thickening of the uterine lining
4. Menstruation
3-5 days
If the egg is not fertilized, progesterone
secretion decreases and the lining of
the uterus breaks down
The lining of the uterus is sloughed off
and discharged from the body through
the vagina as a result (period).
Check your hw
answers using
the transparency.
(VI)
Male
Reproductive
System
Figure 39–12 The Male
Reproductive System
Section 39-3
(A)
Testes
Are the male gonads
Produce sperm
Sperm is produced in the
seminiferous tubules and stored in
the epididymis
Sperm then leaves the epididymis
through the vas deferens and into
the urethra (which is a tube inside
the penis)
The process
The penis is a structural
adaptation for internal fertilization
Glands secrete a liquid into the
urethra which combines with the
sperm cells. This liquid serves as
a transport medium for the sperm
cells and is called semen
Testes also produce the male sex
hormone called testosterone
Testosterone regulates the maturation of
sperm and the development of
secondary sex characteristics such as
beard development and voice pitch
Scrotum- sac in which the testes are
located
a) outside the body
b) keeps the temperature 1-2 degrees
Celsius cooler than normal body
temperature
c) this provides an optimum
temperature for sperm production
HEAD with NUCLEUS &
ACROSPORE
Shaft (middle region)
TAIL (MOTILITY)
Vasectomy
Male sterilization or
vasectomy is a simple
procedure in which a
piece of each vas
deferens is cut out just
above the epididymis
and the cut ends are
tied. This procedure is
normally done under
local anesthetic in the
doctor's office.
Because the sperm
stored in the epididymis
can no longer flow
through the vas
deferens, the man's
ejaculate does not
contain sperm.
(III) Fertilization and Implantation
1. Fertilization occurs in the
fallopian tubules (oviduct)
2. If the egg is not fertilized within 24
hours after ovulation, it will
deteriorate
3. After fertilization, the zygote
undergoes cleavage and becomes
an embryo
(I) Sexual
Reproduction
Two parents give rise to new offspring
by the fusion of nuclear materials from
two different cells
Offspring are not identical to the parent
Variations exist, which increases the
species ability to adapt to the changing
environment
(A) Reproductive
System
Gonads- specialized organs that
produce gametes
a) ovaries - female gonad
- produce ova (egg)
b) testes - male gonad
- produce sperm cell
(B)
Hermaphrodite
Contain both male and
female reproductive
structures
(C)
Gametogenesis
Process by which gametes
are produced in the gonads
Two types:
- Spermatogenesis
- Oogenesis
Oogenesis
The primary oocyte goes
through first meiotic
division and the cytoplasm
of the cell is divided
unequally
The larger daughter cell is
called the secondary
oocyte and the smaller
daughter cell is called the
polar body
During second meiotic
division, 1 mature ovum is
produced and 3 polar
bodies
Spermatogenesis
Primary spermatocyte
goes through first
meiotic division and
form two daughter
cells of equal size
Each daughter cell
(secondary
spermatocyte) goes
through the second
meiotic division
forming four motile
sperm cells of equal
Comparison of Ova and
Sperm
Egg cells contain stored food in
the form of yolk
Egg cells are larger than sperm
Sperm are motile, egg cells are
not
(B) Fertilization
The fusion of the nuclei of
one sperm with one ova (egg)
to produce a zygote
Sperm (n) + Ovum (n) =2n
Sperm (23) + Ovum (23) = 46
Parthenogenesis
•An embryo develops from an unfertilized egg
•typically involves the development of eggs into viable offspring from
females without fertilization by sperm..
• Parthenogenesis is no longer only for lower invertebrates, such as aphids,
mites and nematode worms--it's also been found in fish, bees, birds and
lizards.
the second polar body -- the daughter cell produced along with the egg in the second
stage of meiosis -- acts like a sperm and re-enters the egg. Essentially the egg fertilizes
itself! As this polar body contains identical genetic material to the egg, having been
produced by normal division of an already haploid cell, the resulting diploid cell has only
half the genetic diversity of the female's original cells. Thus fewer bands appear in the
DNA fingerprint of the offspring.
Parthenogenesis
Fertilization
Union of a haploid
sperm nucleus with
a haploid egg
nucleus

n
n
This results in a
diploid zygote with
the full number of
chromosomes
2n
Fertilization
Union of a haploid
sperm nucleus with
a haploid egg
nucleus
This results in a
diploid zygote with
the full number of
chromosomes
Fertilization and the Stages
of Mitosis
Two types of
Fertilization
External Fertilization
Internal Fertilization
**Parthenogenesis**
External Fertilization
•Eggs are fertilized outside the
body of the female
•Large number of eggs are
required
•This type of fertilization is
found in an aquatic environment
Ex: fish and frogs
Spawning???
http://www.umces.edu/2002Session/oyster.html
External
Fertilization
External
Fertilization
External
Fertilization
External
Fertilization
What are some
differences between
External and Internal
Fertilization?
Provide examples!!!
External
Fertilization
External
Fertilization
External
Fertilization
External Fertilization
Internal
Fertilization
Takes place inside the body
of the female
Less eggs are required
Ex: mammals, birds and
reptiles
Internal
Fertilization
The embryo arrives in the uterus 5-10
days after fertilization
The embryo implants into the uterine
wall and establishes pregnancy
Placenta- nourishes the embryo
Umbilical cord- attaches the embryo to
the placenta
Amnion- embryo develops inside the
amniotic sac which contains amniotic
fluid that serves as a shock absorber
Gestation Period- length of pregnancy
(approximately nine months)
Fertilization
Good Review Webpage
http://regentsprep.org/Regents/biology/biology.cfm
Fertilization and
Implantation
Section 39-4
Fallopian tube
Day 2
Day 3
Day 1
Day 4
4 cells
Morula
Day 7
Blastocyst
2 cells
Fertilization
Zygote
Day 0
Implantation of
blastocyst
Uterine wall
Ovary
Egg released
by ovary
http://regentsprep.org/Regents/biology/units/reproduction/index.cfm
http://regentsprep.org/Regents/biology/biology.cfm
Development
The zygote, which is a fertilized egg consisting of one cell, will
begin to divide rapidly by mitosis forming the early developing
human embryo. Fertilization and the initial stages of this
mitotic cell division occur in the oviduct. The early embryo is
migrates down the fallopian tube and completes most of its
development in the wall of the uterus.
Do Now
Ectoderm
Mesoderm
Endoderm
Looking at the diagram above. Hypothesize the
systems that will develop from these three layers.
Reproductive
Muscles,
Skeleton
Digestive
Nervous
ETC
It is the three germ layers that give rise to all
the tissues and organs of an animal
Ectoderm
Mesoderm
Endoderm
Nervous system
bones and
muscles
lining of digestive
tract
blood and blood
vessels
lining of trachea,
bronchi, and
lungs
Digestive System
lining of mouth,
nostrils, and anus
epidermis of skin, reproductive and
excretory system
sweat glands,
hair, and nails
dermis layer of
skin
liver, pancreas
thyroid,
parathyroid
urinary bladder
The Three germ layers
Do Now
Identify what is the purpose of the
following:
The placenta:
The umbilical cord:.
The amniotic fluid:
Do Now answers
The placenta is a combination of maternal and fetal
tissue which allows for the exchange of materials with
the fetus and mother. Needed materials such as
food and oxygen diffuse through the placenta to the
fetus, while wastes from the fetus diffuse to the
mother.
The umbilical cord is a fetal structure containing
blood vessels which allows materials to be carried
between the fetus and placenta in both directions.
The amniotic fluid surrounds the fetus and helps to
provide a shock absorber to protect the fetus against
mechanical injury in the event the mother is shaken
or injured in some manner.
Human Development
Fetal Development
Development is a highly regulated
process After this small cluster of cells called
the gastrula forms in humans, tissues begin
to form. In humans, the
embryonic development of essential organs
occurs in early stages of pregnancy. During
the first three months of human development,
organs begin to form.
The human embryo is usually referred to as
a fetus when human like features become
visible in its structure.
All organs and body features are developed
by the end of the sixth month. During
the last three months of pregnancy, organs
and features develop well enough to function
after birth.
What are some things that could
affect fetal development?
6 weeks
4 months
What are some things that could
affect fetal development?
The embryo (or fetus) may encounter
risks from faults in its genes and from its
mother's exposure to environmental
factors such as:
inadequate diet
 use of alcohol (Fetal alcohol syndrome)
 Tobacco
 Drugs
 other toxins
 infections

Reproductive Technologies
Reproductive technology has medical, agricultural, and
ecological applications. In many instances, these
technologies have progressed at a faster rate than the
ethical considerations resulting from these technologies.
Some of these techniques include birth control methods
used to block the process of fertilization.
Many technologies now exist to enhance the process of
fertilization and development in humans and other
organisms.
 Amniocentesis
 Hormone therapy can cause increased egg production.
 Surgery can open blocked fallopian tubes in females and
the vas deferens in males.
 In vitro fertilization (test-tube babies) is a widely used
technique to aid infertile couples, allowing them to have
children where this otherwise would not be possible.
Amniocentesis
Fetal cells are
removed and
surveyed for
genetic
disorders
Reproductive Technologies
(IV) Multiple Births
1. Identical twins- Develops from one
zygote separating into two during
cleavage. One sperm and one egg is
involved and therefore the babies will
look identical and must be of same sex
(IV) Multiple Births
1. Identical twins- Develops from one
zygote separating into two during
cleavage. One sperm and one egg is
involved and therefore the babies will
look identical and must be of same sex
Identical twins
do not have
identical
fingerprints.
They are a
product of their
environment.
Conjoined Twins
Conjoined “Siamese”
Twins Chang and Eng
Eng Bunker---Chang Bunker
Born: May 11, 1811
Died: January 11, 1874
The developing embryo begins to
split into identical twins but then
stops part way leaving the
partially separated egg to mature
into a conjoined fetus.
They are more often female than
male (ratio of 3:1)
They occur as often as once in
every 40,000 births but only once
in every 200,000 live births.
40% are still born
70% are female - even though monozygotic twins are
more frequently male than female.
75% are still born or die within 24 hours.
Cephalophagus
Dicephalus
This refers to one body with two heads.
Ischophagus
Anterior union of the lower half of the body
http://www.conjoined-twins.i-p.com/
Conjoined twins
Parasitic twins:
Asymmetrical conjoined twins, one twin being small,
less formed, and dependent upon the other.
Fetus in fetu:
Situation in which an imperfect fetus is contained
completely within the body of its sibling.
(V) Multiple Births
Fraternal twins- Develop from two separate
eggs, each fertilized by separate sperm
cells. Therefore, the babies may not look
identical and could be of different sex.
Simply ciblings!
(V) Multiple Births
Fertility drugs often cause production of
more than one ovum during ovulation.
Septuplets = 7 ova + 7 sperm (7 zygotes)
(V) Multiple Births