2. ORGANISIMAL REPRODUCTION
All living things are capable of giving rise
to organisms similar to themselves. They
have a life span after which they die. For
example, man has a life span of about 75
years in developed countries while that of
a dog is about 10 years.
REPRODUCTION
is indispensable for the survival as well as
the evolution of the species.
3. ASEXUAL and SEXUAL
REPRODUCTION
There are TWO types of
reproduction, namely, asexual and
sexual reproduction
Asexual reproduction there is
only one parent with no special
reproductive organs and no sex
cells involved. It is simple and
rapid. The descendents look like
the parent except for the size.
4. Sexual reproduction
involves two parents which
contribute sex cells or gametes
that unite to produce a new
individual.
Gametes- A cell that fuses with
another reproductive cell of the
opposite sex during fertilization
forming a zygote that develops
into a new individual.
5. 2 types of Gametes
1) egg or ovum- produced by
female
2) spermatozoa or sperm- by the
male.
Both cells have half the
chromosome number of the
parents (or are haploid)
6. Asexual Reproduction in Animals
Asexual Reproduction is found only among
the simple forms of animals such as
protozoans, sponges, coelenterates, bryozoans
and a few others. It is absent in higher
invertebrates (mollusks and arthropods) and
all vertebrates. In animals the forms of
asexual reproduction are fission, budding,
fragmentation and spore formation.
7. Types of Asexual Reproduction
➔ Fission is a common among
protozoans like Amoeba, Paramecium.
In this method the body of the parent is
divided into two equal parts, each of
which will become similar to the
parent. It is either (crosswise) or
longitudinal (lengthwise).
➔ Budding is an unequal division of
the organism.
8. GEMMULLES- are internal buds
found in sponges that are the result
of asexual reproduction, and are a
response to a hostile environment.
➔ Fragmentation this involves the
breaking of the individual into two
or more parts, each capable of
developing into new individuals.
9. Sexual Reproduction in Animals
Involves a gamete or gametes. The
production of spermatozoa referred to as
spermatogenes is occurs in the testis
while development of egg cells or ova
(pathogenesis) occurs in the ovary.
10. Forms of Sexual Reproduction
Conjugation
Parthenogenesis
Hermaphroditism
Biparental reproduction
11. Conjugation
This is the simpliest for of asexual reproduction
and is commonly found in paramecium. Two
individuals come together and exchange a
portion of their nuclear material.
Hermaphroditism
One individual has both male and female
gonads. In short, it is monotonous (from the
Greek word “mono”, one and “oiks”, house).
Generally, hermaphrodites do not practice self-
fertilization rather they have cross-fertilization.
12. Parthenogenesis
This is a modification of sexual reproduction in
which an unfertilized egg develops into a complete
individual. It may occur for several generations
followed by a biparental generation in which the
egg is fertilized.
The fertilized eggs (=diploid) become the females
(future queens and workers) while the unfertilized
ones (=haploid) become males (=drones).
13. Biparental Reproduction
Is the most common form of reproduction
found among many invertebrates and all
vertebrates. It involves separate distinct
male and female individuals with gonads
producing either the male or female
gametes but not both. This condition
called dioecious.
14. Anatomy of the Human
Reproductive System
(Vertebrates Reproductive System)
15. In vertebrates the plan includes the following:
(1) gonad- to produce sperm and egg and sex
hormones
(2) ducts- to transport gametes
(3) special organs- to transfer and receive gametes
(4) accessory glands (both endocrine and exocrine)
-to provide secretions required in reproductive
process.
16. Male Reproductive System
The paired gonads (testes) are found in scrotal
sacs descended from the body cavity where the
lower temperature favors spermatogenesis. The
testis which secretes testosterone (male
hormones) contains many highly coiled fine
tubes (seminiferous tubules) where the
development of the sperm takes place. From the
tubules, the sperm leave the testis via tiny
ducts, the vas efferens, into the coiled
epididymis and then to the vas deferens.
17. Passing through the epididymis, the cellular
debris are removed and the fertilizing of
the sperm is enhanced. The deferent duct
joins its opposite from the other testis and
enter the penis as a common duct, the
urethra, which conduct both sperm and
urine into the female reproductive tract.
18. The exocrine glands opens into
the reproductive channels:
(1) the seminal vesicle- which opens into each vas
deferens before it meets the urethra.
(2) Prostate gland- a single fused gland
(3) Cowper's gland- found near base of penis, both
of which secrete into the urethra.
Fluid form these structures which form part of the
seminal discharge provides food to the sperm,
lubricates the passageways, and counteracts the
acidity of the urine so as not to harm the sperm.
19.
20. PARTS FUNCTION/S
testis Produce sperms and male
sex hormones
epididymis Helps in maturation of sperm
Vas deferens Passageway of sperm
to urethra
Seminal vesicle Contribute to seminal fluid
Prostate gland Contribute to seminal fluids
Cowper's gland Contribute to seminal fluid
urethra Passageway of sperm from
vas deferens to outside of body
penis Organ of copulation
21. The female reproductive system contains paired
ovaries, oviducts or fallopian tubes, a single
uterus or womb, the vagina and accessory glands.
The almond-sized ovaries alternately produce a
mature ovum on the average once every 28 days.
The released ovum or egg is received by the
fallopian tube where fertilization takes place.
Within one week fertilized egg travels to the uterus,
a highly muscular organ, where it is implanted. A
new organ, the placenta is formed from fetal and
maternal tissues.
Female Reproductive System
22. Through the placenta maternal blood containing
food and oxygen are made available to the
developing fetus while carbon dioxide and
nitrogenous materials are carried through the
maternal blood for disposal through the mother's
respiratory and excretory organs, respiratory and
excretory organs, respectively. Gestation period
takes about nine months after which the baby is
delivered through the vagina, which is also
adapted to receive the penis of the male.
24. PARTS FUNCTION/S
Ovaries Produce eggs/ ova and
sex hormones
Fallopian tube Site of fertilization
uterus Site of implantation of embryo
cervix Passageway of baby
during delivery
vagina
Passageway of semen
during sexual intercourse
and of baby during delivery.
25. Menstrual Cycle is a coordinated by
hormones.
Two coordinated cycles
Ovarian cycle which results in the release
of the ovum
Uterine cycle which is prepared to receive
the developing embryo.
26. The menstrual cycle involves the release of an egg from
the ovary (in ovarian cycle), and the build-up of the
uterine walls (in uterine cycle) and role of hormones.
27. Pregnancy
If the egg is fertilized, the zygote starts to
divide forming a blastula (blastocyst). After
implantation in the uterus, the cells covering
the blastula start to secrete another hormone,
the human chorionic gonadotropin, which
maintains the corpus luteum until the placenta
is formed. High levels of estrogen and
progesterone are maintained during pregnancy
by the placenta and so the ovarian cycle ceases
until delivery of the fetus.
28. Towards the end of the third trimester of
pregnancy the ratio of estrogen-progesterone
shifts in favor of estrogen. Estrogen
stimulates contraction of uterine walls while
progesterone inhabits it. Oxycontin secretion
by the pituitary gland of both mother and
fetus increases at the time of labor, and this
stimulates uterine constraction. The strong
constraction of the uterine walls mark the
beginning of childbirth or parturition.
29. Lactation is also controlled by hormones.
Proclatin from the posterior pituitary gland
promotes the milk production of the
mammary glands. As the baby suckles, a
neural signal from the breast causes the
release of oxytocin. This hormone
stimulates the contraction of the muscles of
the breast, thus ejecting the milk through
the ducts of the mammary glands.
30. ONTOGENETIC DEVELOPMENT
Involves a gamete or gametes. The
production of spermatozoa referred to as
spermatogenes is occurs in the testis
while development of egg cells or ova
(pathogenesis) occurs in the ovary.
31. Stages in the
development of
a representative
vertebrate, the
frog, until
maturity. The
stages from
fertilization
through
hatching or birth
are known
collectively as
embryogenesis.
32. The development of an individual involves
several stages described as follows:
1. Gametogenesis
The development of the ova (oogenesis) ovary
and testis, respectively.
2. Fertilization
The next phase in ontogenetic development is
fertilization or the fussion of the ovum and
sperm. Although only one sperm is needed to
fertilize the egg, a large number of sperm are
required in the process to dissolve the egg
membranes.
33. 3. Cleavage
The rapid and repeated divisions of the fertilized egg
is called cleavage. The unicellular egg is transformed
into a multicellular blastula or blastoderm with a
cavity called blastocoel. No growth occurs thus the
cells or blastomeres become increasingly smaller
during this stage. There is just an increase in blastular
DNA.
4. Gastrulation
The next phase of development is gastrulation. This
stage establishes the three layers (germ layers) of the
embryo. The group of cells from the surface of the
blastoderm move inside to give rise to the innermost
layer (endoderm) and the middle layer (mesoderm).
What is left becomes the outermost layer (estoderm).
34. 5. Organogenesis
From the three germ layers, the organs are
formed (organogenesis). The ectoderm
gives rise to the nervous system (brain and
spinal cord and sense organs) and the
epidermis. From the mesoderm the
skeletal, muscular, excretory, reproductive
and circulatory systems and dermis of the
skin are derived. The endoderm develops
the respiratory and digestive systems.
35. Fates of the Embryonic Germ
Layers in Vertebrates
GERM LAYERS ORGANS DERVIED FROM THE GERM LAYERS
Ectoderm
Brain and spinal cord; linings of mouth and
anus; lens of eye; inner ear; epidermis of skin;
hair and nails; sweat and oil glands; feather
Mesoderm
epimere
mesomere
hypomere
Dermis of skin; skeletal muscles; skeletal system
gonads and kidneys with their ducts heart,
blood vessels and cells; coelem; smooth muscles
of digestive system.
Endoderm
Inner linings of digestive and repiratory tracts
(including lungs, liver, pancreas, thyroid and urinary
bladder)
36. Methods of Birth Control
METHOD MODE OF
ACTION
ADVANTAGES DISADVANTAGES
“The Pill” Inhibits
ovulation
Highly effective;
regulates
menstrual cycle
Possible risks of
thromboembolism,
hypertension, heart disease
and infertility; minor
discomfort in some women
Condom
Prevents
sperm entry
into egg
mechanically
No side effects;
protection
against sexually
transmitted
diseases
Could break; slightly
decreased sensation for male
Spermicides
(sponges,
foam, jellies,
creams )
Chemically
kill sperms
No side effects;
some vaginal
sponges are
effective for 24
hours in vagina
Some evidence of birth
defects
37. Intra-Uterine
Device (IUD)
Not known; may
stimulate
inflammatory
reaction
Provides
continuous
protection;
very effective
Cramps; increased
menstrual flow; risk of
pelvic inflammatory
disease and infertility;
not recommended for
women who have not
completed child-bearing
Withdrawal
(coitus
interuptus)
Male withdrawal
of penis from
vagina before
ejaculation
No side effects
Not reliable; some fluid
secreted before ejaculation
may contain enough
sperms
Strerilization
Vasectomy
Tribal ligation
Prevents sperms
from leaving
prevent ovum
from leaving
uterine tube
Most reliable
method
Often not reversible
Rhythm Abstinence
during fertile
period
No side effects Not very reliable
38. Some Common Sexually Transmitted
Diseases (STD)
DISEASES/
CAUSATIVE
ORGANISM
COURSE OF DISEASES /SYMPTOMS TREATMENT
Genorrhea
(a gonococcus
bacterium)
Redness and swelling at site of infection
due to bacterial toxins;symptoms in males:
pus discharges from penis;painful
urination;in women later it may cause pelvic
and other infections like damage to heart
meninges and joints; can spread to
epididymis;uterine tube and ovaries,
causing sterility.
Penicillin or
other
antibiotics, no
symptoms in
early stages
Genital
herpes
(herpes
simplex type 2
virus)
Tiny, painful blisters appear on genitals
which may develop into ulcers; recurs
periodically; females may be predisposed to
cervical cancer, threat to fetus or newborn
baby
No effective
cure; some
drugs reduce
severity
39. Syphilis
(spirochete
bacterium)
Bacteria enters body and spread thru
lymphatic and circulatory route;primary
chancre (a small painless ulcer) forms at
site of infection and highly infectious but
heals in about a month;eventually lesions
(gummae) occur consuming parts of body
or damaging liver, bone, spleen
Penicillin
Chlamydia
(a bacterium)
Discharge and burning sensation during
urination; maybe asymptomatic; common
cause of nongonococcal urethritis in males
Doxycylin
(antibiotic)
Genital
candidiasis
('yeast'
infection)
Soreness, discharge and irritation; common in
females; may be asymptomatic in males Drugs
AIDS (HIV-1
virus)
Mild infections resembling mononucleusis; later
lymph glands become swollen; some develop
neuropsychological disorder (dementia
complex); usually leads to comma and death
No known
cure yet
