Science 9
Ch.4 Human Reproduction
Name:_____________________
1
Male Reproductive System:
The male reproductive system performs two major functions:
1. the production of sperm cells
2. the deposition of these cells within the female reproductive tract
Sperm production occurs in the testes. They are located in the scrotum where the
temperature is 1-2 degrees Celsius cooler than normal body temperature.
This provides an optimum temperature for sperm production and storage.
From testes, sperm move through several tubes including the urethra. The urethra is
a tube contained within the penis. The penis is a structural adaptation for internal
fertilization
Glands secrete a liquid into these tubes. The liquid serves as a transport medium for
the sperm (an adaptation for life on land). This liquid and the sperm constitute
semen.
In addition to producing sperm, the testes also produce the male sex hormone,
testosterone. This regulates the maturation of sperm and the development of
secondary sex characteristics such as beard development and voice pitch.
Male Reproductive Diagram:
Science 9
Ch.4 Human Reproduction
Name:_____________________
Female Reproductive System:
Ovaries are paired structures located within the lower portion of the body cavity.
Ovaries produce eggs in tiny cavities called follicles. Following ovulation, the egg
cell is transported through the oviduct (Fallopian Tube) to the uterus. At the lower
end of the uterus known as the cervix is a muscular tube, the vagina
At birth, all of the potential eggs that a female will ovulate are present in immature
form. Usually only one egg is released at the time of each ovulation.
In addition to eggs, the ovaries also produce the female sex hormones estrogen and
progesterone. These regulate the development of secondary sex characteristics such
as the development of the mammary glands and the broadening of the pelvis. The
hormones also have a coordinating role in the menstrual cycle.
Female Reproductive Diagram:
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Science 9
Ch.4 Human Reproduction
Name:_____________________
3
Menstrual Cycle:
The menstrual cycle begins at puberty and ceases at menopause. Menopause is the
permanent cessation of the menstrual cycle. The duration of this cycle is
approximately 28 days but may vary considerably and may be interrupted by
pregnancy, illness, and other factors.
The menstrual cycle consists of four stages:
1. Follicle Stage
This stage involves the maturation of an egg within the follicle and the
secretion of the hormone estrogen. Estrogen initiates visualization of the
uterine lining
2. Ovulation
Ovulation is the release of an egg from the follicle.
3. Corpus Luteum
The corpus Luteum forms from the follicle following ovulation. It
secretes progesterone which enhances the vascularization of the uterine
lining.
4. Menstruation
Menstruation is the periodic shedding of the thickened uterine lining. It
occurs when fertilization does not take place.
Example: Hormones in Human Female:
Science 9
Ch.4 Human Reproduction
Name:_____________________
4
Hormones:
The reproductive cycle of the human female involves the interaction of the hormones
from the hypothalamus, pituitary gland, and ovaries.
During the menstrual cycle, under the influence of the hypothalamus, the pituitary
gland releases the hormones (FSH and LH) which influence the functioning of the
ovaries. The ovaries, in turn, secrete hormones (estrogen and progesterone) which
produce changes in the uterus.
In addition, the hormones from the ovaries regulate the secretion of hormones by
pituitary gland and the hypothalamus. This is an example of a negative feedback
mechanism
Ovulation and Fertilization:
Science 9
Ch.4 Human Reproduction
Name:_____________________
5
Fertilization
 Fertilization usually occurs in the upper portion of the oviduct (Fallopian
Tube).
 If the egg is not fertilized within approximately 24 hours after ovulation,
it deteriorates.
 Cleavage of the fertilized egg begins in the oviduct, and six to 10 days
later; the resulting embryo may become implanted in the uterine lining.
 If more than one egg is released and fertilized, multiple births may result.
 Embryo: The organism in the early stages of growth and differentiation
from fertilization to, in humans, the beginning of the third month of
pregnancy. After that point in time, it is termed a fetus.
 Fetus: The unborn offspring from the end of the 8th week after
conception (when the major structures have formed) until birth. Up until
the eighth week, the developing offspring is called an embryo.
Science 9
Ch.4 Human Reproduction
Name:_____________________
Identical twins develop from one zygote which separates during cleavage.
Fraternal twins develop from two eggs, each fertilized by separate sperm cells.
In Vitro Fertilization
The technique of in vitro fertilization and subsequent implantation that has been
perfected in animals and has now been applied to humans.
Diagram of In Vitro Process
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Science 9
Ch.4 Human Reproduction
Name:_____________________
Fetal Development:
A. Prenatal Development
1. Prenatal development includes the following processes:
a. Cleavage occurs in the oviduct
b. Gastrulation usually after the embryo
is implanted in the uterus
c. Differentiation and growth result in the
formation of specialized tissues &
organs from the embryonic layers of
the gastrula
2. The processes
involved in prenatal
development are
dependent upon the
supplying of a proper
balance of nutrients to
the developing
embryo.
3. Some structures
associated with
prenatal development are: the placenta, amnion, & umbilical cord.
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Science 9
Ch.4 Human Reproduction
Name:_____________________
8
B. Birth
Birth usually occurs after a gestation period of approximately nine months
C. Postnatal Development
1. Development continues with various parts of the body growing at
different rates.
2. Although the development of the organism is often assumed to conclude
with the mature adult, it actually continues throughout the life of the
organism and terminates with death.
3. The term aging is applied to the complex developmental changes that
occur naturally with the passage of time.
4. Various parts of the body develop at different rates until the adult stage is
reached, at which time growth ceases.
5. Teratogens: Any agent that can disturb the development of an embryo or
fetus. Teratogens may cause a birth defect in the child. Or a teratogen
may halt the pregnancy outright. The classes of teratogens include
radiation, maternal infections, chemicals, and drugs.
D. Puberty:
The reproductive tissues develop slowly. This development is controlled by
hormones. The time at which the individual is capable of reproduction is called
puberty. Puberty usually occurs between the ages of 9-14 in females, and
between 12-18 in males.
E. Aging:
After maturity is reached, the structures and functions of the body systems slowly
weaken. This process is called aging, and it is a normal part of the continuing
development of the individual. The causes of aging are not understood. The rate
of aging varies among individuals and appears to be the result of an interaction of
both hereditary and environmental factors.
F. Death:
The aging processes eventually end in death of the organism. No precise
definition of the moment of death has been agreed upon. One definition is the
irreversible cessation of all brain functions.