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HS 130 Anatomy & Physiology II
Unit 9 Seminar
Chapters 20 & 21
Reproduction,
Growth and Development
Male Reproductive System
• Structural plan
 Reproductive organs are classified as
essential or accessory
 Essential organs of reproduction are the
gonads (testes in males), which produce
sex cells called sperm
Testes
• Testes: the gonads of men
 Structure and location
 Testes in scrotum—lower temperature
 Covered by tunica albuginea, which
divides testis into lobules containing
seminiferous tubules
 Interstitial cells produce testosterone
What is the
importance of the
lower temperature
of the scrotum?
Tubules of the Testis and Epididymis
the testicle is the darker sphere in the center
Spermatozoa
Spermatogenesis
What are the steps in the
process of
spermatogenesis?
Female Reproductive System
How does the location of the female gonads differ from
the location of the male gonads?
Ovaries
• Microscopic structure
 Ovarian follicles—contain oocyte, an
immature sex cell (about 1 million at
birth)
 Primary follicles—are covered with
granulosa cells (about 400,000 at puberty)
 Secondary follicles have a hollow chamber
called the antrum
 Corpus luteum forms after ovulation from
ruptured follicle
Ovaries
What is the role of the corpus luteum if fertilization
occurs?
Ovaries
Menstrual Cycle
Menstrual Cycle
Summary of Male and Female
Reproductive Systems
• Male organs
Designed to produce, store, and
introduce mature sperm into the
female reproductive tract
• Female organs
Designed to produce ova, receive the
sperm, permit fertilization, facilitate
fetal development and birth, and
perform lactation
Prenatal Period
• Prenatal period begins at conception and
continues until birth
• Science of fetal growth and development is
called embryology
Approximately how long does pregnancy last?
Why is prenatal care so important?
Fertilization and Implantation
•Fertilization is a specific
biological event
•occurs when the male
and female sex cells fuse
•after union between a
sperm cell and the ovum
has occurred, the cycle of
life begins.
•scanning electron
micrograph shows
spermatozoa attaching
themselves to the surface
of an ovum
•only one will penetrate
and fertilize the ovum.
• After three days of cell division, the zygote
has developed into a solid cell mass called a
morula
• Continued cell division of the morula produces
a hollow ball of cells called a blastocyst
• The blastocyst implants in the uterine wall
about 10 days after fertilization
• The blastocyst forms the amniotic cavity and
chorion of the placenta
Implantation and Early Development
How does the embryo receive nutrients before the
placenta is functional?
Primary Germ Layers
The Placenta
What are the functions of the placenta?
Birth Defects
• Any structural or functional abnormality
present at birth
 May be caused by genetic factors
 Abnormal genes
 Abnormal number of chromosomes
 May be caused by environmental factors
 Environmental factors are called
teratogens
 Especially harmful during the first
trimester
Postnatal Period
• Postnatal period begins at birth and lasts until
death
• Divisions of postnatal period into isolated time
frames can be misleading
• Life, growth, and development are continuous
• Obvious changes in the physical appearance
occur between birth and maturity
Infancy
• First four weeks is called neonatal period
• Cardiovascular and respiratory changes
occur at birth
 Fetus is totally dependent on mother
 Newborn must immediately become
totally self-supporting
Childhood
• Extends from end of
infancy to puberty
• Overall rate of growth
remains rapid but
decelerates
• Continuing
development of motor
and coordination skills
• Loss of deciduous or
baby teeth and
eruption of permanent
teeth
Adolescence
• Average age range of adolescence varies from
13 to 19 years
• Period of rapid growth results in sexual
maturity (adolescence)
• Appearance of secondary sex characteristics
regulated by secretion of sex hormones
• Growth spurt typical of adolescence; begins in
girls at age 10 and in boys at age 12
Adulthood
• Bones’ growth plates are fully closed in
adult
• Other structures such as the sinuses
acquire adult placement
• Adulthood characterized by maintenance
of existing body tissues
• Older adulthood
 Every organ system of the body
undergoes degenerative changes
Effects of Aging
• Skeletal system
 Aging causes changes in the texture,
calcification, and shape of bones
 Bone spurs develop around joints
 Bones become porous and fracture easily
Effects of Aging
• Integumentary system (skin)
 With age, skin sags and becomes
 Thin
 Dry
 Wrinkled
Effects of Aging
• Urinary system
 Nephron units decrease in number by
50% between ages 30 and 75
 Blood flow to kidney and ability to form
urine decrease
Effects of Aging
• Respiratory system
 Calcification of costal cartilages makes
it difficult for rib cage to expand and
contract normally
 Wasting of respiratory muscles
decreases respiratory efficiency
 Respiratory membrane thickens;
movement of oxygen from alveoli to
blood is slowed
Effects of Aging
• Cardiovascular system
 Degenerative heart and blood vessel
disease is among the most common and
serious effects of aging
 Hardening of arteries (arteriosclerosis)
may result in rupture of blood vessels
 Hypertension or high blood pressure is
common in older adulthood
Effects of Aging
• Special senses
 Eye lenses become hard and cannot
accommodate for near vision
 Decreased transmission of sound waves
caused by loss of elasticity of eardrum
and fixing of the bony ear ossicles is
common
 Some degree of hearing impairment is
universally present in the aged
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