Download The Reproductive System

The Reproductive System
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
The Reproductive System
 Gonads—primary sex organs
 Testes in males
 Ovaries in females
 Gonads produce gametes (sex cells) and
secrete hormones
 Sperm—male gametes
(Spermatogenesis)
 Ova (eggs)—female gametes
(Oogenesis)
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Functions
1. Produces, nurtures and transports
gametes (ova/sperm)
2. Secrets hormones
3. Provide a means for fertilization
4. Provides an environment for maturation
of a zygote (female reproductive system
only)
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Divisions of the Male Reproductive System
A. Testes
B. Duct System
C. Accessory Glands
D. External Genitalia
We will discuss each of these in more detail
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
A. Testes
Each teste is
surrounded by a
membrane. This
membrane extends
into each testis
forming partitions
that divide the
testis into
approximately 250
compartments, or
lobules.
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Seminiferous tubules
 1-4 found in each lobule
 tightly coiled
 sperm-forming factories
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Rete testis
*May or may not be
considered an actual
part of the duct system
depending on the
reference being used
 Network of ducts
(channels)
 Take immature sperm
cells from seminiferous
tubules to epididymus
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2 Types of Cells within the testis
1. Interstitial cells: produce androgens
(male hormones) such as testosterone
2. Spermatogenic: sperm-producing
cells
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
B. Duct System
1. Epididymis
2. Ductus (vas) deferens
3. Ejaculatory Duct
4. Urethra
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
1. Epididymis
 Comma-shaped,
tightly coiled tube (20
ft)
 Found on the superior
part of the testis along
the posterior lateral
side
 Functions to mature
and store sperm cells
(at least 20 days)
 Muscles in the
epididymis walls move
sperm to the vas
deferens
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2. Ductus Deferens (Vas Deferens)
 Carries sperm from
the epididymis to
the ejaculatory
duct
 Passes over the
bladder
 Moves sperm by
peristalsis
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Vasectomy
cutting of the
ductus deferens
at the level of the
testes to prevent
transportation of
sperm
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
3. Ejaculatory Duct
 Unites the ductus
deferen with the
urethra
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Urinary Bladder
4. Urethra
 Extends from the base of the urinary
bladder to the tip of the penis
 Carries both urine and sperm
 Sperm enters from the ejaculatory
duct
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 16.2b
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C. Accessory Organs
1. Seminal vesicles
2. Prostate
3. Bulbourethral glands (Cowper)
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1. Seminal Vesicles
 Located at the base of the bladder
 Produces a thick, yellowish secretion (60% of
semen)
 Fructose (sugar)
 Vitamin C
 Prostaglandins (hormones)
 Other substances that nourish and activate
sperm
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2. Prostate
 Encircles the upper part of the
urethra
 Secretes a milky fluid
 Helps to activate sperm
 Enters the urethra through several
small ducts
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
3. Bulbourethral Glands
 Pea-sized gland inferior to the
prostate
 Produces a thick, clear mucus
 Cleanses the urethra of acidic
urine
 Serves as a lubricant during
sexual intercourse
 Secreted into the penile urethra
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 16.2a
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Semen
 Mixture of sperm and accessory gland secretions
 Advantages of accessory gland secretions
 Fructose provides energy for sperm cells
 Alkalinity of semen helps neutralize the acidic
environment of vagina
 Semen inhibits bacterial growth
 Elements of semen enhance sperm motility
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
D. External Genitalia
1. Scrotum
2. Penis
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1. Scrotum
 Divided sac of skin outside the abdomen
 Maintains testes at 3°C lower than normal
body temperature to protect sperm viability
 Muscles move testes up toward body or
lower away from body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
2. Penis
 Delivers sperm into the female reproductive tract
 Regions of the penis
 Shaft
 Glans penis (enlarged tip)
 Prepuce (foreskin)
 Folded cuff of skin around proximal
end
 Often removed by circumcision
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Figure 16.2a
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 Internally there are three areas of spongy erectile
tissue around the urethra
 Erections occur when this erectile tissue fills with
blood during sexual excitement
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings