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Biology 12
Reproduction – The Male Reproductive System
Name: KEY
Date:_____________________
(C14)
Learning Goal: To analyse the functional inter-relationships of the male reproductive system
(Cowper’s glands)
1. Fill in the following chart by identifying the structures and functions:
Structure
Testes
Seminiferous Tubules
Interstitial Cells
Scrotum
Epididymis
Ductus (Vas) Deferens
Seminal Vesicles
Prostate Gland
Cowper’s Glands
(bulbourethral gland)
Description of Structure
Three tightly collided seminiferous
tubules composed of
compartments called lobules in the
testis. Altogether, these tubules
have a combined length of
250meters.
Cells between the seminiferous
tubules.
Surrounds the testicles, divided by
a septum.
Tightly coiled ducts lying outside
the testes.
Sperm enters the vas deferens
from the epididymis. Passes into
the abdominal cavity, where it
curves around the urinary bladder
and empties into an ejaculatory
duct.
Pair of vesicles lies at the base of
the bladder, each has a duct that
joins with the vas deferens.
A single, donut-shaped gland that
surrounds the upper portion of the
urethra just below the urinary
bladder.
Pea-sized organs that lie
underneath the prostate on either
side of the urethra
Function
Packed with cells undergoing spermatogenesis
– the production of sperm.
Secrete the male sex hormones, the androgens,
the most important being testosterone.
Sac like structure that holds the testes
Ducts where sperm mature and are stored
Conduct and also store sperm
Contribute nutrients and fluid to semen
Contributes basic fluid to semen
Produces a clear, salty, viscous secretion known
as pre-ejaculate. This fluid helps to lubricate the
urethra for sperm to pass through, neutralizing
traces of acidic urine in the urethra, and helps
flush out any residual urine or foreign matter.
Penis
Long shaft and an enlarged tip
called the glands penis. At birth,
Organ of sexual intercourse
covered by a layer of skin called
foreskin.
Urethra
Receives sperm from the vas
deferens, in the abdominal cavity.
Conducts sperm
2. Describe the path of sperm from the seminiferous tubules to the urethral opening:
Seminiferous tubules epididymis  vas deferens 
ejaculatory duct  urethra
3. Fill in the following chart by identifying the components seminal fluid (as contributed by the Cowper’s glands,
prostate gland, and seminal vesicles), and describe the functions of each component.
Gland
Cowper’s Gland
Prostate Gland
Seminal Vesicles
Components of Seminal Fluid
Function
a clear secretion into the lumen of the
urethra to lubricate it. Mucus. 5%
Increase mobility of sperm cells in the vagina
a whitish (sometimes clear), thin fluid
containing proteolytic enzymes, citric acid,
acid phosphatase, zinc and lipids. 25%
yellowish viscous fluid rich in fructose,
amino acids, proteins, and other substances
that makes up about 70% of human semen
Helps to stabilize the DNA containing
chromatin in the sperm cells. A zinc deficiency
may result in decrease fertility.
Nutrients for possible use of the sperm
Main energy source of sperm cells.
4. In the following mature sperm, identify the tail (flagellum), midpiece, head, and acrosome of a mature sperm and fill
out the chart below.
Sperm Structure
Acrosome
Description of Structure
Function
Cap that covers the head
Contains enzymes needed to penetrate the
egg.
Head
Midpiece
Contains the nucleus
densely coiled chromatin fibres
filamentous core with many mitochondria
spiralled around it
Mitochondria provide the energy (ATP) for the
movement
Tail (flagellum)
Slashing movements that provide the mobility.
Contains microtubules.
Male Reproduction: Hormones
1. Describe the functions of testosterone:
 Development and function of male reproductive organs (primary role)
 Secondary role is puberty
o Noticeable hair on face and chest
o Prominent Adam’s apple
o Deeper voice
o Taller
o Broader shoulders – greater muscle development
o Longer legs and trunk lengths
o Receding hairline and balding
2. Describe the homeostatic regulation of testosterone levels by the
hypothalamus, anterior pituitary, and testes by filling out the blanks below:
Testosterone and sperm production is maintained at a steady level by negative
feedback.
For example, if testosterone levels are too LOW:
- The hypothalamus secretes gonadotropin releasing hormone GnRH.
- The anterior pituitary secretes luteinizing hormone LH and follicle
stimulating hormone FSH
- Because increased LH, the interstitial cells in the testes secrete more
testosterone.
- Because of increased FSH and testosterone, the seminiferous tubules
in the testes produce more sperm.
If testosterone levels are too HIGH:
- The hypothalamus secretes less GnRH.
- The anterior pituitary secretes less LH and less FSH
- Because of decreased LH, the interstitial cells in the testes secrete less
testosterone.
- Because of decreased FSH and testosterone, the seminiferous tubules
in the testes produce less sperm.
Seminiferous Tubules
Interstitial Cells