IB BIOLOGY HL
FURTHER HUMAN PHYSIOLOGY
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Non functional until puberty
◦ Reproduction not biologically important for the
individual!
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Major structural differences between males
and females
◦ Male Reproductive System
◦ Female Reproductive System
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GONADS
Function to produce GAMETES necessary for
sexual reproduction of offspring!
TESTES (Male Gonad)
OVARIES (Female Gonad)
Function to secrete SEX HORMONES required for
reproductive system organ maintenance and
development!
Testosterone / Androgens  Male
Estrogens / Progesterone  Female
 GAMETES:
Sex Cells that combine to form
offspring (FERTILIZATION)
Male Gamete:
Spermatocytes/Sperm
Female Gamete:
Oocytes/Ova
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Allow for fertilization and nuturing/support
of embryo/fetus.
Includes:
◦ Ducts (urethra ; fallopian tubes)
◦ Glands (prostate ; mammary)
◦ External genitalia (penis ; vagina)
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The production of gametes by the gonads!
◦ Spermatogenesis (males)
◦ Oogenesis (females)
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Timing of gamete production:
◦ Males: Begins at puberty…continues for life!
◦ Females: Begins / ends prior to birth!
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The process by which gametogenesis occurs!
Diploid (2n) cells in the gonads produce
haploid (n) gametes!
Meiosis I
Meiosis II
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II
http://www.johnkyrk.com/meiosis.html
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Testes
Scrotum
Seminiferous Tubules
Epididymis
Vas deferens
Accessory Glands
Penis
Urethra
Brain !
the concentration of the
hormone Testosterone
must be high enough
to stimulate sperm
production !
ONSET OF
PUBERTY
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Multiple Target Cells for Testosterone!
SECONDARY SEX CHARACTERISTICS – Voice
Deepens, Beard Grows, Body Hair,
increased muscle mass
FSH and Testosterone stimulate the
development of Sperm.
When large numbers of sperm have been
produced in the Testes, Puberty is
completed - THE REPRODUCTIVE SYSTEM IS
NOW FUNCTIONAL !
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Oval shaped paired gonads
Develop in abdominal cavity of male
Just prior to birth, descend into scrotum
Must remain in scrotum for LIFE…
Temp in scrotum ~3 degrees cooler than
internal body temp:
Sperm production REQUIRES lower temp!
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External sac housing testes
Testicular descent ~ 7month in utero
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Cryptorchidism
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Response to temperature changes
◦ Dartos muscle:
 Smooth muscle
 Wrinkles skin covering scrotum
◦ Cremaster muscle:
 Skeletal muscle
 elevates testes
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Hundreds of small tubes within each testis
Site of Meiosis! (ie: spermatogenesis occurs
here)
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Contain two cell types:
◦ Spermatogenic cells
 Target cells for testosterone
 Site of spermatogenesis (meiosis)
◦ Interstitial Cells
 Secrete testosterone
Interstitial cells
Spermatogenic cells
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Site of sperm
maturation and
storage
~20 day process
to gain motility
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HEAD – containing:
Nucleus (w/ 23 Chromosomes)
Acrosome: “Cap” containing enzymes for
penetration of protective layers
surrounding
the ovum
MIDPIECE – containing:
Mitochondria: supply Energy required to
reach the ovum
TAIL – consists of:
Flagellum: propels sperm toward the
ovum
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Extends from epididymis into abdominal
cavity
Carries sperm, upon sexual arousal, to the
urethra
Runs through center of prostate gland
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Exocrine Glands
Produce secretions that combine with sperm.
Sperm + glandular secretions =
SEMEN
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Location: Inferior to urinary bladder
Secretion:
◦ Nutrients
◦ Enzymes
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Prostate Secretion activates sperm!
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Location: posterior wall of urinary bladder
Secretion: Alkaline fluid high in…
◦ Sugar
◦ Vitamin C
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Fluid flows to urethra via ejaculatory duct
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Location: inferior to Prostate Gland
Secretion:
◦ Mucus
◦ Functions to neutralize acidity of urine in urethra
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Functions to deliver sperm to female
reproductive system
Internally composed of 3 cylinders of
Erectile Tissue:
◦ Corpus Cavernosum (2)*
◦ Corpus Spongiosum (1)*
*Engorge with blood during sexual stimulation,
producing an ERECTION
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Transports sperm from abdomen (via vas
deferens) to external environment (via penis)
1.
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6.
Brain perceives sexual stimulus
NO (nitrous oxide) released in smooth
muscle lining arterioles of erectile tissue
Arterial muscles relax, arterioles dilate
Arterioles fill with blood
Engorged arterioles compress venules
Blood is trapped in erectile tissue
arterioles. Erection achieved.
7. Prolonged sexual stimulus results in spinal
reflex impulse…
8. Causes contraction of:
*vas deferens
*bulbourethral gland
*prostate gland
* seminal vesicles
9. Semen empties into urethra
10. Urethral sphincter muscles contract
11. Semen forcefully ejected from urethra
Ejaculation