BIOLOGY PRELIMINARY NOTES
KIARA DURKIN
HUMAN REPRODUCTION
Fertilisation: fusion of sperm nucleus with an egg nucleus to form a diploid zygote
Male Reproductive System
Composition
• Primary sex organ: testis
• Ducts: epididymis; sperm duct (vas deferens); urethra
• Accessory glands (e.g. prostate gland)
• External genitalia: penis
Scrotum
• Functions:
- Temperature regulator (testis 2-3˚C cooler than body temperature);
cold = testis pulled closer to abdomen; warm = suspended away from body
- Contains testis
Testis
• Embryonic stage = testis in abdominal cavity; before birth = descend into scrotum
• Consist of lobules of seminiferous tubules (highly convoluted)
• Germinal epithelium line tubules
• Between tubules = endocrine interstitial cells, cells of Leydig
• Functions:
- Produce sperm (by germinal layer) + testosterone (by interstitial cells)
Ducts
• Epididymis (seminiferous tubules combined to form a highly convoluted tubule) functions:
- Immature sperm mature to become motile + fertile
- Sperm is stored (if they stay longer than several months they are broken down by
epithelial cells of epididymis and are reabsorbed)
• Sperm duct/ vas deferens (muscular continuation of epididymis) functions:
- Pushes mature sperm forward by peristaltic waves (strong contractions of smooth inner
walls of ducts) from epididymis to urethra = ejaculation
• Urethra (duct at end of uro-genital system leading to exterior) function:
- Transportation of semen and urine
Prostate gland
Gland that surrounds urethra at base of bladder
Can be removed surgically – old age may enlarge gland, exerts pressure on urethra = takes longer
to empty bladder
• Function:
- Secretes fluid that aids transport of sperm; contains enzymes that increase sperm
activity
Cowper’s gland
Found at base of penis
KIARA DURKIN
HUMAN REPRODUCTION
Fertilisation: fusion of sperm nucleus with an egg nucleus to form a diploid zygote
Male Reproductive System
Composition
• Primary sex organ: testis
• Ducts: epididymis; sperm duct (vas deferens); urethra
• Accessory glands (e.g. prostate gland)
• External genitalia: penis
Scrotum
• Functions:
- Temperature regulator (testis 2-3˚C cooler than body temperature);
cold = testis pulled closer to abdomen; warm = suspended away from body
- Contains testis
Testis
• Embryonic stage = testis in abdominal cavity; before birth = descend into scrotum
• Consist of lobules of seminiferous tubules (highly convoluted)
• Germinal epithelium line tubules
• Between tubules = endocrine interstitial cells, cells of Leydig
• Functions:
- Produce sperm (by germinal layer) + testosterone (by interstitial cells)
Ducts
• Epididymis (seminiferous tubules combined to form a highly convoluted tubule) functions:
- Immature sperm mature to become motile + fertile
- Sperm is stored (if they stay longer than several months they are broken down by
epithelial cells of epididymis and are reabsorbed)
• Sperm duct/ vas deferens (muscular continuation of epididymis) functions:
- Pushes mature sperm forward by peristaltic waves (strong contractions of smooth inner
walls of ducts) from epididymis to urethra = ejaculation
• Urethra (duct at end of uro-genital system leading to exterior) function:
- Transportation of semen and urine
Prostate gland
Gland that surrounds urethra at base of bladder
Can be removed surgically – old age may enlarge gland, exerts pressure on urethra = takes longer
to empty bladder
• Function:
- Secretes fluid that aids transport of sperm; contains enzymes that increase sperm
activity
Cowper’s gland
Found at base of penis
