Transcript Ch16 Male Repro

Notice: This presentation contains actual pictures of human reproductive anatomy
Chapter 16
The Reproductive System
Intro & Male
The Reproductive System
1. Gonads – primary sex
organs
 Testes in males
 Ovaries in females
2. Gonads produce gametes
(sex cells) and secrete
hormones
 Sperm – male
 Ova (eggs) – female
Male Reproductive System
 Testes
 Accessory organs
 Duct system
 External genitalia
- Seminal vesicle
- Penis
- Epididymis
- Prostate gland
- Scrotum
- Ductus deferens
- Bulbourethral gland
- Urethra
Testes
 Tunica albuginea –
capsule that
surrounds each
testis
 Septa –
extensions into
testis; dividing it
into lobules
Testes
Each lobule contains 1-4
seminiferous tubules
 Tightly coiled
 Sperm-forming factories
 Empty sperm into the rete
testis
Sperm travels through the
rete testis to epididymis
Interstitial cells produce
androgens such as
testosterone
Epididymis
 Comma-shaped, tightly
coiled tube
 Superior and along
posterior lateral side
 Matures and stores
sperm cells (at least 20
days)
 Expels sperm with the
contraction of muscles in
the epididymis walls to
the vas deferens
Ductus Deferens
 Carries sperm
from epididymis to
ejaculatory duct
 Passes through
inguinal canal &
over bladder
 Moves by
peristalsis
 Ends in the ejaculatory duct
which unites with urethra
 Spermatic cord –
ductus deferens,  Vasectomy – cutting of the
ductus deferens at the level
blood vessels,
and nerves in a
of the testes to prevent
connective tissue
transportation of sperm
Urethra
 Extends from the base of
bladder to the tip of penis
 Carries both urine and sperm
 Sperm enters from the
ejaculatory duct
Regions:
Prostatic urethra –surrounded
by prostate
Membranous urethra – from
prostatic urethra to penis
Spongy (penile) urethra – runs
the length of the penis
Seminal Vesicles
 Located at the base of the bladder
 Produces a thick, yellowish secretion
(60% of semen)
- Fructose (sugar)
- Vitamin C
- Prostaglandins
- Substances that nourish & activate sperm
Prostate Gland
 Encircles upper part of
urethra
 Secretes a milky fluid
- Helps activate sperm
- Enters urethra through
several small ducts
Bulbourethral Glands
 Pea-sized gland inferior
to prostate
 Produces a thick, clear
mucus
- Cleanses urethra of
acidic urine
- Lubricant during
intercourse
- Secreted into penile
urethra
Semen
 Mixture of sperm & gland
secretions
 Advantages of secretions
- Fructose provides energy
- Alkalinity neutralizes
acidic vagina
- Semen inhibits bacterial
growth
- Elements of semen
enhance sperm motility
External Genitalia
 Scrotum
- Divided sac of skin
outside abdomen
- 3°C lower than body
temp to protect
sperm
External Genitalia
 Penis- Delivers sperm
into female repro tract
- Shaft
- Glans penis
(enlarged tip)
- Prepuce (foreskin)
 Folded cuff of
skin around
proximal end
 Often removed
by circumcision
External Genitalia
 3 areas of spongy
erectile tissue
around the urethra
Spermatogenesis
 Production of
sperm cells
 Begins at puberty
and continues
throughout life
 Occurs in the
seminiferous
tubules
Processes of Spermatogenesis
 Follicle stimulating hormone
(FSH) regulates
 Spermatogonia (stem cells) rapid mitosis to produce more
stem cells before puberty
First division of a stem cell becomes
1 stem cell & 1 primary spermatocyte
 Primary spermatocytes
undergo meiosis
 Haploid spermatids
Anatomy of a Mature Sperm Cell
 Late spermatids - distinct regions
- Head –DNA covered by
acrosome
- Midpiece
- Tail
 Sperm cells = mature spermatids
 Spermatogenesis takes 64 to 72
days
 Only human flagellated cell
Testosterone Production
- Most important hormone of testes
- Produced in interstitial cells
- Functions
 Organ development
 Sex drive
 Secondary sex characteristics
- Deepening of voice
- Increased hair growth
- Larger skeletal muscles
- Thicker bones
Regulation
of Male
Androgens
(Sex
Hormones)