chapter 16 the reproductive system intro & male notice: this presentation contains actual...
TRANSCRIPT
Chapter 16The Reproductive System
Intro & Male
Notice: This presentation contains actual pictures of human reproductive anatomy
The Reproductive SystemThe Reproductive System1. 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 SystemMale Reproductive System Testes
Duct system
- Epididymis
- Ductus deferens
- Urethra
Accessory organs
- Seminal vesicle
- Prostate gland
- Bulbourethral gland
External genitalia
- Penis
- Scrotum
TestesTestes
Tunica albuginea – capsule that surrounds each testis
Septa – extensions into testis; dividing it into lobules
TestesTestesEach 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
EpididymisEpididymis
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 DeferensDuctus Deferens Carries sperm
from epididymis to ejaculatory duct
Passes through inguinal canal & over bladder
Moves by peristalsis
Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue
Ends in the ejaculatory duct which unites with urethra
Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm
UrethraUrethra 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 VesiclesSeminal 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 GlandProstate Gland
Encircles upper part of urethra
Secretes a milky fluid
- Helps activate sperm
- Enters urethra through several small ducts
Bulbourethral GlandsBulbourethral Glands Pea-sized gland inferior
to prostate
Produces a thick, clear mucus
- Cleanses urethra of acidic urine
- Lubricant during intercourse
- Secreted into penile urethra
SemenSemen
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 GenitaliaExternal Genitalia
Scrotum
- Divided sac of skin outside abdomen
- 3°C lower than body temp to protect sperm
External GenitaliaExternal 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 GenitaliaExternal Genitalia
3 areas of spongy erectile tissue around the urethra
SpermatogenesisSpermatogenesis
Production of sperm cells
Begins at puberty and continues throughout life
Occurs in the seminiferous tubules
Processes of SpermatogenesisProcesses 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 CellAnatomy of a Mature Sperm Cell
Only human flagellated cell
Late spermatids - distinct regions
- Head –DNA covered by acrosome
- Midpiece
- Tail
Sperm cells = mature spermatids
Spermatogenesis takes 64 to 72 days
Testosterone ProductionTestosterone 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 Regulation of Male of Male Androgens Androgens (Sex (Sex Hormones)Hormones)