1. Misericordia Univeristy
Reproduction: Male
General Physiology
Dr. Tony Serino
Misericordia Univeristy
Biology Dept.

2. Reproduction Function: Survival of species
Production of sex cells (gametes)
Transport the gametes toward each other
Allow gametes to meet (fertilization)
Promote the generation, maintenance and rearing of progeny

3. Gonads: undergo Meiosis to produce gametes
Meiosis (divided into Meiosis I and II)
Meiosis I
Assorts chromosomes by homologous pairs
Then separates the pairs randomly
Reduces the number of chromosomes by half; Diploid to Haploid (2n  n)
Meiosis II
Separates sister chromatids
Progeny cells now have one DNA per chromosome

6. Male Reproduction Gonads: Testis Gamete: Spermatozoa (sperm)
Duct system: to store and transport sperm from gonad to external environment
Supporting structures:
Allow sperm maturation
Allow survival of sperm in ext. environment
Deposit sperm into female vagina
Sensory functions

7. Male Reproductive Anatomy

8. Human Sperm

9. Spermatogenesis in the Testis

10. Seminiferous Tubule
Sertoli Cell
(Leydig Cells)

12. Accessory Sex Glands
Add seminal fluid to sperm to form semen; seminal fluid accounts for 90-95% of semen volume
Seminal fluid will include water, alkaline buffers, mucous, fructose, prostaglandins and enzymes (clotting and de-clotting, anti-bacterial)
Three glands:
Seminal Vesicle ~60% of semen volume
Prostate Gland ~30% of semen volume
Bulbourethral (Cowper’s) Gland <5%

13. Accessory glands (medial view)

14. Male Urethra

15. Scrotum and Spermatic Cord

16. Scrotum and Spermatic cord
Provide physical support to testes
Regulate testicular temperature
Cremaster muscle position can change tesits temp.
Pampiniform plexus acts as heat counter current exchanger with testicular artery

17. Penis: Erectile Tissue
Root of Penis (Bulb)
(Crura)
Corpus Spongiosum

18. Male Hormones
ABP

20. Male Sexual Response Arousal –Sexual excitement Plateau Orgasm
Triggered by:
Touching of genital skin
Mechanical stimulation of pressure receptors in penis
Erotic sights, sounds, and smells
Thoughts and memories
Increased myotonia (muscle tension) throughout body, BP, breathing and HR
Sexual stimulation leads to erection of penis
Plateau
Increased accumulation of blood in erectile tissues
Bulbourethral gland secretes small amount of mucoid fluid to neutralize male urethra and lubricate glans
The testes are drawn upward by increased contractions vas deferens and cremaster muscles
Orgasm
Ejaculation –rhythmic contractions propel semen out of the penis

21. Sexual Excitation: Erection
Enlargement and stiffening of the penis
Parasympathetic (through the local release of NO) vasodilation of arterioles leading to the erectile tissue of penis
As corpora cavernosa enlarge they reduce blood flow through the penile veins; this increases engorgement
Erection reflex controlled by both the brain and the sacral spinal cord

22. Erection

23. Male Orgasm
Begins when stimulation reaches a critical point (accompanied by feelings of inevitability)
2 part spinal reflex:
Emission –movement of semen into the urethra
Vas deferens, ejaculatory duct, prostate and seminal vesicle contract and push their fluids into the urethra through sympathetic stimulation
The external sphincter of the urethra remains closed as pressure builds
The bladder sphincter muscle constricts preventing urine and semen from mixing (sympathetic control)
Ejaculation –expulsion of semen from the urethra
The external sphincter relaxes as a second spinal reflex triggers rapid rhythmic contractions of the bulbospongiosus and ischiocavernosus muscles and urogenital diaphragm; propels semen out (200in/sec)
Contractions of muscles throughout body
Accompanied with intense pleasure, increased HR, BP, respirations
Followed by a quick relaxation and refractory period