Human Anatomy and Physiology Reproduction in males
Reproduction Dormant until puberty Manufacture and delivery of sperm Hormones : testosterone, gonadotropic hormones, androgens
Male overview Accessory glands Seminal vesicles, prostate gland, bulbourethral gland
Sperm production Formed in seminiferous tubules (non-motile) Travel along epididymis (6 meters - 4 days travel) Stored (up to 1 month) in epididymis (motile) Sertoli cells and epididymis secrete hormones and nutrients
Accessory glands Semen = sperm plus secretions 1. Seminal vesicles 60% semen volume Yellow fluid (pH 3 - 7) Fructose and citric acid (nutrients) Prostaglandins (decreasing cervical mucus, reverse peristalsis of uterus and fallopian tubes)
Accessory glands 2. Prostate gland 3. Bulbourethral gland 30% semen volume Alkaline fluid (neutralizes citric acid and female vaginal acidity) 3. Bulbourethral gland Alkaline solution (neutralizes acid urine in male urethra)
Mature sperm
Spermatogenesis regulation GnRH released LH and FSH release FSH works on Sertoli cells (sustentacular) causing ABP release LH causes release of testosterone Spermatogenesis is enhanced Inhibin released by Sertoli cells inhibits release of GnRH
Hormonal effects 1. Increase in growth of genitalia 2. Facial hair, axillary hair (chest, pubis, back) 3. Baldness 4. Voice: enlargement of the larynx 5. Skin: increase in thickness, oil glands 6. Muscle: increase in growth 7. Bone: increase in thickness
Sperm delivery Erection - parasympathetic reflex from sacral region of spinal cord Relaxes smooth muscle Arteries dilate, simultaneous constriction of veins Blood rushes into erectile tissue Inhibitors: alcohol inhibits higher brain function
Sperm delivery Ejaculation: sympathetic control. Nerve discharge from nerves on L1 and L2 Result contraction of reproductive ducts and accessory glands bladder sphincter muscle contract smooth muscles surrounding penis contraction