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

testes epididymis ductus deferens

urethratip of penis

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

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 effects1. 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