Human Anatomy and Physiology

1
Human Anatomy and Physiology

• Reproduction in males

2
Reproduction

• Dormant until puberty
• Manufacture and delivery of sperm
• Hormones testosterone, gonadotropic hormones,
  androgens

3
Male overview

• Accessory glands
• Seminal vesicles, prostate gland, bulbourethral
  gland

4
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

5
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)

6
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)

7
Mature sperm
8
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

9
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

10
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

11
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